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.
Also called: Peptostreptococcus, Finegoldia magna, Parvimonas micra, Peptoniphilus, Anaerococcus, Veillonella (Gram-negative anaerobic coccus)
Quick facts
- Type
- Bacterium · 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
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 →
- Empyema, aspiration pneumonia and lung abscess Parapneumonic effusion and empyema →
- Periodontitis and dental abscess (Parvimonas micra) Periodontitis →
- Postpartum and post-abortion pelvic infection Puerperal infection (postpartum endometritis and maternal sepsis) →
- Diabetic foot and other chronic skin and soft-tissue infections Diabetic foot →
- Intra-abdominal abscess 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:
Prevention
- Oral hygiene and dental care
- Aseptic surgery and obstetric care
- Foot care in diabetes
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.
Connections
← Back to the group: 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 (Clinical Microbiology Reviews (ASM), 1998); Mixed Anaerobic Infections - Infectious Disease - MSD Manual Professional Edition (MSD Manual Professional Edition, 2025).
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Representative model, for educational purposes only.