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539 Cards in this Set
- Front
- Back
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What are the "major" Aerobic, Gram-Positive cocci?
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Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, enterococcus
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What are the "minor" Aerobic, Gram-Positive cocci?
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Staphylococcus epidermidis, Streptococcus agalctiae
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What is GAS?
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Streptococcus pyogenes
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What is GBS?
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Streptococcus agalactiae
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Categorize Staphylococcus aureus
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Aerobic, Gram-Positive Cocci; catalase positive, coagulase positive
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Categorize Enterococcus
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Aerobic, Gram-Positive Cocci
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What are the "major" Aerobic, Gram-Positive bacilli?
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none
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What are the "minor" Aerobic, Gram-Positive bacilli?
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Liseria monocytogenes, Bacillus cereus, Bacillus anthracis
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Categorize Anthrax (Bacillus anthracis)
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Aerobic, Gram-Positive bacilli
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What are the "major" Aerobic, Gram-Negative Cocci?
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Neisseria miningitidis, Neisseria gonorrhoeae
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What are the "minor" Aerobic, Gram-Negative Cocci?
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none
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What are the two major categories of Aerobic, Gram-Negative Bacilli?
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Enterobacteriacea and non-enterobacteriaceae
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What are the major Enterobacteriaceae (aerobic, gram-negative bacilli)
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Escherichia coli, Salmonella enteritidis, Shigella species
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What are the minor Enterobacteriaceae (aerobic, gram-negative bacilli)
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Salmonella typhi, Yersinia enterocolitica, Yersinia pestis
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What are the major Non-enterobacteriaceae aerobic, gram-negative bacilli
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Campylobacter jejuni, Helicobacter pylori, Pseudomonas aeruginosa, Haemophilus influenzae, Legionella pneumophila, Bordetella pertussis
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What are the minor Non-enterobacteriaceae aerobic, gram-negative bacilli
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Vibrio cholerae
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What are the major anaerobic, gram-negative bacilli?
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Bacteroides fragilis
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What are the major spirochetes?
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Borrelia burgdorferi, Treponema pallidum
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What are the bacteria that are not categorized by shape?
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Chlamydia trachomatis, Mycobacterium tuberculosis, Rickettsia rickettsii
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Which bacteria do NOT stain with gram stain?
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Chlamydia trachomatis, Mycobacterium tuberculosis
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In what tissue is corynebacterium diphtheriae usually found?
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Throat
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In what tissue is Neisseria gonorrhoeae usually found?
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Urogenital epithelium
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In what tissue is Streptococcus mutans usually found?
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Tooth surfaces
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In what tissue is Vibrio cholerae usually found?
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Small intestine epithelium
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In what tissue is Escherichia coli usually found?
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Small intestine epithelium
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In what tissue is Staphylococcus aureus usually found?
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Nasal membranes
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In what tissue is Staphylococcus epidermidis usually found?
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Skin
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Three examples of extracellular pathogens?
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Streptococcus pneumoniae, Neisseria gonorrheae, Staphylococcus aureus
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Four examples of Toxin Producers?
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Vibrio cholerae, Clostridium botulinum, Clostridium tetani, Bordetella pertussis
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Four examples of intracellular bacterial pathogens?
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Salmonella typhi, Legionella pneumophilia, Listeria monocytogenes, Yersinia pestis
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What is an obligate pathoge?
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One that has not been found anywhere but in association with its host
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What is a facultative pathogen?
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One that can grow or survive in the environment as well as its host
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What is an obligate intracellular pathogen?
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One that can only grow inside of host cells; cannot be cultured extracellularly
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What is a facultative intracellular pathogen?
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Can grow both inside and outside of cells; can be cultured on an agar surface in the lab
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What would be a quantitative indication of a decrease in virulence?
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Increase in LD50
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Virulence in what bacteria is associated with pedestal formation?
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EPEC (enterpathogenic Escherichia coli)
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Six examples of non-immune defense mechanisms
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Species resistance, individual resistance, anatomical and mechanical defenses or barriers, microbial antagonism, tissue bactericides, complement
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What is an example of antigenic disguise being used by a bacteria to overcome host defenses?
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Protein A of S. aureus
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What bacterial structure is used to evade complement?
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Capsules
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What is invasion?
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general: to enter the host's tissues and disseminate; specific: entering host CELLS
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Example of a "dead end" in transmission?
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Legionella pneumophilia; cannot be transmitted from person to person
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Categorize Neisseria gonorrhoeae
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Aerobic gram-negative coccus
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How does Neisseria gonorrhoeae prevent infected individuals from developing effective immunity?
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Phase switching and antigenic variation; also produces protease which specifically cleaves human IgA1 and coats itself with sialic acid
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What is endotoxin?
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Lipopolysaccharide (LPS) in Gram-negative bacteria; Cell wall components in Gram-positive bacteria
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What are enterotoxins?
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Like exotoxins but functio nin lumen of gut
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What are pyogenic exotoxins?
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Super antigens secreted by Streptococcus pyogenes and Staphylococcus aureus that directly stimulate T cell proliferation and cytokine production; result in fever, shock, and rash
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What are toxoids?
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Inactivated toxins used as vaccines
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Describe (categorize) Clostridium tetani
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Gram-positive, ANaerobic rod with terminal spores
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Where is Clostridium tetani found?
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Ubiquitous in soil and gut of animals and humans
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What causes disease from Clostridium tetani?
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Exotoxin is neurotoxin; blocks release of GABA resulting in paroxysm of spasms; may be genralized or localized
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Best way to combat tetanus?
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Vaccine; antitoxin only removes unbound toxin so disease lasts weeks to months once contracted
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How to treat tetanus?
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Removal of focus ofinfection and penicillin
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Intracellular pathogen that causes tuberculosis?
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Mycobacterium tuberculosis
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Intracellular pathogen that causes leprosy?
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Mycobacterium leprae
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Intracellular pathogen that causes listeriosis?
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Listeria monocytogenes
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Intracellular pathogen that causes typhoid fever?
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Salmonella typhi
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Intracellular pathogen that causes bacillary dysentery?
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Shigella dysenteriae
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Intracellular pathogen that causes the plague?
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Yersinia pestis
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Intracellular pathogen that causes pneumonia?
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Legionella pneumophilia
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Is rocky mountain spotted fever pathogen intra or extra cellular?
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Intracellular
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Intracellular pathogen that causes chlamydia and trachoma?
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Chlamydia
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How does Listeria monocytogenes spread?
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Taken up into host cell, then ruptures vacuolar membrane; once inside cytoplasm, able to replicate and divide; Polymerizes actin tails to push bacterium into neighboring cells and then uses phospholipases to spread to next cell
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What type of symptoms does Listeria monocytogenes cause?
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Range from mild diarrhea to invasive infection with sepsis and meningitis
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Five main groups of wbc's?
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Basophil, Eosinophil, Lymphocyte, Monocyte, Neutrophil
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WBC's that are granulocytes?
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Neutrophils, eosinophils, basophils
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WBC's that are "mononuclear"?
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lymphocytes, monocytes
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What is necessary to have inflammation?
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Vascular system in that part of the body
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How is inflammation described "clinically"?
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Acute = short duration; Chronic = longer duration
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What is inflammation described by immune system involvement?
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Innate or Adaptive
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How is inflammation described by infiltrate?
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Acute = phagocytes; Chronic = mononuclear cells
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In what three ways in inflammation described?
