Çizmeci Zeynep, Otlu Barış, Aktaş Elif, Ördekçi Seyhan, Açıkgöz Özlem, Güleç Nuray
University of Health Sciences Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Clinical Microbiology Laboratory, Istanbul, Turkey.
Inonu University Faculty of Medicine, Department of Medical Microbiology, Malatya, Turkey.
Mikrobiyol Bul. 2018 Jan;52(1):13-22. doi: 10.5578/mb.66475.
In recent years, the ST131 clone was identified as a high risk pandemic clone among Escherichia coli isolates by multilocus sequence typing (MLST) studies and has been associated with extended spectrum beta-lactamase (ESBL) production (often with CTX-M-15) and antibiotic resistance especially against fluoroquinolones. The aim of this study was to determine the rate of high risk ST131 clone in ESBL producing E.coli isolates in our region, to investigate the sensitivity of MALDI-TOF MS in the detection of ST131 clone, and to compare the frequency of antimicrobial resistance among ST131 and non-ST131 isolates. A total of 251 urinary and 50 non-urinary E.coli isolates identified in our hospital central laboratory between February 2016-February 2017 were included in the study. Real-time PCR and MALDI-TOF MS methods were used for the detection of E.coli ST131 clone. For the statistical evaluation of the rate of antibiotic resistance among isolates of ST131 and non-ST131 clones, chi-square test was used. p value under 0.05 was considered as significant. Of the 301 isolates, 110 (36.6%) and 92 (30.6%) isolates were identified as ST131 clone by real-time PCR and MALDI-TOF MS, respectively. According to real-time PCR results, 91 (36.3%) of 251 urinary isolates and 19 (38%) of 50 non-urinary isolates were found as ST131 clone; there was no statistically significant difference between the groups. Ciprofloxacin resistance was found to be significantly higher in ST131 isolates than the non-ST131 isolates (78.2%, n= 86 vs. 53.4%, n= 102). No statistically significant difference was determined for the other antibiotics tested. For the detection of E.coli ST131 clone; sensitivity of MALDI-TOF MS was 84%, specificity was 100% while positive predictive value was 100% and negative predictive value was 92%. In conclusion, further investigation of the high risk E.coli ST131 clone in our country, in which ESBL ratios and antibiotic resistance rates, especially in fluoroquinolones, are high, is important for the development of new strategies to control antibiotic resistance. MALDI-TOF MS method is particularly useful for easy and fast detection of the high risk E.coli ST131 clone.
近年来，多位点序列分型（MLST）研究将ST131克隆鉴定为大肠杆菌分离株中的高风险大流行克隆，且其与超广谱β-内酰胺酶（ESBL）的产生（通常为CTX-M-15）以及抗生素耐药性相关，尤其是对氟喹诺酮类抗生素耐药。本研究旨在确定我们地区产ESBL的大肠杆菌分离株中高风险ST131克隆的比例，研究基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）检测ST131克隆的敏感性，并比较ST131和非ST131分离株之间的抗菌药物耐药频率。2016年2月至2017年2月期间在我院中心实验室鉴定出的251株尿液和50株非尿液大肠杆菌分离株被纳入本研究。采用实时荧光定量PCR和MALDI-TOF MS方法检测大肠杆菌ST131克隆。对于ST131和非ST131克隆分离株之间抗生素耐药率的统计学评估，采用卡方检验。p值小于0.05被认为具有统计学意义。在301株分离株中，分别有110株（36.6%）和92株（30.6%）通过实时荧光定量PCR和MALDI-TOF MS鉴定为ST131克隆。根据实时荧光定量PCR结果，251株尿液分离株中有91株（36.3%），50株非尿液分离株中有19株（38%）被发现为ST131克隆；两组之间无统计学显著差异。发现ST131分离株对环丙沙星的耐药率显著高于非ST131分离株（78.2%，n = 86 vs. 53.4%，n = 102）。对于所检测的其他抗生素，未确定有统计学显著差异。对于大肠杆菌ST131克隆的检测；MALDI-TOF MS的敏感性为84%，特异性为100%，阳性预测值为100%，阴性预测值为92%。总之，在我国对高风险大肠杆菌ST131克隆进行进一步研究很重要，我国的ESBL比例和抗生素耐药率较高，尤其是氟喹诺酮类抗生素，这对于制定控制抗生素耐药性的新策略具有重要意义。MALDI-TOF MS方法对于快速简便地检测高风险大肠杆菌ST131克隆特别有用。
