Anaerobic Bacteriology Flashcards
(23 cards)
What is an obligate anaerobe?
0% O2, Strict
Bacteroides, Prevotella, Fusobacterium spp.
What is a facultative anaerobe?
Can grow in atmospheric O2 or anaerobic environment
What is aerotolerant?
Up to 5% O2, grows best in anaerobic but can grow in reduced or atmospheric O2
What are endogenous anaerobes?
Anaerobic human normal flora, opportunistic
What are exogenous anaerobes?
Not human normal flora, from soil and environment
What is the best way to obtain an sample for anaerobic culture?
- Tissue biopsy
- Aspiration using needle or syringe
What specimens are not recommended and why? (Collection techniques)
Swab specimens
- Prone to drying
- Easily contaminated
- Fibres can hold onto microorganisms
If using a swab for collection, what is recommended?
- Oxygen-free transport medium
- “Flock swabs”
What are the 3 kinds of anaerobic transport systems?
- Rubber-stoppered vial for liquid specimens
- Oxygen-free collection tube for swabs
- Self-contained anaerobic bag for tissue specimens
What 2 organisms have brick-red fluorescence under long-wave UV lieght?
- Prevotella spp.
- Porphyromonas spp.
Which organisms have sulfur granules?
- Actinomyces spp.
- Propionibacterium spp.
- Eubacterium nodatum
Methods for direct detection for C.diff toxin?
- Tissue culture for sytotoxin (Toxin B)
- Latex agg (A or B)
- ELISA (A or B)
What can be done differently in a Gram stain for anaerobic Gram negatives?
- Safranin 3-5 minutes
- 0.5% basic fuchsin
- Diff [ ] reagents
- Gram enhancers after decolourization (suppresses background)
List the anaerobic media that can be used.
- Anaerobic BA
- Bacteroides bile esculin (BBE)
- Laked kanamycin-vancomycin blood (LKV) agar
- Anaerobic PEA
- Egg yolk agar (EYA) (for C.diff)
- Cycloserine cefoxitin fructose agar (CCFA) (for C.diff)
- Schaedler’s broth
- Thioglycollate broth (enriches small #’s)
Incubation requirements for anaerobes?
- 35-37 for 48hrs
- Early exposure to O2 can kill orgs.
- Re-inc up to 5 days
- Thio broth 7 days, use for subculture
Describe method for jar incubation.
- Gas packs
- Palladium catalyst for O2 removal
- Methylene blue or resazurin indicators (change to white)
Jar should be:
- warm to touch (w/in minutes)
- Mist on inner walls
- Strip is white
What are the antibiotics used for presumptive ID of anaerobes?
- Kanamycin
- Colistin
- Vancomycin
List common tests for anaerobic ID.
- Catalase
- Spot indole
- Nitrate disc
- Bile disc (Gram neg)
- SPS disc (Gram pos cocci)
- Susceptibility Discs (k,v,c)
- Lecithinase production on egg yolk agar (EYA)
- Lipase production
- Urease
- Nagler reaction (Gram pos )
- Reverse CAMP (Gram pos)
List methods for definitive ID of anaerobes.
- PRAS biochemicals
- Mini biochemicals (ex: api 20A)
- Correlate gram, colony morph and site of infection.
Antimicrobial therapy for: Bacteroides fragilis group, other Bacteroides spp, Porphyromonas spp, Prevotella spp, Fusobacterium spp.
- Beta-lactams/ combos, imipenem, metronidazole, chloramphenicol
- Cefoxitin (cephalosporin)
- Moxifloxacin (fluoroquinolone)
Antimicrobial therapy: Clostridium spp.
- Penicillins +/- beta-lactamase inhibitors, imipenem
- Metronidazole/vanco for C.diff
Botulism + C.perfringens: Non
Antimicrobial therapy: Actinomyces spp, Propionibacterium spp.
- Penicilins +/- beta-lactamase inhibitor combos, imipenem, cefotaxime, ceftizoxime
Antimicrobial therapy: Peptostreptococcus spp.
- Penicilins, most cephalosporins, imipenem, vanco, clindamycin, chloramphenicol
