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202 Cards in this Set
- Front
- Back
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Bugs that don't gram stain
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Treponema (too thin, need dark field microscopy), Rickettsia (intracellular), Chlamydia (intracellular, lacks muramic acid in cell wall), Mycobacteria (high lipid content acid-fast stain needed), Mycoplasma (no cell wall), Legionella (intracellular, need silver stain)
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Bacterial Growth Curve
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-lag phase: metabolic activity without division
-log: rapid cell division -stationary: nutrient depletion with slow growth and spore formation -death: prolonged nutrient depletion with build up of waste products and death |
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Exotoxin Features
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-produced by both gram positive and negative
-polypeptide secreted from the cell -located in a plasmid or bacteriophage -high toxicity with various effects -induces high titer antibodies called antitoxins; toxoids are used as vaccines -destroyed rapidly at 60C (except staph enterotoxin); typically caused by tetanus, botulism, and diptheria |
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Endotoxin Features
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-come from outer cell membrane of gram negative bacteria and listeria
-lipopolysaccharide that is not secreted from the cell -found in bacterial chromosomes -there is a low toxicity -fever and shock are clinical effects produced by TNF and IL-1 -poorly antigenic with no vaccines available -heat stable at 100C for an hour -typical disease is meningococcemia (sepsis) |
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Bacterial Virulence Factors
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S. aureus protein A: Binds Fc region of IG
IgA protease (S. pneumo, H.flu, Neisseria): cleaves IgA, polysaccharide capsules inhibit phagocytosis Group A Strep M protein: prevents phagocytosis |
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Superantigens (S. aureus and S. pyrogenes)
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-bind directly to MHC II and T-cell receptor simultaneously to activate release of IFN-γ and IL-2
-S.aureus: TSST-1 causes toxic shock (fever, rash, shock); others include enterotoxin (food poisoning) and exfoliatin (scalded skin syndrome) -S. pyrogenes: scarlet fever, erythrogenic toxin causes toxic shock like syndrome |
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ADP Ribosylating A-B toxins (C. diptheriae, V. Cholera, E. Coli, B. pertussis)
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-B(binding) binds receptor on cell surface enabling endocytosis, A(active) attaches an ADP-ribosyl to a host protein and alters cell function
-C. Diptheriae: inactivates EF-2 causing psuedomembrane in throat -V. Cholera: ADP ribosylation of G protein stimulating adenylyl cyclase; increased Cl in gut and decreased Na absorption, rice water diarrhea -E. Coli: Heat-Labile stimulates adenylate cyclase and Heat-Stable stimulates guanylate cyclase, watery diarrhea -B. pertussis: increases cAMP by inhibiting G inhibitor, whopping cough, inhibits chemokine receptor that causes lymphocytosis |
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Other Toxins (C. perfringens, C. tetani, C. botulinum, B. antracis, Shigella, S. pyrogenes)
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-C. perfringens: α toxin causes gas gangrene, double zone of hemolysis on blood agar
-C. tetani: blocks inhibitory neurotransmitter GABA and glycine -C. botulinum: blocks AcH release causing anticholinergic symptoms -B. anthracis: one toxin in the complex is adenylate cyclase -Shigella: shiga toxin (also in E. Coli 0157:H7) cleaves host cell rRNA (60S); enhances cytokine release causing HUS -S.pyrogenes: Streptolysin O (ASO antibody) used in diagnosis of rheumatic fever |
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Endotoxin Effects
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-macrophage activation: IL-1 (fever), TNF (fever, tissue necrosis) and NO (hypotension)
-activates complement: C3a (hypotension, edema) and C5a (neutrophil chemotaxis) -activates Hageman factor: coagulation cascade (DIC) |
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Pigment Producing Bacteria
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-S. aureus: yellow
-P. aeruginosa: blue-green -Serratia marcescens: red |
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Special Culture Requirements
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-H. flu: Chocolate agar with factor V(NAD) and X(hematin)
-N. gonorrheoeae: Thayer-Martin media -B. pertussis: Bordet-Gengou (potato) agar -C. diptheriae: Tellurite, plate, Loeffler's media -M. tuberculosis: Lowenstein-Jensen -Lactose-fermenters: pink on MacConkey's agar -Legionella: Charcoal yeast with increased iron and cysteine -Fungi: Sabouraund's agar |
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Stains
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-Congo Red: amyloid
-Giemsa's: Borrelia, Plasmodium, tyrpanosomes, Chlamydia -PAS: glycogen, mucopolysaccharides (used to diagnose Whipple's disease) -Ziehl-Neelsen: acid fast due to high lipid content -India ink: crytpococcus neoformans -Silver stain: Fungi and Legionella |
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Transformation
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DNA taken up directly from environment by competent prokaryotic and eukaryotic cells. Any DNA can be used.
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Conjugation
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-F+ x F-: F+ has genes for conjugation and transfers replicated plasmid through pilus (plasmid DNA only, to chromosomal genes transfered)
-HFr x F-: F+ can become incoroprated into bacterial chormosomal DNA; replication of plasmid DNA can include flanking chromosomal DNA |
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Transduction
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Generalized: LYTIC phage infects bacteria, leading to cleavage of bacterial DNA and synthesis of viral proteins. Parts of bacterial chromosomal DNA can become packaged in viral capsid, when virus infects another bacteria genes are transferred
Specialized: LYSOGENIC phage infects bacteria, viral DNA is incorporated into bacterial chromosome. When DNA is excised can flank bacterial genes, incorporation into viral capsid can be transferred to another bacteria |
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Transposition
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Segment of DNA can "jump" (excision and reicorporation) from one location to another and transfer genes from plasmid to chromosome or visa versa. During excision flanking of chromosomal DNA can happen and be transferred to another bacterium
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Lysogeny (genetic code for bacteral toxin encoded in lysogenic phage)
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ShigA-like toxin
Botulinum toxin Cholera toxin Diptheria toxin Erythrogenic toxin (S. pyrogenes) "ABCDE" |
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Obligate Aerobes
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Nagging Pests Must Breathe
-Nocardia, Psuedomonas, M. tuberculosis and Bacillus -P. AERuginosa is and AERobe in burn wounds, nosocromial pneumonia and cystic fibrosis pnuemonia |
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Obligate Anaerobes
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Know the ABCs
Actinomyces, Bacteroides and Clostridium: lack catalase and/or superoxide dismutase (suseptible to oxidative damage); usually foul smelling, difficult to culture, and produce gas in tissue -normal in GI tract flora -aminoglycosides are ineffective as they require O2 to get into the cell |
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Intracellular Bugs
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-OBLIGATE: Rickettsia and Chlamydia (can't make own ATP)
-FACULTATIVE: Salmonella, Nisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia (Some Nasty Bugs May Live FacultativeLY) |
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Encapsulated Bacteria
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-positive Quellung reaction: capsule swells with specific anticapsular antisera added
-ex: S. pneumo, H. flu (B serotype), N. meningitidis, and Klebsiella pneumoniae -capsule serves as an antigen in vaccines, conjugation with protein increases immunogenicity and T-cell dependent response |
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Spores (bacterial)
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-only formed in certain gram positive rods when nutrients are limited (end of stationary phase)
-highly resistant to heat and chemicals -have dipicolinic acid in the core and no metabolic activity -need to autoclave to kill spores -found in soil: B. anthracis, C. perfringens, C. tetani -also B. cereus and C. botulinum |
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Urease Positive Bugs
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Proteus(causes UTIs and see alkaline pH in urine), Ureaplasma, Noccardia, Cryptococcus, H.pylori, Klebsiella
"PUNCH K" |
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Beta Hemolytic bacteria
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-S. aureus: catalase and coagulase positive, grows on mannitol sugar
-S. pyrogenes (group A): catalase negative and bacitracin sensitive -S. agalactiae (group B): catalase negative and bacitracin resistant -Listeria monocytogenes: tumbling motility |
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Staphylococcus Aureus
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C: 1)inflammatory disease (skin infection, organ abscesses, pneumonia)
2)Toxin mediated: toxic shock syndrome (TSST-1 - binds MHC II and T-cell receptor = polyclonal T-cell activation), scalded skin syndrome, main cause of skin infection along with group A strep (exfoliative toxin), rapid onset food poisoning (exotoxin - preformed) 3)MRSA infection: serious cause of nosocomial and community aquired infection, resistant to Beta lactams by an ALTERED PENICILLIN-BINDING PROTEIN 4) Acute Bacterial Endocarditis, tricuspid valve preferentially(IV drug users) Virulence: Protein A binds Fc-IgG inhibiting complement fixation and phagocytosis |
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Streptococcus Pyrogenes (group A β hemolytic)
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C: 1)pyrogenic - PHaryngitis, cellulitis, impetigo
