bacteriology anaerobes Flashcards
What is an obligate anaerobe?
Only grow in the absence of oxygen (or at very low oxygen tension)
* can live in necrotic tissue, low pH due to negative oxidation-reduction potential
Where do non spore forming anaerobic bacteria come from?
Part of the normal flora of:
* Skin (esp. skin folds)
* mucus membranes of the:
Upper respiratory tract
Gastrointestinal tract
Lower genitourinary tracts
The major shareholders within the normal flora
They outnumber the facultative anaerobes 5:1 on mucocutaneous surfaces
How do NSF anaerobes cause dz?
Need host compromise
opportunistic
can be in tissue necrosis
Where do NSF anaerobes cause dz?
At/near sites where part of the normal flora
AND these sites have necrotic tissue
e.g., abscesses, areas of trauma, periodontal pockets, necrotic bite wounds, necrotic lung etc., etc
How do NSF anaerobes cause disease? Virulence factors?
Tolerance of oxygen in more virulent species of bacteria
Extracellular or cell bound enzymes
Endotoxin (gram -)
Capsule
Synergy between community members (work as a TEAM to produce disease)
When do you suspect anaerobes as culprits?
Foul smell*
Production of gas
Black discolouration at the site*
Location of infection (Near where they live)
History e.g. Bites wound
Mixed/filamentous organisms on smear
Failure to culture
Diseases that NSF anaerobes cause?
CAT FIGHT ABSCESS
periodontal dz
pleuropneumonia/pyothorax
pyometra (dogs, cats)
peritonitis
How to treat NSF anaerobic infections
Drainage of any fluid
Debridement of necrotic tissue (removes organisms, inflammatory by-products + niche)
Copious lavage
Empirical antibiotics
* Empirical as susceptibility testing difficult
* Most commonly used:
* Metronidazole,
* Clindamicin (not horses)
* Penicillin + βlactamase inhibitor (e.g., amoxicillin-clavulanate)
* Do NOT use aminoglycosides or old generation quinolones
* Need to also address FA bacteria (e.g. E. coli etc)
Nursing support as needed (e.g. IV fluids)
