Rifaximin microbiology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]
Microbiology
Mechanism of Action
Rifaximin is a non-aminoglycoside semi-synthetic antibacterial derived from rifamycin SV. Rifaximin acts by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase resulting in inhibition of bacterial RNA synthesis.
Escherichia coli has been shown to develop resistance to rifaximin in vitro. However, the clinical significance of such an effect has not been studied.
Rifaximin is a structural analog of rifampin. Organisms with high rifaximin minimum inhibitory concentration (MIC) values also have elevated MIC values against rifampin. Cross-resistance between rifaximin and other classes of antimicrobials has not been studied.
Rifaximin has been shown to be active against the following pathogen in clinical studies of infectious diarrhea as described in the Indications and Usage section: Escherichia coli (enterotoxigenic and enteroaggregative strains).
For HE, rifaximin is thought to have an effect on the gastrointestinal flora.
Susceptibility Tests
In vitro susceptibility testing was performed according to the National Committee for Clinical Laboratory Standards (NCCLS) agar dilution method M7-A6 [see References ]. However, the correlation between susceptibility testing and clinical outcome has not been determined.
References
Adapted from the FDA Package Insert.