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122 Cards in this Set
- Front
- Back
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SPIROCHETES
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Know the morphology and style of movement of the Spirochetes
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Axial filaments rotate propelling the bacterium in a corkscrew-like motion
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Explain the pathogenesis of Treponemum pallidum
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Transmitted sexually or transplacentally; enters break kin or mucous membranes
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What protein does T. pallidum produce to facilitate its invasion?
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Hyalonuronidase that disrupts the ground substance, facilitating its spread
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Explain the three stages of Syphilis
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Primary - produces chancre at site of infection that heals spontaneously --> Asymptomatic period (for 24 weeks); Secondary – red maculopapular rash, flat papules, systemic involvement à latent period (for years); Tertiary - CNS degeneration, cardiovascular lesions, gumma
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What is the granulomatous lesion associated with Syphilis called?
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Gummas
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How is congenital Syphilis transmitted and what can happen to the fetus or child?
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Transmitted through placenta in first 10-15 weeks of pregnancy; Spontaneous abortion, stillbirth, or CNS and structural abnormalities can occur
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Treponema pallidum usually elicits two types of antibodies. What are they directed against and how are they used clinically?
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Treponemal – directed against treponemal surface proteins; FTA; Nontreponemal – directed against normal phospholipid components; SCREENING, MONITORING
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What kind of microcopy is used to visualize treponema pallidum?
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Dark field microscopy (light microscope won’t pick up because of its thinness)
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Name 3 diseases that mimic Syphilis and how they are transmitted
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Bejel, Yaws, Pinta; Transmitted through direct skin contact caused by poor hygiene and crowded living
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What is unusual about the type of DNA Borrelia burgdorferi possesses?
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It has LINEAR DNA
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How is B. burgdorferi transmitted to the host?
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By a tick bite
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What animals serve as the primary reservoir for B. burgdorferi?
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Mice and other rodents
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What type of animals serve as the primary hosts for Lyme disease?
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Deer and other mammals
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Describe the three stages of Lyme disease.
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First Stage: after 3-32 days; rash, flu-like symptoms; Second Stage: arthritis, cardiac complications, neurological complications; Third Stage: chronic arthritis and progressive CNS disease
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Know the name of the rash associated with initial infection and be able to describe it.
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Erythema chronicum migrans: red circular lesion with clear center that appears at the site where the tick bite occurred
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What is the most common arthropod-borne disease in US ?
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Lyme disease
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What is the most sensitive and accurate diagnostic test for B. burgdorferi?
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Polymerase chain reaction
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Borrelia Recurrentis is responsible for what illness?
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Relapsing Fever
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How is Relapsing Fever transmitted?
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Body lice
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Describe the symptoms caused by Relapsing Fever and the reason for this pattern.
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Febrile stage (fever, chills, headache, myalgia, malaise) and nonfebrile stage; This is due to its ability to change its surface protein antigens
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When are you most likely to be able to see Borrelia recurrentis in a Wright stained blood smear?
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During the febrile stage
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What are the epidemiology and natural hosts of L. interrogans?
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World-wide infection ; wild and domestic animals are reservoirs
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How is Leptospirosis acquired by humans and what organism causes this illness?
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By skin abrasions or conjunctiva or exposure to contaminated urine
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Who is at risk for Leptospirosis?
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People who work with animals (farmers, meat handlers, veterinarians)
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During the second stage of Leptospirosis what isotype (IgG, IgM, or igE?) of antibody has been found to circulate at high levels?
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IgM antibodies
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What is Weil’s disease and what organism causes it?
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Vascular damage causing hepatic and renal failure; caused by Leptospira interogans
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What are three other names for Weil’s disease?
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Infectious jaundice, Marsh fever, Swineherd's disease
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What is the best test to confirm L. interrogans?
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Serologic agglutination tests
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In what types of clinical samples of L. interrogans can the spirochete be visualized?
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Urine, blood, and CSF
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MYCOPLASMA AND CHLAMYDIA
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Structural characteristics of mycoplasma and consequences
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Don’t have PDG cell wall (no gram stain or CW synthesis antibiotics)
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Mycoplasma: Requirements for growth and requirements for a lipid not usually present in bacteria
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Must get cholesterol from external source (e.g. serum)
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Natural habitat of the genus Mycoplasma
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Found in mouth and GU tract of mammals
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Mode of transmission and typical disease for M. pneumoniae
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Respiratory droplets
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Cold agglutinins and their use in diagnosis of M. pneumoniae
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AgI reacts with M. pneumoniae IgM abs
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Preferred diagnostic tests for M. pneumonia
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Complement fixation, ELISA, PCR
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Bacteria in Mycoplasma pneumoniae that cause genital infections
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Ureaplasma urealyticum: urethritis and ednemtritis; Mycoplasma hominis: postabortal and postpartum fever, PID
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General characteristics of chlamydia.
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Small, round to avoid; Obligate intracellular parasites; No PDG or muramic acid
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Life cycle of Chlamydia and the roles played by the elementary body and the reticulate body
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Elementary Body: infectious but metabolically inactive; Reticulate Body: non-infectious but metabolically active (in cytoplasm)
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Major types of infection caused by C. trachmoatis
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Trachoma (A, B, C); Inclusion conjunctivitis in newborns (ICN) (D-K); Lymphogranuloma venereum (LGV)
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How microbiological diagnosis of infection is made for C. trachomatis
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DNA amplification, immunofluorescent staining of inclusion bodies of Abs
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Typical infections for C. pneumoniae
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Respiratory infections (pharyngitis, laryngitis, bronchitis, pneumonia)
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Route oftransmission of C. pneumoniae
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Respiratory droplet
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Typical infections for C. psittaci
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LRI ranging from mild to severe pneumonia; Fever, hacking dry cough, flu-like symptoms; Liver and spleen infections
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Route of transmission for C. psittaci
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Dust contaminated w/ respiratory secretions or feces of injected birds
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MYCOBACTERIA, ACTINOMYCETES, AND NOCARDIA
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Know general characteristics and what mycobacteria and actinomycetes have in common and different
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Long chain mycolic acid and PDG in CW
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How an ‘acid-fast’ stain is performed and why some bacteria are acid-fast
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Their lipid-rich CW prevents staining by the Gram stain but can be detected by acid fast staining
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The appearance on Gram and acid-fast stain of mycobacteria and actinomycetes
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Gram positive rods
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Characteristics of the Mycobecterium in terms of growth rate, envelope structure, resistance to unfavorable environments.
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Some grow slowly (M. tuberculosis) or not at all (M. leprae); resistant to drying
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Natural host and mode of transmission for M. tuberculosos.
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Natural host is human macrophages; Transmitted through close person-to-person contact, where an infected person sheds Irg #’s of organisms by coughing and a second person inhales the respiratory aerosols
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The course of typical lung disease for M. tuberculosos.
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Begins in middle or lower lung (can contain multiple tubercles); Disseminated TB results from tubercle erosion, spreads through bloodstream, results in granulomas in any organ
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Define Tubercule:
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Granuloma formation
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Granuloma:
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Tumor made of granules
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Gaseous center
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Cheese-like necrotic area
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Miliary disease
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Small discreet nodules on CXR
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Typical clincal signs and sympoms of TB.
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Cough/hemoptysis, weight loss, fever/chills/night sweats
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How MTB is cultured and strengths and limitations of culture for diagnosis.
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Can be cultured on specialized media such as Lowenstein-Jenson agar
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Use of sputum smear for diagnosis and monitoring of therapy for M. tuberculosos.
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Positive PCR for M. tuberculosis
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Two techniques for acid-fast stain.
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Ziehl-neeson or Kinyoun
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Use of the genetic amplification and PCR in diagnosis of mycobacterial infections.
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Nucleic acid probes can be used to detect M. tuberculosis DNA that has been amplified by PCR
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How skin testing is performed; nature of a positive test; what a positive test does and does not indicate; why a person with TB might show a negative test.
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Extracted and partially purified preparations of these protein derivates (purified protein derivatives, or PPDs) are used as skin test reagents to measure exposure); Immunosuppressed persons might show a negative PPD
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Components of the immune system important in defense against mycobacteria, and how mycobacteria are able to resist them.
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Macrophages ingest the bacilli; Bacilli multiply in them, causing additional macrophages to come (forming early tubercle); Many macrophages die after a few weeks; Bacilli released; Caeous center formed in tubercle, surrounded by mass of macrophages and lymphocytes (may become dormant here); Mature tubercle is formed with fibroblasts; Liquefaction continues until tubercle ruptures
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How multi-drug resistance is thought to emerge and the problems this poses for therapy in TB.
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Many patients non-compliant over long term
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The BCG vaccine: antigenic component, effectiveness, uses.
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Antigenic component is from bovine tuberculosis bacills, mycobacterium bovis, that lost its virulence in humans; 80% effective at best for 15 years, used for M. tuberculosis
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What is the disease produced by M. leprae. (name for it in US Public Health Service)
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Leprosy (Hansen Disease)
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The two major variants Leprosy and their relation to the nature of the immune response.
