Tikveşli Soner, Cevahir Nural, Kaleli Ilknur
Silopi Devlet Hastanesi, Mikrobiyoloji Laboratuvani, Sirnak.
Mikrobiyol Bul. 2009 Oct;43(4):553-62.
Rapid spread of CTX-M type extended-spectrum beta-lactamases (ESBL) between the members of Enterobacteriaceae receives attention increasingly all throughout the world. The aim of this study was to investigate the presence of CTX-M type ESBL in Klebsiella pneumoniae clinical strains by phenotypic and molecular methods. A total of 217 non-repetitive K. pneumoniae strains isolated from clinical specimens (152 urine, 20 sputum, 17 wound swabs, 13 blood, 9 tracheal aspirate, 3 CSF and 3 conjunctival swab samples) of inpatients (n = 128) and outpatients (n = 89) admitted to Pamukkale University Medical Faculty Hospital, between January 2006-January 2007, were included to the study. In vitro antimicrobial susceptibilities were determined by disk diffusion technique in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines, and CT (cefotaxime)/CTL (cefotaxime-clavulanate) containing Etest strips (AB Biodisk, Sweden) were applied for phenotypic detection of cefotaximase production. PCR was performed for the detection of CTX-M genes and the subgroups, while the clonal relatedness of the CTX-M positive isolates was investigated by random amplified polymorphic DNA (RAPD) analysis. While imipenem resistance was not detected in any of the isolates, highest rates of resistance were detected for ampicillin (94%) and cephalothin (64.5%) in 217 K. pneumoniae strains. Using the E-test 39.6% (86/217) of the isolates were found positive, and CTX-M positivity was significantly higher in the strains isolated from inpatients (87.4%) than outpatients (12.6%) (p < 0.001). CTX-M gene was identified in 22.1% (19/86) of the E-test positive isolates. All of the CTX-M positive isolates were identified as CTX-M group-1. The highest resistance rates of CTX-M-1 strains were detected for amoxycillin-clavulanate (94.7%) and netilmicin (89.5%), while the lowest rates were detected for ciprofloxacin (26.3%), trimethoprim/sulphamethoxazole (26.3%) and amikacin (42.1%). RAPD identified 11 different banding patterns among the 19 CTX-M-1 positive isolates, the most frequent clusters being Kp3 (n = 3), Kp4 (n = 3) and Kp5 (n = 3). Five of the 8 isolates from pediatric intensive care unit and 4 of the 5 isolates from other pediatric wards exhibited the same band pattern indicating a possible clonal dissemination. Continuous surveillance of beta-lactamases and the identification of their types in gram-negative enteric bacteria has important clinical impact, since it can often provide valuable information for effective infection control measures and for the choice of appropriate antimicrobial therapy.
CTX-M型超广谱β-内酰胺酶（ESBL）在肠杆菌科细菌成员之间的快速传播日益受到全球关注。本研究旨在通过表型和分子方法调查肺炎克雷伯菌临床菌株中CTX-M型ESBL的存在情况。2006年1月至2007年1月期间，从帕穆克卡莱大学医学院医院收治的住院患者（n = 128）和门诊患者（n = 89）的临床标本（152份尿液、20份痰液、17份伤口拭子、13份血液、9份气管吸出物、3份脑脊液和3份结膜拭子样本）中分离出217株非重复的肺炎克雷伯菌菌株纳入研究。根据临床和实验室标准协会（CLSI）指南，采用纸片扩散法测定体外抗菌药物敏感性，并使用含头孢噻肟（CT）/头孢噻肟-克拉维酸（CTL）的Etest试纸条（瑞典AB Biodisk公司）进行头孢噻肟酶产生的表型检测。进行PCR检测CTX-M基因及其亚组，同时通过随机扩增多态性DNA（RAPD）分析研究CTX-M阳性分离株的克隆相关性。在所有分离株中均未检测到亚胺培南耐药，在217株肺炎克雷伯菌菌株中，氨苄西林（94%）和头孢噻吩（64.5%）的耐药率最高。使用Etest检测发现39.6%（86/217）的分离株呈阳性，从住院患者中分离的菌株CTX-M阳性率（87.4%）显著高于门诊患者（12.6%）（p < 0.001）。在Etest阳性分离株中，22.1%（19/86）鉴定出CTX-M基因。所有CTX-M阳性分离株均鉴定为CTX-M-1组。CTX-M-1菌株对阿莫西林-克拉维酸（94.7%）和奈替米星（89.5%）的耐药率最高，而对环丙沙星（26.3%）、甲氧苄啶/磺胺甲恶唑（26.3%）和阿米卡星（42.1%）的耐药率最低。RAPD在19株CTX-M-1阳性分离株中鉴定出11种不同的条带模式，最常见的聚类为Kp3（n = 3）、Kp4（n = 3）和Kp5（n = 3）。儿科重症监护病房的8株分离株中有5株以及其他儿科病房的5株分离株中有4株表现出相同的条带模式，表明可能存在克隆传播。持续监测革兰氏阴性肠道细菌中的β-内酰胺酶及其类型具有重要的临床意义，因为它通常可为有效的感染控制措施和合适抗菌治疗的选择提供有价值的信息。
