Emergence of Clostridium tertium as a pathogen in neutropenic patients.

Although usually considered a non-pathogen, Clostridium tertium was isolated from 10 immunosuppressed patients including seven patients with bacteremia. This organism can grow aerobically and can be easily disregarded as a contaminant. It also has a somewhat unusual susceptibility pattern, with significant resistance to the penicillins, cephalosporins, and clindamycin, possibly explaining its emergence in immunocompromised patients already receiving multiple antibiotics.