Gram-positive, strictly anaerobic cocci are included in the genera Peptococcus and Peptostreptococcus. The only species in the first genus is Peptococcus niger, whereas the latter comprises a number of species. The anaerobic cocci are commonly observed in normal human flora. In a pathogenic context they are usually only encountered as components of mixed florae together with other anaerobes or facultative anaerobes. These bacteria invade tissues through dermal or mucosal injuries and cause subacute purulent infections. Such infections are either localized in the head area (cerebral abscess, otitis media, mastoiditis, sinusitis) or lower respiratory tract (necrotizing pneumonia, pulmonary abscess, empyema). They are also known to occur in the abdomen (appendicitis, peritonitis, hepatic abscess) and female genitals (salpin-gitis, endometriosis, tubo-ovarian abscess). Gram-positive anaerobic cocci may also contribute to soft-tissue infections and postoperative wound infections. See p. 317ff. for clinical details of anaerobe infections.
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