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Clinical time course, immune system involvement, cellular infiltrate
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A clinically acute inflammation would involve which part of the immune system? Which type of infiltrate?
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Innate immune system; could be either type of infiltrate
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A clinically chronic inflammation would involve which part of the immune system? Which type of infiltrate?
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Adaptive immune system; could be either type of infiltrate
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What types of cells are present in an acute cellular infiltrate?
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Neutrophils and macrophages
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What types of cells are present in a chronic cellular infiltrate?
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Lymphocytes, plasma cells, and macrophages
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What are the six general patterns of inflammation?
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Exudative, mononuclear, granulomatous, eosinophilic, cytopathic, necrotizing
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What type of inflammation is exudative inflammation?
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Acute infiltrate using the innate immune system
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What are the clinical signs of exudative inflammation?
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Pus and rubor, calor, tumor, dolor
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What types of organisims cause exudative inflammation?
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Extracellular bacteria; gram positive cocci and gram negative rods; some extracellular fungi
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Acute tonsillitis shows what pattern of inflammation?
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Exudative
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Acute appendicitis shows what pattern of inflammation?
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Exudative
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What is edema?
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Excess fluid in the interstitial spaces
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What pattern of inflammation can lead to abscess formation?
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exudative
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What type of infiltrate is seen with mononuclear inflammation?
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Chronic infiltrate (lymphocytes, plasma cells, macrophages)
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What types of organisms cause mononuclear inflammation?
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Intracellular viruses, bacteria, and parasites; spirochetes; any infectious process persisting a very long time
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What type of infiltrate and what clinical time course would you see with acute viral pneumonia?
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Clinically acute; chronic inflammatory infiltrate
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What type of infiltrate and what clinical time course would you see with acute viral meningitis?
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Clinically acute; chronic inflammatory infiltrate
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What type of infiltrate and what clinical time course would you see with chronic, unresolving pneumonia?
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Clinically chronic; chronic inflammatory infiltrate
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What type of infiltrate and what clinical time course would you see with chronic meningitis?
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Clinically chronic; chronic inflammatory infiltrate
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What is granulomatous inflammation?
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Subtype of chronic inflammation involving a collection of activated macrophages that often fuse to form giant cells
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If you see giant cells, what type of inflammation is it?
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Granulomatous
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What is the hallmark of granulomatous inflammation?
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Epithelioid histiocytes (activated macrophages with abundant pink cytoplasm); also called epithelioid cells
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What is another way of describing granulomas?
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Delayed type hypersensitivity reaction (Type IV)
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What is the goal of a granuloma?
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To wall off an infection
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If I say "granulomatous inflammation", you say…
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tuberculosis
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What types of organisms cause granulomatous inflammation?
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Poorly degradable intracellular microbes; Mycobacteria, some fungi, some worms
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In an AIDS patient with low CD4 counts, what type of infection can you see?
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Atypical mycobacterium called mycobacterium avium intracellulare (MAI); because patient cannot form granulomas, they can't contain the infection and you see masses of macrophages stuffed with mycobacteria that cannot be killed
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What causes "cytopathic" inflammation patterns?
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Viruses like measles or HPV
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If you see intranuclear inclusions in a cell, what is the infecting organism?
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Herpes virus
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If you see intranuclear and cytoplasmic inclusions in cells, what is the infecting organism?
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Cytomegalovirus (CMV)
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Cells that stain purple with gram stain are?
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Gram positive
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Do gram + or - cells have an outer membrane?
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Negative
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What is major component of prokaryotic cell walls?
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Peptidoglycan murein
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How does lysozyme kill bacteria?
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Cleaves at particular site of polysaccharide making up cell walls
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Positive
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What do pneumococcus, H. influenzae,and N. meningitidis have in common?
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All have capsules
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Examples of bacterial structures recognized by TLRs?
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lipoproteins, LPS, flagellin
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What is the grouping system of streptococci based on?
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carbohydrates present in cell wall
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What is Group A Strep? What is niche?
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Streptococcus pyogenes; oropharynx
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What is Group B Strep? What is niche?
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Streptococcos agalactiae; mostly found in newborns; can caues UTI and invasive infection
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What is Group D Strep? What is niche?
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Enterococcus faecalis; human GI tract
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Classify Streptococcus pneumoniae?
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Non beta-hemolytic streptococcus
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What type of hemolysis is found with GAS?
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beta
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How to identify GAS?
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Gram positive cocci; catalase negative; beta hemolytic; bacitracin sensitive
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If you had a gram positive cocci that was catalase positive and coagulase positive, what would you have?
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staphylococcus aureus
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If you had a gram positive cocci that was catalase positive and coagulase negative, what would you have?
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a coagulase-negative staphylococcus species (eg staphylococcus epidermidis)
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If you had a gram positive cocci that was catalase negative, beta hemolytic, and resistant to bacitracin, what is it?
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a beta-hemolytic streptococcus that is NOT GAS
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What would be a gram positive cocci that is catalase negative, alpha hemolytic, and optochin sensitive?
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streptococcus pneumoniae
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What would be a gram positive cocci that is catalase negative, alpha hemolytic, and optochin resistant?
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alpha-hemolytic streptococci
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What is the environmental reservoir for GAS?
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none
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What is antigen for Group A Strep? How many different serotypes are there?
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M-protein; over 80 known serotypes; accounts for why streptococal pharyngitis is often a recurrent infection
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What are risk factors for GAS infection?
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crowding (ie classrooms) and winter months
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What causes TSS-like syndrome?
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Streptococcus pyogenes (GAS)
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What are the post-infectious complications of GAS?
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Rheumatic fever and acute glomerulonephritis
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What types of localized infection are possible with GAS?
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pharyngeal or cutaneous
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What are examples of disseminated infection caused by GAS?
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Bacteremia, septic arthritis, pneumonia
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What are the sequelae of pharyngitis (GAS)?
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Acute rheumatic fever and glomerulonephritis
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What causes scarlet fever rash?
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Erythrogenic toxin from GAS
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What causes impetigo?
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GAS infection or staph aureus
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What is strawberry tongue a sign of?
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Scarlet Fever rash (GAS toxin)
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What causes necrotizing fasciitis?
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GAS infection deep in subcutaneous tissues that spreads along fascial planes
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What is a post-infection sign of GAS?
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desquamation
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Golden crusty lesions are called what?
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Impetigo
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What is damaged in rheumatic heart disease?
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Heart valves
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What is usual followup to rheumatic fever?
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Maintenance of low-dose antibiotic treatments, especially for first 3-5 years to prevent recurrence
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What must be present to diagnose glomerulonephritis or rheumatic fever?
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Evidence of recent Strep A infection -- eg antibody production in blood
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What is major difference between TSS caused by Streptococcus and Staphylococcus?
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With GAS, most patients have disseminated rather than localized infections
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How to prevent rheumatic fever or glomerulonephritis?
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Treat initial GAS infection
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Drug of choice for GAS? Alternatives if resistant?
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Oral penicillin; alternatives are erythromycin, clindamycin, cephalexin
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Describe/Categorize Group B Strep
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Small gram-positive coccus grows in pairs and chains; Beta or non-hemolytic; catalase-negative; bacitracin resistant
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What is species name of Group B Strep?
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Streptococcus agalactiae
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How to differentiate between Group A and B Strep?
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GAS is bacitracin sensitive
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Where is reservoir of Group B Strep?
