First detection and sequence analysis of the bla-CTX-M-15 gene in Lebanese isolates of extended-spectrum-β-lactamaseproducing Shigella sonnei
First detection and sequence analysis of the bla-CTX-M-15 gene in Lebanese isolates of extended-spectrum-β-lactamaseproducing Shigella sonnei
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DOI：
10.1179/136485907x193860
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发表时间：
2007-09-01
影响因子：
--
通讯作者：
Araj, G. F.
中科院分区：
文献类型：
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作者：
Matar, G. M.;Jaafar, R.;Araj, G. F.
志贺氏菌中出现的超广谱β-内酰胺酶（ESBL）可对第三代头孢菌素产生耐药性，这引起了全世界越来越多的关注。然而，迄今为止，产 ESBL 志贺氏菌仅被报告过七次，尽管来自七个不同的国家。在黎巴嫩，从 2004 年 7 月至 2005 年 10 月期间诊断的 30 例志贺菌病病例中发现了三种产生 ESBL 的宋内沙门氏菌临床分离株。所有三种菌株均被发现对阿莫西林、头孢噻肟、头孢他啶、氨曲南、甲氧苄啶/磺胺甲恶唑、庆大霉素和卡那霉素具有耐药性。每个都含有 bla-CTX-M 基因，序列分析结果表明其属于 bla-CTX-M-15 类型，编码在 70 kb 质粒上，两侧是插入元件 (ISEcp1)。在两个产 ESBL 菌株的染色体上也检测到了 bla-TEM-1 基因。在所有三个分离株的染色体上均检测到含有 dhfr1、aadA1 和 sat1 基因的 2 类整合子，但在质粒上未检测到。未检测到氟喹诺酮修饰因子[QnrA、QnrB、QnrS 或AAC(6')-Ib-cr]。 RAPD 分析结果与抗菌药物敏感性数据相结合，表明每种分离株都是独特的。总之，产 ESBL 的宋内沙门氏菌分离株的出现首次在黎巴嫩得到证实。这些分离株对第三代头孢菌素的耐药性是由质粒编码的 CTX-M-15 酶介导的。
The emergence in Shigella species of extended-spectrum beta-lactamases ( ESBL) that impart resistance to third-generation cephalosporins is a growing concern world-wide. So far, however, ESBL-producing Shigella have only been reported seven times, albeit from seven different countries. In Lebanon, three ESBL-producing clinical isolates of S. sonnei were recovered from 30 cases of shigellosis diagnosed between July 2004 and October 2005. All three were found to be resistant to amoxycillin, cefotaxime, ceftazidime, aztreonam, trimethoprim/sulphamethoxazole, gentamicin, and kanamycin. Each harboured the bla-CTX-M gene, and the results of sequence analysis indicated this to be of the bla-CTX-M-15 type and encoded on a 70-kb plasmid, flanked by an insertion element ( ISEcp1). The bla-TEM-1 gene was also detected on the chromosomes of two of the ESBL-producing isolates. Class-2 integrons containing dhfr1, aadA1 and sat1 genes were detected on the chromosomes of all three isolates but not on the plasmids. Fluoroquinolone- modifying factors [QnrA, QnrB, QnrS or AAC(6')-Ib-cr] were not detected. The results of RAPD analysis, combined with data on antimicrobial susceptibility, indicated that each isolate was unique. In conclusion, the emergence of ESBL-producing isolates of S. sonnei has been demonstrated for the first time in Lebanon. The resistance of these isolates to third-generation cephalosporins was mediated by the CTX-M-15 enzyme, which was plasmid-encoded.