Detection of Beta-lactamases in Multi-resistant Citrobacter Strains / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To investigate beta-lactamases production in multi-resistant Citrobacter strains isolated from the First Affiliated Hospital of Anhui Medical University.METHODS Standard agar dilution method was used to determine the minimal inhibitory concentration(MIC) of 52 clinically isolated Citrobacter strains,improved three-dimensional tests were performed to detect the ESBLs-producing,AmpC-producing and MBL-producing strains in 31 Citrobacter isolates,then beta-lactamases-encoding genes were amplified by polymerase chain reaction(PCR).RESULTS Thirty one Citrobacter strains were resistant to many beta-lactams antibiotics.Twenty four strains ESBLs-producing,3 AmpC-producing and 2 ESBLs-producing plus AmpC-producing strains have been detected by improved three-dimensional tests,and not found MBL-producing ones.Twenty strains had blaTEM gene and 1 strain had blaSHV gene,8 strains had blaCTX-M-1 gene,15 strains had blaCTX-M-13 gene and 5 strains had blaCIT gene by PCR.CONCLUSIONS Multi-resistant Citrobacter strains produce one or more types of ESBLs and AmpC beta-lactamase,it may be an important reason of resistance to beta-lactams antibiotics.