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animals
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Niche of Group B Strep?
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Lower GI and urinary trachts; transient vaginal colonization
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What is the leading cause of neonatal infection?
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Group B Strep
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In what population do you see most Group B Strep infections?
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in utero or after birth
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Risk factors for Group B Strep infection?
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Premature birth; Prolonged rupture of chorioamniotic membranes; teenage pregnancy
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How to prevent Group B Strep infection?
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prophylaxis for vaginally or rectally colonized women during late pregnancy; paripartum treatment of neonates with antibiotics for deliveries involving premature rupture of membranes or signs of infection
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Describe/Categorize Staphylococcus aureus
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Gram positive; catalase positive; coagulase positive
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Important points of Staphylococcus epidermidis?
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Common skin flora; common contaminant of blood cultures; forms biofilms on catheters; does NOT cause cutaneous infection
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Three general categories of Staph aureus clinical manifestations?
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superficial lesions; systemic and deep-seated infections; toxin-mediated
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Most common food poisoning?
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Staph aureus toxin
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What causes Toxic Shock Syndrome?
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non-specific stimulation of T-cells by superantigen
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What is the primary nosocomial pathogen?
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MRSA
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What percentage of nosocomial MRSA infections are susceptible only to vancomycin?
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50%
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What is the strain of staphylococcus aureus that is causing community acquired infections?
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USA300
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What is common feature of many pathogens of the human respiratory tract?
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Encapsulated -- block action of complement in many different ways
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What are the common etiologic agents of bacterial meningitis for individuals under 2 months of age?
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Group B streptococcus; Escherichia coli
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What are the common etiologic agents of bacterial meningitis for individuals over 2 months of age?
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streptococcus pneumoniae; neisseria meningitidis; haemophilus influenzae type b
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Describe/Categorize Streptococcus pneumoniae
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gram positive cocci; alpha hemolytic; catalase negative; sensitive to optichin and bile salts
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What are two common causes of acute otitis media?
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Non-typeable Haemophilus influenzae and Streptococcus pneumoniae
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Majority of outpatient antibiotic courses prescribed by us physicians were for what cagetory of disease?
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upper respiratory tract infections
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rust colored sputum is sign of what?
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streptococcus pneumoniae causing pneumonia
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What is pattern of pneumonia caused by streptococcus pneumoniae?
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Lobar pneumonia; consolidation of entire lobe
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What is mechanism of pneumococcal resistance for beta-lactam antibiotics?
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altered penicillin binding proteins with reduced affinity for penicillins
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Reservoir for Hemophilus influenzae?
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Humans (only natural host)
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Common cause of buccal cellulitis or epiglottitis?
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Haemophilus influenzae
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Special growth requirements for haemophilus influenzae?
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Hemin and NAD (nicotinamide adenine dinucleotide)
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Second most common cause of bacterial respiratory tract infections?
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Haemophilus influenzae
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What type of Haemophilus influenzae is prevented by immunization?
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Type B
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Drug of choice for H. influenzae? Resistance?
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Penicillin (nearly 80 percent still susceptible)
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Mechanism of resistance to penicillins by H. influenzae?
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Expression of beta-lactamase --> many cephalosporins remain effective
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Categorize Neisseria meningitis?
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Gram negative; diplococcus; polysaccharide capsule
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What part of human does Neisseria meningitis tend to colonize?
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Posterior nasopharynx
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Which types of Neisseria meningitis do we NOT have vaccines for?
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B
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Two presentations of infection with Neisseria meningitidis?
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Meningococcemia (skin lesions) and acute bacterial meningitis
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What are petachiae and purpura signs of?
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Meningococcemia from Neisseria meningitidis
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Drug of choice for neisseria meningitis?
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Penicillin or third generation cephalosporin
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Best treatment of encapsulated organisms?
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PREVENTION!
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Three encapsulated pathogens of human repiratory tract?
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Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis
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What is a conjugate vaccine?
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Combines polysaccharide antigen of capsule to protein carrier; converts Tc-cell independent to T-cell dependent immune response
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For which pathogens are conjugate vaccines available?
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Haemophilus influenzae type b; Streptococcus pneumoniae; Neisseria meningitidis
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Three gram-negative pathogens of the human respiratory tract?
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Bordetella pertussis; Pseudomonas aeruginosa; Legionella pneumophilia
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What causes whooping caugh?
|
Bordetella pertussis
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Describe/categorize Bordetella pertussis
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Small, aerobic, gram-negative coccobacilli
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What causes pathogenicity of Bordetella pertussis?
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Exotoxins: pertussis toxin, adenylate cyclase toxin, tracheal cytotoxin
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Problem with treatment of Bordetella pertussis?
|
Can't distinguish symptoms from those of common (viral) cold until too late to treat
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Drug of choice for Bordetella pertussis?
|
Erythromycin, but usually too late except for limiting contageous spread
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Describe/categorize Pseudomonas aeruginosa
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Gram negative rod; aerobic; ubiquitous and oportunistic
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What pathogen produces fluorescent pigment (used to ID in lab)?
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Pseudomonas aeruginosa
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What is common cause of ventillator associated pneumonia?
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Pseudomonas aeruginosa
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Common cause of swimmer's ear?
|
Pseudomonas aeruginosa
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Ubiquitous, opportunistic pathogen that is widely distributed in moist environment?
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Pseudomonas aeruginosa
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Special growth requirements for Pseudomonas aeruginosa?
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None
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Common chronic infection in CF patients?
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Pseudomonas aeruginosa
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Is Pseudomonas aeruginosa an intracellular, extracellular or toxin mediated pathogen?
|
Extracellular and toxin-mediated
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Which respiratory tract pathogens need special media to be cultured in lab?
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Pertussis and legionella pneumophila
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Describe/categorize Legionela pneumophila
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Gram negative, motile, small coccobacilli; does not gram stain well
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Niche of Legionela pneumophila?
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Parasite of aquatic protozoa; in humans, falsely recognizes macrophages as host
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Common environmental cause of Legionela pneumophila infection?
|
Cooling towers/air filtration systems
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What is Pontiac fever?
|
Asymptomatic, flu-like infection with Legionela pneumophila
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What subpopulations are at increased risk of Legionela pneumophila?
|
Elderly, male, heavy tobacco or alcohol use
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Which type of immune response is more important for combating Legionela pneumophila infections?
|
Cellular immunity
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What is necessary to grow Legionela pneumophila in culture (in lab)?
|
Special media -- buffered charcoal-yeast extract
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Major difference between respiratory tract and gut?
|
Gut is sterile proximally and increasingly colonized distally; respiratory tract is inverse
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Describe major characteristics of Enterobacteriaceae family?
|
Gram-negative rods; found mostly but not exclusively in gut; facultative anaerobes
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What are three major gram-negative anaerobic pathogens (rods) of GI tract?
|
Bacteroides fragilis, Porphyromons gingivalis, Prevotella bivius
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What does Bacteroides fragilis infection cause?
|
Intra-abdomnal infection
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What does Porphyromons gingivalis infection cause?
|
Peridontitis
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What does Prevotella bivius infection cause?
|
Pelvic infection
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What are four gram-positive anaerobic pathogens (rods) of GI tract?
