Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1318 page)

   Broth, like enriched thioglycolate medium or chopped meat broth

   
Turnaround time:
Incubation for 5–7 days

   Additional time is required for positive cultures for additional testing required for isolation, confirmation as anaerobic (aerotolerance testing), identification, susceptibility testing, and further characterization, as needed. Anaerobic infections are frequently polymicrobial; final results may require several weeks for full laboratory evaluation, if needed.

   Special Collection and Transport Instructions

   See “Aerobic Culture” for a general discussion of collection and transport instructions

   Because of the anaerobic endogenous flora, specimens from the following sites should not be submitted for anaerobic culture: sputum or bronchoscopically collected lower respiratory specimens, swabs from skin or mucosal surfaces, specimens from the GI tract (including fistulae, stoma surfaces, and so on), superficial ulcers or eschars, including decubitus ulcers, vaginal or cervical swabs or urine (except suprapubic aspirate urine).

   When submitting samples, ensure that sufficient specimen is collected for all of the diagnostic testing required (e.g., aerobic, fungal, and/or mycobacterial cultures and stains). Minimize exposure to atmospheric oxygen and transport in an anaerobic transport system. Do not refrigerate or freeze specimens for anaerobic culture. Note the following: Specimens collected and transported for anaerobic culture are also acceptable for aerobic bacterial, fungal, or mycobacterial culture, provided a sufficient volume of specimen is provided.

   Interpretation

   
Expected results:
No anaerobic pathogen isolated.

   Limitations

   Anaerobic infections are frequently polymicrobial. Initial isolation and aerotolerance testing may require repeated subculture of the primary culture media. Many anaerobic pathogens are slow growing and biochemically indolent, making identification, susceptibility testing, and further characterization of isolates in the laboratory much slower than most aerobic bacterial pathogens. Therefore, patient care decisions must often be made before results of testing are available, limiting the clinical utility of extensive workup of mixed anaerobic cultures.

   
Common pitfalls