NDM-1 gene and other carbapenemase genes in Acinetobacter baumannii in Jiangxi area

Abstract:

ObjectiveTo understand the carriage of NDM1 and other carbapenemases in carbapenemresistant Acinetobacter baumannii(CRAB) in Jiangxi area, and provide laboratory basis for the prevention and control of healthcareassociated infection (HAI). MethodsSixtyfour strains of CRAB isolated from clinical specimens from 3 tertiary firstclass hospitals in Jiangxi area from January 2015 to June 2016 were collected, susceptibility to commonly used antimicrobial agents were detected with KirbyBauer method. Carbapenemases and metalloenzyme in CRAB were screened with modified Hodge test and EDTAdisk synergy test respectively, carbapenems gene was detected by polymerase chain reaction (PCR)， NDM1producing Acinetobacter baumannii (A. baumannii) were performed conjugation test.ResultsThe resistance rates of CRAB  to ampicillin/sulbactam, ciprofloxacin, gentamicin, and levofloxacin were up to 95.31%, 98.44%, 90.63%, and 54.69% respectively. The positive rates of modified Hodge test and EDTAdisk synergy test were 76.56% and 96.88% respectively. PCR amplification result showed that 87.50%（n=56） of CRAB carried OXA23 and VIM1 genes，18.75%（n=12）carried SIM， 3.13%(n=2）carried OXA-24，and 26.56%（n=17) carried NDM1. CRAB carrying NDM1 gene were all from The First Affiliated Hospital of Nanchang University, 64.70%（11/17）of which were pandrugresistant strains. Conjugation test result showed that NDM1producing strains could transfer NDM1 gene to recipient strain Escherichia coli J53, then acquired resistance to imipenem. ConclusionAntimicrobial resistance rates of clinically isolated CRAB in this area are high, OXA23 and VIM1 genes are the main carbapenemase genes, NDM1 gene positive CRAB is detected, and there may be a clonal spread of NDM1 gene in hospital, effective measures should be taken as soon as possible to prevent and control the spread of NDM1 positive CRAB.