CLS07 - Anaerobic Organisms

  1. 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
  2. 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
  3. 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
  4. Difference between adult and infant botulism
    • adult: ingestion of pre-formed toxin
    • infant: ingestion of C. botulinum spore and toxin release from GI tract
  5. 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
  6. 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+
  7. 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
  8. 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+
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. Clinical important of anaerobic cocci
    Minor players, mostly normal flora
Card Set
CLS07 - Anaerobic Organisms
CLS07 - Anaerobic Organisms