Antimicrobial susceptibility test and resistance gene analysis of clinical isolates of Salmonella enteritidis

ObjectiveTo analyze drug resistance and the mutations of resistance genes of Samlonella enteritidis isolated from diarrhea patients in China.MethodsThe suspected strains were identified with conventional biochemical test and serum agglutination test.Antibiotic susceptibility test was performed according to KB methods.The DNA gyrase A and to poisomerase IV parC genes were amplified by PCR technique,and the amplified products were sequenced.ResultsTotally 20 Samlonella enteritid is strains were identified.All of the strains were sensitive to cipro floxacin,gentamycin,ceftazidmie and imipenem,and resistant to nalidixic acid.Of all strains,75% presented multi drugre sistance(MDR).Nucleotide sequence analysis showed that all of the strains had mutations in codonsAsp87 and Gly133 in quinolone resistance determining region(QRDR)of gyrAgene,while the Gly133 point mutation was novel.Mutation was not found in parC gene.ConclusionThe results showed severe multi drug resistance of clinically isolated strains of Salmenella enteritidis,and nalidix acid resistance is common.This is probably attributable to pointmutations in QRDR of gyrA gene.The an tibiotics should be prudently used for the treatment of Samlonella infections.