Objective To investigate the incidence of extended spectrum β
lactamases (ESBLs) of E.coli and K. pneumoniae in
Hua Shan Hospital of Shanghai Medical University and their relationship with antibiotic resistance patterns.Methods ESBLs producing strains in E.coli and K. pneumoniae were detected by double disc synergy test, inhibitor potentiated disc diffusion test and inhibitor combined with minimum inhibitory concentrations (MIC) determination of third generation cephalosporins. The
bacterial susceptibility testing of ESBLs producing strains was assayed by Kirby Bauer method.Results The incidence of ESBLs was 25% in E.coli and 57% in K. pneumoniae. ESBLs producing strains were more resistant to third generation cephalosporins and aztreonam, but few of which was resistant to imipenem. The susceptibility rate of these strains to cefoxitin was about 80%. Most strains were resistant to amikacin and ciprofloxacin.Conclusion Extended spectrun β lactamases play a most important role in bacterial resistance to third generation cephalosprins and monobactams. We should pay much attention to detecting ESBLs producing strains and their susceptibility to antibiotics.