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Anaerobic bacteria: History and role in normal human flora

John G Bartlett, MD
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Sheila Bond, MD


Anaerobic bacteria are the predominant cultivable forms of life in the human body. While the role of these microbes as pathogens was well established at the turn of the 20th century, they are often neglected in part due to the fact that clinical laboratories show great variation in application of recommended methods for recovery and identification of anaerobes. Important features that may limit detection of some of these organisms are:

The lack of resources and lack of perceived need for this technology, depending to some extent on the healthcare institution size and population served. Provider demand is also a factor. Nevertheless, virtually all labs provide Gram stains that frequently show the often unique morphology of these bacteria.

Fastidious growth requirements that often limit recovery.

Ubiquity on mucocutaneous surfaces that hampers obtaining meaningful cultures due to difficulty avoiding contamination by normal flora.

The presence of mixed flora including other known pathogens often requires clinical expertise to differentiate pathogens requiring treatment and commensals that do not.

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Literature review current through: Nov 2017. | This topic last updated: Jun 20, 2017.
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