Prevalence and Dissemination of oqxAB in Escherichia coli Isolates from Animals, Farmworkers, and the Environment

Abstract

OqxAB has recently been identified as one of the mechanisms of plasmid-mediated quinolone resistance (PMQR).Compared to what is observed for other PMQR determinants, there is a paucity of data with regard to the prevalence and epidemiology of OqxAB and its contribution to resistance to different antimicrobials. In this study, the prevalence and dissemination of oqxAB and other PMQR genes in Escherichia coli isolates from animals, farmworkers, and the environment in 2002 in China were investigated. Of the 172 E. coli isolates, 39.0% carried oqxA, while only 4.1%, 2.9%, and 0.6% carried qnr (1 qnrB6 isolate, 5 qnrS1 isolates, and 1 qnrD isolate), qepA, and aac(6)-Ib-cr, respectively. Among the 33 isolates from farmworkers, 10 (30.3%) were positive for oqxA. oqxAB was associated with IS26 and was carried on the 43-to 115-kb IncF transferable plasmid. Transconjugants carrying oqxAB showed 4-to 16-fold increases in the MICs of quinolones, 16-to 64-fold increases in the MICs of quinoxalines, 8-to 32-fold increases in the MICs of chloramphenicol and trimethoprim-sulfamethoxazole, and 4-to 8-fold increases in the MICsof florfenicol compared to the levels for the recipient. The pulsed-field gel electrophoresis (PFGE) analysis showed that the high levels of prevalence and dissemination of oqxAB in E. coli in animal farms were primarily due to the transmission of plasmids carrying oqxAB, although clonal transmission between human and swine E. coli isolates was observed. It is concluded that oqxAB was widespread in animal farms in China, which may be due to the overuse of quinoxalines in animals. This study warrants the prudent use of quinoxalines in food animals.

Complete Nucleotide Sequence of a bla KPC -Harboring IncI2 Plasmid and Its Dissemination in New Jersey and New York Hospitals

“…Strain BK15692 was initially screened by a multiplex real-time PCR for K. pneumoniae ST258 clone identification and the presence of bla KPC (18), and the sequence type (ST) was further confirmed by multilocus sequence typing (MLST) (19). ␤-Lactam (bla CTX-M , bla SHV , bla TEM , bla GES , bla NDM , bla VIM , bla IMP , bla , bla ACT-1 , bla ACC , bla BIL-1 , bla CMY , bla DHA , bla FOX , bla LAT , bla MIR-1 , and bla MOX ), aminoglycoside (aadA1, aadA2, aadB, aadA5, strA, strB, aphA1, aphA2, aphA6, aacC1, aacC2, aacC4, aacA4, armA, rmtC, and rmtB), and fluoroquinolone (qnrA, qnrB, qnrC, qnrD, qnrS, oqxA, and oqxB) resistance genes were investigated by PCR using methods described elsewhere (20)(21)(22)(23)(24). Plasmid incompatibility groups were determined using the PCR methods described previously (25,26).…”

Plasmid-Mediated Quinolone Resistance

“…It has a wide substrate specificity including chloramphenicol, trimethoprim, and quinolones such as ciprofloxacin, flumequin, norfloxacin, and nalidixic acid (13). oqxAB has been found on plasmids in clinical isolates of E. coli and K. pneumoniae and in the chromosome and on plasmids of S. enteritis flanked in both locations by IS26-like elements (202)(203)(204)(205)(206)(207). In E. coli isolates from farms in China where olaquindox was in use, oqxAB was found on transmissible plasmids in 39% of isolates from animals and 30% of isolates from farm workers (204).…”

A Fluoroquinolone-Resistant Escherichia coli Clinical Isolate without Quinolone Resistance-Determining Region Mutations Found in Japan

“…It confers resistance to several antimicrobial agents, such as olaquindox, trimethoprim, and chloramphenicol, and a slight decrease in susceptibility to fluoroquinolones (3). Isolation of oqxAB-harboring Enterobacteriaceae has been reported only in Sweden and Denmark, South Korea, and China (3,5,7), and isolates derived from human patients have been reported only in South Korea. This letter provides the first report of oqxAB-harboring E. coli in Japan.…”