Dissemination and Characterization of Plasmids Carrying oqxAB-blaCTX-M Genes in Escherichia coli Isolates from Food-Producing Animals

Abstract

BackgroundThe association of PMQR and ESBLs in negative-bacteria isolates has been of great concern. The present study was performed to investigate the prevalence of co-transferability of oqxAB and bla CTX-M genes among the 696 Escherichia coli (E. coli) isolates from food-producing animals in South China, and to characterize these plasmids.MethodsThe ESBL-encoding genes (bla CTX-M, bla TEM and bla SHV), and PMQR (qnrA, qnrB, qnrS, qnrC, qnrD, aac(6’)-Ib-cr, qepA, and oqxAB) of these 696 isolates were determined by PCR and sequenced directionally. Conjugation, S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blotting experiments were performed to investigate the co-transferability and location of oqxAB and bla CTX-M. The EcoRI digestion profiles of the plasmids with oqxAB-bla CTX-M were also analyzed. The clonal relatedness was investigated by PFGE.ResultsOf the 696 isolates, 429 harbored at least one PMQR gene, with oqxAB (328) being the most common type; 191 carried bla CTX-M, with bla CTX-M-14 the most common. We observed a significant higher prevalence of bla CTX-M among the oqxAB-positive isolates (38.7%) than that (17.4%) in the oqxAB-negative isolates. Co-transferability of oqxAB and bla CTX-M was found in 18 of the 127 isolates carrying oqxAB-bla CTX-M. These two genes were located on the same plasmid in all the 18 isolates, with floR being on these plasmids in 13 isolates. The co-dissemination of these genes was mainly mediated by F33:A-: B- and HI2 plasmids with highly similar EcoRI digestion profiles. Diverse PFGE patterns indicated the high prevalence of oqxAB was not caused by clonal dissemination.Conclusion bla CTX-M was highly prevalent among the oqxAB-positive isolates. The co-dissemination of oqxAB-bla CTX-M genes in E. coli isolates from food-producing animals is mediated mainly by similar F33:A-: B- and HI2 plasmids. This is the first report of the co-existence of oqxAB, bla CTX-M, and floR on the same plasmids in E. coli.

Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli

“…without the IS26 elements (11,12). The high prevalence of oqxAB has been reported among E. coli and Salmonella isolates of animal or meat origins in China (13)(14)(15)(16)(17). In the current study, we investigated the association of plasmid-mediated oqxAB and nitrofurantoin resistance in E. coli isolates originating from human and animal sources.…”

Complete Sequence of the FII Plasmid p42-2, Carrying bla CTX-M-55 , oqxAB , fosA3 , and floR from Escherichia coli

“…This problem has been exacerbated in recent years with the emergence of multidrug resistance (MDR) plasmids conferring resistance to most classes of antimicrobials (2). Plasmids of the incompatibility F (IncF) group, representing one of the most frequently encountered plasmid types (3), have frequently been associated with MDR phenotypes, including extended-spectrum ␤-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) genes (4,5). In a previous study of ours, IncF plasmids recovered from Escherichia coli strains of food-producing and companion animals were investigated, and most of them carried numerous resistance determinants, such as bla CTX-M , rmtB, oqxAB, and floR (4,6).…”

“…Plasmids of the incompatibility F (IncF) group, representing one of the most frequently encountered plasmid types (3), have frequently been associated with MDR phenotypes, including extended-spectrum ␤-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) genes (4,5). In a previous study of ours, IncF plasmids recovered from Escherichia coli strains of food-producing and companion animals were investigated, and most of them carried numerous resistance determinants, such as bla CTX-M , rmtB, oqxAB, and floR (4,6). The spread of these multiresistance plasmids has prompted worldwide concern because of coresistance to multiple antimicrobial agents that facilitates the survival of bacteria under the selective pressure of antibiotics.…”

Prevalence and antimicrobial resistance profiles of Escherichia coli isolated from free-range pigs

“…Thirty-nine E. coli isolates were positive for floR with a detection rate of 31.7％, which was lower than that found in E. coli isolated from chickens and pigs raised in intensive breeding farms in China [26,27]. Nevertheless, this result indicated that floR gene was relatively prevalent in Laiwu black pig-derived E. coli.…”