global effect of <i>rpob</i> mutation on protein expression in <i>enterococcus faecium</i>

Background]<i>enterococcus faecium</i> is an important nosocomial pathogen and has developed resistance to multiple antibiotics, such as vancomycin. nitrofurantoin is active against <i>e. faecium</i> and <i>e. faecalis</i>, including vana and vanbpositive isolates.[objectives]to investigate the role of <i>rpob</i> mutation in <i>e. faecium</i>.[methods]the growth rate and reactive oxygen species (ros) levels were determined. the proteomic profiles of <i>e. faecium</i> b42 and its rif^r mutant b42r7 were also compared. complement experiments were performed to elucidate the role of nitroreductase in nitrofurantoin resistance.[results]the rif^r mutant (b42r7, <i>rpob</i> h489d) of <i>e. faecium</i> had a lower growth rate and higher ros levels. overexpression of nitroreductase in <i>e. faecium</i> b42r7 was observed in proteomic analyses. enhanced expression of nitroreductase in <i>escherichia coli</i> increased the sensitivity to nitrofurantoin.[conclusions]the <i>rpob</i> mutation in <i>e. faecium</i> not only altered the susceptibility to rifampin, but also affected global protein expression, including nitroreductase. nitroreductase expression in <i>e. faecium</i> b42r7 might play a role in nitrofurantoin resistance.