title: Detection of the SHV genotype polymorphism of the extended-spectrum β-lactamase-producing Gram-negative bacterium.
abstract: The prevalence of extended-spectrum β-lactamases (ESBLs) is due to the extensive usage of the extended-spectrum cephalosporins and leads to huge financial loss worldwide, whilst presenting a challenge to the clinical treatment. The aim of the present study was to delineate the frequency of ESBL occurrence in Enterobacteriaceae and confirm the SHV genotype. A random collection of 153Escherichia coliisolates (E. coli) and 70Klebsiella pneumoniaeisolates were tested. The amplification products obtained by polymerase chain reaction were sequenced. Isolates with novel mutations were transformed toE. coliDH5 α. The minimum inhibitory concentration (MIC) was obtained by a microdilution method. The relevance ratio of ESBL was 67.7% and the proportion of the SHV β-lactamase gene (blaSHV) was 18.5%. A new genotype of β-lactamase was demonstrated and submitted to GenBank. A total of 12 mutational sites were found in 28 ESBL-producing isolates, including four nonsense mutations. Sensitive-rates of 28 ESBL-producing isolates to imipenem were 100%, and resistant-rates to penicillin, amoxicillin and oxacillin were 100%. The MIC of DH5 α-F8 to penicillin, oxacillin, cefoxitin, cefotaxime, cefepime, cefoperazone/sulbactam, imipenem and netilmicin was 512, 512, 2, 0.03, 0.06, 4, 0.015 and 32 respectively. In conclusion, ESBL and SHV-28 is the most prevalentbla. Imipenem is the most effective antibiotic to ESBL, and the 4th-generation cephalosporins and β-lactamase inhibitor compound are also effective. ESBL is mediated by plasmids and able to spread among different Enterobacteriaceae. In conclusion, new mutations of theblaSHVgene exist from at least 2010.
authors.affiliation: Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Junlong
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Ji
authors.affiliation: College of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Deng
authors.affiliation: First Affiliated Hospital, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China.
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Ni
authors.affiliation: Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Xiaokang
authors.initials: X
authors.lastname: Liu
keywords: Escherichia coli; Klebsiella pneumoniae; SHV genotype; antibiotic sensitivity; extended-spectrum β-lactamase; mutation; transconjugation