Jouini Ahlem, Vinué Laura, Slama Karim Ben, Sáenz Yolanda, Klibi Naouel, Hammami Salah, Boudabous Abdellatif, Torres Carmen
Laboratoire MBA, Département de Biologie, Faculté de Sciences de Tunis, Campus Universitaire, 2092 Tunis, Tunisia.
J Antimicrob Chemother. 2007 Nov;60(5):1137-41. doi: 10.1093/jac/dkm316. Epub 2007 Sep 13.
To assess the occurrence of extended-spectrum beta-lactamases (ESBLs) in Escherichia coli isolates of faecal samples of animals (n = 40) and food samples (n = 38) obtained in Tunisia in 2006, and to characterize the type of ESBLs, their genetic environments and the associated resistance genes.
Samples were inoculated in supplemented media (2 mg/L cefotaxime) for isolation of broad-spectrum cephalosporin-resistant E. coli isolates (one isolate/sample). ESBLs and their genetic environments as well as integrons and their gene cassette composition were characterized by PCR and sequencing.
ESBL-producing E. coli isolates were detected in 10 of the 38 food samples analysed (26%) and in none of the tested animal faecal samples. Genes found were as follows (number of isolates): bla(CTX-M-1) (5), bla(CTX-M-1) + bla(TEM-1b) (1), bla(CTX-M-14) + bla(TEM-1b) (2), bla(CTX-M-8) (1) and bla(SHV-5) (1). All ESBL-positive isolates showed unrelated PFGE patterns. ISEcp1 and IS903 were detected surrounding bla(CTX-M-14), and ISEcp1/IS26 and orf477 surrounding some of the bla(CTX-M-1) genes. Four of the ESBL-positive strains harboured class 1 integrons including different gene cassette combinations.
ESBLs, mainly of the CTX-M class, are detected in E. coli of food origin in Tunisia, being the first time that this mechanism has been detected in food E. coli strains in Africa.
评估2006年在突尼斯采集的动物粪便样本（n = 40）和食品样本（n = 38）中分离出的大肠杆菌中广谱β-内酰胺酶（ESBLs）的发生情况，并鉴定ESBLs的类型、其基因环境及相关耐药基因。
将样本接种于添加了培养基（2 mg/L头孢噻肟）中，以分离对广谱头孢菌素耐药的大肠杆菌分离株（每个样本一株分离株）。通过PCR和测序对ESBLs及其基因环境以及整合子及其基因盒组成进行鉴定。
在分析的38份食品样本中有10份（26%）检测到产ESBLs的大肠杆菌分离株，而在检测的动物粪便样本中均未检测到。发现的基因如下（分离株数量）：bla(CTX-M-1)（5株）、bla(CTX-M-1)+bla(TEM-1b)（1株）、bla(CTX-M-14)+bla(TEM-1b)（2株）、bla(CTX-M-8)（1株）和bla(SHV-5)（1株）。所有ESBL阳性分离株均显示出不相关的PFGE图谱。在bla(CTX-M-14)周围检测到ISEcp1和IS903，在一些bla(CTX-M-1)基因周围检测到ISEcp1/IS26和orf477。4株ESBL阳性菌株携带1类整合子，包括不同的基因盒组合。
在突尼斯的食品源大肠杆菌中检测到ESBLs，主要为CTX-M类，这是首次在非洲的食品大肠杆菌菌株中检测到这种机制。
