Rifampin and Rifaximin Resistance in Clinical Isolates of Clostridium difficile

摘要: Rifaximin, a poorly absorbed rifamycin derivative, is promising alternative for the treatment of Clostridium difficile infections. Resistance to this agent has been reported, but no commercial test rifaximin resistance exists and molecular basis not previously studied in C. difficile. To evaluate whether rifampin Etest would be suitable substitute susceptibility testing clinical setting, we analyzed vitro susceptibilities 80 isolates from our collection by agar dilution compared these results obtained Etest. We found data agree with susceptibility; MICs both antimicrobials all were either very low or high. Fourteen rifaximin-resistant (MIC, ≥32 μg/ml) unique patients at diverse locations three countries identified. Molecular typing analysis showed that nine (64%) belonged epidemic BI/NAP1/027 group responsible multiple outbreaks increased disease severity United Kingdom, Europe, North America. The was investigated sequence rpoB, which encodes β subunit RNA polymerase, target rifamycins. Resistance-associated rpoB differences resulted specific amino acid substitutions an otherwise conserved region RpoB resistant isolates. Seven different identified isolates, divided into five distinct groups restriction endonuclease typing. These suggest associated independently derived rather than disseminated rifamycin-resistant clones. propose mutations predicts organism.