OqxAB, a quinolone and olaquindox efflux pump, is widely distributed among multidrug-resistant Klebsiella pneumoniae isolates of human origin

摘要

Use of antibiotics among livestock contributes to the selection and dissemination of multidrug resistant (MDR) bacteria (1). Olaquindox and carbadox are quinoxaline derivatives with antibacterial properties that prevent dysentery and enhance weight gain in suckling pigs (2). Resistance to quinoxalines is mediated by the efflux pump OqxAB, which also extrudes antibiotics such as chloramphenicol and fluoroquinolones (3). The gene encoding this efflux pump, oqxAB, was initially detected within plas-mid pOLA52, which was found in Escherichia coli isolated from swine manure (4). Dissemination of oqxAB has been noted in Salmonella species, and the original genetic reservoir of oqxAB was traced to the chromosome of Klebsiella pneumoniae (5, 6). Surprisingly, OqxAB has been reported only in clinical isolates of K. pneumoniae from China, South Korea, and Spain (7-9).