Detection and antimicrobial susceptibility testing for AmpC β-lactamase producing strains of acinetobacter baumannii isolated from neonatal intensive care units

Objective To investigate the proportion and drug resistance of AmpC β-1actarnases producing strains for acinetobacter baumannii isolated from neonatal intensive care units(NICU).Methods Acinetobacter baumannii strains were isolated from NICU during January,2006 to December,2009.Drug susceptibility test was evaluated by Kirby-Bauer procedure.Isolates with the production of AmpC β-lactamases were detected by the improved cefotaxime three-dimensional test.Results 109 isolates of acinetobacter baumannii were confirmed during the period,and among which 35.8%(39/109) were AmpC β-lactamases producing strains.The drug resistance rates of AmpC β-lactamases producing strains were 92.3%-100% to the third-generation of cephalosporins,while the rates were 7.6%-33.0% to imipenem,amikacin,ciprofloxacin,piperacillin/tazobactant and cefperazone/sulbactam.The drug resistance rates of acinetobacter baumannii were higher in AmpC β-lactamases producing isolates than that in no AmpC β-lactamases producing ones.Conclusion NICU isolated acinetobacter baumannii had high proportion of AmpC β-lactamases producing strains,which were resistant to some commonly used antibiotics,especially the third and fourth generation of cephalothin,or had multiple drug resistance.Additional attention should be given to antibiotics selection for the clinical treatment.