title: High prevalence of plasmid-mediated quinolone resistance determinant aac(6')-Ib-cr amongst Salmonella enterica serotype Typhimurium isolates from hospitalised paediatric patients with diarrhoea in China.
abstract: In this study, the antimicrobial susceptibilities and prevalence of plasmid-mediated quinolone resistance determinants amongst Salmonella enterica serotype Typhimurium isolates from hospitalised paediatric patients with diarrhoea in China were investigated. In total, 40 (64.5%) of 62 S. Typhimurium isolates were resistant to ciprofloxacin (minimum inhibitory concentration ≥0.5 μg/mL), comprising 28 isolates with low-level resistance and 12 isolates with high-level resistance. All ciprofloxacin-resistant isolates were multiresistant to other antimicrobial agents. Four pulsed-field gel electrophoresis (PFGE) clusters were found amongst the 40 ciprofloxacin-resistant isolates, amongst which PFGE clusters A, B, E and D accounted for 7, 4, 1 and 28 isolates, respectively. Two isolates with high-level ciprofloxacin resistance had two mutations in the quinolone resistance-determining regions (QRDRs) of gyrA and parC. The remaining ciprofloxacin-resistant isolates had only one mutation in the QRDR of gyrA. All 62 S. Typhimurium isolates were negative for qnr genes and qepA and 23 (37.1%) of the isolates were positive for aac(6')-Ib-cr. Nineteen isolates harbouring aac(6')-Ib-cr belonged to PFGE cluster D. A high prevalence of ciprofloxacin resistance and aac(6')-Ib-cr was found amongst S. Typhimurium isolates in China from hospitalised paediatric patients with diarrhoea not receiving quinolones. A single mutation in the QRDR of gyrA as well as production of AAC(6')-Ib-cr contributed to ciprofloxacin resistance. Clonal spread was responsible for the dissemination of aac(6')-Ib-cr amongst S. Typhimurium isolates.
authors.affiliation: Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, China.
authors.forename: Fangyou
authors.initials: F
authors.lastname: Yu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Yu
authors.forename: Jingye
authors.initials: J
authors.lastname: Pan
authors.forename: Qiaoqiao
authors.initials: Q
authors.lastname: Li
authors.forename: Lehe
authors.initials: L
authors.lastname: Yang
authors.forename: Cong
authors.initials: C
authors.lastname: Chen
authors.forename: Chao
authors.initials: C
authors.lastname: Zhuo
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Li
authors.forename: Xueqing
authors.initials: X
authors.lastname: Zhang
authors.forename: Jinwei
authors.initials: J
authors.lastname: Huang
authors.forename: Liangxing
authors.initials: L
authors.lastname: Wang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002675:Child, Preschool; D002681:China; D016000:Cluster Analysis; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D003967:Diarrhea / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D020125:Mutation, Missense; D010957:Plasmids; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase