Manual of Clinical Microbiology


Bacteroides, Porphyromonas, Prevotella, Fusobacterium, and Other Anaerobic Gram‐Negative Rods

Last Updated:2023
Taxonomy and Description of the Group

Most of the obligately anaerobic, Gram‐negative, non‐spore‐forming rods of clinical relevance belong to the phylum Bacteroidetes, order Bacteroidales, including families Bacteroidaceae, Porphyromonadaceae, Prevotellaceae, and Rikenellaceae, and to the ...

Epidemiology and Transmission

Gram‐negative anaerobic rods inhabit the mucosal surfaces of the oral cavity and gastrointestinal tract of animals and humans. Infants acquire oral and intestinal anaerobic commensals mainly from their mother and…

Clinical Significance

Anaerobes, originating mainly from the indigenous microbiota, are detected typically in polymicrobial infections associated with mucosal surfaces close to the site where they reside. Most infections are acquired when the…

Collection, Transport, and Storage of Specimens

General guidelines for collection, transport, and storage of specimens are discussed in chapters 13 and 19 of this Manual. Specimens suitable for the isolation of anaerobes include blood, tissue biopsies,…

Direct Examination

The gross appearance, fluorescence under long‐wave UV light, and odor of the specimen can give the laboratory valuable clues to the presence of anaerobes. A fetid or putrid odor due…

Isolation Procedures

Except for blood and joint fluid cultures, the use of liquid medium as the only anaerobic culture technique is not acceptable (91). The use of solid nonselective medium…


After anaerobic incubation, the relative quantities of distinct colony types are recorded. Plates should be examined with a dissecting microscope to facilitate detection. Even after incubation for 7 days, certain…

Antimicrobial Susceptibilities

Antimicrobial resistance among Gram‐negative anaerobes continues to rise (340–344). This means that important anaerobic pathogens are not per se susceptible to piperacillin‐tazobactam, carbapenems, or metronidazole but…

Evaluation, Interpretation, and Reporting of Results

Knowledge about the resident microbiota and awareness of the role of anaerobic bacteria in disease permit the clinician to anticipate the likely infecting species at different body sites…

Section Editor: Johann Pitout

Volume Editor: Alexander McAdam

Editors in Chief: Karen C. Carroll and Michael A. Pfaller

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