Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland.
J Antimicrob Chemother. 2014 Apr;69(4):977-81. doi: 10.1093/jac/dkt469. Epub 2013 Nov 27.
To identify the mechanism(s) underlying cefotaxime resistance in 118 of 21,641 (0.55%) non-typhoidal Salmonella enterica isolates collected from humans throughout England and Wales from January 2010 to September 2012.
Non-duplicate isolates (n = 118) resistant to cefotaxime (MICs >1 mg/L) were screened by PCR for genes encoding CTX-M extended-spectrum β-lactamases (ESBLs) and associated ISEcp1-like elements, and for genes encoding acquired AmpC, SHV, TEM, VEB, PER and GES β-lactamases. Sequencing was used to identify specific alleles in selected isolates. Carbapenem resistance was sought by ertapenem disc screening.
Seventy-nine isolates (0.37% of all referred S. enterica) produced ESBLs, 37 isolates (0.17%) produced CMY-type AmpC enzymes, and 1 isolate had both enzyme types; the mechanism of cefotaxime resistance in 3 isolates could not be identified. Group 1 CTX-M genes were identified in 57 isolates belonging to 22 serotypes, with CTX-M-1 (n = 11), -15 (n = 9) and -55/57 (n = 8) the most prevalent alleles among the 29 (51%) investigated. CTX-M-2 (n = 5), -14 (n = 5), -8 (n = 1) and -65 (n = 1) were also identified. TEM-52 was identified in two isolates and SHV-12 in seven isolates. There was no evidence of carbapenem resistance. ESBL and AmpC genes were detected in both domestically acquired and travel-associated salmonellae. Eighty-nine isolates (75%) were multidrug resistant (resistant to at least three antimicrobial classes) and 42 (36%) had decreased susceptibility to ciprofloxacin (MICs 0.25-1 mg/L), with a further 13 (11%) isolates resistant (MICs >1 mg/L).
The prevalence of CTX-M and acquired AmpC genes in human non-typhoidal S. enterica from England and Wales is still low, but has increased from 0.03% in 2001-03 to 0.49% in 2010-12. Resistance to third-generation cephalosporins requires monitoring as it may reduce therapeutic options.
从 2010 年 1 月至 2012 年 9 月期间在英格兰和威尔士采集的 21641 例非伤寒沙门氏菌感染患者中，确定 118 例（0.55%）对头孢噻肟耐药的非伤寒沙门氏菌的耐药机制。
通过 PCR 对 118 例头孢噻肟（MIC>1mg/L）耐药的非重复分离株进行 CTX-M 型超广谱β-内酰胺酶（ESBLs）及其相关的 ISEcp1 样元件、获得性 AmpC、SHV、TEM、VEB、PER 和 GES β-内酰胺酶基因的检测，并对所选分离株进行测序以鉴定特定等位基因。通过厄他培南纸片筛选寻找碳青霉烯类耐药性。
79 株（所有送检的沙门氏菌的 0.37%）产生 ESBLs，37 株（0.17%）产生 CMY 型 AmpC 酶，1 株同时产生两种酶；3 株分离株的头孢噻肟耐药机制无法确定。22 种血清型中有 57 株菌携带 1 型 CTX-M 基因，其中 CTX-M-1（n=11）、CTX-M-15（n=9）和 CTX-M-55/57（n=8）是 29 株（51%）研究株中最常见的等位基因。还鉴定出 CTX-M-2（n=5）、CTX-M-14（n=5）、CTX-M-8（n=1）和 CTX-M-65（n=1）。2 株菌携带 TEM-52，7 株菌携带 SHV-12。无碳青霉烯类耐药证据。在国内获得和旅行相关的沙门氏菌中均检测到 ESBL 和 AmpC 基因。89 株（75%）为多药耐药（至少对 3 种抗菌药物耐药），42 株（36%）对环丙沙星的敏感性降低（MICs 0.25-1mg/L），进一步有 13 株（11%）分离株耐药（MICs>1mg/L）。
英格兰和威尔士人类非伤寒沙门氏菌中 CTX-M 和获得性 AmpC 基因的流行率仍然较低，但已从 2001-03 年的 0.03%增加到 2010-12 年的 0.49%。第三代头孢菌素的耐药性需要监测，因为它可能会降低治疗选择。
