MICROBIOLOGY AND PATHOGENESIS

Clostridia are pleomorphic, gram-positive, spore-forming organisms. Most species are obligate anaerobes; some (e.g., C. septicum, C. tertium) can grow—but not sporulate—in air.

• In humans, clostridia reside in the GI and female genital tracts and on the oral mucosa.
• Clostridial species produce more protein toxins than any other bacterial genus; the C. perfringens epsilon toxin is among the most lethal and is considered a potential agent of bioterrorism.