Study on extended spectrum β-lactamase and AmpC enzyme in imipenem-resistant Acinetobacter baumannii

Objective: To analyse the resistant genotype and phenotype of 54 strains imipenem-resistance Acinetobacter baumannii(IRABA) isolated from 54 patients.Methods: The strains of ABA were detected and antimicrobial susceptibility test were conducted by VITEK 2-compact system.ESBLs and AmpC enzyme were detected in 54 strains by improved three-dimensional test;AmpC and blaTEM genes were amplified by PCR,and genes of partial positive products were sequenced.Results: The rate of drug resistances in 54 strains of imipenem-resistant A.baumannii isolated from patients all exceeded 77 % except to levofloxacin,mempenem and cefoperazone/sulbactam.Three-dimensional test indicated that 36 strains(66.7 %) were only AmpC enzyme positive,6 strains(11.1 %) were only ESBLs positive,6 strains(11.1 %) were both ESBLs and AmpC enzyme positive.PCR and sequencing found 54 strains(100.0 %) produced ampC and blaTEM-1.Conclusion: The phenomenon of multi-drug resistance of Acinetobacter baumannii to antibiotic is severe.Carrying ampC and blaTEM-1 genes may be the main reason for the resistance to β-lactams.