title: A Contribution of MdfA to Resistance to Fluoroquinolones in Shigella flexneri.
abstract: In this study, we measured the drug resistance conferred by mdfA mutations in two Shigella flexneri strains. A mutant in mdfA genes was constructed by polymerase chain reaction-based, one-step inactivation of chromosomal genes. The antimicrobial susceptibility of parent and mutant strains to fluoroquinolones was determined by minimal inhibitory concentration (MICs). The △mdfA mutants were somewhat more susceptible to fluoroquinolones than the parent strains. The low level changes in MICs of the △mdfA mutants suggest that mdfA contributed the fluoroquinolone resistance in S flexneri. This finding found that the increased expression level of an MdfA efflux pump mediated fluoroquinolone resistance, but it is not likely a major effecter of higher resistance levels.
authors.affiliation: Division of Enteric Bacterial Infections, Korea National Institute of Health, Osong, Korea.
authors.forename: Jun-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Se-Mi
authors.initials: SM
authors.lastname: Jeon
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Kim
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Park
authors.forename: Seong-Han
authors.initials: SH
authors.lastname: Kim
keywords: MdfA; Shigella flexneri; efflux pump; fluoroquinolones resistance