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Anaerobe Bacterial Culture

Anaerobic infections are usually caused by leakage of normal flora into a sterile body site, following disruption of a mucosal barrier. The most commonly isolated gram-negative anaerobic pathogens include Bacteroides, Fusobacterium, Prevotella, and Porphyromonas. Gram-positive anaerobic pathogens include Anaerococcus and a variety of Clostridium species. The most frequent sites of infection include skin and soft tissue, pleuropulmonary and abdominal spaces, and female genital tract. Anaerobic infections are characterized by suppuration or abscess formation and tissue necrosis. When anaerobes are suspected to be the causative agent of an infection, physicians must specifically request an anaerobic culture.

Specimens for anaerobic culture should be collected only from an acceptable site and in such a way as to avoid contamination with normal flora. This is best accomplished by aspiration with a needle and syringe or with tissue or biopsy samples. Swabs are strongly discouraged since they provide a limited quantity of specimen, allow exposure to oxygen that is lethal to anaerobes, and are often contaminated with normal flora. For these reasons, swabs should only be used during surgery and only when aspiration or biopsy is not possible. In the instance that a swab must be collected, the eSwab transport system should be utilized.


Infection Source

Acceptable Specimens


Lung tissue

Transtracheal aspirate

Bronchial brushing


Thoracentesis fluid

Urinary tract

Suprapubic bladder aspirate

Nephrostomy specimen


Peritoneal fluid

CAPD fluid

Abscess aspirate


Biopsy tissue

Female genital tract

Culdoscopy specimen

Endometrial aspirate

Abscess aspirate

IUD for Actinomyces

Sinus tract or draining wound

Aspirate by syringe as deeply as possible after surface decontamination

Surgical specimen from depth of wound or bone lesion

Curettings and tissue biopsies

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