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Clostridium tetani, Clostridium perfringens, Clostridium botulinum, Clostridium difficille
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What is the genus of Gram-positive cocci that infect GI tract?
|
Peptostreptococcal species
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|
What does Propionibacterium acnes cause?
|
Prosthetic device infections
|
|
|
What does Clostridium tetani cause?
|
Wound poisoning
|
|
|
What does Clostridium perfringens cause?
|
Gas gangrene
|
|
|
What does Clostridium botulinum cause?
|
Food and wound poisoning
|
|
|
What does Clostridium difficille cause?
|
antibiotic-associated colitis
|
|
|
What causes gas gangrene?
|
Clostridium perfringens
|
|
|
Big points about Klebsiella?
|
Enterobacteriacea (gram-negative rod) that is highly resistant to most antibiotics
|
|
|
Three major sites in body that anaerobes colonize?
|
Oral cavity, GI tract, female genital tract
|
|
|
Most anaerobic infection is ____________ by nature
|
polymicrobial
|
|
|
Most common anaerobe isolated from clinical infections?
|
Bacteroides fragilis, Porphyromons gingivalis, Prevotella bivius
|
|
|
Describe process of abscess formation
|
Acute inflammatory response with a neutrophil influx, central necrosis, and walling off of the infection
|
|
|
What is common immune response to Bacteroides fragilis infection? What causes this?
|
Abscess formation; Caused by response to capsular polysaccharide, which resists phagocytosis
|
|
|
Foul odor and gas production is sign of what type of infection?
|
Anaerobic
|
|
|
Best treatment of abscess?
|
Drain it!
|
|
|
Bacteroides fragilis sensitivity to penicillin?
|
Typically resistant due to beta-lactamase expression
|
|
|
Treatment of choice for Bacteroides fragilis infection?
|
Metronidazole
|
|
|
Treatment of choice for anaerobic infection?
|
Metronidazole
|
|
|
Categorize/describe Helicobacter pylori
|
Gram negative curved rod; highly motile; specialized to colonize stomach and duodenum
|
|
|
What is Helicobacter pylori infection associated with?
|
Gastritis, peptic ulcers, gastric adenocarcinoma
|
|
|
What special adaptations does Helicobacter pylori have?
|
Ability to survive in acid rich environment of stomach
|
|
|
What infection leads to increased risk of gastric adenocarcinoma?
|
Helicobacter pylori
|
|
|
What is a difficulty of treating Helicobacter pylori?
|
Must raise stomach pH in order for antibiotics to function; eg would be proton pump inhibitor plus clarithromycin plus amoxicillin
|
|
|
What are the two species of Enterococcus? Which is more problematic?
|
E. faecalis (more prevalent) and E. faecium (more resistant and problematic)
|
|
|
Describe/categorize enterococcus
|
Gram positive cocci in singles, pairs, chains; facultative anaerobe; major habitat is GI tract of humans and other animals
|
|
|
Second most common cause of nosocomial infection?
|
Enterococcus
|
|
|
Most common cause of enterococcus infection?
|
Nosocomial
|
|
|
Four types of diseases that enterococci can produce?
|
UTI; bacteremia/septicemia (esp. catheter associated); endocarditis; intra-abdominal/pelvic infection
|
|
|
What drugs are enterococci susceptible to?
|
Very few; intrinsic resistance to all penicillins, cephalosporins, and others; develops resistance to macrolides, tetracycline, vancomycin, and others
|
|
|
Drug of choice for SENSITIVE strains fo enterococci?
|
Ampicilin
|
|
|
Three general mechanisms for development of bacterial gastroenteritis
|
Ingestion of preformed toxin with rapid onset of illness; ingestion of organisms that produce toxins in vivo; infection by enteroinvasive organisms with delayed onset of illness
|
|
|
What are two pathogens that cause diarrhea through preformed toxin?
|
S. aureus and B. cereus
|
|
|
What are five pathogens that cause diarrhea through toxin production in vivo?
|
C. perfringens, B. cereus, ETEC, EHEC, C. difficile
|
|
|
What are four pathogens that cause diarrhea through tissue invasion?
|
C. jejuni, Salmonella, Shigella, EIEC
|
|
|
How does Bacillus cereus cause gastric distress?
|
Short-incubation: ingestion of preformed toxin; long-incubation: ingestion of organisms that produce toxin in vitro, diarrhea more common with this form
|
|
|
How long is normal incubation period for enteroinvasive organisms?
|
1-3 days
|
|
|
Three common enteric pathogens referred to HUP?
|
Campylobacter, Salmonella, Shigella
|
|
|
Describe/categorize Bacillus cereus
|
Gram positive rods, facultative anaerobic, motile, spore forming; beta hemolytic, catalase positive
|
|
|
Describe/categorize Clostridium perfringens
|
Anaerobic, gram-positive, large spore forming rods; double zone of beta hemolysis surrounding complete hemolysis
|
|
|
Describe/categorize Shigella species
|
Gram-negative rods, facultative anaerobe, member of Enterobacteraceae; oxidase negative, appears as non-lactose fermentor on MacConkey agar
|
|
|
Name four species of Shigella
|
S. dysenteriae, S. flexneri, S. boydii, S. sonnei
|
|
|
About how many individual Shigella bacteria does it take to infect a human?
|
~10
|
|
|
What are symptoms of Shigella infection?
|
Fever, cramps, bloody/mucoid diarrhea
|
|
|
Which species of Shigella is most common in US?
|
S. sonnei (serogroup D)
|
|
|
Which two GI tract pathogens are genetically "the same" organism?
|
Shigella and E. coli
|
|
|
Describe mechanism of pathogenesis for Shigella?
|
Obtains access to subepithelial location, where it causes extensive apoptosis of macrophages; allows escape of bacteria into tissues and efficient basolateral entry to epithelial cells, followed by cell-to-cell spreading
|
|
|
Under what circumstances is Shegellosis most common in the US?
|
Day care centers and areas with crowded living conditions such as urban centers or residential institutions
|
|
|
Describe/categorize Salmonella species
|
Facultative anaerobe, Gram-negative rod; member of Enterobacteraceae; motile; oxidase negative; non-lactose fermenter on MacConkey agar; two species
|
|
|
What are the two species of Salmonells?
|
S. enterica (six subtypes I-VI), S. bongori
|
|
|
What is infectious dose of Salmonella?
|
Large -- >10E7 organisms
|
|
|
Major point about Salmonella typhi?
|
NOT self limiting; presents nonspecifically with abdominal pain, fever, chills
|
|
|
Method of choice for diagnosis of Salmonella?
|
Culture
|
|
|
Describe/categorize Campylobacter species?
|
Gram negative; microaerobic; oxidase positive, catalase positive; able to hydrolyze sodium hippurate
|
|
|
Describe course of campylobacter infection?
|
1-3 days incubation; fever, abdominal pain, watery or bloody diarrhea, nausea and vomiting
|
|
|
Rare complication of Campylobacter infection?
|
Guillain-Barre syndrome
|
|
|
What is Guillain-Barre syndrome? Associated with?
|
Acute, self-limited, immune mediated attack of peripheral nervous system resulting in ascending motor paralysis; associated with campylobacter infection; very rare complication of EBV
|
|
|
Diagnosis of campylobacter?
|
Stool culture using selective media
|
|
|
Most common cause of Traveler's diarrhea?
|
ETEC
|
|
|
ETEC?
|
Entertoxigenic E. coli
|
|
|
EPEC?
|
Enteropathogenic E. coli
|
|
|
EHEC?
|
Enterohemorrhagic E. coli
|
|
|
EIEC?
