Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
J Antimicrob Chemother. 2013 Oct;68(10):2249-54. doi: 10.1093/jac/dkt208. Epub 2013 Jun 12.
Resistance to extended-spectrum cephalosporins (ESCs) in Escherichia coli can be due to the production of ESBLs, plasmid-mediated AmpCs (pAmpCs) or chromosomal AmpCs (cAmpCs). Information regarding type and prevalence of β-lactamases, clonal relations and plasmids associated with the bla genes for ESC-R E. coli (ESC-R-Ec) detected in Switzerland is lacking. Moreover, data focusing on patients referred to the specialized outpatient clinics (SOCs) are needed.
We analysed 611 unique E. coli isolated during September-December 2011. ESC-R-Ec were studied with microarrays, PCR/DNA sequencing for blaESBLs, blapAmpCs, promoter region of blacAmpC, IS elements, plasmid incompatibility group, and also implementing transformation, aIEF, rep-PCR and MLST.
The highest resistance rates were observed in the SOCs, whereas those in the hospital and community were lower (e.g. quinolone resistance of 22.6%, 17.2% and 9.0%, respectively; P = 0.003 for SOCs versus community). The prevalence of ESC-R-Ec in the three settings was 5.3% (n = 11), 7.8% (n = 22) and 5.7% (n = 7), respectively. Thirty isolates produced CTX-M ESBLs (14 were CTX-M-15), 5 produced CMY-2 pAmpC and 5 hyper-expressed cAmpCs due to promoter mutations. Fourteen isolates were of sequence type 131 (ST131; 10 with CTX-M-15). blaCTX-M and blaCMY-2 were associated with an intact or truncated ISEcp1 and were mainly carried by IncF, IncFII and IncI1plasmids.
ST131 producing CTX-M-15 is the predominant clone. The prevalence of ESC-R-Ec (overall 6.5%) is low, but an unusual relatively high frequency of AmpC producers (25%) was noted. The presence of ESC-R-Ec in the SOCs and their potential ability to be exchanged between hospital and community should be taken into serious consideration.
产超广谱头孢菌素酶（ESBLs）的大肠杆菌（Escherichia coli）对 ESBLs、质粒介导的 AmpC（pAmpCs）或染色体 AmpC（cAmpCs）的耐药性。目前瑞士缺乏有关 ESC-R 大肠杆菌（ESC-R-Ec）的β-内酰胺酶的类型和流行率、克隆关系和与其相关的 bla 基因的质粒的信息。此外，还需要针对专门门诊（SOCs）的患者的数据。
我们分析了 2011 年 9 月至 12 月期间分离的 611 株独特的大肠杆菌。采用微阵列、blaESBLs、blaAmpC、blaAmpC 启动子区、IS 元件、质粒不相容群的 PCR/DNA 测序研究 ESC-R-Ec，还进行了转化、IEF、rep-PCR 和 MLST。
SOCs 的耐药率最高，而医院和社区的耐药率较低（例如，喹诺酮耐药率分别为 22.6%、17.2%和 9.0%；SOCs 与社区相比，P = 0.003）。三个环境中 ESC-R-Ec 的流行率分别为 5.3%（n = 11）、7.8%（n = 22）和 5.7%（n = 7）。30 株产生 CTX-M ESBLs（14 株为 CTX-M-15），5 株产生 CMY-2 pAmpC，5 株由于启动子突变而高表达 cAmpC。14 株为 ST131（10 株为 CTX-M-15）。blaCTX-M 和 blaCMY-2 与完整或截断的 ISEcp1 相关，主要携带于 IncF、IncFII 和 IncI1 质粒上。
产 CTX-M-15 的 ST131 是主要克隆。ESC-R-Ec 的流行率（总体为 6.5%）较低，但 AmpC 产生菌的频率（25%）较高，值得关注。SOCs 中 ESC-R-Ec 的存在及其在医院和社区之间可能的交换能力应引起高度重视。
