Study on phenotype and genotype of multiresistant Acinetobacter baumannii

Objective To analyse the resistant genotype and phenotype of 31 strains of multiresistant Acinetobacter baumannii in clinical isolation from our hospital. Methods Antibiotic susceptibility tests were performed by K-B methods,three dimensional extract tests were performed to detect extended spectrum β-lactamase(ESBL)-producing strains and cephalosporinase(AmpC)-producing strains,metallo-β-lactamases(MBL)-producing strains were detected by synergetic tests,and the resistant genes were amplified by polymerase chain reaction(PCR). Results In 31 strains of multiresistant Acinetobacter baumannii,90% were susceptible to imipenem;22% were resistant to cefoperazone/sulbactam and 74% were intermediate;other antibiotic susceptibility was not over 6%;2 strains produced ESBL;93% strains produced AmpC and 19% strains produced ESBL at the same time.bla_(TEM),aacA4 and gyrA genes were positive in all strains;ampC genes in 96% strains were positive;bla_(PER) and bla_(OXA-23) genes were both positive in 2 strains,another strain carried bla_(OXA-23) genes. Conclusions Carring several resistant genes including bla_(TEM),and ampC,aacA4,mutation of gyrA and bla_(PER),bla_(OXA-23) et al may be main reason that causes Acinetobacter baumannii multidrug resistant.