3.10 Clostridium Species

Microbiology review for the USMLE Step 1 exam

• Clostridium species are spore-forming anaerobic gram-positive rods that secrete toxins
• Four main species: Clostridium difficile, Clostridium perfringens, Clostridium botulinum, Clostridium tetani
• Clostridium difficile: common cause of antibiotic-associated diarrhea, caused by overgrowth of C. diff in gut after taking antibiotics that do not kill it, treatment involves stopping offending antibiotic and changing to one that can kill C. diff
• Clostridium perfringens: associated with acute GI infections, usually acquired through consuming contaminated food, symptoms include abdominal pain, watery diarrhea and vomiting
• Clostridium botulinum: acquired through eating contaminated food, causes flaccid paralysis through production of botulinum toxin which disrupts synaptic signaling
• Clostridium tetani: causes tetanus, acquired through introduction of spores through breaks in skin, produces tetanus toxin which causes muscle stiffness and spasms.