2)toxigenic - scarlet fever, toxic shock syndrome 3)immunologic - rhumatic fever (SPECCulation: Subcutaneous nodules, Polyarthritis, Erythema marginatum, Chorea, Carditis(1st mitral, 2nd aortic)), acute glomerulonePHritis (puffy kid with "coca cola" urine) Antibodies to M protein enhance host defense BUT can give rise to rheumatic fever Tx: penicillin and clindamycin (shuts down toxin production) |
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Streptococcus Pneumoniae
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C: MOPS: Meningitis, Otitis Media (kids), Pneumonia ("rusty" sputum), Sinusitis
-Encapsulated (detected by Quellun Rxn) and has an IgA protease -Sepsis in sickle cell anemia and splenectomy -pneumovax (25 most common capsular polysaccharide antigens) available for immunocompromised and elderly |
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Group B Strep (S. agalactiae)
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Bacitracin resistant, β hemolytic
C: pneumonia, meningitis and sepsis mainly in BABIES <4wks (birth canal passage) |
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Enterococci (Enterococcus faecalis and E. faecium)
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C: UTI and subacute endocarditis
-Lancefield group D includes enterococci and nonenterococci group D streptococci (Lancefield based on differences in C carbohydrate on bacterial cell wall). Variable hemolysis -VRE (vancomycin resistant enterococci) are important cause of nosocomial infection -Enterococci hardier than nonenterococcal group D - can grow in 6.5% NaCl (lab test) -Entero=intestine, faecalis=feces, strepto=twisted, coccus=berry |
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Staphylococcus Epidermidus
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-Infects prosthetic devices and catheters
-Component of normal skin flora -Contaminates blood cultures (must do 2 draws from 2 separate sites to confirm infection) -Tx: vancomycin |
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Streptococci Viridians
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-α hemolytic (verde-green), resistant to Optichin (differentiates from S. pneumo)
-normal flora of the oropharynx causing dental caries (S. mutans) and subacute bacterial endocarditis (S. sanguis) |
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Clostridia (with exotoxins)
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-gram positive, spore forming, obligate ANAEROBE bacilli
-C. tetani: produces exotoxin causing tetanus (TETanus is TETanic paralysis: blocks glycine release from Renshaw cells in spinal cord); toxin moves from NMJ to interneurons; vaccine - inactivated toxin (toxoid) C. botulinum: makes preformed heat labile toxin inhibiting ACh release at NMJ=botulism; adults - ingestion of preformed toxin (home-canned, zip lock storage, smoked fish), babies - ingestion of spores (honey) C. perfringens: α toxin (lecithinase) causes myonecrosis (gas gangrene) and hemolysis C. difficile: produces cytotoxin (toxin A: diarrhea, toxin B: kills enterocytes) causing PSUEDOMEMBRANOUS COLITIS; often secondary to Ab use (clindamycin and ampicillin); tx: metronidazole or vancomycin |
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Corynebacterium Diphtheriae
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C: Diptheria via exotoxin encoded by β prophage; exotoxin inhibits protein synthesis via ADP ribosylation of EF-2
Symptoms: psuedomembranous phayrngitis (grayish-white membrane) with lymphadenopathy Diagnosis: gram-positive "club shaped" rods with metachromatic granules, grows on Tellurite agar and coagulates in Loeffer's blood A serum Vaccine: inactivated diptheria toxin |
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Bacillus Anthracis
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-gram positive, aerobic, spore-forming rod producing the anthrax toxin
-only bacteria with a protein capsule (antiphagocytic) C: Anthrax: contact leads to malignant pustule (painless ulcer) and black skin leseions (vesicular papules covered by black eschar) that can progress to bactermia and death; inhalation of spores leads to flu-like symptoms rapidly progressing to fever, pulmonary hemorrhage, mediastinitis and shock (Woolsorters' disease: inhalation from contaminated wool) Exotoxin: EF(edema factor increases adenyl cyclase), PA (protective antigen helps EF) and LF (lethal factor releases TNF-α and IL-1) |
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Bacillus Cereus
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-spores in food release exotoxin, food poisoning (reheated rice)
-no capsule, motile -Tx: none, self-limiting |
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Listeria Monocytogenes
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-only gram positive facultative intracellular anaerobe and producer of ENDOTOXIN
-listerolysin O is major virulence factor: escapes phagolysosomes of macrophages -Aquired by ingestion of unpasteurized milk/cheese or by vaginal transmission during birth. Form "actin rockets" and move from cell to cell C: ammnionitis, septicemia, and spontaneous abortion in pregnant women; widespread granulomas and neonatal meningitis in neonates; meningitis in immunocompromised; and gastroenteritis in healthy people Tx: need to add ampicillin/TMP-SMX when this bug is suspected |
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Actinomyces vs. Nocardia
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-both are gram-positive rods forming long branching filaments resembling fungi
-Actinomyces Israelii: gram positive ANAEROBE that can drain through sinus tract of skin (normal oral flora, "yellow sulfur granules" in sinus tract) -Nocardia Asteroides: gram positive and weakly acid-fast AEROBE found in SOIL (never part of normal flora), causes pulmonary infection in immunocompromised Tx: SNAP - Sulfa (TMP/SMX) for Nocardia; Actinomyces use Penicillin |
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Penicillin and Gram Negative Bugs
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-gram neg. are resistant to benzylpenicillin G but may be susceptible to penicillin derivatives like ampicillin
-gram neg. outer membrane layer inhibits entry of penicillin G and vancomycin |
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Neisseria Gonorrhoeae
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-gram negative cocci, glucose fermenter, produces IgA protease
-NO polysaccharide capsule, maltose fermentation, vaccine -sexually transmitted C: gonorrhea, septic arthritis (most common cause of septic arthritis in young sexually active people), neonatal conjuntivitis, PID -Tx: ceftriaxone and doxycycline/azithromycin for cross coverage for Chlamydia; erythromycin eyedrops for conjunctivitis (also cross covers) |
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Neisseria Meningitidis
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-gram negative cocci, glucose fermenter, produces IgA protease
-DOES HAVE polysaccharide capsle, maltose fermentation, vaccine (capsular polysaccharide) -transferred by respiratory and oral secretions C: meningococcemia and meningitis, Waterhouse-Friedrichsen syndrome (adrenal hemorrhage, endotoxin in LPS causes hemorrhage=petechiea) -infants and army recruits are most at risk |
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Haemophilus Influenzae
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-small gram neg. coccobacillary rod, produces IgA protease, aerosol transmission, most INVASIVE disease causing epiglottitis and meningitis come from capsular type B (polyribitol phosphate)
C: HaEMOPhilus: Epiglottitis, Meningitis, Otitis media, Pneumonia -culture on chocolate agar requiring factor V(NAD) and X (hematin) for growth Tx: ceftriaxone for meningitis and rifampin prophylaxis for close contacts -vaccine: type B capsular polysaccharide conjugated to diphtheria toxoid/ other protein, given btwn 2 and 18 mo. of age |
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Enterobacteriaceae
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-E. Coli, Salmonella, Shigella, Klebsiella, Enterobacter, Serratia, Proteus
-Think COFFEe: All species have Capsular K antigen (virulence); somatic O antigen (polysaccharide of endotoxin); Flagellar (H) antigen found on motile species (not Shigella or Klebsiella); Ferment glucose and are oxidase negative; Enterobacteriaceae |
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Moraxella
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-3rd most common cause of otitis media in kids
-seen in COPD exacerbations |
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HACEK
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-low grade fever, heart vegetations with negative cultures
-Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella) -need to allow growth for 2 weeks in culture |
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Klebsiella
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-pneumonia in alcoholics and diabetics
-red currant jelly sputum -also cause of nosocomial UTIs - 3 A's: Aspiration pneumonia, Abscess in lungs, Alcoholics - 2nd most common cause of gram negative sespis in hospital (E.Coli is the most common) -Tx: ceftriaxone, ciprofloxacin |
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Lactose Fermenting Enteric bacteria
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-grow pink colonies on MacConkey's agar
-Lactose is KEE to grow on MacConKEE's agar: Klebsiella, E.Coli, Enterobacter and Citrobacter -on EMB: E.Coli grows in a metallic green color |
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Salmonella vs. Shigella
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-both are non-lactose fermenters, invade intestinal mucosa and can cause bloody diarrhea, transition via animal reservoir
-Salmonella have flagella and can disseminate hemotogenously (Salmon swim); only one that produces H2S; symptoms can be prolonged with antibiotic treatment and there is typically a monocytic response: S. typhi causes typhoid fever (fever, diarrhea, headache, rose spots on abdomen, can remain in gall bladder chronically) -Shigella: more virulent, don't have flagella but can propel themselves by actin polymerization, trasition via "Food, Fingers, Feces, Flies" |
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Yersinia Enterocolitica
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Transmitted from pet feces(puppies), contaminated milk, or pork
Outbreaks common in day-care Can mimic Chron's or appendicitis |
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Bugs causing Food Poisoning
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-Vibrio parahaemolyticus and V. vulnificus in contaminated SEAFOOD. V. vulnificus can also cause wound infections from contact with contaminated shellfish.
