Antibiotic resistance phenotypes and genotypes of ESBLs and AmpC ?-lactamases from Klebsiella oxytoca / 中华检验医学杂志

ABSTRACT

Objective To study antibiotic resistance phenotypes and genotypes of extended spectrum ?-lactamases (ESBLs) and AmpC ?-lactamase-producing Klebsiella oxytoca isolated from specimens of respiratory tract in children.Methods Bacterial isolates were identified by API or VITEK32. Agar dilution was used for antibiotic susceptibility test,and ESBLs and AmpC were detected by confirmatory test recommended by CLSI/NCCLS and by 3-aminophenylboronic acid (APB) disk potentiation test, respectively.Microarray was used to determine the genotypes of ESBLs and AmpC ?-lactamases.Genotypes of Klebsiella oxytoca were determined by enterobacterial repetitive intergenic consensus (ERIC)- PCR.Results ESBLs were positive in 129 out of 165 isolates (78.2%).Both ESBLs and AmpC ?- lactamases were positive in 16 out of 165 isolates (9.7%).AmpC ?-lactamase alone producer was not detected in term of phenotype and genotype.CTX-M was the most common type of ESBLs and DHA was the only type of AmpC ?-lactamase in these isolates.Most antibiotic resistant strains of Klebsiella oxytoca possessed the same genotype by ERIC-PCR.Although all strains were susceptible to carbpenem,Klebsiella oxytoca with ?-lactamases were more resistant to other antibiotic agents than those without ?- lactamases.Conclusions There is high prevalence of ESBLs production among Klebsiella oxytoca isolated from children in Urumqi.The main genotypes of ESBLs and AmpC ?-lactamases are CTX-M and DHA.