Detection of AmpC and Extended-spectrum β-Lactamases Producing Enterobacteriaceae Strains in Lower Respiratory Tract Infections

OBJECTIVE To detect AmpC and extended-spectrum β-lactamases producing Enterobacteriaceae strains in lower respiratory tract infections. METHODS Adopting modified three dimensional extract test to detect (AmpC) β-lactamases producing and AmpC β-lactamases combined with ESBLs producing strains. Using method recommended by the National Committee for Clinical Laboratory Standards (NCCLS) to detect ESBLs producing strains. RESULTS Among 242 clinical Enterobacteriaceae isolates, which were resistant to the first-, second- and at least one kind of third-generation cephalosporins, AmpC β-lactamases, ESBLs and AmpC β-lactamases combined with ESBLs producing strains were found in 21, 110, and 6 strains, the incidence being 8.7%, 45.5%, and 2.5%, respectively. AmpC β-lactamases were detected in 42.1% of Enterobacter cloacae and ESBLs detected in 64.5% of Klebsiella pneumoniae. CONCLUSIONS It is important to select proper method to detect AmpC β-lactamases and ESBLs in time.