-B. cerus in reheated rice and S. aureus in meats, mayo, custard *both start quickly and end quickly* -Clostridium perfringens in reheated meat dishes -C. botulinum in improperly canned foods (bulging cans) -E.Coli 0157:H7 in undercooked meat -Salmonella in poultry, meat and eggs |
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Bugs causing bloody diarrhea
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Campylobacter: comma- or s- shaped; growth at 42C; oxidase positive; secretes LT like toxin and unknown toxin to kill mucosal cells
Salmonella: lactose negative; flagellar motility; self limiting Shigella: lactose negative; very low ID50; produces Shiga toxin (inhibits 60S ribosome inhibiting protein sythesis) Enterohemorrhagic E.Coli: 0157:H7; can cause HUS; makes Shiga-like toxin Enteroinvasive E.Coli: looks like 0157:H7 but has a FEVER; invades colonic mucosa Yersinia enterolitica: day care outbreaks; psuedoappendicitis C. diff: (causes both watery and bloody) psuedomembranous colitis Entamoeba histolytica: protozoan |
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Bugs that cause Watery Diarrhea
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Enterotoxigenic E.Coli: Traveler's diarrhea; produces ST (cGMP) and LT (cAMP) toxins
V. Cholera: comma-shaped; rice-water diarrhea C. perfringens: also causes gas gangrene Protozoa: Giardia, Cryptosporidium (in immunocompromised) Viruses: Rotovirus, Adenovirus, Norwalk virus (norovirus) |
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cAMP inducers
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-V. Cholera permanently activates Gs (rice water diarrhea)
-Pertussis toxin disables Gi (whopping cough) also promotes lymphocytosis by inhibiting chemokine receptors -E.Coli - Heat Labile Toxin -Bacillus anthracis has Edema Factor (EF), bacterial adenylate cyclase (increases cAMP) *Cholera, pertussis and E.coli toxins act via ADP ribosylation to permanently activate adenylate cyclase (increasing cAMP), while anthrax EF is an adenylate cylase |
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Legionella Pneumophilia
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-gram negative rod; poorly gram stains (use silver stain); grows on charcoal yeast extract culture with iron and cysteine; aerosol transmission from water source, air conditioner (no person to person transmission)
C: Legionnaires' disease: severe pneumonia; Pontiac fever: mild influenza Tx: erythromycin "French Lgionnaire(soldier) with silver helmet, sitting on a campfire (charcoal) with his iron dagger - he's no sissy (cystine) |
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Bacteroides fragilis vs. Melaninogenicus and Fusobacterium
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-see abcess in patients with major TRAUMA to the intestine (not found in the mouth)
-NOT usually associated with aspiration pneumonia -anaerobic, tx: with metronidazole -M and F are found in the mouth and can be associated with aspiration pneumonia |
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Pseudomonas Aeruginosa
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C: PSUEDOmonas (wound and burn infections): Pneumonia (esp. in CF); Sepsis (black skin lesions); External otitis (swimmer's ear); UTI; Drug use (endocarditis, rt. sided like S. aureus) and Diabetic Osteomyelitis; also hot tub folliculitis
-aerobic gram negative rod; non-lactose fermenting, oxidase positive -produces pyocyanin(blue-green) pigment with a grape like odor -comes from a water source -produces endotoxin (fever, shock) and exotoxin A (inactivated EF-2) -Tx: aminoglycosides plus extended-spectrum penicillin(piperacillin, ticarcillin) |
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Helicobacter pylori
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C: gastritis and up to 90% of duodenal ulcers; risk factor for peptic ulcer, gastric adenocarcinoma and lymphoma
-gram negative rod, urease positive (urease breath test) -creates alkaline environment -Tx: triple therapy: 1)bismuth (pepto-bismol), metronidazole and either tetracycline or amoxicillin; or 2)(more expensive) metronidazole, omeprazole (PPI) and clarithromycin |
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Zoonic Bacteria
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"Big Bad Bugs From Your Pet"
-Bartonella henselae: cat scratch fever from a cat scratch -Borrelia burgdorferi: Lyme disease from tick bites; Ixodes ticks live on deer and mice -Brucella spp: Brucellosis/Undulant fever; dairy products, contact with animals (think meat packer, farmer, vet, travler's consuming dairy) -Francisella tularensis: Tularemia; tick bite, rabbits, deer; see an ulcer in the skin -Yersinia pestis: Plague; flea bite, rodents, prarie dogs (think camping in AZ)*if suspected give gentamycin* -Pasteurella multocida: Cellulitis; animal bite from dog or cat |
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Gardnerella vaginalis
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-pleomorphic, gram-variable rod
-causes vaginosis (off-white/gray vaginal discharge with "fishy" smell), nonpainful -Mobiluncus, an anareobe, is also involved -sexually transmitted -Tx: metronidazole -clue cells, vaginal epithelial cells covered in bactera, are visible under the microscope |
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Mycobacterium Tuberculosis
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Infection in nonimmune host (usually a child): infection --> primary tb (ghon complex: TB granulomas (ghon focus-usually in lower lobe) with lobar and perihilar lymph node involvement)
Can lead to 1)heal by fibrosis->immunity and hypersensitivity ->Tuberculin positive 2) progressive lung disease (HIV, malnutrition) -> death (rare) 3) severe bacteremia -> miliary TB -> death 4) preallergic lymphatic or hematogenous dissemination -> dormant tubercle bacilli -> Reactivation in adult life -> either 1)Extrapulmonary TB (CNS-tuberculoma/meningitis; Vertebral body - Pott's disease; lymphadenitis; renal; GI) or 2)Secondary TB - Fibrocaseous cavitary lesion (usually in the upper lobe) Partially immune host (usually adult): Reinfection --> secondary TB -> fibrocaseous lesion |
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Mycobacteria
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M. Tuberculosis: often resistant to multiple drugs; symptoms include fever, night sweats, weight loss and hemoptysis
M. kansasii: pulmonary TB like symptoms M. scrofulaceum: cervical lymphadenitis in kids M. avium-intracellulare: often resistant to multiple drugs; causes disseminated disease in AIDS (marker of a CD4+ count <50) *All mycobacterium are acid-fast (meaning wash with acid doesn't dissolve methylene blue stain)* |
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Mycobacterium Leprae
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-acid-fast bacillus that likes cool temperatures: infecting skin and superficial nerves; cannot be grown in vitro
-reservoir in US: armadillos C: Leprosy (Hansen's disease) that has 2 forms: lepromatous (worse due to failure of cell mediated immunity, leads to death) and tuberculoid (self-limited) Symptoms: lepromatous - loss of eyebrows, nasal collapse, lumpy earlobe and "leonine facies" Tx: long term oral dapsone (toxicity is hemolysis and methemoglobinemia); alt. tx: rifampin and combo of clofazimine and dapsone |
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Rickettsiae
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-obligate intracellular anaerobes (true for Chlamydiae as well) that need CoA and NAD; cause classic triad of headache, fever and rash (vasculitis)
-all except Coxiella are transmitted by arthropod; Coxiella is atypical rickettsia becase it is transmitted via aerosol and causes pneumonia Tx: tetracyclin is treatment of choice for most Rickettsial infections |
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Rickettsial diseases and vectors
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"Rickettsia on the wRists and Typhus on the Trunk" - Rickettsial rash starts on hands and feet, Typhus starts centrally and spreads out
R. rickettsii: Rocky Mountain Spotted Fever (tick) R. typhi: Endemic typhus (fleas) R. prowazekii: Epidemic typhus (human body louse) Ehrlichia: Ehrlichiosis (tick) Coxiella burnetii: Q fever (inhaled aerosols) - Q is for Queer because there is no rash, no vector, negative Weil-Felix (cross reacting Proteus vulgaris antigens for diagnosis of Rickettsia), causitive organism (endospore) can survive outside for a long time, and doesn't have Rickettsia genus name *Tx: all are treated with tetracycline* |
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Rickettsia Rickettsii
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C: Rocky Mountain Spotted Fever from a tick bite
Symptoms: rash on palms and soles (migrating to wrists, ankles and last trunk), headache, fever -endemic to the EAST COAST *palm and sole rash seen in RMSF, syhilis and coxsackievirus A (hand, foot and mouth diseae)* |
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Weil-Felix Reaction
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-assay for antirickettsial antibodies
-cross-react with Prtoeus antigen -usually positive for typhus and RMSF but not Q fever |
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Chlamydiae
