Modern Anaerobic Bacteriology Practice: Identification and Antimicrobial Susceptibility Testing

MALDI-TOF MS and sequencing have revolutionized anaerobic bacteriology testing, rendering anaerobe identification both accurate and rapid. Novel applications of MALDI-TOF MS and new commercially available anaerobe culture media plates are recent tools that have become available to clinical microbiology laboratories to decrease time to reporting of anaerobes. Antimicrobial resistance is also on the rise in anaerobes, and identification to the species level—particularly for Bacteroides and Parabacteroides—should be performed to guide antimicrobial empiric therapy. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) method of anaerobe disk diffusion is relatively new to the field and is allowing anaerobe AST to be more accessible to clinical microbiology laboratories. Additionally, testing of B. fragilis strains for potential cfiA-mediated carbapenem resistance has also recently become available via a MALDI-TOF MS platform. Finally, the Clinical and Laboratory Standards Institute (CLSI) recently published an updated anaerobe antibiogram in the M100 document covering many different anaerobe species. Anaerobe antibiograms are helpful for laboratories and clinicians to guide empiric therapy. Given the evolving anaerobe antimicrobial resistance landscape and the strong emphasis on antimicrobial stewardship, updated anaerobe susceptibility data via cumulative antibiograms and other patient testing data are needed to inform empiric and targeted therapy decisions.