破傷風菌
"Clostridium" species produce more toxins and exhibit higher degrees of virulence than any other bacterial taxon. "Clostridium" infections are usually opportunistic, and occur in individuals with serious preexisting medical conditions. However, "Clostridium" infections are also known to occur in healthy individuals. Four species of "Clostridium" ("Clostridium botulinum", "Clostridium perfringens", "Clostridium tetani", and "Clostridium sordelli") are responsible for most human infections. Since "Clostridium" is an obligate anaerobe taxon, the bacterium infects hypoxic tissues, which had become anaerobic due to restricted blood flow, degradation of blood vessels, or atherosclerosis. Immunocompromised individuals exhibit higher susceptibility for infection and higher mortality rates.