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-cannot make its own ATP, obligate intracellular anaerobes, no peptidoglycan or muramic acid, cause mucosal infections
-has 2 forms: 1)Elementary body which is small and dense Entering the cell via endocytosis 2) initial or Reticulate body that Replicates by fission; lab diagnosis - cytoplasmic inclusions seen on Giemsa or fluorescent antibody-stained smear -C. trachomatis causes Reiter's syndrome (reactive arthritis, nogonococcal urethritis, conjunctivitis), and PID; complication Fitz-Hugh Curtis syndrome (perihepatits), sterility, ectopic preg. and chronic pain -C. pneumoniae and C. psittaci (bird/avian reservoir) cause atypical pheumonia: transmitted by aerosol -Tx: erythromycin or tetracycline |
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Chlamydiae life cycle
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Attachment and entry of elementary body --> formulation of Reticulate body --> multiplication of reticulate bodies by binary fission --> reorganization of reticulate bodies into elementary bodies (see development of large cytoplasmic inclusion) --> multiplication ceases --> release of extracellular infections elementary bodies --> attatchment and entery of elementary body (starts over)
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Chlamydia Trachomatis serotypes
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Types A,B and C: cause chronic infection and blindness in Africa (ABC = Africa/Blindness/Chronic infection)
Types D-K: urethritis/PID, ectopic pregnancy, neonatal pneumonia, or neonatal conjunctivitis (neonatal stuff aquired during passage through birth canal, can treat with oral erythromycin) Types L1, L2, and L3: Lymphogranuloma venereum (acute lymphadenitis - positive Frei test) |
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Spirochetes
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-spiral-shaped bacteria with axial filaments (specialized periplasmic flagella)
-include Borrelia, Leptospira, and Treponema (BLT. B is Big) -only Borrelia can be visualized with aniline dyes (Wright's or Giemsa stain) in light microscopy -Treponema can be seen in dark-field microscopy |
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Leptospira interrogans
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-looks like a question mark found in water contaminated with animal pee
-Symptoms: flulike, fever, headache, abdominal pain, and jaundice - prevalent in the tropics -Weil's disease (icterohemorrhagic leptospirosis) - severe form with jaundice and azotemia from liver and kidney dysfunction, fever, hemorrhage and anemia Tx: empirically with doxycycline or erythromycin |
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Borrelia burgdorferi
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C: Lyme disease (common in northeastern US in the summer months) and is transmitted by tick Ixodes, classic symptom is erythema chronicum migrans (expanding "bull's eye" red rash with central clearing) and can also affect joints, CNS and heart
-mice are important reservoirs and deer are required for the tick life cycle Stages: 1) erythema chronicum migrans, flulike symptoms 2) neurologic and cardiac manifestations 3) chronic monoarthritis and migratory polyarthritis "BAKE a Key Lyme pie: Bell's palsy, Arthritis, Kardiac block, Erythema migrans" Tx: doxycycline |
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Treponemal disease
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-spirochetes
-T. pallidum causes syphilis -T. pertenue causes yaws (tropical infection that is not an STD, but VDRL is positive); see disfigurement of the face |
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Treponema Pallidum
|
C: Syphillus
Symptoms: PRIMARY: presents with painless chancre (localized) SECONDARY: disseminated disease with constitutional symptoms, maculopapular rash (palms and soles), condylomata lata (warm wart like lesion in moist areas); there are many treponemes in the chancres of primary and secondary syphilis TERTIARY: gummas (granulomas in bone and skin), aortitis, neurosyphilis (tabes dorsalis), Argyll Robertson pupil (prostitute's pupil: accommodates but doesn't react) *Signs of neurosyphillus: broad based gait, positive Romberg, Charcot joints, stroke w/o HTN* CONGENITAL: saber shins, saddle nose (bone and teeth are affected), CN VIII deafness, Hutchinson's teeth |
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VDRL vs. FTA-ABS
|
FTA-ABS: specific for treponemes, turns positive in earliest disease and remains positive the longest ("FTS-ABS = Find The Antibody-ABSolutely")
-Active infection (+VDRL, +FTA); Probably false positive (+VDRL, -FTS); Successfully treated (-VDRL, +FTS) |
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VDRL False Positives
|
-detects nonspecific antibody that reacts with beef cardiolipin
-used for diagnosis of syphilis (cheapest, easiest test to do; should be done first and confirmed with a FTS-ABS) but has many biologic false positives -things that cause false positives: VDRL: Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus and Leprosy |
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Mycoplasma Pneumoniae
|
-no cell wall (packed with sterols), not seen on gram stain, only bacterial membrane with cholesterol and common in patients <30 (frequent outbreaks in military recruits or prisons)
C: classic cause of atypical pneumonia (insidious onset, headache, nonproductive cough, diffuse interstitial infiltrate); Xray looks wors than the patient -High titers of cold agglutinins (IgM) and grown on Eaton's agar Tx: tetracycline or erythromycin (penicillin resistant because there is no cell wall) |
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Candida Albicans
|
-systemic or superficial fungal infection (budding yeast with pseudohyphae in culture at 20C; germ tube formation at 37C)
C: thrush esophagitis in immunocompromised patients, endocarditis in IV drug users, vaginitis (post-antibiotic), diaper rash -transmission is by inhalation of spores, no person to person spread -Tx: nystatin for superficial infection (swish and swallow) and amphotericin B for serious systemic infection |
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Histoplasmosis
|
Location: Missisippi and Ohio river valleys; found in bird or bat droppings; intracellular (tiny yeast inside macrophages); 3-5 micrometers
C: pneumonia |
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Blastomycosis
|
Location: States east of the Mississippi Riover and Central America.
-"Big, Broad-Based Budding" Cold = Mold, Heat = Yeast; culture on Sabouraud's agar, 5-15 micrometers -C: inflammatory lung disease and can disseminate to skin and bone, forms granulomatous nodules |
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Coccidioidomycosis
|
Location: Southwestern US (Cali, AZ, NM); San Joaquin Valley or desert (desert bumps) "valley fever"
-C: pneumonia and meningitis; can disseminate to bone and skin -spherule filled with endospores, 20-60 micrometers |
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Paracoccidioidomycosis
|
Location: Rural Latin America
-"captain's wheel" appearance |
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Systemic Mycoses (histo, blasto, coccidio, paracoccidio)
|
-all are caused by DIMORPHIC fungi which are grown in soil (low temperature) and yeast in tissue (at higher/body temp 37c) EXCEPT coccidioidomycosis that is spherule in tissue
-all cause pneumonia and can disseminate -Tx: fluconazole or ketoconazole for local infection; amphotericin B for systemic (systemic can mimic TB: granuloma formation) *Side note: most fungal spores are ASEXUAL (both coccidio and histo are transmitted by inhalation of asexeual spores)* |
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Malassezia furfur
|
C: cutaneous mycoses (tinea pedis (athlete's foot), cruris (jock itch), corporis (ringworm), capitis (scalp); occurs in hot, humid weather
Tx: topical miconazole, selenium sulfide (selsun: dandruff shampoo) "Spagetti and meatball" appearance on KOH prep |
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Cutaneous Mycoses (cont.)
|
-pruritic lesions with central clearing resembling a ring
-caused by dermatophytes (microsporum, trichophyton, and epidermophyton) -will see mold hyphae in KOH prep, NOT DIMORPHIC -pets are reservoir for Microsporum and can be treated with topical azoles |
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Opportunistic fungal infections (Candida and Aspergillus)
|
-Candida: thrush in immunocompromised (neonates, steroids, AIDS, diabetes), vulvovaginitis (high pH, diabetes, use of antibiotics), disseminated candidiasis (to any organ), chronic mucocutaneous candidiasis; germ tube test is diagnostic
--> psuedohyphae + budding yeasts -Aspergillus fumigatus: allergic bronchopulmonary aspergillosis, lung cavity aspergilloma ("fungus ball"), invasive aspergillosis (especially in immunocompromised individuals and those with chronic granulomatous disease); MOLD with septate hyphae that branch at a V-shaped (45 degree angle), NOT DIMORPHIC --> 45 degree angle branching septate hyphae, rare fruiting bodies |
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Opportunisitic Fungal Infections (Cryptococcus and Mucor/Rhizopus spp.)
