[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Other clinically important bacteria](https://durgical.com/en/microbiology/groups/other-clinically-important-bacteria/) › Anaerobic Gram-positive cocci # Anaerobic Gram-positive cocci - Bacterium ## Gram-positive? Thick peptidoglycan wall: stains purple. - For completeness Anaerobic cocci of the mouth, gut, vagina and skin that join other bacteria to form foul-smelling abscesses. Updated Nov 13, 2026 Also called: Peptostreptococcus, Finegoldia magna, Parvimonas micra, Peptoniphilus, Anaerococcus, Veillonella (Gram-negative anaerobic coccus) ## Quick facts **Type** Bacterium · [Other clinically important bacteria](https://durgical.com/en/microbiology/groups/other-clinically-important-bacteria/) **Gram / shape** Gram-positive · Cocci in pairs **Spread** Spread after aspiration **Causes** Brain abscess · Empyema · Intra-abdominal abscess **Treatment** Drainage or debridement is central On this page - The basics Key points - At a glance - Morphology - Transmission - Memory aid - What the colours mean - Clinical Virulence factors - Diseases it causes - Clinical picture - Diagnosis - Treatment Treatment - Prevention - Study Test yourself - Connections Connections ## Key points - Peptostreptococcus and relatives: the Gram-positive anaerobes of mixed abscesses. - Brain, lung, dental, pelvic and diabetic foot infections, usually polymicrobial. - Penicillin and metronidazole are usually active. ## At a glance **Gram** Gram-positive **Shape** Cocci in pairs, chains or clusters **Oxygen** Obligate anaerobes **Family** Peptostreptococcaceae and related families **Stain** May stain weakly and look Gram-negative ## Morphology - Gram-positive anaerobic cocci; many retain the stain poorly - Slow-growing on anaerobic media - Veillonella is a small Gram-negative anaerobic coccus of the mouth and gut, usually a commensal ## Transmission - Endogenous from the patient's own mucosal and skin flora - Spread after aspiration, dental infection, surgery, childbirth or skin ulcers - Not spread from person to person **Reservoir:** Mouth, upper airway, gut, female genital tract and skin ### Isolation precautions What the care team adds to standard precautions. - Standard ## Virulence factors - Low virulence alone; they act in synergy with other anaerobes and aerobes in mixed infections - Finegoldia magna is the most virulent, with surface proteins that bind host proteins ## Diseases it causes - Brain abscess (often polymicrobial) [Brain abscess →](https://durgical.com/en/conditions/brain-abscess/) - Empyema, aspiration pneumonia and lung abscess [Parapneumonic effusion and empyema →](https://durgical.com/en/conditions/parapneumonic-effusion-and-empyema/) - Periodontitis and dental abscess (Parvimonas micra) [Periodontitis →](https://durgical.com/en/conditions/periodontitis/) - Postpartum and post-abortion pelvic infection [Puerperal infection (postpartum endometritis and maternal sepsis) →](https://durgical.com/en/conditions/puerperal-infection/) - Diabetic foot and other chronic skin and soft-tissue infections [Diabetic foot →](https://durgical.com/en/conditions/diabetic-foot/) - Intra-abdominal abscess [Intra-abdominal abscess →](https://durgical.com/en/conditions/intra-abdominal-abscess/) ## Clinical picture - Almost always part of a mixed infection - Clues: foul pus, gas in tissue, an abscess next to a mucosal surface ## Diagnosis - Pus or tissue (not swabs) in anaerobic transport - Anaerobic culture; growth may take several days - MALDI-TOF mass spectrometry identifies the genus and species ## Treatment Drainage or debridement is central; penicillins are usually active, as are metronidazole, carbapenems and beta-lactam/beta-lactamase inhibitors. Clindamycin resistance has been reported, so it is not always reliable. Drug class only; doses and regimens are set by the clinician from the current guideline. In Pharmacology: - [Benzylpenicillin (penicillin G)](https://durgical.com/en/pharmacology/benzylpenicillin/) - [Metronidazole](https://durgical.com/en/pharmacology/metronidazole/) - [Ampicillin + sulbactam](https://durgical.com/en/pharmacology/ampicillin-sulbactam/) - [Clindamycin](https://durgical.com/en/pharmacology/clindamycin/) ## Prevention - Oral hygiene and dental care - Aseptic surgery and obstetric care - Foot care in diabetes ## Memory aid «Peptos are team players»: they rarely fight alone, but they never miss a mixed abscess. ## Test yourself Think of the answer, then tap the question to see it. ## Which genus is the classic anaerobic Gram-positive coccus? Peptostreptococcus (with Finegoldia, Parvimonas, Peptoniphilus and Anaerococcus). ## What kind of infection do anaerobic cocci usually cause? Mixed (polymicrobial) abscesses near mucosal surfaces. ## Which sample is best for anaerobic culture? Pus or tissue sent in anaerobic transport, not a surface swab. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/anaerobic-gram-positive-cocci/) ## What the colours mean **Gram-positive** Thick peptidoglycan wall: stains purple. **Gram-negative** Thin wall with an outer membrane: stains pink. **Acid-fast** Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain. ## Connections ## Related 4 - [Bacteroides fragilis](https://durgical.com/en/microbiology/bacteroides-fragilis/) - [Fusobacterium, Prevotella and Porphyromonas](https://durgical.com/en/microbiology/fusobacterium-prevotella-and-porphyromonas/) - [Streptococcus anginosus group](https://durgical.com/en/microbiology/streptococcus-anginosus-group/) - [Actinomyces israelii](https://durgical.com/en/microbiology/actinomyces-israelii/) ## Related conditions 6 - [Brain abscess](https://durgical.com/en/conditions/brain-abscess/) - [Parapneumonic effusion and empyema](https://durgical.com/en/conditions/parapneumonic-effusion-and-empyema/) - [Periodontitis](https://durgical.com/en/conditions/periodontitis/) - [Puerperal infection (postpartum endometritis and maternal sepsis)](https://durgical.com/en/conditions/puerperal-infection/) - [Diabetic foot](https://durgical.com/en/conditions/diabetic-foot/) - [Intra-abdominal abscess](https://durgical.com/en/conditions/intra-abdominal-abscess/) [← Back to the group: Other clinically important bacteria](https://durgical.com/en/microbiology/groups/other-clinically-important-bacteria/) Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Gram-Positive Anaerobic Cocci](https://pmc.ncbi.nlm.nih.gov/articles/PMC121377/) (Clinical Microbiology Reviews (ASM), 1998); [Mixed Anaerobic Infections - Infectious Disease - MSD Manual Professional Edition](https://www.msdmanuals.com/professional/infectious-diseases/anaerobic-bacteria/mixed-anaerobic-infections) (MSD Manual Professional Edition, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/microbiology/anaerobic-gram-positive-cocci/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/anaerobic-gram-positive-cocci/