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Clostridium general - micro app, ___robic, unique features, most common spp?
- Gram positive bacilli
- obligate anaerobes
- endospore-forming (location/shape of spores help speciate)
- C. perfringens is most common isolate
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Clostridium perfringens - habitat, disease, virulence factors, gram stain (specific), ID,
- habitat: normal flora GI, soil
- disease: food poisoning - toxin ingestion
- myonecrosis (gas gangrene) - α toxin released in tissues, lecithinase liquefies tissue
- vir: α toxin (in type A) - self-limiting food poisoning in meat, gravy
- β toxin (in type C) - necrotizing enterocolitis, onset in <6 hrs, fatal if untreated
- gram: g+ rods like boxcars, spores rare - large/central
- ID: double zone of B hemolysis, reverse CAMP w/ group B strep
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Clostridium botulinum - habitat, disease, virulence factors, gram stain, colony
- habitat: soil, honey, contaminated food (esp canned food)
- disease: botulism (foodborne, wound, adult, infant) - all can be fatal
- toxin prevents release of acetylcholine (muscle can't contract)
- vir: neurotoxins A-G (A,B,C assoc w/ human disease)
- extremely potent, leading to paralysis/death
- *potential agent of bioterrorism
- gram: GPR (easily decolorized), spores subterminal "tennis racket"
- colony: usually jagged/irregular edges
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Difference between adult and infant botulism
- adult: ingestion of pre-formed toxin
- infant: ingestion of C. botulinum spore and toxin release from GI tract
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Clostridium difficile - habitat, clin imp, disease, virulence factors, treatment, preferred specimen/plating
- habitat: environment, animal GI
- *some humans have as normal GI flora
- clin: one of the most common nosocomial infections
- antibiotic use changes normal GI flora, allowing C. diff to take hold
- Easily transmitted via aerosolized/contact spores (special precautions)
- disease: watery diarrhea
- pseudomembranous colitis - colonic mucosa studded w/ inflammatory plaques creating a pseudomembrane of fibrin, WBCs, and dead colon cells
- complications - kidney failure, dehydration, toxic megacolon, death
- vir: Toxin A (enterotoxin) - diarrhea
- Toxin B (cytotoxin) - colitis
- treatment: stop current antibiotic treatment, give metronidazole/vancomycin
- spec: fresh stool on CCFA (reduces normal flora, will appear yellow) or anaerobic blood agar
- *irregular edges
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Clostridium septicum - disease, virulence factors, gram, colony morph, ID
- disease: myonecrosis (20% of all cases)
- typhilitis (neutropenic colitis) - rapidly fatal infection w/ sepsis in IMC
- vir: 4 toxins (α, β, Δ, ε)
- gram: GPR, can stain unevenly, spores are "citron bodies"
- colony: medusa head on Brucella (not PEA)
- motile swarming w/in 24 hours
- ID: reverse CAMP negative, esculin+, gelatin+
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Clostridium tetani - habitat, disease, vir factors, treatment, gram, colony morph, ID
- habitat: soil, contaminated objects
- disease: tetanus (caused by tetanospasmin) - prevents release of neurotransmitters causing constant muscle contraction (respiratory failure in 10%)
- vir: tetanospasmin
- tetanolysin (minor B hemolysis)
- treatment: anti-toxin, not antibiotics
- gram: GPR, spores have drumstick appearance
- colony: irregular margin, proteus-like swarming
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Propionibacterium acnes - clin imp, disease, gram, ID
- clim: most common no-spore GPR (skin contaminate)
- disease: joint infections
- gram: very unique spider-like clumps under scope
- ID: Indole+, catalase+
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Bacteroides general - clinical imp, micro, virulence factors, spp
- clin: most commonly encounter bacterium in anaerobic infections
- micro: GNR
- vir: capsules, endotoxin, succinic acid (prevents phago), various enzymes (tissue damage)
- *requires breach of mucosal integrity
- spp: reported as fragilis group
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Bacteroides fragilis - habitat, diseases, colony morph, ID,
- habitat: major colon normal flora, oral cavity
- disease: infections, abscesses, ulcers, sepsis
- *accompanied by foul odor
- colony: black colonies on bile esculin agar
- ID: growth on 20% bile, black colonies on BBE
- KVC = RRR
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Prevotella - habitat, micro, colony morph, ID
- habitat: normal flora oral cavity
- micro: GNR
- colony: black colonies on SBA
- ID: brick red fluorescence (UV)
- KVC = RRV
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Porphyromonas - micro, colony morph, ID
- micro: GNR, often w/ coccoid shapes
- colony: may be pigmented (mask fluorescence)
- ID: pink/orange/red fluorescence (UV)
- KVC = RSR
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Fusobacterium nucleatum - habitat, micro, colony morph, ID
- habitat: isolated from biofilms in oral cavity
- micro: GNR
- colony: bread crumb-like colonies
- ID: chartreuce (brt grn) fluorescence (UV)
- KVC = SRS
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Clinical important of anaerobic cocci
Minor players, mostly normal flora
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