Resistant Characteristic and Mechanisms of Imipenem Resistance in Acinetobacter baumannii / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To investigate the resistance of Acinetobacter baumannii(ABA),and the mechanism of imipenem resistance in A.baumannii.METHODS All specimens were identified by VITEK-60 and the drug resistance was detected by Kirby-Bauer test.Three dimensional test was used to detect ESBLs and AmpC.PCR and DNA sequencing were performed to determine VIM,IMP,OXA-23 and OXA-24 ?-lactamases.Outer membrane protein was analyzed by SDS-PAGE,Reserpine synergistic inhibition test was used to study the active efflux mechanism.RESULTS Totally 120 strains were isolated from sputum(76.9%),and 16 strains from secretion(10.3%).ICU was the main infected department(51 strains,32.7%).The resistance to sulperazone was the lowest(20.5%),and to imipenem accounted for 38.5%,Of the 20 imipenem resistant strains,10 strains were ESBLs positive(50%),and 20 strains were AmpC positive(100%).VIM,IMP and OXA-24 ?-lactamases were not detected out,19 strains(95%) produced OXA-23.Compared to the imipenem-sensitive strains,the resistant strains lacked the outer membrane protein of 22?103,29?103 and 33?103.The MICs of A.baumannii to imipenem were not decreased by reserpine which demonstrated that excretive mechanism was negative.CONCLUSIONS ICU is the main infected department for ABA.The resistance rate is increasing for longer-term usage of carbopenem;OXA-23 production is the important resistance mechanism in ABA,AmpC production and outer membrane protein lacking show close relation to the drug-resistance in A.baumannii.