|
Enteroinvasive E. coli
|
|
|
EAEC?
|
Enteroaggregative E. coli
|
|
|
DAEC?
|
Diffusely adhering E. coli
|
|
|
What single strain of E. coli can be differentiated in the laboratory?
|
O157:H7, form of EHEC
|
|
|
Most isolates of E. coli appear as __________ on MacConkey agar?
|
lactose-fermenters; pink colonies
|
|
|
Pathogenesis of ETEC?
|
Produces cholera-like enterotoxin; induces watery diarrhea (enterotoxigenic)
|
|
|
Pathogenesis of EPEC?
|
Destroys normal microvillar architecture of small bowel enterocytes (pedestal formation) ("Enteropathogenic")
|
|
|
Pathogenesis of EHEC?
|
Elaborates Shiga toxin (Stx) ("Enterohemorrhagic")
|
|
|
How to detect EHEC?
|
Detect Stx toxin in stool
|
|
|
Pathogenesis of EIEC?
|
Invades colonic epithelial cell, lyses phagosome and moves through cell by nucleating actin microfilaments ("Enteroinvasive")
|
|
|
Pathogenesis of EAEC?
|
Adheres to small and large bowel epithelia in thick biofilm and elaborates enterotoxins and cytotoxins ("Enteroaggregative")
|
|
|
Pathogenesis of DAEC?
|
Elicits signal transduction effect in small bowel enterocytes that causes growth of long finger-like cellular projections ("Diffusely adhering")
|
|
|
What can be associated with EHEC?
|
Hemolytic uremic syndrome (renal failure)
|
|
|
Describe/categorize Clostridium difficile
|
Anaerobi; gram-positive spore forming; large rods
|
|
|
Usual situation of C. difficile infection?
|
Antibiotic associated diarrhea in healthcare settings; disruption of intestinal flora allows organism in colonized patients to express its toxins
|
|
|
Pathogenesis of C. difficile?
|
Produces two major toxins: TcdA and TcdB; both target Ras superfamily; cause cytopathic effects and disrupt tight junction of epithelial barriers and enhance migration of neutrophils into intestines
|
|
|
Possible causes of nausea and vomiting within 1-6 hours?
|
S. aureus and B. cereus
|
|
|
Possible causes of abdominal cramps and diarrhea within 8-16 hours?
|
C. perfringens and B. cereus
|
|
|
Possible causes of Diarrhea within 16-72 hours?
|
Salmonella, Shigella, Campylobacter, (and Yersinia enterocolitica, EIEC, Listeria monocytogenes)
|
|
|
Possible causes of bloody diarrhea without fever within 72-120 hours?
|
E. coli (O157 and other stx producing strains)
|
|
|
Possible causes of persistent diarrhea lasting more than 14 days?
|
Giardia lamblia, cyclospora cayetanensis, Cryptosporidium parvum, Entamoeba histolytica
|
|
|
Stool culture is primary test for detection of ?
|
Salmonella, Campylobacter, Shigella
|
|
|
Gram stain can be helpful for identification of what enteric pathogens?
|
Campylobacter, Salmonella, Shigella
|
|
|
Toxin testing can be helpful for identification of which enteric pathogens?
|
C. difficile and E. coli that produces stx
|
|
|
What is XDR-TB?
|
Strains of tuberculosis that are resistant to any fluoroquinolone and at least one of the three injectable second line drugs (capreomycin, kanamycin, amikacin)
|
|
|
What is MDR-TB?
|
Strains of tuberculosis that are resistant to at least the two main first-line TB drugs (isoniazid and rifampicin)
|
|
|
Describe/categorize tuberculosis
|
Rod shaped, often slightly bent, non-motile, non-spore-forming; do not gram stain; acid fast; grow very slowly with doubling time of 12-18 hours; strickt aerobes
|
|
|
Five first line drugs for tuberculosis?
|
Isoniazid, Streptomycin, Pyrazinamide, Ethambutol, Rifampin (always used in combination)
|
|
|
Lipids and mycobacteria?
|
Mycobacteria especially rich in lipids; contributes to resistance and acid fastness as well as slow growth
|
|
|
Categorize Mycobacteria cellular relationship?
|
Facultative intracellular
|
|
|
Pathogenesis of Mycobacteria due to?
|
Hypersensitivity of sensitized host to bacterial products
|
|
|
Three major stages of tuberculosis?
|
Primary; Development of cell-mediated immunity; secondary tuberculosis
|
|
|
What is direct cause of symptoms of tuberculosis? (fever, weight loss, night sweats)
|
Immunologic reaction (TNF-alpha; IFN-gamma; IL-1)
|
|
|
Major points on tuberculosis vaccination?
|
BCG is attenuated strain of Mycobacteria bovis; effectiveness varies widely; induces tuberculin positivity
|
|
|
Runyon Classification of mycobacteria
|
According to growh and pigment production; Groups I-IV
|
|
|
Group I Mycobacteria?
|
Slow growing photochromogens (need light to form pigments)
|
|
|
Group II Mycobacteria?
|
Slow growing scotochromogens (don't need light to form pigments)
|
|
|
Group III Mycobacteria?
|
Slow growing non-chromogens
|
|
|
Group IV Mycobacteria?
|
Rapid growers
|
|
|
Lyme disease major points?
|
Caused by Borrelia burgdorferi (spirochete), carried by black legged tick; early manifestation is bull's eye rash
|
|
|
What diseases are caused by spirochites?
|
Syphilis and Lyme disease
|
|
|
Pathogenesis of Borrelia burgdorferi?
|
Extracellular pathogen; causes disease by migrating through tissues, adhering to host cells, and evading host immune system
|
|
|
Signs of early disseminated Lyme disease?
|
Secondary EM, muscle aches, fever, headaches, fatigue, facial palsy
|
|
|
Signs of late disseminated Lyme disease?
|
Swelling and pain of one or more joints (often knee); neurological disease (ataxia, memory loss, mood changes, sleep disturbances)
|
|
|
Drug of choice for treating Lyme disease?
|
Doxycycline; Amoxicillin is 2nd choice; Intravenous antibiotic for late disseminated disease involving neurologic abnormalities
|
|
|
How is Lyme disease diagnosed?
|
Bull's eye rash or flu-like symptoms in summer WITHOUT respiratory/GI symptoms; serologic diagnosis
|
|
|
What causes Rocky Mountain Spotted Fever?
|
Rickettsia rickettsii
|
|
|
Describe/categorize Rickettsia rickettsii?
|
Gram negative, obligate intracellular;
|
|
|
Symptoms of RMSF?
|
Sudden headache, fever, chills, muscle aches, characteristic rash (Starts on palms and soles the spreads to trunk)
|
|
|
What is direct cause of pathogenesis of RMSF?
|
Damage to cell membrane of vascular cells leads to leakage of RBC's
|
|
|
Treatment of RMSF?
|
Doxycycline, chloramphenicol, fluoroquinolones
|
|
|
What pathogens use actin-based motility?
|
R. rickettsia; Listeria; Shigella; Vaccinia virus
|
|
|
Describe/categorize Yersinia pestis
|
Gram negative; extracellular pathogen
|
|
|
Natural reservoir of Yersinia pestis?
|
Wild rodents; in USA this is prarie dogs
|
|
|
General purpose of Type Three and Type Four secretion systems?
|
Ways of manipulating host cells
|
|
|
Which four groups of antibiotics work on cell wall synthesis?