|
-Cryptococcus neoformans: cryptococcal meningitis, cryptococcosis; heavily encapsulated yeast; NOT DIMORPHIC; found in soil and pigeon poop; culture on Sabouraund's agar and stains with INDIA INK, latex agglutinatiom test detects polysaccharide capsilar antigen; "soap bubble" lesions in the brain
--> 5-10 micrometer yeasts with wide capsular "halo", narrow-based unequal budding -Mucor and Rhizopus spp: Mucormycosis; MOLD with irregular neoseptate hyphae branching at wide angles(>90 degrees); disease is mostly in ketoacidotic diabetic and leukemic patients; can proliferate in walls of blood vessels and cause infarction and necrosis of tissue; rhinocerebral, frontal lobe abscesses --> irretular broad (empty looking) nonseptate hyphae, wide-angle branching |
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Pneumocystis jiroveci (formerly carinii)
|
-yeast (originally classified as a protozoan), inhaled
C: diffuse interstitial pneumonia (PCP); most infections are asymptomatic, immunosuppression (eg. AIDS) predisposes to disease -diffuse bilateral CXR appearance, diagnosed by lung biopsy or lavage (methenamine silver stain of lung tissue) -Tx: TMP/SMX, pentamidine, dapsone -start prophylaxis when CD4<200 cells/mL in HIV patients |
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Sporothrix Schenckii
|
-yeast forms with unequal budding; dimorphic fungus living on vegetation
-traumatically introducedinto the skin, typically by a thorn ("rose gardener's disease"), causes local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis) C: sporotrichosis, little systemic illness, cigar-shaped budding yeast visible in pus Tx: itraconazole or potassium iodide |
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Giardia Lamblia
|
Disease: bloatin, flatulence, foul-smelling diarrhea (often seen in campers/hikers)
Transmission: cysts in water Diagnosis: trophozoites or cysts in stool Treatment: metronidazole |
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Trichomonas Vaginalis
|
Disease: Vaginitis: "frothy" foul-smelling, greenish-yellow discharge, itching and burning "strawberry mucosa"
Transmission: Sexual Diagnosis: Trophozoites (corkscrew motility) on wet mount Treatment: metronidazole |
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Trypanosoma Cruzi
|
Disease: Chagas' disease (dilated cardiomyopathy, megacolon, megaesophagus); predominately in South America
Transmission: Feduviid bug (kissing bug) Diagnosis: Blood smear Treatment: Nifurtimox |
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Trypanosoma (T. gambiense, T. rhodesiense)
|
Disease: African Sleeping Sickness
Transmission: Tsetse fly Diagnosis: Blood smear Treatment: Suramin for blood-borne disease or melarsoprol for CNS penetration |
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Leishmania Donovani
|
Disease: Visceral leishmaniasis (kala-azar): spiking fevers, hepatoslenomegaly, pancytopenia
Transmission: Sandfly Diagnosis: Macrophages containing amastigotes Treatment: Sodium stibogluconate |
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Plasmodium (P. vivax, P. ovale, P. malariae, P. falciparum)
|
Disease: Malaria - cyclic fever, headache, anemia, splenomegaly; Malaria - severe (cerebral) with P. falciparum; P. vivax and P. ovale have dormant forms in liver (hypnozoites) --> relapsing malaria
Transmission: Mosquitos (anopheles) Diagnosis: Blood smear Treatment: Chlorquine (primaquine to prevent relapse caused by P. vivax, P. ovale), sulfadoxine + pyrimethamine, mefloquine, quinine |
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Isospora/Cyclospora
|
-cause severe diarrhea in immune compromised patients
tx: TMP/SMX |
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Babesia
|
Disease: Babesiosis - fever and hemolytic anemia, predominately in northeastern US
Transmission: Ixodes tick Diagnosis: Blood smear, no RBC pigment, appears as "maltese cross" Treatment: Quinine, clindamycin |
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Cryptosporidium
|
Disease: Severe diarrhea in AIDS; mild disease (watery diarrhea) in non-immunocompromised
Transmission: Cysts in water Diagnosis: Cystson acid-fast stain Treatment: none |
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Toxoplasma Gondii
|
Disease: Brain abscess in HIV, birth defects (ring-enhancing brain lesions)
Transmission: Cysts in meat or cat feces; crosses placenta (pregnant women should avoid cats) Diagnosis: serology, biopsy Treatment: Sulfadiazine + pyrimethamine |
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Entamoeba Histolytica
|
Disease: Amebiasis - bloody diarrhea (dysentery), liver abscess, RUQ pain
Transmission: Cysts in water Diagnosis: serology and/or trophozoites or cysts in stool; RBCs in cytoplasm of entamoeba Treatment: Metronidazole and iodoquinol |
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Naegleri Fowleri
|
Diagnosis: Rapidly fatal meningoencephalitis
Transmission: Swimming in freshwater lakes (enter via cribiform plate) Diagnosis: Amoebas in spinal fluid Treatment: none |
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Acanthomoeba
|
Disease: chronic granulomatous brain infection in AIDS patients; corneal infection/keratinitis in contact lens wearers
Treatment: antimicrobial eyedrops |
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Enterobius vermicularis
|
"pinworm" (roundworm)
Disease: Intestinal infection and pruritis around the anus(scotch tape test) Transmission: Food contaminated with eggs Treatement: Mebendazole/pyrantel pamoate |
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Ascaris Lumricoides
|
"giant roundworm" (roundworm)
Disease: Intestinal infection, eggs visible in the feces Transmission: Fecal oral Treatment: Mebendazole/pyrantel pamoate |
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Trichinella Spiralis
|
(roundworm)
Disease: Inflammation of the muscle (larvae encyst in the muscle), periorbital edema Transmission: Undercooked meat (usually pork) Treatment: Thiabendazole |
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Strongyloides Stercoralis
|
(roundworm)
Disease:intestinal infection causing vomitin, diarrhea and anemia Transmission: Larvae in the soil penetrate the skin Treatement: Ivermectin/thiabendazole |
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Ancylostoma duodenale, Necator americanus
|
"hookworms" (roundworm)
Disease: Intestinal infection can cause anemia (sucks blook from intestinal walls) Transmission: Larvae penetrate skin of feet Treatment: Mebendazole/pyrantel pamoate (worms are BENDy; treat with meBENDazole) |
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Dracunculus Medinensis
|
(roundworm)
Disease: Skin inflammation and ulceration, bug "pokes out the uterus" and lays eggs Transmission: Drinking water Treatment: Niridazole or pull it out with a stick |
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Onchocerca volvulus
|
(roundworm)
Disease: River blindness, with skin nodules and "lizard skin"; can have allergic reaction to the microfilaria Transmission: Female black flies Treatment: Ivermectin (IVERmectin for rIVER blindness) |
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Loa Loa
|
(roundworm)
Disease: Swelling in the skin (can see worm crawling in conjunctiva) Transmission: Deer fly Treatment: Diethylcarbamazine |
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Wuchereria Bancrofti
|
(roundworm)
Disease: Elephantitis -blockage of lymphatics Transmission: Female mosquito Treatment: Diethylcarbamazine |
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Toxocara Canis
|
(roundworm)
Disease: Granulomas (if in retina = blindness) and visceral larba migrans Transmission: Food contaminated with eggs Treatment: Diethylcarbamazine |
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Taenia Solium
|
(tapeworm - cestode)
Disease: Intestinal tapeworms; cysticercosis and neurocysticercosis (mass lesions in the brain, "swiss cheese" appearance) Transmission: Ingestion of larvae encysted in undercooked pork Treatment: Praziquantel for intestinal worms and cysticercosis; albendazole for neurocysticercosis |
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Echinococcus Granulosus
|
(tapeworm - cestode)
Disease: Cysts in liver, cause anaphylaxis if echinococcal antigens are released from cyts Transmission: Eggs in dog poop and can be ingested causing liver cysts Treatment: Albendazole |
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Schistosoma
|
(flukes - trematodes)
Disease: Granulomas, fibrosis, and inflammation of spleen and liver Transmission: Snails are hosts and cercariae penetrate the skin Treatment: Albendazole |
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Clonorchis Sinensis
|
(flukes - trematodes)
Disease: Inflammation of the biliary tract --> pigmented gall stones; also associated with cholangiocarcinoma Transmission: Undercooked fish Treatment: Praziquantel |
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Paragonimus Westermani
|
(fluke - trematode)
Disease: Inflammation and secondary bacterial infection of the lung Transmission: undercooked crab meat |
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Nematode routes of infection
|
Ingested (You'll get sick if you EAT these) - Enterobius, Ascaris, Trichenella
Cutaneous (These get into your feet from the SANd) - Strongyloides, Ancylostoma, Necator |
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Parasite Hints (brain cysts/seizures; liver cyst; B12 deficiency; biliary tract disease; hemoptysis; portal HTN; hematuria, bladder cancer; microcytic anemia; perianal pruritus)
|
Brain cysts/seizures - Taenia solium (cysticercosis)
Liver cysts - Echinococcus granulosus B12 def - Diphyllobothrium latum Biliary tract disease - Clonorchis sinensis Hemoptysis - Paragonimus wetermani Portal HTN - Schistosoma mansoni Hematuria/bladder cancer - Schistosoma haematobium Microcytic anemia - Ancylostoma, Necator Perianal pruritus - Enterobius |
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Tricky T's
|
Typhoid fever - Salmonella typhi
