南方医科大学学报

南方医科大学学报 ›› 2018, Vol. 38 ›› Issue (12): 1521-.doi: 10.12122/j.issn.1673-4254.2018.12.20

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血流感染O16-ST131和O25b-ST131型大肠埃希菌的流行、系统发育群及耐药性

钟一鸣，张晓荷，刘文恩，杨芳，晏群，刘清霞，李艳明，李虹玲，邹明祥   

  • 出版日期:2018-12-20 发布日期:2018-12-20

Bloodstream infections with Escherichia coli O16-ST131 and O25b-ST131: molecular epidemiology, phylogenetic analysis and antimicrobial resistance

  • Online:2018-12-20 Published:2018-12-20

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摘要： 目的探讨大肠埃希菌ST131型菌株的流行，及其与非ST131耐药性是否存在差异，ST131感染者与非ST131感染者临床 特征是否存在差异。方法通过收集中南大学湘雅医院2016年1月~12月血流感染患者大肠埃希菌非重复菌株144株，采用多 重PCR方法进行系统发育分群，采用等位基因特异性PCR进行ST131菌株筛选及O血清型分型，收集144例患者的临床信息， 比较ST131感染者与非ST131感染者的临床特征有无差异，采用Vitek2 compact药敏分析仪检测细菌的耐药性。结果系统发 育分群结果显示，144株大肠埃希菌菌株以B2群为主，占41.0%（59/144），其次分别为F群、B1群和E群，分别占16.7%（24/144）、 13.9%（20/144）和13.2%（19/144）；其中9株（6.3%）属于ST131型，包括8株O25b-B2-ST131和1株O16-B2-ST131；9例ST131患 者中，医院感染患者有7例，占77.8%。ST131感染者的人口特征和临床特征与非ST131感染者相似。ST131型菌株对哌拉西 林/他唑巴坦、亚胺培南、厄他培南、阿米卡星耐药率较低，但对头孢唑林、头孢曲松、环丙沙星、左氧氟沙星、庆大霉素以及复方新 诺明耐药率>50%，ESBLs阳性率达77.8%，多重耐药率高达88.9%，并高于非ST131型菌株，但差异并无统计学意义。结论本 地区血液分离大肠埃希菌中，B2 群和F群为最常见系统分群，ST131 型菌株检出率较低，国内首次在血流感染中分离出O16- ST131菌株，ST131感染者的临床特征与非ST131感染者相似，ST131型菌株多重耐药率及ESBLs阳性率高，应引起重视。

Abstract: Objective To investigate the phylogenetics and prevalence of bloodstream infections with Escherichia coli ST131, the antimicrobial resistance profiles of the pathogens, and the clinical features. Methods Non-duplicate Escherichia coli isolates were collected from 144 patients with bloodstream infections in our hospital between January and December, 2016. The phylogenetic groups of the isolates were analyzed using multiplex PCR, and O serotyping of ST131 strains was performed by allele-specific PCR. The clinical characteristics of the 144 patients were analyzed to define the differences in the clinical features between patients with ST131 infection and those with non-ST131 infection. Antibiotic susceptibility of the isolates was determined using the Vitek 2 compact system. Results The phylogenetic group analysis showed a domination by group B2 (41.0% [59/144]), followed by group F, group B1 and group E, which accounted for 16.7% (24/144), 13.9% (20/144), and 13.2% (19/144), respectively. Nine strains (6.3% ) of Escherichia coli were identified to be ST131 strains, among which 8 were O25b-B2-ST131 strains and 1 was O16-B2-ST131 strain. Of the 9 cases of ST131 infection, 7 (77.8%) were found to occur in a nosocomial setting. The demographic characteristics and clinical features of the ST131-infected patients were similar to those of non-ST131-infected patients. ST131 strains were sensitive to piperacillin/tazobactam, imipenem, ertapenem, and amikacin, but showed high resistance rates to cefazolin, ceftriaxone, ciprofloxacin, levofloxacin, gentamicin, and trimethoprim/ sulfamethoxazole (all over 50%). The positivity rate of ESBLs in the ST131 strains was 77.8%, and the multidrug resistance rate reached 88.9% , which was higher than that of non-ST131 isolates, but the difference was not statistically significant. Conclusions The most common phylogenetic groups of Escherichia coli isolates from patients with bloodstream infections are group B2 and F, and the positivity rate of ST131 is low. We for the first time detected O16-ST131 in patients with blood-borne infections in China. The clinical features of ST131-infected patients are similar to those of non-ST131-infected patients. The positivity rate of ESBLs and the multidrug resistance rate are high in ST131 strains, which may raise concerns in the future.