Clinical Medical Examination Center, Northern Jiangsu People's HospitalYangzhou, China.
Key Laboratory of Clinical In Vitro Diagnostic Techniques of Zhejiang Province, Department of Clinical Laboratory, First Affiliated Hospital, College of Medicine, Zhejiang UniversityHangzhou, China.
Front Cell Infect Microbiol. 2017 May 18;7:188. doi: 10.3389/fcimb.2017.00188. eCollection 2017.
In China, has been a leading cause of foodborne outbreaks and bacterial infectious diarrhea since the 1990s, and most infections have been associated with the pandemic O3:K6 and its serovariants. However, a comprehensive overview of the sero-prevalence and genetic diversity of the pandemic clone in China is lacking. To compensate for this deficiency, pandemic isolates in both clinical and environmental Chinese samples collected from multiple studies were analyzed in this study. Surprisingly, as many as 27 clinical pandemic serovariants were identified and were widely distributed across nine coastal provinces and two inland provinces (Beijing and Sichuan). O3:K6, O4:K68, and O1:KUT represented the predominant clinical serovars. Only four environmental pandemic serovariants had previously been reported, and they were spread throughout Shanghai (O1:KUT, O3:K6), Jiangsu (O3:K6, O4:K48), Zhejiang (O3:K6), and Guangdong (O4:K9). Notably, 24 pandemic serovariants were detected within a short time frame (from 2006 to 2012). The pandemic isolates were divided into 15 sequence types (STs), 10 of which fell within clonal complex (CC) 3. Only three STs (ST3, ST192, and ST305) were identified in environmental isolates. Substantial serotypic diversity was mainly observed among isolates within pandemic ST3, which comprised 21 combinations of O/K antigens. The pandemic O3:K6 serotype showed a high level of sequence diversity, which was shared by eight different STs (ST3, ST227, ST431, ST435, ST487, ST489, ST526, and ST672). Antimicrobial susceptibility testing revealed that most isolates shared similar antibiotic susceptibility profiles. They were resistant to ampicillin but sensitive to most other drugs that were tested. In conclusion, the high levels of serotypic and genetic diversity of the pandemic clone suggest that the involved regions are becoming important reservoirs for the emergence of novel pandemic strains. We underscore the need for routine monitoring to prevent pandemic infection, which includes monitoring antimicrobial responses to avoid excessive misuse of antibiotics. Further investigations are also needed to delineate the specific mechanisms underlying the possible seroconversion of pandemic isolates.
在中国，自 20 世纪 90 年代以来， 一直是食源性暴发和细菌性感染性腹泻的主要原因，大多数感染与大流行 O3:K6 及其血清型有关。然而，目前缺乏对中国大流行克隆体血清流行率和遗传多样性的全面概述。为了弥补这一不足，本研究对来自多个研究的临床和环境中国样本中的大流行分离株进行了分析。令人惊讶的是，多达 27 种临床大流行血清型被鉴定出来，并广泛分布在 9 个沿海省份和 2 个内陆省份（北京和四川）。O3:K6、O4:K68 和 O1:KUT 代表主要的临床血清型。以前只报道过 4 种环境大流行血清型，它们分布在上海（O1:KUT、O3:K6）、江苏（O3:K6、O4:K48）、浙江（O3:K6）和广东（O4:K9）。值得注意的是，在短时间内（2006 年至 2012 年）检测到 24 种大流行血清型。大流行分离株分为 15 个序列型（ST），其中 10 个属于克隆复合体（CC）3。仅在环境分离株中鉴定出 3 个 ST（ST3、ST192 和 ST305）。主要观察到大流行 ST3 内分离株的血清型多样性较大，其中包含 21 种 O/K 抗原组合。大流行 O3:K6 血清型表现出高水平的序列多样性，由 8 个不同的 ST（ST3、ST227、ST431、ST435、ST487、ST489、ST526 和 ST672）共享。抗生素敏感性测试显示，大多数分离株具有相似的抗生素敏感性谱。它们对氨苄西林耐药，但对大多数其他测试药物敏感。总之，大流行克隆体的高血清型和遗传多样性水平表明，相关地区正在成为新型大流行菌株出现的重要储存库。我们强调需要进行常规监测，以预防大流行 感染，包括监测对抗生素的反应，以避免抗生素的过度滥用。还需要进一步研究来描绘大流行分离株可能发生血清转化的具体机制。
