Abstract:

Abstract:Objective
To identify the antimicrobial resistance and the mutations in acrAB-tolC efflux pump and marOR regulated genes in Shigella,then analyze their relations.Methods One hundred and fifty-nine clinical isolates of Shigella were collected.Susceptibility tests of tetracycline( TE),chloramphenicol(C),ampicillin(Am),gentamycin(GM),norfloxacin (NOR) and selectrin(SMZ-TMP) and organic-solvent tolerance test were performed in all isolates.The acrA,acrB,tolC and marOR genes of these isolates were amplified by polymerase chain reaction (PCR) respectively.The PCR products were digested by restriction endonuclease Taq Ⅰ or Hinf Ⅰ,then analyzed by single strand conformation polymorphism (SSCP).Results In 159 clinical isolates,137 multi-drug strains and 4 sensitive strains were discovered.The rate of multi-drug resistance was 86.2%. 122 strains were organic-solvent tolerance and the rate of organic-solvent tolerance was 76.7%. The marOR and acrAB-tolC genes were found in all strains and the lack of the four genes were not found. SSCP analysis revealed that the rates of mutations in marOR,acrA,acrB and tolC genes were 17.4%,5.8%,3.9%， and 2.6%,respectively.Conclusion  The Shigella spp.has high multi-drug resistance rate and organic-solvent tolerance rate,and the mutation rate of marOR gene is high too.

Key words: Shigella;marOR gene;acrAB-tolC efflux pump gene;multi drug resistance