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Abstract：
This 4-month-long prospective observational study investigated the epidemiological characteristics, genetic composition, transmission pattern, and infection control of carbapenem-resistant Escherichia coli (CREC) colonization in patients at an intensive care unit (ICU) in China. Phenotypic confirmation testing was performed on nonduplicated isolates from patients and their environments. Whole-genome sequencing was performed for all E. coli isolates, followed by multilocus sequence typing (MLST), and antimicrobial resistance genes and single nucleotide polymorphisms (SNPs) were screened. The colonization rates of CREC were 7.29% from the patient specimens and 0.39% from the environmental specimens. Among the 214 E. coli isolates tested, 16 were carbapenem resistant, with the blaNDM-5 gene identified as the dominant carbapenemase-encoding gene. Among the low-homology sporadic strains isolated in this study, the main sequence type (ST) of carbapenem-sensitive Escherichia coli (CSEC) was ST1193, whereas the majority of CREC isolates belonged to ST1656, followed by ST131. CREC isolates were more sensitive to disinfectants than were the carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates obtained in the same period, which may explain the lower separation rate. Therefore, effective interventions and active screening are beneficial to the prevention and control of CREC. IMPORTANCE CREC represents a public health threat worldwide, and its colonization precedes or occurs simultaneously with infection; once the colonization rate increases, the infection rate rises sharply. In our hospital, the colonization rate of CREC remained low, and almost all of the CREC isolates detected were ICU acquired. Contamination of the surrounding environment by CREC carrier patients shows a very limited spatiotemporal distribution. As the dominant ST of the CSEC isolates found, ST1193 CREC might be considered a strain of notable concern with potential to cause a future outbreak. ST1656 and ST131 also deserve attention, as they comprised the majority of the CREC isolates found, while blaNDM-5 gene screening should play an important role in medication guidance as the main carbapenem resistance gene identified. The disinfectant chlorhexidine, which is used commonly in the hospital, is effective for CREC rather than CRKP, possibly explaining the lower positivity rate for CREC than for CRKP.
摘要：
这项为期4个月的前瞻性观察研究调查了流行病学特征，遗传组成，传输模式，中国重症监护病房（ICU）患者碳青霉烯类耐药大肠杆菌（CREC）定植的感染控制。对来自患者及其环境的非重复分离株进行表型确认测试。对所有大肠杆菌分离株进行全基因组测序，其次是多位点序列分型（MLST），筛选抗菌素耐药基因和单核苷酸多态性(SNPs)。患者标本的CREC定植率为7.29％，环境标本的CREC定植率为0.39％。在测试的214株大肠杆菌中，16个是耐碳青霉烯，blaNDM-5基因被鉴定为显性碳青霉烯酶编码基因。在本研究中分离出的低同源性散发菌株中，碳青霉烯敏感型大肠杆菌(CSEC)的主要序列类型(ST)为ST1193,而大多数CREC分离株属于ST1656,其次是ST131.CREC分离株对消毒剂的敏感性高于同期获得的耐碳青霉烯类肺炎克雷伯菌(CRKP)分离株,这可以解释较低的分离率。因此,有效的干预措施和积极的筛查有利于CREC的预防和控制。IMPORTANCECREC代表着全球范围内的公共卫生威胁，其定植先于感染或与感染同时发生；一旦定植率增加，感染率急剧上升。在我们的医院里,CREC的定殖率仍然很低，检测到的几乎所有CREC分离株都是ICU获得的。CREC携带者患者对周围环境的污染显示出非常有限的时空分布。作为CSEC分离株的主要ST，ST1193CREC可能被认为是值得关注的菌株，有可能导致未来的爆发。ST1656和ST131也值得关注，因为它们构成了发现的大多数CREC分离株，而blaNDM-5基因作为碳青霉烯类主要耐药基因的鉴定,应在用药指导中发挥重要作用。消毒剂氯己定,通常在医院使用，对CREC而不是CRKP有效，可能解释了CREC的阳性率低于CRKP的阳性率。
