Clostridia are often the primary agents in the following: Emphysematous cholecystitis Gas gangrene of the uterus (which may occur after delivery and was previously common among patients who had a septic abortion) Certain other female genital tract infections (tubo-ovarian, pelvic, and uterine abscesses) Infection after perforation in colon carcinoma The primary organisms are C perfringens and, in the case of colon carcinoma, C septicum.