Plasmid-Mediated Quinolone Resistance Determinant qnrA Gene in Klebsiella pneumoniae Isolated from Health Chickens

All of the 195 clinical isolates of Enterobacteriaceae from chickens were screened for the qnrA by PCR. Susceptibility of qnrA-producing to 8 antimicrobial agents was determined by agar disc diffusion method. Conjugation experiment was performed by using Escherichia coli J53 Az^R as the recipient strain. Southern hybridization was done with plasmid DNA and genetic DNA. IntIⅠwas screened from the qnrA positive strains.The results showed that a qnrA1 gene was identified in a Klebsiella pneumoniae GDKA1. GDKA1 showed resistance to sulfamethoxazole,ampicillin, spectinomycin, chloramphenicol, and tetracycline, susceptible to ciprofloxacin (MIC= 0.019 mg·L^-1) and cefotaxime (MIC=0.047 mg·L^-1) and intermediate to nalidixic acid (MIC= 12 mg·L^-1). A transconjugant was selected during the conjugation experiment and hybridization with qnrA1-specific probes revealed that the qnrA1 gene was located in plasmid DNA.Tranconjugant T_GDKA1 showed a little higher quinolone MIC than E. coli J53 Az^R but not as high as GDKA1. IntI1 was detected in qnrA gene positive strain.In conclusion，qnrA1 gene in K. pneumoniae isolated from health chicken might be transmitted together with class I integron to people through food chain. The presence of qnrA1 gene in health animal commensal bacteria should be noticed.