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22 Cards in this Set

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Anaerobe Overview
only grow in the absence of oxygen (or at very low oxygen tension)
Long exposure of bacteria to O2 is lethal (range of tolerance varies)
Require the Eh (oxidation-reduction potential) to be less than -100mV (necrotic tissue favors their growth as well as areas w/ low pH)
Who are the NSF anaerobes?
large group of morphologically diverse bacteria
-some are g -
-others are g+
-some are cocci, rods, branching rods
NSF anaerobes: Gram negative rods
often have pointed ends
-bacteroides
- Porphyromonas
-Prevotella
-Fusobacterium
-Dichelobacter
NSF anaerobes: Gram positive cocci
Peptostreptococcus
Peptococcus
NSF anaerobes: gram positive rods
Propionibacterium
Lactobacillus
Eubacterium
Bifidobacterium
Actinomyces (some)
Where do NSF Anaerobes hang out?
part of the normal flora of: skin (esp skin folds), mucous membranes of (GI tract, Upper resp. tract, lower genitourinary tract)
major shareholders within the normal flora
How do anaerobes grow in areas where oxygen is present?
vary in oxygen tolerance
ecological niche
presence of physical factors (mucus, tartar, skin folds)
synergy with aerobes and facultative anaerobes
What is the role of normal flora?
play an important role in health maintenance
act as security by limiting attachment and growth of dangerous newcomers
they can become an issue if they overgrow and/or move out of their usual location into nearby sterile areas
What needs to happen for disease to occur with the NSF anaerobes
infections are always opportunistic
a change to host (tissue injury) and/or
a change to environment (antibiotic therapy) and/or
agent of disease can change from NF to pathogen
what predisposing factors upset the host-pathogen relationship
breakdown of normal host defences
change in association b/w normal flora (overgrowth of some bacteria)
Poor blood supply and tissue necrosis
decreased host resistance
prior use of antibiotics
overwhelming contamination of normally sterile area
prior infection with aerobes/facultative anaerobes
where do NSF anaerobes cause disease?
-at/near sites where they are part of normal flora
AND
these sites have necrotic tissue
NSF anaerobes: how do they produce disease (virulence factors)?
tolerance of oxygen in more virulent species of bacteria
extracellular or cell bound enzymes
endotoxin
capsule
synergy between community members (work as team to prod. dz)
When should you suspect anaerobes as culprits of disease?
Fever, pain, swelling (necrotic tissue)
foul smell***
location of infection (near scene of crime)
Production of gas *****
black discoloration at site ****
History (eg bite wound)
Mixed/filamentous organisms on smear
failure to culture
Cat fight abscess
-most common infectious dz for vet
NF of oral cavity innoculated into a traumatized area (closes so doesn't allow aeration/drainage)
both facultative anaerobes and strict anaerobes involved
FA multiply first until O2 runs out (2d) then strict anaerobes go wild
Periodontal disease
in many different animals
often secondary to other disease like mild gingivitis
can progress to tooth root abscesses
Pleuropneumonia or Pyothorax
in many diff. animals
often secondary to other disease: 1. bacterial/viral- bordetella/viruses then Klebsiella THEN NSFA 2. aspiration
associated with chronic infections
poor prognosis
Pyometra
mostly dogs and cats
often secondary to other disease
1. cystic endometrial hyperplasia
2. bacterial infections (E. coli then anaerobes)
associated w/ chronic infections
poorer prognosis
Ovine Foot rot
specific disease of sheep
Caused by Dichelobacter nodosus in synergy with Arcanobacter pyogenes, Fusobacterium necrophorum (Mixed infection)
pilli to attach
protease to cause underrunning of sole
disease of economic importance in sheep industry
Diseases that are don't/rarely caused by NSFA
cystitis
otitis externa
septicemia
endometritis in horses (but are involved in pyometra)
Diagnosis of NSFA
how samples are collected is import.
-don't bother with swabs
-collect sample into (blood culture bottle, syringe and cap the end, place into vacutainer)
place solid tissue into container w/ min. air space or anaerobic specific devices
**always make a smear at the same time
do not refrigerate; and submit ASAP
Treatment of NSFA infections
1. drainage of any fluid
2. debridement of necrotic tissue (MUST)
3. copious lavage
4. +/- emperical antibiotics
5. Nursing support as needed
Empirical antibiotics when treating NSFA infections
penicillin, metronidazole, amoxicillin-clavulanate, clindamicin (not in horses)
don't use aminoglycosides or quinolones
need to address FA bacteria