Peptostreptokoki

Peptostreptokoki, or peptostreptococci, refers to a group of anaerobic, Gram-positive cocci that are part of the normal human mucosal and skin flora but can act as opportunistic pathogens when they invade sterile body sites. Historically classified within the genus Peptostreptococcus, many species have been reclassified into new genera such as Finegoldia, Parvimonas, and Peptoniphilus. The term peptostreptococci is still used in clinical contexts to describe these anaerobic cocci, particularly in mixed infections.

Morphology and laboratory characteristics vary by species but generally include small, non-spore-forming cocci that are catalase-negative and require anaerobic culture for optimal growth. They may appear in pairs, short chains, or clusters on Gram stain and are often cultured from polymicrobial specimens.

Habitat and clinical relevance: Peptostreptokoki are common inhabitants of the oral cavity, gastrointestinal tract, and genitourinary tract. They are usually harmless unless they translocate to non-native sites, where they can contribute to a range of infections, especially in polymicrobial contexts.

Clinical infections: They are implicated in dental and maxillofacial infections, head and neck infections, brain abscesses, intra-abdominal and pelvic infections, and soft tissue infections. In many cases, they accompany anaerobic Gram-negative or facultative bacteria, forming part of complex infectious communities.

Diagnosis and treatment: Diagnosis relies on anaerobic culture and/or molecular methods. Antimicrobial susceptibility is generally favorable to penicillin, though some strains produce beta-lactamases and may require beta-lactamase inhibitors or alternative agents. Treatment strategies often cover mixed anaerobic flora and may include penicillin-based regimens, carbapenems, or beta-lactamase inhibitor combinations, depending on the site and severity of infection.