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

Clostridium Pathogenicity 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

Clostridium Pathogenicity 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

Clostridium Pathogenicity 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

Clostridium Pathogenicity 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 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.