Prevalence of ESBLs and PMQR Encoding Genes in Escherichia coli Isolated from Edible Fish in Guangdong

Two hundred and eighteen Escherichia coli isolates were collected and identified from edible fish in this study. Susceptibilities of 218 isolates to 17 antimicrobials were performed by agar dilution method. Prevalence of ESBLs and PMQR encoding genes was detected by PCR. Broth mating was applied to explore the transfer of ESBLs and/or PMQR determinants from 10 ESBLs and/or PMQR positive isolates to E. coli C600. Susceptibility results showed that resistance occurance of 218 E. coli to 17 antimicrobials ranged from 0.5% to 72.5%. Two ESBLs encoding genes were detected in 112 ampicillin-resistant isolates, including bla_CTX-M-79 and bla_CTX-M-14. Beta-lactamase genes, bla_LEN-4 and bla_LEN-17 were also detected in 2 isolates. Fifty-nine of 80 ciprofloxacinresistant isolates harboured PMQR determinants, of which 33 were qnrB, 5 qnrD, 21 qnrS, and 6 aac(6′)-Ib-cr. No isolates were detected to carry qnrA, qnrC and qepA. The results of conjugation experiments showed that ESBLs and/or PMQR determinants may be transferred on a same plasmid to E. coli C600.