|
Penicillins, cephalosporins, carbapenems, vancomycin
|
|
|
What group of antibiotics acts on DNA replication?
|
Quinolones
|
|
|
What antimicrobial acts on RNA polymerase?
|
Rifampin
|
|
|
What two groups of antibiotics act on folate metabolism?
|
Sulfa drugs, trimethoprim
|
|
|
What three antibiotics act on protein synthesis through 50S ribosome?
|
Erythromycin, clindamycin, chloramphenicol
|
|
|
What two antibiotics act on the cell membrane?
|
polymyxin, daptomycin
|
|
|
What three antibiotics act on protein synthesis through 30S ribosome?
|
Tetracycline, tigecycline, aminoglycosides
|
|
|
Three general mechanisms of antibiotic resistance?
|
Alter antibiotic; alter target site; alter transport into or out of cell
|
|
|
Four subclasses of beta-lactam antibiotics?
|
Penicillins, cephalosporins, carbapenems, monobacams
|
|
|
Mechanisms of beta-lactam antibiotics?
|
Bind to transpeptidases and inhibit crosslinking of peptidoglycan layer (cell wall synthesis)
|
|
|
Compare penicillin and ampicillin/amoxicillin?
|
Ampicillin has better coverage of some gram negative organisms (H. influenzae and E. coli)
|
|
|
Four ways pathogens develop resistance to beta-lactams?
|
Produce beta-lactamase; change penicillin binding proteins; decrease permeability; efflux pumps
|
|
|
What bacteria can produce beta-lactamase?
|
Staph aureus, H. influenza, Bacteroides fragilis, many gram-negative bacilli, some enterococci
|
|
|
What bacteria have resistance to beta-lactams through modified penicillin binding proteins?
|
Pneumococcus and many enterococci
|
|
|
How have we tweaked penicillins to make them more effective against gram negatives, anaerobes, and staph aureus?
|
Added beta lactamase inhibitors
|
|
|
How can you tweak penicillins to make them more effective against bacteria that have altered PBP's?
|
Increase dose
|
|
|
What are first generation cephalosporins good against?
|
Strep Grp A/B; Pneumococcus; Staph aureus; E. coli; Klebsiella
|
|
|
What are second generation cephalosporins good against?
|
Strep Grp A/B; Pneumococcus; Staph aureus; H. influenzae, Meningococcus, E. coli; Clostridium
|
|
|
What are third generation cephalosporins good against?
|
Strep Grp A/B; Pneumococcus; Staph aureus; H. influenzae, Meningococcus, E. coli; Klebsiella, Enterobacter, serratia Clostridium
|
|
|
Major points about cephalosporins?
|
Do not cover enterococcus; later generations better against gram-negatives; 5-15% cross over for penicillin allergies
|
|
|
Examples of carbapenems?
|
Imipenem and meropenem
|
|
|
What are carbapenems good against?
|
Pretty much everything; some resistance in pseudomonas aeruginosa
|
|
|
What are monobactams good against?
|
Gram negative aerobic bacteria
|
|
|
Example of monobactam?
|
Aztreonam
|
|
|
How does vancomycin work?
|
Inhibits cell wall synthesis
|
|
|
What is vancomycin used for?
|
Gram positives; used for MRSA and other beta lactam resistant gram positives; oral form used for C. difficile colitis
|
|
|
What is mechanism of vancomycin resistant staph aureus?
|
Either acquiring Van A operon from enterococcus or due to thicking of cell wall causing decreased penetration of antibiotic (may decrease effectiveness of other antibiotics)
|
|
|
What are the three main macrolides and what is general use?
|
Erythromycin, clarithromycin, azithromycin; substitute for penicillin in gram positive non-life threatening infections; commonly used for upper resp. tract infections
|
|
|
What class of drugs is used to treat Legionella, Bordatella pertussis, Chlamydia, and bacterial gastroenteritis caused by Campylobacter?
|
Macrolides
|
|
|
What is the mechanism of resistance to macrolides?
|
Ribosomal mutation
|
|
|
What are four main fluoroquinolones and what is general use?
|
Ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin; broad spectrum against aerobic bacteria; contraindicated for pediatrics
|
|
|
What is mechanism of resistance to fluoroquinolones?
|
Mutations in DNA gyrase
|
|
|
What are three main aminoglycosides and what is general mechanism of use?
|
Gentamicin, tobramycin, amikacin; inhibits 30s ribosomal protein synthesis
|
|
|
What is main use of aminoglycosides?
|
Aerobic, enteric gram negative rods; often combined with penicillin or cephalosporin for synergistic killing of gram positive organisms
|
|
|
General cautions about aminoglycosides?
|
Renal toxicity (generally reversible); IV only; low therapeutic index; active even after levels in serum drop
|
|
|
General use and action of Trimethoprim/Sulfamethaxazole?
|
Blocks folate metabolism; broad spectrum aerobic activity
|
|
|
General cautions about trimethoprim/sulfamethaxazole?
|
Stevens Johns syndrome due to hypersensitivity; bone marrow suppression
|
|
|
Big points about Metronidazole
|
Unknown mechanism of action; excellent activity agains anaerobic bacteria; good penetration into CNS; used for C. difficile colitis
|
|
|
What is mechanism of resistance for MRSA?
|
MecA gene encodes an altered Penicillin Binding Protein
|
|
|
What is mechanism of resistance for penicillin resistant Pneumococcus?
|
Altered penicillin binding proteins
|
|
|
What is mechanism of resistance for penicillin resistant enterococci?
|
Beta lactamase and altered penicillin binding proteins; faecium more resistant than faecalis
|
|
|
Inducible beta-lactamase resistance is possible in which organisms?
|
Enterobacter, pseudomonas, serratia, citrobacter
|
|
|
What bacteria causes syphilis?
|
Treponema pallidum subspecies pallidum
|
|
|
Notes about bacteria the causes syphilis?
|
Treponema pallidum subspecies pallidum; corkscrew shaped, motile; cannot be cultured; can't see under light microscope
|
|
|
Incubation period for syphilis?
|
Depends on inoculum; 9-90 days
|
|
|
What develops at site of inoculation in syphilis?
|
Primary lesion (chancre); heals within 1-6 weeks
|
|
|
Describe secondary syphilis
|
"Great imitator"; Rash, fever, malaise, mucous patches, headaches, arthritis, etc.
|
|
|
Describe latent syphilis
|
No clinical manifestations, but positive serology;
|
|
|
Describe tertiary syphilis
|
can be gummatous, cardiovascular, or neurosyphilis; average onset 10-15 for former, 20-30 for latter
|
|
|
How is syphilis diagnosed?
|
Two step serological screening
|
|
|
Treatment for syphilis?
|
Penicillin
|
|
|
What are two most common bacterial STDs?
|
Gonorrhea and Chlamydia
|
|
|
Name and structure of bacteria that causes gonorrhea?
|
Gram negative diplococcus; Neisseria gonorrhoeae; no capsule; requires 5% CO2 for isolation in culture
|
|
|
Gold standard for diagnosis of gonorrhea?
|
Non culture based PCR tests; inculude non-invasive urine based tests
|
|
|
Treatment of gonorrhea?
|
Ceftriaxone; avoid fluoroquinolones in philadelphia because of increased resistance; always treat for chlamydia co-infection if not ruled out
|
|
|
Name and structure of bacteria that causes chlamydia?