Typhus - caused by R. typhi, R. prowazekii, and R. tsutsugamushi Chlamydia trachomatis - bacteria, STD Treponema - spirochete; causes syphilis (T. pallidum) or yaws (T. pertenue) Trichomonas vaginalis - protozoan, STD Trypanosoma - protozoan, causes Chagas' disease Toxoplasma - protozoan, a TORCH infection Trichinella spiralis - nematode in undercooked meat |
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Viral genomes
|
DNA: all viruses EXCEPT parvoviridae are dsDNA; all are linear exept papilloma, polyoma, and hepadnavirus (circular)
RNA: all RNA viruses EXCEPT Reoviridae are ssRNA NAKED: nucleic acids from most dsDNA (execpt pox and HBV) and + strand ssRNA (mRNA) viruses are infectious; naked nucleic acids of - strand ssRNA and dsRNA viruses are NOT infectious, require enzymes contained in teh complete virion |
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Viral envelopes
|
NAKED (nonenveloped) viruses include: Calcivirus, Picornavirus, Reovirus, Parvovirus, Adenovirus, Papilloma, and Polyoma
"Naked CPR and PAPP smear -generally enveloped viruses acquire envelopes from the plasma membrane when they exit the cell; exceptions are herpes virus which get the envelope from nuclear membranes |
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Viral ploidy
|
-all viruses are haploid (1 copy of DNA or RNA) except retroviruses that have 2 identical ssRNA molecules
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Viral Replication
|
DNA: all replicate in nucleus (except poxvirus)
RNA: all replicate in cytoplasm (excetp influenza and retrovirus) |
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Viral Pathogens
|
DNA enveloped viruses: Herpesviruses (HSV types 1 and 2, VZV, CMV, EBV), HBV, smallpox virus
DNA nucleocapsid: Adenovirus, papillomaviruses, parvovirus RNA enveloped: Influenza, parainfluenza, RSV, meases, mumps, rubella, rabie, HTLV, HIV RNA nucleocapsid: Enteroviruses (poliovirus, coxsackievirus, echovirus, HAV), rhinovirus, reovirus (rotavirus) |
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DNA Virus Characteristics
|
-are HHAPPPPPy viruses (Hepadna, Herpes, Adeno, Pox, Poly, Parvo, Papilloma)
-are double stranded: except PARVO (single stranded) -are linear: exceptpapilloma and polyoma (circular and supercoiled) and hepadena (circular and incomplete) -are icosahedral: except pox (complex -replicate in the nucleus: except pox (carries it's own DNA dependent RNA polymerase) |
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Herpesvirus
|
Envel: Y
DNA Struc: DS linear Med Imp: HSV 1 - oral (and some genital) lesions, keratocunctivitis; HSV 2 - genital (and some oral) lesions; VZV - chickenpox, zoster, shingles; EBV - mononucleosis, Burkitt's Lymphoma; CMV - infection in immunosuppressed pts. (esp. transplant recipients), congenital defects; HHV-6 - roseola (exanthem subitum); HHV-8 - Kaposi's sarcoma (associated with herpesvirus (KSHV)) |
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Hepadnavirus
|
Envel: Y
DNA Struc: DS - partially circular Med Imp: HBV - acute or chronic hepatitis, vaccine available, not a retrovirus but has reverse transcriptase |
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Adenovirus
|
Envel: Y
DNA Struc: DS linear Med Imp: Febrile phayngitis (sore throat), pneumonia, conjunctivitis ("pink eye") |
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Parvovirus
|
Envel.: N
DNA Struc.: SS linear (-) Med Imp: B19 virus - aplastic crisis in sickle cell disease, "slapped cheeks" rash (erythema infectiosum - fifth disease) - arthralgias/arthritis in adults around kids, hydrops fetalis in preg. women |
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Papillomavirus
|
Envel: N
DNA Stuc: DS circular Med Imp: HPV - warts, CIN, cervical cancer |
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Polyomavirus
|
Envel: N
DNA Stuc: DS circular Med Imp: JC - progressive multifocal leukoencephalopathy (PML) in HIV |
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Poxvirus
|
Envel: Y
DNA Struc: DS linear (largest DNA virus) Med Importance: Smallpox, although eradicated, could be used in germ warfare; vaccine - cowpox ("milkmaid's blisters"); molluscum contagiosum (see in AIDS patients) |
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Picornavirus
|
Envel: N
RNA Struc: SS + linear Capsid: Icosahedral Med Imp: Poliovirus - polio-Salk/Sabin vaccines (IPV/OPV); Echovirus - aseptic meningitis; Rhinovirus - "common cold"; Coxsackievirus - aseptic meningitis, herpangina - febrile phayngitis, hand, foot and mouth disease, myocarditis; HAV - acute viral hepatitis PicoRNAvirus = small RNA virus PERCH on a "peak" (pico) |
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Calcivirus
|
Envel: N
RNA Struc: SS + linear Capsid: Icosahedral Med Imp: Norwalk virus - viral gastroenteritis |
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Reovirus
|
Envel: N
RNA Struc: DS linear (10-12 segments) Capsid: Icosahedral (double) Med Imp: Reovirus - colorado tick fever; rotavirus - #1 cause of fatal diarrhea in kids |
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|
Flavivirus
|
Envel: Y
RNA Struc: SS + linear Capsid: Icosahedral Med Imp: HCV; Yellow Fever (arbovirus); Dengue (arbovirus) - "back breaking pain" and fever; St. Louis Encephalitis (arbovirus); West Nile Virus (arbovirus) - usually asymptomatic, but can have encephalitis with decreased conciousness and motor paresis |
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Togavirus
|
Envel: Y
RNA Stuc: SS + linear Capsid: Icosahedral Med Imp: Rubella (German measles); Easterm equine encephalitis (arbovirus); Western equine encephalitis (arbovirus)d |
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|
Retrovirus
|
Envel: Y
RNA Stuc: SS + linear Capsid: Icosahedral Med Imp: have reverse transcriptase; HIV - AIDS; HTLV - Tcell leukemia |
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|
Coronavirus
|
Envel: Y
RNA Struc: SS + linear Capsid: Helical Med Imp: Coronavirus - "common cold" and SARS |
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|
Orthomyxovirus
|
Envel: Y
RNA Struc: SS - linear (8 segments) Capsid: Helical Med Imp: Influenza virus |
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|
Paramyxovirus
|
Envel: Y
RNA Struc: SS - linear (nonsegmented) Capsid: Helical Med Imp: (PaRaMyxovirus) Parainfluenza - croup; RSV - bronchiolitis in babies (tx: ribavirin); Measles - Rubeola; Mumps - parotiditis, orchiditis |
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|
Rhabdovirus
|
Envel: Y
RNA Struc: SS - linear Capsid: Helical Med Imp: Rabies |
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|
Filovirus
|
Envel: Y
RNA Struc: SS - linear Capsid: Helical Med Imp: Ebola/Marburg hemorrhagic fever - often fatal! |
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|
Hepevirus
|
Envel: N
RNA Struc: SS + linear Capsid: Icosahedral Med Imp: HEV - acute hepatitis |
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|
Arenavirus
|
Envel: Y
RNA Struc: SS + circular Capsid: Helical Med Imp: LCV - lymphocytic choriomeningitis; Lassa fever encephalitis - spread by mice |
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|
Bunyavirus
|
Envel: Y
RNA Struc: SS + circular (3 segments) Capsid: Helical Med Imp: California encephalitis (arbovirus); Sandfly/Rift Valley fevers; Crimean-Congo Hemorrhagic Fever (arbovirus); Hantavirus - hemorrhagic fever, pneumonia from a deer mouse |
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|
Deltavirus
|
Envel: Y
RNA Struc: SS - circular Capsid: Helical Med Imp: HDV - acute or chronic hepatitis, need to co-infect with HBV |
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|
Viral Vaccines
|
-Live attenuated: induce humoral and cell mediated immunity but have reverted to virulence on rare occasions; measles, mumps, rubella, Sabin polio, VZV, yellow fever, smallpox
-Killed: induce only humoral immunity but are stable (won't revert to virulence); Rabies, Influenza, salk Polio and HAV (RIP Always) Recombinant - HBV (antigen = HBsAg) *Dangerous to give live vaccines to immunocompromised patients or their close contacts |
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Viral Genetics (Recombination, Reassortment, Complementation, Phenotypic mixing)
|
Recombination: exchange of 2 genes between 2 chromosomes by crossing over w/in regions of significant base sequence homology
Reassortment: viruses with segmented genomes (influenza) exchange segments, high frequency recombination, cause of worldwide pandemics Complementation: when 1 of 2 viruses that infect the cell has a mutation that results in nonfunctional protein, nonmutated virus "complements" the mutated one by makin a functional protein serving both viruses Phenotypic Mixing: simultaneous infection of a cell with 2 viruses, genome of virus A can be partially or completely coated (forming pseudovirion) with the surfae proteins of virus B, type B protein coat determines the infectivity of phenotypically mixed virus; progeny from the infection have type A coat encoded by the type A genetic material |
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|
Negative Stranded Viruses
|
"Always Bring Polymerase Or Fail Replication Horribly"
Must transcribe negative strand into positive using RNA polymerase -Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthomyxoviruses, Filoviruses, Rhabdoviruses, and Hepatitis Delta virus |
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|
Segmented Viruses
|
"BOAR"
All are RNA viruses -Bunyavirus, Orthomyxovirus, Arenavirus, and Reovirus -segments can undergo reassortment, causing antigenic shifts that lead to world wide pandemics (eg. influenza has 8 segments - flu pandemics) |
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|
Herpesviruses
|
HSV1: D - gingivostomatitis, keratoconjuntivitis, temporal lobe encephalitis, herpes labialis; T - respiratory secretions, saliva
HSV2: D - Herpes genitalis, neonatal herpes; T - sexual contact, perinatal VZV: D - varicella-zoster (shingles), encephalitis, pneumonia; T - respiratory secretions EBV: D - Infectious mononucleosis, Burkitt's lymphoma; T - Respiratory secretions CMV: D - Congenital infection, mononucleosis (negative monospot), pneumonia, cells have "owl's eye" appearance; T - congenital, transfusion, sexual contact, saliva, urine, transplant (dx: buffy coat of centrifuged blood and CMV antigen) HHV8: D - Kaposi's Sarcoma (HIV patients) T - sexual contact |
