Anaerobes of Clinical Importance Part Two MLAB 2434 – Microbiology Keri Brophy-Martinez.
-
Upload
laura-bond -
Category
Documents
-
view
221 -
download
3
Transcript of Anaerobes of Clinical Importance Part Two MLAB 2434 – Microbiology Keri Brophy-Martinez.
Anaerobes of Clinical Importance
Part Two
MLAB 2434 – Microbiology Keri Brophy-Martinez
Frequently Encountered Anaerobes
• Gram-positive spore-forming anaerobic bacilli– Clostridium• Epidemiology
– Normal flora of lower intestinal tract– Found in soil– Most from exogenous sources
ClostridiumPathogenicity
• Botulism– Agent: Clostridium botulinum– Spread: veggies, mushrooms, fish, honey– Toxin: neurotoxin acts on neuromuscular junctions of
peripheral nervous system causing neuroparalytic illness– Clinical Forms: foodborne, wounds– Clinical Features: Symmetrical, descending weakness or
paralysis; floppy baby syndrome; clear mental status– Diagnosis: collect serum and feces to demonstrate toxin– Prevention: adequate canning and cooking of foods
ClostridiumPathogenicity
• Gas gangrene (myonecrosis)– Agent: Clostridium perfringens– Spread: contamination of wounds– Clinical features: Muscle becomes
necrotic; contains gas– Lab Diagnosis: boxcar-shaped gpr,
double zone of beta-hemolysis
ClostridiumPathogenicity
• Tetanus– Agent: Clostridium tetani– Spread: skin penetration by contaminated
materials or surgery– Toxin: tetanospamin acts on CNS to produce
prolonged muscle spasms– Clinical features: Muscle spasm,
hyperexcitability, odd facial expressions– Lab Diagnosis: Gpr with oval, terminal or
subterminal spores, gives a “drumstick” or “tennis racket” appearance
– Prevention: immunization
ClostridiumPathogenicity
• Pseudomembranous colitis– Agent: Clostridium difficile– Spread: nosocomial infection– Critical factors for disease to occur: normal bowel flora
disruption, organism must be toxin producing– Toxin: toxin A(enterotoxin) Toxin B(cytotoxin)– Clinical features: diarrhea, inflammation of bowel, bowel
is necrotic (see WBC’s and fibrin forming a pseudomembrane)
– Lab diagnosis: C. difficle is most often detected via by EIA or PCR
Gram-positive non-spore-forming anaerobic bacilli
• Most are from endogenous sources and are therefore opportunists– Propionibacterium
• Epidemiology– Normal skin flora
• Pathogenicity– Seen as a contaminant in blood cultures– Causes acne – May cause subacute bacterial endocarditis and
bacteremia– Affinity for medical devices
Propionibacterium:Lab Diagnosis
• Coccoid, club-shaped or branched morphology– Chinese letters
• Microaerotolerant• Catalase positive• Indole positive• Reduces nitrate
Actinomyces species
– Epidemiology• Normal flora in mouth, head, neck, GI tract, female
genital tract, and upper respiratory system.• Pathogenicity
– Eye Infections– Cervicitis and endometritis in women using IUD’s– Actinomycosis (head and neck infections)
• Lab Diagnosis– Short to filamentous, branching rod; can be beaded;
may see sulfur granules on direct specimen exam– Molar tooth appearance on media; slow grower;
fastidious
Actinomyces
Gram-positive non-spore-forming anaerobic bacilli
• Bifidobacterium• Eggerthella/Eubacterium• Lactobacillus
Gram Negative Non-spore formers- Anaerobic Cocci
• Veillonella– Epidemiology• Normal flora in mouth, upper respiratory
tract, GI tract and vagina
– Pathogenicity• Associated with peridontal and soft tissue
infections of the mouth, bite wounds, head, neck and pulmonary infections
Gram Positive, Non-Spore Formers- Anaerobic Cocci
• Peptostreptococcus species
– Epidemiology• Normal flora in mouth, skin, genitourinary and GI
tracts
– Pathogenicity• Can cause any type of infection
Gram-negative Non-spore Formers- Anaerobic Bacilli
• Bacteroides fragilis group– Epidemiology• Normal flora of mouth, URT, intestinal tract,
urogenital tract
– Pathogenicity• Wounds, abscesses in body sites below the
diaphragm• Bacteremia
Bacteroides fragilis group:Lab Diagnosis
• Pale staining, pleomorphic rod with rounded ends; safety pin appearance
• Look for growth on BBE, see esculin hydrolysis around the colony, precipitated bile
• Can use antibiotic disk, GLC for Id
Porphyromonas spp.
• Epidemiology
– Normal flora of mouth, URT, intestinal tract and urogential tract
• Pathogenicity• Assocaited with opportunistic infections• Soft tissue infection below waist
• Lab Diagnosis• Red fluorescence under UV light• Black pigmented colonies on KV• Can use antibiotic disks to id
Prevotella spp.
• Epidemiology• Normal flora of mouth, URT, intestinal tract,
urogenital tract• Pathogenicity– Peridontitis– Head and neck and pleuropulmonary infections
• Lab diagnosis– GNR is short chains or pairs– KV media see black pigment– Can use antibiotic disk for id
Fusobacterium Spp.
• Epidemiology• Normal flora of mouth, URT, intestinal tract,
urogenital tract• Pathogenicity– Respiratory tract– Head and neck infections
• Lab diagnosis– GNR is long, thin, fusiform, and pleomorphic– Do not grow well on KV– Can use antibiotic disk for id
References
• http://www.labsupplyoutlaws.com/products/Lab-Equipment/Microbiology-Apparatus/Environmental-Systems-for-Microbiology/BD-BBL-Bio-Bag-Environmental-Chambers.htm
• Kiser, K. M., Payne, W. C., & Taff, T. A. (2011). Clinical Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education.
• Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders.