Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
Mol Med Rep. 2013 Oct;8(4):1251-5. doi: 10.3892/mmr.2013.1626. Epub 2013 Aug 12.
Escherichia coli is a common cause of community‑ and hospital‑acquired urinary tract infections, and class 1 integrons are the prior elements of gene transference in the capture and distribution of gene cassettes among clinical gram-negative bacillus. In the present study, the resistance of Escherichia coli to antimicrobial agents was investigated. A total of 97 isolates were found to be susceptible to 16 antimicrobial agents and were detected in the production of extended β‑lactamases (ESBLs), distribution of CTX‑M‑type β‑lactamases, presence and characterization of class 1 integrons and a variable region of integron‑positive isolates. Escherichia coli isolates possessing CTX‑M (31; 32%) were detected in 19 isolates (61.5%). The presence of ESBLs was associated with resistance to penicillins, third-generation cephalosporins, ciprofloxacin, aminoglycosides and monocyclic β‑lactam antibiotics. Escherichia coli isolates (69; 71.1%) possessed class 1 integrons associated with resistance to ciprofloxacin and numerous third-generation cephalosporins, penicillins, tobramycin and trimethoprim‑sulfamethoxazole. The four gene cassette arrangements were as follows: dfrA17‑aadA5, aadA1, aacC4‑cmlA1 and dfr2d, and 8 carried two disparate class 1 integrons. Five isolates presented class 1 integrons containing no gene cassettes. The distribution of ESBLs and class 1 integrons in Escherichia coli were prevalent with drug resistance in Chengdu. In addition, the resistance range of Escherichia coli isolates that harboured ESBLs and carried class 1 integrons were similar. The current study demonstrated the presence of class 1 integrons and ESBLs, which jointly mediate the resistance of Escherichia coli isolates to a number of antibacterial agents.
大肠埃希菌是社区和医院获得性尿路感染的常见原因，而 1 类整合子是临床革兰氏阴性杆菌中捕获和分布基因盒的基因转移的前体元素。在本研究中，研究了大肠埃希菌对抗菌药物的耐药性。共发现 97 株对 16 种抗菌药物敏感的分离株，这些分离株产生了扩展β-内酰胺酶（ESBLs），分布了 CTX-M 型β-内酰胺酶，存在并表征了 1 类整合子和整合子阳性分离株的可变区。在 19 株（61.5%）分离株中检测到携带 CTX-M（31；32%）的大肠埃希菌。ESBLs 的存在与对青霉素类、第三代头孢菌素类、环丙沙星、氨基糖苷类和单环β-内酰胺类抗生素的耐药性有关。携带 1 类整合子的大肠埃希菌分离株（69；71.1%）对环丙沙星和许多第三代头孢菌素类、青霉素类、妥布霉素和甲氧苄啶-磺胺甲恶唑具有耐药性。四种基因盒排列方式如下：dfrA17-aadA5、aadA1、aacC4-cmlA1 和 dfr2d，8 株携带两种不同的 1 类整合子。5 株分离株携带不含基因盒的 1 类整合子。ESBLs 和 1 类整合子在大肠埃希菌中的分布在成都较为普遍，且具有耐药性。此外，携带 ESBLs 和携带 1 类整合子的大肠埃希菌分离株的耐药范围相似。本研究表明，1 类整合子和 ESBLs 的存在共同介导了大肠埃希菌分离株对多种抗菌药物的耐药性。
