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22 Cards in this Set
- Front
- Back
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Anaerobe Overview
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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) |
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Who are the NSF anaerobes?
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large group of morphologically diverse bacteria
-some are g - -others are g+ -some are cocci, rods, branching rods |
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NSF anaerobes: Gram negative rods
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often have pointed ends
-bacteroides - Porphyromonas -Prevotella -Fusobacterium -Dichelobacter |
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NSF anaerobes: Gram positive cocci
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Peptostreptococcus
Peptococcus |
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NSF anaerobes: gram positive rods
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Propionibacterium
Lactobacillus Eubacterium Bifidobacterium Actinomyces (some) |
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Where do NSF Anaerobes hang out?
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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 |
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How do anaerobes grow in areas where oxygen is present?
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vary in oxygen tolerance
ecological niche presence of physical factors (mucus, tartar, skin folds) synergy with aerobes and facultative anaerobes |
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What is the role of normal flora?
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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 |
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What needs to happen for disease to occur with the NSF anaerobes
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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 |
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what predisposing factors upset the host-pathogen relationship
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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 |
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where do NSF anaerobes cause disease?
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-at/near sites where they are part of normal flora
AND these sites have necrotic tissue |
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NSF anaerobes: how do they produce disease (virulence factors)?
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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) |
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When should you suspect anaerobes as culprits of disease?
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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 |
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Cat fight abscess
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-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 |
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Periodontal disease
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in many different animals
often secondary to other disease like mild gingivitis can progress to tooth root abscesses |
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Pleuropneumonia or Pyothorax
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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 |
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Pyometra
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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 |
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Ovine Foot rot
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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 |
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Diseases that are don't/rarely caused by NSFA
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cystitis
otitis externa septicemia endometritis in horses (but are involved in pyometra) |
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Diagnosis of NSFA
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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 |
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Treatment of NSFA infections
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1. drainage of any fluid
2. debridement of necrotic tissue (MUST) 3. copious lavage 4. +/- emperical antibiotics 5. Nursing support as needed |
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Empirical antibiotics when treating NSFA infections
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penicillin, metronidazole, amoxicillin-clavulanate, clindamicin (not in horses)
don't use aminoglycosides or quinolones need to address FA bacteria |
