[Detection of drug resistance due to the plasmid-mediated AmpC β-lactamase and genotype analysis in Klebsiella pneumoniae resulting in respiratory infections in children].

OBJECTIVE: To investigate the production and AmpC β-lactamase in Klebsiella (K.) pneumoniae resulting in respiratory infections in children, AmpC β-Lactamase genotypic resistance and typical resistance to common antibiotics so as to provide some references for selecting drugs in clinical treatment. METHOD: Microbiological identification was performed with the VITEK 60 System, extended spectrum β lactamases (ESBLs) were detected in accordance with the confirmatory test recommended by Clinical and Laboratory Standards Institute (CLSI) and drug sensitivity was determined with Kirby-Bauer method. Suspected positive strains of AmpC β-lactamase were screened with cefoxitin disk diffusion. The genotypes were analyzed by cefoxitin three-dimensional test, conjugation test and PCR sequencing. RESULT: Of the 135 isolates, 30.37% were ESBLs positive, 15.56% were AmpC β-lactamase positive. The positive rates for only AmpC β-Lactamase, both AmpC β-Lactamase and ESBLs, and only ESBLs were 8.15%, 7.41% and 22.96% respectively. The resistant genotypes for AmpC β-Lactamase-positive strains was that 19 strains were of DHA-1 type and 2 were of ACT-1 type. The resistance to drugs in β-lactamase-producing strains was obviously higher than that in non-β-lactamase-producing strains and more serious in those strains producing both AmpC β-Lactamase and ESBLs. Sensitivity of β-lactamase, non-β-lactamase and ESBLs producing strains to imipenem was as high as 100 percent. CONCLUSION: ESBLs- and AmpC-β-lactamase-producing strains of K. pneumoniae resulting in respiratory infections in children in Taizhou city, have a higher detection rate in Taizhou and AmpC-β-lactamase is mainly of DHA-1 genotype. AmpC-β-lactamase- and ESBLs-producing strains are highly resistant, so to restrict the use of β-lactam antibiotics is an important step to reduce the epidemic of β-lactamase-producing strains infection.