Gene Cloning and Characterization of SdrM, a Chromosomally-Encoded Multidrug Efflux Pump, from Staphylococcus aureus

There are more than 30 genes for putative multidrug efflux pumps in the chromosome of Staphylococcus aureus. Only a few of these have been analyzed so far. Here we cloned a new gene, SA1972, using a PCR method, from the chromosome of S. aureus N315. We found that the product SA1972 could lead to elevated resistance against several antimicrobial agents such as norfloxacin, acriflavine and ethidium bromide. We designated the gene as sdrM. We observed elevated energy-dependent efflux of acriflavine in S. aureus cells introduced with the sdrM gene. We conclude that SdrM is a multidrug efflux pump belonging to the major facilitator (MF) superfamily.