[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.