Study on molecular mechanisms of antibiotic resistance and plasmids genotype in multi-drug resistant Acinetobacter baumannii

Objective To investigate the antibiotic resistance,integron,transposon and plasmids genotype in 66 strains of multi-drug resistant Acinetobater baumannii(MDRAB) isolated from the First Affiliated Hospital of Guangzhou Medical College.Methods Resistant features to 18 kinds antibiotics were analyzed by VITEK-2 Compact.DNA was extracted from 66 strains of MDRAB and then the genetic marker of integron qacE△1-sull and transposon tnpU were amplified by polymerase chain reaction(PCR).Plasmids were extracted for the analysis of their phylogeny.Results The results showed that the positive rate of integron qacE△1-sull is 31.8%,and the positive rate of transposon tnpU is 30.3%.The strains of carrying genetic marker have a high resistance rate,especially for Ceftriaxone,Ampicillin,Aefotetan,Cefazolin and Nitrofurantoin was approaching or reached 100%,but for Amikacin and cefoperazone-sulbactam the resistance rates were 5% and 20%,respectively.Among the 19 strains out of 66 strains with multi-drug resistance,63.2% isolates were found containing qacE△1-sull and 36.8% containing the tnpU.The positive rate of harboring plasmids in 66 strains was 70%,with a molecular weight range 1～20 kb and 1 to 3 plasmids.12 of these strains showing a plasmid DNA band of same size.Conclusion The multi-drug resistant rate of Acinetobater baumannii was high and the resistance patterns were wide.The positive rates of the integron qacE△1-sull and transposon tnpU for multi-drug resistant of Acinetobactor baumannii is high,and it was the main reason that caused Acinetobacter baumannii multi-drug resistant.