Anaerobic Gram-Positive Rods Clinical Microbiology Review 204
PATHOGENICITY GRAM STAIN OTHER
Actinomyces
Clostridium botulinum
Clostridium difficile
Clostridium perfringens
Sulfur granules may be seen in
discharge. Crush & stain to re-
veal characteristic Gram-stain
morphology. “Molar tooth”
colonies.
Reportable disease. Toxin
testing at public health labs.
Yellow ground-glass colonies on
cycloserine cefoxitin fructose
agar (CCFA). Usually not cultured.
Must demonstrate toxin produc-
tion. Toxins A & B. Tissue culture
or EIA.
Most commonly isolated
Clostridium. Double zone of
beta hemolysis on SBA.
Infects brain, face, lungs, genitals
Botulism due to ingestion of toxin in
inadequately cooked or improperly
canned foods. Infant botulism due to
ingestion of spores in honey. Wound
botulism from injection drug use
Antibiotic-associated diarrhea,
pseudomembranous colitis
Normal in GI tract. Causes gas
gangrene, food poisoning
Short or long GPR. Branched
or unbranched. Banded ap-
pearance. Can break into
club-shaped rods resembling
diphtheroids.
GPR with oval subterminal
spores.
Thin GPR. May form chains.
Rare oval subterminal spores.
Large GPR with blunt ends in
chains. “Box cars.” Tendency
to stain gram neg. Usually no
spores seen.
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