Matsumura Yasufumi, Noguchi Taro, Tanaka Michio, Kanahashi Toru, Yamamoto Masaki, Nagao Miki, Takakura Shunji, Ichiyama Satoshi
J Antimicrob Chemother. 2017 Apr 1;72(4):1040-1049. doi: 10.1093/jac/dkw530.
To define the population structure of extraintestinal pathogenic Escherichia coli (ExPEC) in Japan and its relationship with antimicrobial resistance and the major resistance mechanisms for fluoroquinolones and β-lactams, we designed a multicentre prospective study.
A total of 329 ExPEC isolates were collected at 10 Japanese acute-care hospitals during December 2014. We defined the clonal groups of ExPEC by fumC and fimH sequencing (CH typing). Antimicrobial susceptibility testing of 18 agents and the detection of mutations in quinolone resistance-determining regions (QRDRs) and β-lactamases were performed.
Among the study isolates, 103 CH types were found, and CH40-30 (25%) and another 10 CH types (35% in total) constituted the major ExPEC population. Ciprofloxacin non-susceptibility, ESBLs and MDR phenotypes were found in 34%, 22% and 33%, respectively. CH40-30, corresponding to the C/H30 clade of the global pandemic ST131 clone, was associated with four QRDR mutations (100%) and bla CTX-M (60%) and was the most frequent type in 15 antimicrobial-non-susceptible populations (dominating 39%-75% of each population, the highest prevalence for ciprofloxacin), the ESBL producers (70%) and the MDR isolates (59%). Isolates that were non-susceptible to nalidixic acid and low-level resistant to ciprofloxacin with one or two QRDR mutations represented 16% of the study isolates and were distributed among the eight major and non-major CH types.
More than half of the ExPEC population in Japan consisted of 11 major clones. Of these clones, the CH40-30-ST131-C/H30 clone was the predominant antimicrobial-resistant population. The presence of major clones with low-level ciprofloxacin resistance supports the potential future success of a non-ST131 fluoroquinolone-resistant clone.
为明确日本肠外致病性大肠杆菌（ExPEC）的种群结构及其与抗菌药物耐药性的关系，以及氟喹诺酮类和β-内酰胺类药物的主要耐药机制，我们设计了一项多中心前瞻性研究。
2014年12月期间，在日本10家急症医院共收集了329株ExPEC分离株。我们通过fumC和fimH测序（CH分型）确定ExPEC的克隆群。对18种药物进行了药敏试验，并检测了喹诺酮耐药决定区（QRDRs）的突变和β-内酰胺酶。
在研究分离株中，发现了103种CH型，其中CH40 - 30（25%）和另外10种CH型（共35%）构成了主要的ExPEC种群。环丙沙星不敏感、产超广谱β-内酰胺酶（ESBLs）和多重耐药（MDR）表型分别占34%、22%和33%。CH40 - 30对应全球大流行的ST131克隆的C/H30分支，与四个QRDR突变（100%）和bla CTX - M（60%）相关，是15个抗菌药物不敏感种群中最常见的类型（在每个种群中占主导地位，为39% - 75%，环丙沙星的患病率最高）、产ESBLs菌株（70%）和MDR分离株（59%）。对萘啶酸不敏感且对环丙沙星低水平耐药且有一两个QRDR突变的分离株占研究分离株的16%，分布在8种主要和非主要的CH型中。
日本超过一半的ExPEC种群由11个主要克隆组成。在这些克隆中，CH40 - 30 - ST131 - C/H30克隆是主要的抗菌药物耐药种群。存在对环丙沙星低水平耐药的主要克隆支持了未来非ST131氟喹诺酮耐药克隆可能取得成功。