|
Chlamydia trachomatis; small gram negative bacillus; obligate intracellular
|
|
|
Immune response to chlamydia?
|
No lasting immunity, but inflammatory response with re-infection is strong and can lead to end organ damage
|
|
|
What causes epididymitis (swelling of scrotal sac, usually unilateral) in young sexually active males?
|
Almost always gonorrhea or chlamydia
|
|
|
What causes disseminated gonococcal infections?
|
Gonococcal bacteremia
|
|
|
What kind of virus is HPV?
|
non-enveloped DNA virus
|
|
|
What tissues does HPV infect?
|
Squamous epithelium of skin or mucous membranes
|
|
|
HPV gene products that have been linked to tumorigenesis?
|
E6 and E7
|
|
|
Can HPV integrate?
|
Yes
|
|
|
Treatment for HPV?
|
None, only preventative vaccines
|
|
|
Vaccine names for HPV?
|
Gardasil and Cervarix
|
|
|
What kind of virus is Influenza?
|
negative stranded RNA; enveloped
|
|
|
Are negative stranded RNA viruses enveloped or not?
|
Yes (all)
|
|
|
What does RNA polymerase packaged with influenza do?
|
Makes + RNA from negative strand to produce proteins, and makes new negative strand to package into new viruses
|
|
|
All negative stranded RNA viruses must be packaged with what?
|
An RNA-dependent RNA polymerase
|
|
|
Segmented negative stranded RNA viruses?
|
Bunya and Influenza
|
|
|
Nonsegmented negative stranded RNA viruses?
|
Paramyxo and Filo
|
|
|
Does influenza have a segmented genome?
|
Yes
|
|
|
Incubation period for influenza?
|
1-4 days
|
|
|
How long is influenza virus shed in respiratory secretions?
|
5 to 10 days
|
|
|
Clinical symptoms associated with flu?
|
Fever, myalgia, sore throat, nonproductive caugh, generalized muscle aches, malaise
|
|
|
Purpose of nucleocapsid protein in influenza?
|
Forms protective shell around genetic material
|
|
|
Proteins in influenza virus that are drug targets?
|
NA, HA, M2
|
|
|
Viral spike proteins in influenza?
|
NA and HA
|
|
|
Protein that is target of antibodies elicited by flu vaccine?
|
HA
|
|
|
What is M2?
|
ion channel in influenza virus that helps trigger uncoating of virus once it enters cell; target of Amantadine and Rimantidine
|
|
|
What is NA?
|
Neuraminidase protein in influenza virus; cleaves sialic acid; target of Relenza and tamiflu
|
|
|
What is HA?
|
Hemagglutinin protein in influenza virus; binds to sialic acid, causing membrane fusion; target of antibodies
|
|
|
three types of influenza?
|
A, B, C
|
|
|
Important notes on Influenza type A?
|
Infects many species; cause of all human pandemics; only type that exhibits subtype variability
|
|
|
Important notes on Influenza type B?
|
infects only humans (mostly children); milder disease
|
|
|
Important notes on Influenza type C?
|
Infects only humans; no epidemics; relatively rare; causes only minor symptoms
|
|
|
Class of viruses that influenza is in? (latin name)
|
Orthomyxovirus
|
|
|
What is antigenic drift?
|
(influenza:) changes in HA and NA proteins with time due to accumulation of mutations; eliminates antibody effectiveness against first type
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What is antigenic shift?
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(Influenza:) exchange of gene segments between two subtypes; requires coinfection of a cell with two different subtypes
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What is FluMist and who should receive it?
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Live-attenuated influenza vaccine; cold-adapted virus; NOT recommended for young children, elderly, pregnant women, or anyone who is immunocompromised
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What makes up typical influenza vaccine?
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Formalin-inactivated trivalent vaccine (2 A's and a B)
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Target of Tamiflu?
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Influenza virus's NA protein
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Target of Amantadine?
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Influenza virus's M2 protein
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Are there effective antivirals for influenza?
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Yes, although most circulating strains are now resistant to Amantadine
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What kind of virus is rabies?
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Negative stranded RNA virus; enveloped
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Family/class of viruses that contains rabies virus?
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Rhabdoviruses
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Cytopathic effects seen with rabies?
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Negri bodies
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How long is incubation period for rabies?
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Typically several weeks
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Four paramyxoviruses?
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Measles, Parainfluenza, Mumps, Respiratory syncytial virus
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What does rubeola cause?
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Measles
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Koplik spots are sign of what disease?
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Measles (rubeola virus)
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What type of rash is seen with measles?
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Both macules and papules that later become confluent
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What causes croup?
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Parainfluenza virus (type of paramyxovirus)
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What does parainfluenza cause in kids and in adults?
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In kids, causes croup; in adults, can cause upper respiratory tract infection
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Incubation period for mumps?
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up to 3 weeks
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Incubation period for measles?
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1-2 weeks
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Swelling of paratids with fever is characteristic of what?
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Mumps
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What is Ribavirin used to treat?
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Respiratory syncytial virus in infants
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Two filoviruses?
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Ebola and Marburg
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What type of virus are herpesviruses?
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Large, enveloped, double-stranded DNA viruses with glycoproteins pikes
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Three groups of herpes viruses?
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alpha, gamma, beta
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Alpha herpes viruses?
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Neurotropic; include HSV-1, HSV-2, VZV
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Beta herpes viruses?
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Neither neuro- nor lympho-tropic; include CMV, HHV-6, HHV-7
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Gamma herpes viruses?
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Lymphotrophic; include EBV and HHV-8
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Herpes virus that causes oral sores?
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HSV-1
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Herpes virus that causes genital ulcers?
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HSV-2
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Herpes virus that causes chickenpox and shingles?
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VZV
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Herpes virus that causes infections in newborns and the immunocompromised (neither neurotropic nor lymphotropic)
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CMV
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Herpes virus that causes rash in children (neither neurotropic nor lymphotropic)
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HHV-6
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Herpes virus that is not known to cause disease?
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HHV-7
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Herpes virus that causes mononucleosis?
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EBV
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Herpes virus that causes Kaposi's sarcoma?
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HHV-8
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Do herpes viruses integrate their DNA into chromosomes?
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No
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Treatment for HSV 1 or 2?
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Acyclovir or Valacyclovir
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How does Varicella zoster enter body?
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Via respiratory route
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Where does VZV establish latency?
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Within sensory neurons of dorsal root ganglia
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Incubation period for chickenpox?
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~14 days
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How to distinguish between chickenpox and small pox?
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Chickenpox rash will have lesions that are at different stages at any one time; a rash caused by smallpox would be more homogeneous with all lesions at same stage of development
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How are herpes viruses spread?
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Via body fluids
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Where does CMV establish latency?
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T cells and macrophages
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When are peaks of infection with CMV?
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Ages 2-5 (day care) and young adults (STD)
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Cytopathic effects seen with CMV?
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Atypical lymphocytes with abundant cytoplasm and irregular nuclei
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Treatment for CMV?
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Glanciclovir (inhibits viral DNA replication)
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What cells does EBV infect?
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B cells and epithelial cells within the oral cavity
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How is EBV spread?
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Saliva
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Does EBV integrate into cellular DNA?
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NO
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What cells are critical for controlling EBV infection?
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CD8 T cells
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Symptoms of infectious mononucleosis
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Most prevalent amont 15-25 year age group; sore throat, fever, lymphadenopathy, fatigue
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Diagnosis of EBV?
