Antibiotic resistance and antibiotic resistance gene transfer of ESBLs-producing Escherichia coli in Naihe, Taian

Abstract:

[Objective] To study the distribution of extended-spectrum β-lactamase-producing Escherichia coli in Naihe, Taian City, as well as its multiple antibiotic resistance and relative antibiotic resistance genes, and further reveal the mechanism of antibiotic resistance gene transmission.[Methods] We used Kirby-Bauer method to determine the antibiotic resistance profiles, PCR for the detection of antibiotic resistance genes and Class I integrons, and multilocus sequence typing among ESBLs-producing Escherichia coli strains, and conducted the bacterial conjugation test.[Results] We isolated 88 ESBLs-producing Escherichia coli strains out of 272 water samples with the detection rate of 32.4% and the multiple antibiotic resistance rate of 59.1%. Resistance genes including bla_TEM, qnrS, AacC2, aac(6')-Ib-cr, oqxA, OXA and AacC4 were detected with the detection rates of 94.3%, 33.0%, 29.5%, 12.5%, 11.4%, 6.8% and 5.6% respectively. 59% of strains carried multiple drug resistance genes. We observed 47 sequence types (STs) in 88 isolates, and 13.6% of them were ST38; we also detected two ST131 strains. The positive rate of Class I integrons was 26.1%, and the predominate gene cassette was dfrA17-aadA5 with detection rate of 13.6%. The conjugation rate was 83.0% (73/88), 72.6% of the conjugates turned into narrower antibiotic resistance profiles. We observed horizontal transfer in all seven antibiotic resistance genes carried by the donor bacteria.[Conclusion] The bacterial multiple antibiotic resistance existed in urban rivers and the resistance genes were capable to transfer horizontally, which could be potential hazard that threatened public health.