Ben Sallem Rym, Ben Slama Karim, Rojo-Bezares Beatriz, Porres-Osante Nerea, Jouini Ahlem, Klibi Naouel, Boudabous Abdellatif, Sáenz Yolanda, Torres Carmen
1 Laboratoire Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis-El Manar , Tunis, Tunisia .
Microb Drug Resist. 2014 Oct;20(5):495-500. doi: 10.1089/mdr.2013.0224. Epub 2014 May 14.
The objective was to determine the location of bla(CTX-M-1) and bla(CMY-2) genes in 33 Escherichia coli isolates previously obtained from healthy humans, pets, and food-producing animals in Tunisia, and to characterize the genetic lineages of isolates. Molecular typing was performed by pulsed-field gel electrophoresis (PFGE)-XbaI and multilocus sequence typing (MLST). Plasmids were analyzed by S1-PFGE, polymerase chain reaction-based replicon typing, and plasmid MLST. Conjugation experiments were performed. The bla(CTX-M-1) and bla(CMY-2) genes were studied by I-Ceu1-PFGE and S1-PFGE, and subsequent hybridization with specific probes. Eighteen different sequence types (STs) were identified among the 30 CTX-M-1-producing isolates, 5 of them being detected in 17 isolates (ST/phylogroup): ST57/D, ST155/B1, ST58/B1, ST10/A, and ST398/A. Most of the bla(CTX-M-1)-positive isolates had different PFGE profiles, with the exception of four human and pet isolates of lineage ST57 with related PFGE profiles (>80% identity). Three CMY-2-producing isolates were typed as ST58/B1, ST117/D, and ST3632/B2. The IncI1 replicon was detected in all the 33 E. coli studied isolates, in many cases in combination with other replicons: IncF, IncX, IncK, IncR, IncY, colE, or IncN. The bla(CTX-M-1) gene was transferred by conjugation in 22 of the 30 positive strains and was located into IncI1 plasmids (ST3-CC3); the bla(CMY-2) gene was located into a conjugative IncI1 plasmid (ST12) of 97 kb in one strain. One bla(CTX-M-1)-positive strain carried the qnrB19 gene in a 33 kb IncX plasmid. Diverse genetic lineages are detected in extended-spectrum beta-lactamase- and AmpC beta-lactamase-producing E. coli from different origins. The bla(CTX-M-1) and bla(CMY-2) genes were associated with conjugative IncI1 (ST3 and ST12, respectively) plasmids in E. coli strains from human and animal origin.
目的是确定先前从突尼斯健康人、宠物和产食用动物中获得的33株大肠杆菌分离株中bla(CTX-M-1)和bla(CMY-2)基因的位置，并对分离株的遗传谱系进行特征分析。通过脉冲场凝胶电泳（PFGE）-XbaI和多位点序列分型（MLST）进行分子分型。通过S1-PFGE、基于聚合酶链反应的复制子分型和质粒MLST分析质粒。进行了接合实验。通过I-Ceu1-PFGE和S1-PFGE以及随后与特异性探针杂交研究bla(CTX-M-1)和bla(CMY-2)基因。在30株产CTX-M-1的分离株中鉴定出18种不同的序列类型（STs），其中5种在17株分离株中检测到（ST/系统发育群）：ST57/D、ST155/B1、ST58/B1、ST10/A和ST398/A。大多数bla(CTX-M-1)阳性分离株具有不同的PFGE图谱，但有4株来自谱系ST57的人和宠物分离株具有相关的PFGE图谱（同一性>80%）除外。3株产CMY-2的分离株分型为ST58/B1、ST117/D和ST3632/B2。在所有33株研究的大肠杆菌分离株中均检测到IncI1复制子，在许多情况下与其他复制子组合存在：IncF、IncX、IncK、IncR、IncY、colE或IncN。bla(CTX-M-1)基因在30株阳性菌株中的22株中通过接合转移，并且位于IncI1质粒（ST3-CC3）中；bla(CMY-2)基因在一株菌株中位于一个97 kb的接合性IncI1质粒（ST12）中。一株bla(CTX-M-1)阳性菌株在一个33 kb的IncX质粒中携带qnrB19基因。在来自不同来源的产超广谱β-内酰胺酶和AmpCβ-内酰胺酶的大肠杆菌中检测到不同的遗传谱系。bla(CTX-M-1)和bla(CMY-2)基因分别与人源和动物源大肠杆菌菌株中的接合性IncI1（分别为ST3和ST12）质粒相关。
