Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, China.
Int J Antimicrob Agents. 2011 Feb;37(2):152-5. doi: 10.1016/j.ijantimicag.2010.10.021. Epub 2010 Dec 15.
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.
本研究调查了中国住院腹泻儿童沙门氏菌 Typhimurium 分离株的抗菌药敏性和质粒介导的喹诺酮耐药决定因素的流行情况。在总共 62 株 S. Typhimurium 分离株中，有 40 株（64.5%）对环丙沙星（最低抑菌浓度≥0.5μg/ml）耐药，其中 28 株为低水平耐药，12 株为高水平耐药。所有环丙沙星耐药分离株对其他抗菌药物均具有多药耐药性。在 40 株环丙沙星耐药分离株中发现了 4 个脉冲场凝胶电泳（PFGE）簇，其中 PFGE 簇 A、B、E 和 D 分别占 7、4、1 和 28 株。2 株高水平环丙沙星耐药分离株在喹诺酮耐药决定区（QRDR）gyrA 和 parC 中具有 2 个突变。其余环丙沙星耐药分离株仅在 QRDR 的 gyrA 中具有 1 个突变。62 株 S. Typhimurium 分离株均未检测到 qnr 基因和 qepA，23 株（37.1%）分离株携带 aac(6')-Ib-cr。19 株携带 aac(6')-Ib-cr 的分离株属于 PFGE 簇 D。在中国，从未接受喹诺酮类药物治疗的住院腹泻儿童中分离出的 S. Typhimurium 分离株中，环丙沙星耐药和 aac(6')-Ib-cr 的发生率很高。gyrA 的 QRDR 中的单个突变以及 AAC(6')-Ib-cr 的产生导致了环丙沙星耐药。克隆传播导致了 aac(6')-Ib-cr 在 S. Typhimurium 分离株中的传播。