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Tuberculoid leprosy: cell-mediated immune response causes lesions; Lepromatous leprosy: cell-mediated immune response depressed
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Compare Actinomycetes and Nocardia in terms of 1) Morphology and staining, 2) most common species, 3) oxygen metabolism, 4)predisposing causes of infection, and 5) type of infection produced
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1) Both G+ filamentous bacilli, 2) most common is Nocardia asteroides, 3) Actinomycetes are ANAEROBIC while Nocardia are AEROBIC, 4) Actinomycetes are ENDOGENOUS from normal flora of respiratory, GI, or GU tracts while Nocardia are EXOGENOUS from water or soil, 5) Actinomycetes are caused by poor oral hygiene or invasive dental work, while Nocardia is opportunistic organism infecting immunosuppressed people with malignancy or drug use; 6) Actinomycetes cause actinomycosis in brain, cervicofacial region, lungs with sulfur granulomas, while Nocardia causes Nocardiosis via pneumonia, brain and kidney abcesses
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CLOSTRIDIA AND ANAEROBIC GRAM NEGATIVE RODS
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All OBLIGATE ANAEROBES (cannot use and is damaged by oxygen); Obtain energy only by FERMENTATION
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Know general characteristics and what Clostridia and other Anaerobic rods have in common and what is different.
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Gram positive; Large, blunt-ended rods that produce ENDOSPORES; Most motile (except perfringens); Part of intestinal flora
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Appearance of cells of Clostridia on Gram stain.
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Intestinal flora, soil, sewage, aquatic settings
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Typical sources of infection with Clostridia.
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Survive as endospores that are resistant to chemical disinfectants, UV irradiation, boiling once
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Form in which Clostridia persist in the environment and resist disinfection.
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Cannot grow in the presence of oxygen; Damaged or inhibited by oxygen in vegetative state
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Whether Clostridia will grow in (1) presence and (2) absence of oxygen.
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Grow them on enriched media with reducing agent to maintain low oxidation-reduction potential; Grow in oxygen-free gaseous atmosphere
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How specimens suspected of containing clostridia must be transferred to the lab and cultured.
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Damage themselves due to lack of enzymes (peroxidase, SOD, catalase)
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Effects of oxygen on anaerobic bacteria and possible reasons.
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Ubiquitous in nature; Normal flora of intestine and vagina; Spores in soil;
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Reservoir of Clostridia perfringens in nature.
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Surgery or trauma
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Conditions which set the stage for clostridial infections.
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Anaerobic cellulitis; Myonecrosis (gas gangrene); Food poisoning; Enteritis necrotans; Clostridial endometritis
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Types of infection produced by Clostridia perfringens.
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Alpha toxin – degrades mammalian cell membranes in ROBC, WBC, and endothelial cells; Enterotoxin – disrupts ion transport to provoke loss of fluid; Degredative enzymes – include proteases, DNases, hyaluronadase, collagenase that liquefy tissue and promote spread of infection
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Modes of action of "alpha-toxin, enterotoxin, and degradative enzymes and how this impacts pathogenicity for Clostridia perfringens
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Remove affected tissue; Hyperbaric oxygen chambers to inhibit pathogenesis; Debridement; amputation
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Additional modes of treatment which may be required for Clostridia perfringens.
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Clinical impression; Gram stain and cellular debris
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Lab identification and diagnosis for Clostridia perfringens
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Adults: Food poisoning (vision, swallowing, nerve dysfunction) from spores or viable organism in food; Infant: Floppy baby syndrome from contaminated honey
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How disease is produced in (1) adults and (2) infants for Clostridium botulinum
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Botulism causes inhibited release of NT at excitatory synapses; Tetatnus causes inhibited release of NT at inhibitory synapses
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Why neuromuscular symptoms in botulism differ from those in tetanus (mechanism and effect of botulinum toxin).
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Decrease wrinkles
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What is botulinum toxin being used for currently?
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Tetanus in puncture wound, burns, surgery, or drugs
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Disease produced (names) by Clostridium tetani and setting in which it occurs.
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Tetanospasmin A fragment (protease) blocks NT release at inhibitory synapse
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Mechanism of action of tetanus toxin and effect.
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Diagnose through clinical findings and racquet-shaped rod; Treat with prompt antiserum
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How Clostridium tetani infections are diagnosed and treated.
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Spastic paralysis at infected site; lock jaw, gradually other muscles involved
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Prognosis of tetanus once symptoms begin.
