EmmdR, a new member of the MATE family of multidrug transporters, extrudes quinolones from Enterobacter cloacae
We cloned a gene, ECL_03329, from the chromosome of Enterobacter cloacae ATCC13047, using a drug-hypersensitive Escherichia coli KAM32 cell as the host. We show here that this gene, designated as emmdR, is responsible for multidrug resistance in E. cloacae. E. coli KAM32 host cells containing the cloned emmdR gene (KAM32/pEMMDR28) showed decreased susceptibilities to benzalkonium chloride, norfloxacin, ciprofloxacin, levofloxacin, ethidium bromide, acriflavine, rhodamine6G, and trimethoprim. emmdR-deficient E. cloacae cells (EcΔemmdR) showed increased susceptibilities to several of the antimicrobial agents tested. EmmdR has twelve predicted transmembrane segments and some shared identity with members of the multidrug and toxic compound extrusion (MATE) family of transporters. Study of the antimicrobial agent efflux activities revealed that EmmdR is an H+-drug antiporter but not a Na+ driven efflux pump. These results indicate that EmmdR is responsible for multidrug resistance and pumps out quinolones from E. cloacae.
KeywordsMultidrug transporter Enterobacter cloacae Resistance MATE Family
This work was supported by an Internal Research Grant from the University of Massachusetts Lowell (G. HE), and an NIH Grant P20 RR016480 (M.F.V.) which is from the NM-INBRE program of the National Center for Research Resources. We truly appreciate Dr. Tomofusa Tsuchiya for providing KAM32 and plasmids. The views presented in this article do not necessarily reflect those of the Food and Drug Administration.
- Fraser S, Anette M, Sinave CP (2010) Enterobacter infections. http://emedicine.medscape.com/article/216845-overview
- Hidron AI, Edwards JR, Patel J, Horan TC, Sievert DM, Pollock DA (2008) NHSN annual update: antimicrobial-resistant pathogens associated with healthcare-associated infections: annual summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention (2006–2007). Infect Control Hosp Epidemiol 29(11):996–1011PubMedCrossRefGoogle Scholar
- Kaneko K, Okamoto R, Nakano R, Kawakami S, Inoue M (2005) Gene mutations responsible for overexpression of AmpC beta-lactamase in some clinical isolates of Enterobacter cloacae. J Clin Microbiol 43:2995–2998Google Scholar
- Leverstein-van Hall MA, Blok HE, Paauw A, Fluit AC, Troelstra A, Mascini EM, Bonten MJ, Verhoef J (2006) Extensive hospital-wide spread of a multidrug-resistant Enterobacter cloacae clone, with late detection due to a variable antibiogram and frequent patient transfer. J Clin Microbiol 44:518–524PubMedCrossRefGoogle Scholar
- Pérez A, Canle D, Latasa C, Poza M, Beceiro A, Tomás Mdel M, Fernández A, Mallo S, Pérez S, Molina F, Villanueva R, Lasa I, Bou G (2007) Cloning, nucleotide sequencing, and analysis of the AcrAB-TolC efflux pump of Enterobacter cloacae and determination of its involvement in antibiotic resistance in a clinical isolate. Antimicrob Agents Chemother 51(9):3247–3253PubMedCrossRefGoogle Scholar
- Rossi F, Baquero F, Hsueh PR (2006) In vitro susceptibilities of aerobic and facultatively anaerobic gram-negative bacilli isolated from patients with intra-abdominal infections worldwide: (2004) results from SMART (study for monitoring antimicrobial resistance trends). J Antimicrob Chemother 58(1):205–210PubMedCrossRefGoogle Scholar