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|
HSV Identification
|
Tzanck test - smear of an opened skin vesicle to detect multinucleated giant cells, used to assay for HSV-1, HSV-2, and VZV
-infected cells have intranuclear Cowdry A inclusions "Tzanck heavens I do no have herpes" |
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|
EBV
|
-herpesvirus that can cause mononucleosis
-infects B cells; characterized by fever, hepatosplenomegaly, pharyngitis, and lymphadenopathy (esp. posterior auricular nodes) -peak incidence is 15-20 years old ("peak kissing years") -positive heteropil antibody test, abnormal circulating cytotoxic T cells (atypical lymphocytes); monospot test - heterophil antibodies detected by agglutination of sheep RBCs -associated with development of Hodgkin's and endemic Burkitt's (Africa) |
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|
Picornavirus
|
PERCH: Poliovirus, Echovirus, Rhinovirus, Coxsackie, HAV
-RNA translated into 1 large polypeptide and cleaved by proteases into viral functional proteins -can cause aseptic (viral) meningitis (except rhino and HAV) |
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|
Rhinovirus
|
picornavirus, nonenveloped, cause of common cold, >100serologic types
"the Rhino has a runny nose" |
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|
Yellow Fever
|
-flavivirus, flavi = yellow (also an arbovirus) transmitted by Aedes mosquitos
-has a human or monkey resevoir -symptoms: high fever, black vomitus, and jaundice; councilman bodies (acidophilic inclusions) may be seen in the liver |
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|
Rubella Virus
|
-togavirus
-causes german measles; fever, lymphadenopathy, arthralgias, and a fine truncal rasj -causes mild disease in children but is a serious congenital infection (toRch) |
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|
Rotavirus
|
-most important global cause of infantile gastroenteritis
-segmented dsRNA virus (reovirus) and major cause of acute diarrhea in the US in the winter -Villous destruction with atrophy leads to decreased absorption of Na and water "ROTA = Right Out The Anus" |
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|
Influenza viruses
|
-orthomyxovirus, enveloped, ssRNA with 8 segments, contains hemagglutinin (HA) and neuraminidase (NA) antigens
-responsible for worldwide influenza epidemics; patients at risk for fatal bacterial superinfection -rapid genetic changes -Genetic Shift (pandemic): reassortment of viral genome (eg. human flu A virus recombines with swine flu A virus) -Genetic Drift (epidemic): Minor - (antigenic dhift) changes based on random mutation Treatment: Amantadine/Rimantadine useful for Influenza A (esp. prophylaxis), high level of resistance to this drug and no longer used; Zanamivir/Oseltamivir (neuraminidase inhibitors) useful for both influenza A and B -killed viral vaccine is major source of protection (given to elderly and healthcare workers) "Sudden Shift is more deadly than graDual Drift" |
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|
Paramyxoviruses
|
-cause disease in children
-croup (stridor and barking cough), measles, mumps and RSV |
|
|
Rubeola (measles) Virus
|
-paramyxovirus causing measles
-Koplick spots (red spots with blue-white center on buccal mucosa) are diagnostic -Subacute Sclerosing Panencephalitis (SSPE) years later, encephalitis (1:2000) and giant cell pneumonia (rarely, usually in immunosuppressed) -rash spreads from head to toe "3C's of measles: Cough, Coryza (inflammation of mucus membranes), Conjunctivitis, and look for Koplick's spots" |
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|
Mumps
|
-paramyxovirus
-symptoms: Parotitis, Orchitis (inflammation of testes), and aseptic Meningitis; can cause sterility (esp. after puberty) "Mumps makes your parotid glands and testes as big as POM - poms" |
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|
Rabies Virus
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-Negri bodies are characteristic cytoplasmic inclusion in neurons infected; travels to the CNS by migrating in a retrograde fashion up nerve axons
-has bullet shaped capsid -has long incubation period (weeks to months) 0causes fatal encephalitis with seizures, hydrophobia, hypersalivation and pharyngeal spasm -more commonly from bite of a bat, racccoon and skunk than dog bites in the US |
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Arboviruses
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-transmitted by arthropods (mosquitos, ticks)
-classic examples: dengue fever and yellow fever; variant of Dengue in Southeast Asia is hemorrhagic shock syndrome ARBOvirus - ARthropod-BOne virus: Flavivirus, Togavirus, Bunyavirus "Fever Transmitted by Bites" |
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Spots! (Rubella, Rubeola, Varicella, Variola, Vaccinia)
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Rubella: togavirus, 3-day german measles
Rubeola: paramyxovirus, measles Varicella: herpesvirus, chichenpox and zoster Variola: poxvirus, smallpox (no longer present outside of lab) Vaccinia: poxvirus, strain used for vaccine |
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HAV
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-RNA picronavirus
-transmitted by fecal-oral route, short incubation (3 weeks) -no carriers "Hep A: Asymptomatic (usually), Acute, Alone (no carriers0" |
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HBV
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-DNA hepadnavirus
-transmitted parenterally, sexually, and by maternal-fetal routes -long incubation (3 months), carriers -cellular RNA polymerase transcribes RNA from DNA template; reverse transcriptase transcribes DNA genome from RNA intermediate; the virion enzyme is a DNA-dependent DNA polymerase "Hep B: Blood Borne" |
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HCV
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-RNA flavivirus
-transmitted primarily via blood and can sometimes resemble HBV in its course -common cause of hepatitis in IV drug users in the US "HepC: Chronic, Cirrhosis, Carcinoma, Carriers" |
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HDV
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-delta agent
-defective virus that requires HBsAg in its envelope -can coinfect with HBV or superinfect (worse prognosis), carriers "HDV - Defective and Dependent on HBV" |
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HEV
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-RNA hepevirus
-transmitted enterically and causes water-borne epidemics -resembles HAV in course, severity, and incubation -high mortality rate in pregnant women "HepE: Enteric, Expectant mothers, Epidemics" |
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Hepatitis Serologic Markers
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IgG HAVAb: indicates prior infection, protects against reinfection
IgM HAVAb: best test to detect HAVE HBsAg: antigen found on surface of HBV, continued presence indicates a carrier state Anti-HBsAg (HBsAb): provides immunity to hep B HBcAg: antigen associated with core of HBV Anti-HBcAg (HBcAb): positive during WINDOW PERIOD. IgM HBcAb is indicator of recent disease. IgG HBcAb means chronic disease HBeAg: second different antigenic determinant of HBV core, important indicator of active viral relication and transmissibility (Beware) Anti-HBeAg (HBeAb): indicates low transmissibility |
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HIV
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-diploid genome (2 molecules of RNA)
-p24 = rectangular capsid protein -gp41 and gp120 = envelop proteins -reverse transcriptase synthesizes dsDNA from RNA; dsDNA integrates into host genome -proteins: gag (viral core proteins (NC, CAp24, MA) pol (protease, reverse transcriptase, integrase) and env (gp120, gp41) -virus binds CXCR4 and CD4 on Tcells and CCR5 and CD4 on macrophages; homozygous CCR5 mutation = immunity, heterozygous mutation CCR5 = slower course |
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HIV diagnosis
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-presumptive diagnosis made with ELISA (sensitive, high false-positive rate and low threshold, RULE OUT test); postive results are confirmed with Western blot assay (specific, high false negative rater and high threshold RULE IN test)
*ELISA/Western Blot look for antibodies to viral proteins, tests are often falsely negative in first 1-2 months of HIV infection and falsely positive initially in babies born to infected moms (anti-gp120 crosses the placenta) -HIV PCR/viral load tests allow physician to monitor effect of the drug therapy on viral load -AIDS diagnosis <200 CD4+, HIV positive with AIDS indicator condition (PCP) or CD4/CD8 ratio is <1.5 |
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Opportunistic infections in AIDS
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BRAIN: Cryptococcal meningitis, toxo, CMV encephalopathy, AIDS dementia, PML (JC virus)
EYES: CMV retinitis MOUTH and THROAT: Thrush (Candida), HSV, CMV, oral hairy leukoplakia (EBV) LUNGS: Pneumocystis jiroveci pneumonia (PCP/PJP), TB, Histoplasmosis GI: cryptosporidiosis, Mycobacterium Avium-Intracellulare complex, CMV colitis, non-Hodgkin's lymphoma (EBV), Isospora belli SKIN: Shingles (VZV), Kaposi's sarcoma (HHV-8) GENITALS: genital herpes, warts, cervical cancer (HPV) |
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HIV-associated infections and CD4+ count
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<400: oral thrush, tinea pedis, reactivation of VZV, reactivation of TB, other bacterial infections (H.flu, S. pneumo, Salmonella)