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DPT vaccine
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How is tetanus infection prevented?
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Pseudomembranous colitis after drug treatment stopped
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Type of disease produced by Clostridium difficile and setting in which it occurs.
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Enzyme immunoassays for exotoxins A and B in stool
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Rapid lab tests on performed on stool samples to confirm infection of C. difficile?
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Most common organism in oral cavity, female genital tract, lower GI tract
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Describe the distribution, characteristics and relative abundance of anaerobic gram negative rods
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Co-infection with facultative organisms that lower oxygen level
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Important characteristics of infections with Anaerobic Gram Negative organisms (e.g. mixed infection with facultative organisms)
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Bacteroides predominant anaerobes in colon; cause disease in tissue or blood due to trauma or surgery
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What is the genera of anaerobic gram n'egative rods most frequently encountered as cause of infection
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Transmitted from colon to blood or peritoneum as a result of abdominal trauma (ENDOGENOUS INFECTION); Bacteroides fragilis is the major disease causing species, causing bacteremia, peritonitis, abscesses
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Epidemiology, Pathology and Clinical significance (sources, diseases) of Bacteroides
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Copious and foul-smelling lesions; Slender gram negative rods mixed with debris and PMNs; Sugar fermentation
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Lab ID/Treatment and prevention of Bacteroides
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Ticks, Lice, Mice, Fleas
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RICKETTSIA
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Know the four major arthropods that transmit the Rickettsiae group
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Gram negative coccobacilli
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What is the morphology of Rickettsia?
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Has leaky plasma membrane that allows easy entry of the hosts nutrients
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What is special about Rickettsia‘s plasma membrane?
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Reproduces in epithelial cell’s nucleus and cytoplasm by binary fission after phagocytosis
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Explain how Rickettsia reproduces and where does this occur in the cell?
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Rickettsia rickettsia causes RMSP; transferred by by wood or dog tick; most common rickettsial infection in US; symptoms include fever, malaise, petechial or hemorrhagic rash on palms/soles, headache, chills; complications include renal or myocardial failure
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Rocky Mountain spotted fever: caused by what organism, transferred by what organisms, epidemiology, symptoms, complications?
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Rickettsia akari; Vector is a mite
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What organism causes Rickettsialpox and what arthropod is the vector?
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Eschar = thick crust that forms at the site of the bite and a papulovesicular rash
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Describe and name the rash caused by Rickettsialpox?
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Rickettssia prowazekii
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Louse borne (epidemic) typhus is caused by what organism?
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Transmitted by infected lice whose infected feces get into the scratched wound
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How is Louseborne Typhus transmitted and name the vector?
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Transmitted by Rickettsia typhi from rats, opossums, cats using the flea as a vector
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How does an individual acquire Murine Typhus?
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Milder form of typhus that occurs in people who previously recovered from the disease, with a latent period of 10-40 years
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What is Brill- Zinsser disease?
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Orientia tsutsugamushi is transmitted by the bite of mite larvae (chiggers)
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What organism causes Scrub Typhus Group and what is the vector?
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Triggers the response of natural killer cells and gamma interferon (cell-mediated immunity)
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Describe how a Rickettsial infection activates the immune system.
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Anaplasma phagocytophilum that infects granulocytes; associated with deer/dog tick
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What causes Human granulocytic anaplasmosis (HGA)?
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Ehrlichia chaffeensis that infects monocytes and macrophages; associated with Lone Star Tick
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Human monocytic ehrlichiosis (HME) is caused by?
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Headaches, myalgia, fever/chills, N/V/A, skin rash, leukopenia and thrombocytopenia
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What are the clinical symptoms caused by Ehrlichia?
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Gram negative
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Describe the structure of Ehrlichia?
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Antibody assays and polymerase chain reaction
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What are the best methods to confirm the diagnosis of Ehrlichia?
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Reservoir is cattle, sheep, and goats
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What is the mode of transmission of Coxiella burnetti?
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Q-fever (“query”) because the cause was unknown
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What is name for disease by Coxiella burnetti and how did it get it?
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Gram negative short, rod-like, non-motile aerobic microorganism
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Describe this organism’s morphology?
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Transmitted through milk, urine, and feces of infected animals; Grows in cytoplasmic vacuoles; stimulated by the low pH of the phagolysosome
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How is this the way Coxiella burnetti is spread, and where it multiplies differentiate it from the other rickettsiae?
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Chronic infective endocarditis
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What is the main complication caused by chronic infection?
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