The cdeA gene, cloned from Clostridium difficile clinical strain 714 under the control of its natural promoter made Escherichia coli and Clostridium perfringens resistant to ethidium bromide and acriflavin but had no effect on the susceptibility of the hosts to the following antibiotics: norfloxacin, ciprofloxacin, gentamicin, erythromycin, tetracyclin, and chloramphenicol. However, it was responsible for fluoroquinolone resistance in E. coli when it was cloned under the control of the Plac promoter. Quantitative reverse transcriptase (RT)-PCR showed that growth of C. difficile clinical strain 253 in the presence of subinhibitory concentrations of ethidium bromide significantly increased the transcription of cdeA, but this was not observed with ciprofloxacin. The deduced protein was homologous to the protein sequences of known efflux pumps from the third cluster (the so-called DinF branch) of the multidrug and toxic compound extrusion (MATE) family. CdeA caused ethidium bromide energy-dependent efflux in whole cells of E. coli. Efflux activity was stimulated by addition of Na+ ions, suggesting that CdeA, like other pumps of the MATE family, is a Na+-coupled efflux pump. CdeA is the first multidrug efflux transporter identified in C. difficile.
Copyright Mary Ann Liebert, Inc.