Bacteroides

(bak-tĕ-royd′ēz″)

A genus of gram-negative, anaerobic, non-spore-forming bacilli that forms most of the intestinal flora and may be found in smaller numbers on the oral, upper respiratory, and genital mucous membranes. Members of the species release an endotoxin that contributes to tissue destruction. They are often found in abscesses or in infections in which gas is found, e.g., on radiographic studies. All species multiply rapidly in necrotic tissue; infections that start in the colon, e.g., may spread to neighboring tissues or the bloodstream producing intra-abdominal abscesses, peritonitis, or septicemia.