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Lymphocytes > 50% of wbcs with >20% atypical lymphocytes
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Treatment for EBV?
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None
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Six major families of viruses that cause respiratory illnes?
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Orthomyxoviridae, paramyxoviridae, picornaviridae, coronaviridae, adenoviridae, herpetoviridae
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Incubation period of most respiratory viruses?
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1-4 days
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Description and family name of respiratory syncytial virus?
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Paramyxovirus family; enveloped; single stranded RNA
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Age peak for RSV infection?
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2-5 months; any age can be infected
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Seasonality for community outbreaks of RSV?
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Winter to early spring
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Five important paramyxoviruses
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measles, mumps, human parainfluenza, respiratory syncytial virus, metapneumovirus
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Single most important agent of respiratory diseases in infancy
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RSV
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How does RSV present in older infants, children and adults?
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flu-like; milder than in young infants
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Treatment for RSV?
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Generally supportive; Synagis, a humanized mouse antibody is available for high-risk children; aerosolized ribavirin can be given to hospitalized infants at greatest risk for serious disease
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What causes parainfluenza?
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Paramyxovirus family; enveloped; single stranded RNA
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Is genome of parainfluenza viruses segmented?
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No
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Is antigenic shift/drift a concern with parainfluenza?
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No
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What age groups does parainfluenza infect?
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Causes croup, bronchiolitis, and pneumonia in infants and young children; can cause mild URI and pharyngitis in all age groups
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Types of parainfluenza?
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Types 1-4; Type 1 and 2 cause croup
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Seasonality for parainfluenza?
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Type 1 and 2 in fall and early winter;
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Top two (viral) causes of lower respiratory tract infection in infants and young children?
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#1 is RSV; #2 is parainfluenza
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Describe adenovirus
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Nonenveloped; icosahedral capsid of hexon and penton capsomered; ds DNA; fibers project from capsid
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Is adenovirus enveloped?
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No
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Type of genome in adenovirus?
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ds DNA
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How many adenovirus infections are asymptomatic?
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55%
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Age group infected with adenovirus?
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Inversely related to age; most common between 6 months and 5 years
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How are adenoviruses spread?
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Respiratory and fecal-oral routes
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What respiratory viruses can be transmetted by fecal oral route?
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Adenoviruses, coronaviruses
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What are clinical signs of adenovirus infection?
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Respiratory and GI syndromes; conjunctivitis; pharyngoconjuctival fever
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Most relevant cause of conjunctivitis?
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Adenovirus
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Cause of pharyngoconjuctival fever?
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Adenovirus
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Family name of virus that contains rhinovirus and characteristics?
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Picornavirus family; small rna virus; naked nucleocapsid; ssRNA; seen in all age groups
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Describe coronavirus
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Enveloped, positive-sense, ssRNA; infect mammals, rodents, and birds; infect adults and children; second only to rhinoviruses as cause of common cold
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Describe human metapneumovirus
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enveloped, ss, negative-sense RNA; member of paramyxoviridae; infects all ages
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Which types of hepatitis can cause chronic infection?
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HBC and HCV
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Categorize HAV
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RNA picornavirus; positive strand rna; non-enveloped; causes only acute infections, usually symptomatic in adults
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Immunity to HAV?
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Usually lifelong after infection
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How is HAV spread?
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fecal-oral route; shellfish are important source
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Treatment for HAV?
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Supportive; self-limiting infection; two vaccines available
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Describe HBV virus
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partially ds DNA virus; enveloped; contains reverse transcriptase; genome can sometimes integrate
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What is Dane particle?
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complete HBV virion; in constrast to virus-like particles found in plasma of people infected with HBV which consist ONLY of Hep B surface Ag (HBsAg)
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What is cause of symptoms in HAV and HBV?
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immune response
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Chronic infection with HBV?
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Possible; approx 5-10% of infected adults do not clear virus and chronic infection results; linked to hepatocellular carcinoma
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What is linked to hepatocellular carcinoma?
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Chronic infection with HBV
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Chances of cirrhosis if infected with chronic HBV?
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20%
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What does HBsAg tell you?
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Current HBV infection; recent acute infection or chronic
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What does HBeAg tell you?
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Correlates with higher titers of HBV and greater infectivity; indicates acute infection
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What persists indefinitely in blood as marker of past infection with HBV?
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IgG anti-HBc
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What markers in blood remain persistently detectible in patients with chronic HBV infection?
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IgG anti-HBc and anti-HBs; HBsAg
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What indicates recent infection with HBV?
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IgM anti-HBc
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What markers in blood indicate an individual who has been vaccinated against HBV but never infected?
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IgG to HBsA only
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Family and descripton of HCV?
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Flavivirus; ssRNA, positive sense; enveloped; even higher mutation rates than HIV
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What percentage of HCV infections become chronic?
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85%; twenty percent of those go onto cirrhosis of liver
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HCV diagnosis?
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HCV antibody; PCR to determine viral load and type of HCV
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Treatment for HCV?
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No vaccine - mutates too rapidly; PEG-interferon + ribavirin; cure is possible
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Describe Hepatitis D virus
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virus parasite; requires prior infection with HBV; if chronic HDV infection is established, typically rapid progression of liver disease
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Family and type for rotavirus?
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Reoviridae; segmented ds RNA
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Family and type for adenovirus?
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Adenoviridae; linear ds DNA
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Family and type for norovirus?
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Caliciviridae; positive ss RNA
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Age incidence and seasonality of gastroenteritis from rotavirus?
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6 months - 2 years; Winter (in temperate zones)
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Age incidence and seasonality of gastroenteritis from adenovirus?
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Infants and young children; Year round epidemics
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Age incidence and seasonality of gastroenteritis from norovirus?
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Children and adults; winter peak but year round occurrence
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Family and type for astrovirus?
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Astroviridae; positive ss RNA
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Age incidence and seasonality of gastroenteritis from astrovirus?
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Mainly young children; year round
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Viral gastroenteritis cause with longest incubation time?
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Adenovirus (8-10 days)
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Viral gastroenteritis cause with longest virus shedding time?
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Norovirus; 1-3 weeks post recovery!
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Leading cause of diarrhea in infants and young children worldwide?
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Rotavirus
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Virus related to norovirus (also causes viral gastroenteritis)?
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Sapoviruses
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Accounts for 60-90% of non-bacterial food and water bourne outbreaks of gastroenteritis in US, Europe, and Japan?
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Noroviruses
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What are koplik's spots associated with?
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Measles
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Four disease-causing general of picornaviruses:
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Enteroviruses; Hepatovirus (HAV); Parechovirus; Rhinoviruses
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What causes epidemics in summer and fall?
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Enteroviruses (cause acute, nonfocal febrile illness in infants and can cause aseptic meningitis)
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Describe Parvovirus B19
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SINGLE stranded DNA virus; family parvoviridae; replicates in erythrocyte precursors; causes hemolytic anemia and fifth disease ("slapped cheek")
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What causes "slapped cheek" disease?
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aka: Fifth disease; parvovirus B19
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Symptoms of HHV-6?
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Exanthem subitum; sudden and acute fever for 3-6 days; erythematous maculopapular rash ("roseola") that last hours to days; seizures can occur
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Structure of rabies virus and name?
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Rhabdovirus; negative stranded RNA; non-segmented
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Structure and family of west nile virus?
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Flavivirus; enveloped; positive strand RNA; icosahedral structure
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