Clostridium perfingens

Clostridium perfingens is a bacterial infection that is one of the most common causes of food poisoning. C. perfingens is ubiquitous in the environment, particularly in decaying vegetation. It is a common component of intestinal bacteria and, in most cases, is kept in check by other bacteria in the digestive tract. Ingestion of the bacteria will not always lead to symptoms. 
The most common cause of infection is eating poultry or similar foods that have been kept on a heat table. The bacteria forms spores that are not destroyed by cooking. In normal circumstances, eating such contaminated food will only result in traces of the bacteria being ingested. However, in such optimum conditions, the spores will reactivate and start multiplying again. To avoid infection, cooked food should be either eaten or refrigerated within two hours after the end of cooking. 
C. perfingens can also be opportunistic. For example, it can enter through wounds in brackish water and cause gangrene. Treatment of such infections can be difficult and usually consists of removal of necrotic tissue, antibiotics and the use of a hyperbaric chamber as the bacteria only thrives in oxygen free environments. 
Clostridium perfringens at Wikipedia