<200: reactivation of HSV, cryptozporidiosis, Isospora, disseminated coccidioidomycosis, Pneumocystis pnuemonia <100: candidal esophagitis, toxoplasmosis, histoplasmosis <50: CMV retinitis and esophagitis, disseminated M. avium-intracellulare, cryptococcal meningoencephalitis |
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Neoplasms and Encephalitis associated with HIV
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Neoplasms: Kaposi's sarcoma (HHV*), invasive cervical carcinoma, primary CNS lymphoma, non-Hodgkin's lymphoma
Encephalitis: late course of HIV infection, virus gains CNS access via infected macrophages, microglial nodules with multinucleated giant cells |
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Prions
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-infectious agent that doesn't contain RNA or DNA, only proteins
-encoded by cellular genes -diseases: Creutzfeldt-Jakob disease (CJD-rapidly progressive dementia); kuru, scrapie (sheep), and "mad cow disease". -associated with spongiform encephalopathy -normal prions have α helical conformation, pathologic prions have β pleated sheets |
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Normal Flora
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SKIN: S. epidermidis
NOSE: S. epidermidis, colonized by S. aureus OROPHARYNX: Viridans group strep DENTAL PLAQUE: Strep mutans COLON: Bacteroides fragilis > E.Coli VAGINA: Lactobacillus, colonized by E.coli and Group B Strep |
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Common causes of Pneumonia
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NEONATES (<4wks): Group B Strep, E.Coli
KIDS (4wks - 18yrs): Viruses (RSV), Mycoplasma, Chlamydia pneumo, Strep. pneumo "Runts May Cough Sputum" ADULTS (18-40): Mycoplasma, C. pneumo, S. pneumo ADULTS (40-65): S. pneumo, H. flu, Anaerobes, Viruses, Mycoplasma ELDERLY: S. pneumo, viruses, anaerobes, H. flu, Gram - rods Special groups: nosocomial (Staph, gram - rods), immunocompromised (staph, gram - rods, fungi, viruses, PCP (w/HIV)), alcoholic/IV drug user (S. pneumo, Klebsiella, Staph), postviral (Staph, H. flu), atypical (mycoplasma, legionella, chlamydia) |
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Common Causes of Meningitis
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NEWBORN (0-6mo.): Group B Strep, E.Coli, Listeria
KIDS (6mo. - 6 yrs): Strep pneumo, Neisseria meningitidis, H. influenza type B, Enteroviruses 6-60yrs: N. meningitidis, Enteroviruses, S. pneumo, HSV 60+yrs: S. pneumo, gram - rods, Listeria Viral causes: enteroviruses (esp. coxsackie), HSV, HIV, West Nile, VZV In HIV: Cryptococcus, CMV, Toxo (brain abscesses), JC virus (PML) *Note: incidence of H. flu meningitis has decreased greatly due to the introduction of the vaccine* |
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CSF Findings in Meningitis
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Bacterial: increased pressure, PMNs, protein and decreased sugar
Fungal/TB: increased pressure, lymphocytes, protein and decreased sugar Viral: increased lymphocytes, normal/increased pressure, normal protein and sugar |
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Osteomyelitis
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Most people - S. aureus
Sexually active - N. gonorrhoeae (rare), septic arthritis more common Diabetics and drug addicts: Psuedomonas aeruginosa Sickle cell - Salmonella Prosthetic replacement - S. aureus and S. epidermidis Vertebral - M. Tuberculosis (Pott's Disease) Cat and dog bites/scratches -Pasturella multocida *ASSUME S. AUREUS with no other info, osteomyelitis occurs mostly in kids, elevated CRP and ESR are classic but nonspecific* |
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Urinary Tract Infections
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Ambulatory - E.Coli (50-80%), Klebsiella (8-10%)
Staph. saprophyticus (10-30%) us second most common cause in young, sexually active, ambulatory women Hospital - E.coli, Proteus, Klebsiella, Serratia, Pseudomonas Epidemiology: women to men 10:1 (short urethra colonized with fecal flora); Predisposing factors (flow obstruction, kidney surgery, catheterization, gynecologic abnormalities, diabetes, and pregnancy) UTI - dysuria, frequency, urgency, suprapubic pain vs. Pyelonephritis - fever, chills, flank pain, and CVA tenderness UTIs are mostly caused by ascending infections. Males: infants think congenital defects, elderly think enlarged prostate |
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UTI Bugs
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"SSEEK PP"
Serratia marcescens - some strains produce a red pigment, often nosocomial and drug resistant Staphylococcus saprophyticus: 2nd leading cause of community-aquired UTI in sexually active women E.Coli: leading cause of UTI, colonies show metallic sheen on EMB Eneterobacter: nosocromial and drug resistant Klebsiella pneumonia: large, mucoid capsule and viscous colonies Proteus mirabilis: causes "swarming motility" on agar, produces urease, associated with struvite stones Psuedomonas: usually nosocomial and drug resistant |
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ToRCHeAS Infections
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Toxo: "classic triad" of chorioretinitis, intracranial calcifications, and hydrocephalus; may be asymptomatic at birth
Rubella: deafness, cataracts, heart defects (PDA, pulmonary artery stenosis) and mental retardation CMV: petechial rash, intracranial calcification, mental retardation, hepatosplenomegaly, microcephaly, jaundice, 90% are asymptomatic at birth *blueberry muffin baby* HIV - hepatosplenomegaly, neurologic abnormalities, frequent infections HSV type 2: encephalitis, conjunctivitis, vesicular skin lesions, often asymptomatic at birth Syphylis: cutaneous lesions, hepatosplenomegaly, jaundice, saddle nose, saber shins, Hutchinson teeth, CN VIII deafness, rhinitis ("snuffles") *Others: Listeria (granulomas), E.Coli and group B can all be acquired placentally or from birth canal |
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PID
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Top Bugs: Chlamydia trachomatis (subacute, often undiagnosed): most common in US; Neisseria gonorrhoeae (acute, high fever)
-Cervical motion tenderness (chandelier sign), purulent cervical discharge -PID can include salpingitis (risk factor for ectopic, infertility, chronic pelvic pain and adhesions), endometriosis, hydrosalpinx and tubo-ovarian abscess -other STDs: Gardnerella (clue cells) and Trochomonas (motile on wet prep) |
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Nosocomial Infections
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*2 most common causes of nosocomial infections in US are E.Coli (UTI) and S. aureus (wound)*
Newborn nursery: CMV, RSV Urinary Catheterization: E.Coli and Proteus mirabilis Respitory Therapy Equipment: Pseudomonas ; presume when AIR or BURNS are involved Work in renal dialysis: HBV Hyperalimentation: Candida Water aerosols: Legionella; water source = legionella |
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Bug Hints
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Pus, empyema, abscess - S. aureus
Pediatric infection - H. influenza (including epiglottitis) Pneumonia in CF, burn - Pseudomonas Branching rods oral infection - Actinomyces Traumatic open wound - Clostridium perfringens Surgical wound - S. aureus Dog or cat bite - Pasteurella Currant Jelly sputum - Klebsiella Sepsis/meningitis in newborn - group B strep |
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Urethritis, cervicitis, PID, prostatis, epididymitis, arthritis, creamy purulent discharge
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Disease: Ghonorrhea
Bug: Neisseria |
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Painless Chancre
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Disease: Primary Syphillis
Bug: Treponema pallidum |
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Fever, lymphadenopathy, skin rashes, condylomata lata
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Disease: Secondary Syphillis
Bug: Treponema pallidum |
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Gummas, tabes dorsalis, general paresis, aortitis, Argyll Robertson pupil
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Disease: Tertiary Syphilis
Bug: Treponema Pallidum |
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Painful penile, vulvar or cervical ulcers; can cause systemic symptoms like fever, headache, myalgias
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Disease: Genital Herpes
Bug: HSV-2 |
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Urethritis, cervicitis, Reiter's syndrome, PID
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Disease: Chlamydia
Bug: Chlamydia trachomatis (D-K) |
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Ulcers, lymphadenopathy, rectal strictures
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Disease: Lymphogranuloma venereum
Bug: C. trachomatis (L1-L3) |
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Vaginitis, Straw-berry colored mucosa
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Disease: Trichomoniasis
Bug: Trichomonas vaginalis |
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Opportunistic infections, Kaposi's sarcoma, Lymphoma
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Disease: AIDS
Bug: HIV |
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Genital warts, koilocytes
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Disease: Condylomata acuminata
Bug: HPV 6 and 11 |
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Jaundice
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Disease: Hepatitis B
Bug: HBV |
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Painful genital ulcer, inguinal adenopathy
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Disease: Chancroid
Bug: Haemophilus ducreyi |
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Noninflammatory, malodorous discharge (fishy smell); positive whiff test, clue cells
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Disease: Bacterial vaginosis
Bug: Gardnerella vaginalis |
