Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis, Tunisia.
Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis, Tunisia; Institut Supérieur des Sciences Biologiques Appliquées de Tunis, Université de Tunis El Manar, 2092 Tunis, Tunisia.
J Glob Antimicrob Resist. 2016 Sep;6:17-21. doi: 10.1016/j.jgar.2016.01.013. Epub 2016 Mar 16.
This study aimed to assess the occurrence of extended-spectrum β-lactamases (ESBLs) in clinical Escherichia coli isolates from Palestine and to characterise their type, genetic environments and associated resistance genes. Twenty-seven broad-spectrum-cephalosporin-resistant E. coli isolates were recovered between April and June 2013 in Gaza Strip hospitals. Characterisation of ESBL genes and their genetic environments, detection of associated resistance genes, and the presence and characterisation of integrons were performed by PCR and sequencing. The clonal relationship among ESBL-positive E. coli strains was determined by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme XbaI. Phylogroup typing and virulence factors were studied by PCR. The following ESBL genes were identified: blaCTX-M-15 (21 isolates); blaCTX-M-14a (2 isolates); blaCTX-M-1 (2 isolates); blaCTX-M-3 (1 isolate); and blaCTX-M-27 (1 isolate). The blaTEM-1 gene was also detected in eight CTX-M-producing strains. The ISEcp1 sequence was found upstream of blaCTX-M in 23 isolates, and orf477 was found downstream of this gene in 24 isolates. IS903 was also detected downstream in three isolates. Six isolates carried class 1 integrons with the gene cassette arrangement dfrA17-aadA5. High clonal diversity was observed among the studied isolates by PFGE (24 unrelated profiles). The virulence gene fimA was detected in 23 isolates, the aer gene in 8 isolates and the papC gene in 7 isolates. The studied isolates belonged to phylogroups B2 (12 isolates), D (12 isolates) and A (3 isolates). This is the first report of the detection of CTX-M class β-lactamases in E. coli of clinical origin in Gaza Strip hospitals.
本研究旨在评估巴勒斯坦临床分离大肠埃希菌中扩展谱β-内酰胺酶（ESBLs）的发生情况，并对其类型、遗传环境和相关耐药基因进行特征分析。2013 年 4 月至 6 月，在加沙地带医院共分离出 27 株广谱头孢菌素耐药大肠埃希菌。采用 PCR 和测序方法对 ESBL 基因及其遗传环境、相关耐药基因的检测、整合子的存在和特征进行了分析。通过 XbaI 限制性内切酶脉冲场凝胶电泳（PFGE）确定产 ESBL 阳性大肠埃希菌菌株之间的克隆关系。通过 PCR 研究了 phylogroup 分型和毒力因子。鉴定出以下 ESBL 基因：blaCTX-M-15（21 株）；blaCTX-M-14a（2 株）；blaCTX-M-1（2 株）；blaCTX-M-3（1 株）；和 blaCTX-M-27（1 株）。在 8 株产 CTX-M 的菌株中也检测到 blaTEM-1 基因。在 23 株菌中发现 blaCTX-M 上游有 ISEcp1 序列，在 24 株菌中发现 blaCTX-M 下游有 orf477 序列。在 3 株菌中还检测到 IS903 下游。6 株菌携带带有基因盒排列 dfrA17-aadA5 的 I 类整合子。通过 PFGE（24 个不相关的图谱）观察到研究分离株具有高度的克隆多样性。23 株菌检测到 fimA 毒力基因，8 株菌检测到 aer 基因，7 株菌检测到 papC 基因。研究分离株属于 B2 组（12 株）、D 组（12 株）和 A 组（3 株）。这是加沙地带医院首次报道临床来源大肠埃希菌中产 CTX-M 类β-内酰胺酶的检测。
