Detection and dissemination of oqxAB gene among Salmonella isolates from food-producing animals.

Susceptibilities of total 31 Salmonella isolates were determined by agar dilution method.oqxAB gene was amplified among 31 Salmonella isolates using specific primers.PCR products were cloned into a vector pMD19-T for sequencing.Conjugation tests were conducted among oqxAB positive Salmonella using Escherichia coli J53AziR as a recipient.The susceptibilities of 31 Salmonella isolates for common use antimicrobials showed that the resistant occurrence for ampicillin was ranked the highest(64.5%),42%-55% for aminoglycosides,chloramphenicols,tetracyclines and fluoroquinolones,and less than 20% for cephalosporins.The occurrence of the oqxAB gene in 31 Salmonella isolates was found to be 39%.Five oqxAB positive conjugants were obtained from matching tests.The minimum inhibitory concentration(MIC) results of 5 transconjugants suggested that streptomycin,tetracycline,chloramphenicol and enrofloxacin resistant determinants were transferable with oqxAB gene on the same plasmid,which was in line with previous reports.Determinants indicated that β-lactams resistance was probably transferred with oqxAB on the same plasmid.