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Anaeróbios

Peptostreptococcus / cocos Gram-positivos anaeróbios

Anaerobic Gram-positive cocci

Identification & Growth

Identification

  • Growth only under anaerobic conditions, catalase-negative
  • Identification by MALDI-TOF from an isolated colony

Growth Conditions

  • Supplemented Brucella agar, anaerobic incubation, 48–96 h; small white colonies

Clinical Significance

  • Polymicrobial abscesses, pelvic infection, diabetic foot, empyema

Intrinsic Resistance

  • Resistant to aminoglycosides and aztreonam

Bench Alerts

  • Almost always part of mixed flora — the report should read 'anaerobic Gram-positive cocci'
  • Penicillin, amoxicillin-clavulanate and metronidazole are the options

Clinical Notes

Clinical presentations

  • Soft-tissue abscesses, odontogenic infections and chronic sinusitis, usually in polymicrobial association.
  • Female pelvic infections, endometritis and tubo-ovarian abscess.
  • Chronic osteomyelitis, diabetic foot infection and indolent prosthetic joint infection.

Specimens and collection

  • Syringe aspirate or tissue biopsy in anaerobic transport medium, with air expelled.
  • Do not use surface swabs or microbiota-contaminated samples, which make interpretation impossible.
  • Plate on supplemented blood agar and incubate anaerobically for 48 h before the first reading.

Epidemiology and at-risk populations

  • They are part of the normal oral, intestinal, skin and female genital microbiota.
  • They predominate in tissue ischaemia, foreign body, trauma and contaminated surgery.
  • Diabetes, peripheral vascular disease and immunosuppression increase frequency and severity.

Resistance and therapeutic implications

  • Generally susceptible to penicillin, beta-lactam/inhibitor combinations, metronidazole and carbapenems.
  • Clindamycin resistance is variable and increasing: do not use it as the sole empirical regimen in severe infection.
  • Drainage and debridement are an indispensable part of treatment; antimicrobials alone do not resolve collections.

Bench and reporting notes

  • Anaerobic Gram-positive cocci in short chains or pairs; confirm strict anaerobiosis with a negative aerobic subculture.
  • Species identification by MALDI-TOF; the nomenclature has been reclassified into several genera (Finegoldia, Parvimonas, Anaerococcus).
  • Report the mixed culture as a whole, flagging the presence of anaerobes, rather than listing isolates without context.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Peptostreptococcus / cocos Gram-positivos anaeróbios in the lab?

Peptostreptococcus / cocos Gram-positivos anaeróbios is identified through growth only under anaerobic conditions, catalase-negative, identification by maldi-tof from an isolated colony.

What are the intrinsic resistances of Peptostreptococcus / cocos Gram-positivos anaeróbios?

This organism is naturally resistant to resistant to aminoglycosides and aztreonam. These drugs should not be reported as susceptible.

Where is Peptostreptococcus / cocos Gram-positivos anaeróbios commonly found?

It is typically associated with polymicrobial abscesses, pelvic infection, diabetic foot, empyema.

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