Xia Xufen, Lv Tao, Zheng Lisi, Zhao Yuhong, Shen Ping, Zhu Danhua, Chen Yunbo
Department of Laboratory Medicine, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, People's Republic of China.
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
Infect Drug Resist. 2024 Dec 11;17:5535-5544. doi: 10.2147/IDR.S492668. eCollection 2024.
sequence type (ST) 81, mainly associated with ribotype (RT) 369, is a TcdA-negative and TcdB-positive genotype and a common ST found in China. Furthermore, ST81 strains are reported with highest resistance rates to many antimicrobial agents. However, given the potential for ST81 transmission, research into the epidemiological characteristics of this type of ST remain limited.
We conducted a genomic epidemiology study addressing the genetic characteristics of ST81 in five tertiary hospitals covering different regions in China between January 2010 and January 2021. Clinical toxigenic strains were identified, typed by multi-locus sequence typing (MLST), and phylogenetic analysis, antimicrobial resistant gene (AMR) identification were performed after all these strains were conducted by whole genome sequencing (WGS).
In total, 108 clinical strains of ST81 were isolated and successfully analyzed by WGS, which showed that the percentage of isolates with AMRs was common in this type of ST. Furthermore, two types of transposons, Tn916 and Tn6189, were also detected. We found that all ST81 genomes were closely related as pairwise core-genomic SNP (cgSNP) distance between the strains was on average 13 cgSNPs (range, 0-425 cgSNPs). Notably, these isolates were split into two sub-lineages (SL I and SL II) by Bayesian analysis, which suggested that both sub-lineages emerged independently. It is noted that some AMRs (such as A, F, and B) and Tn916 were only detected in SL I.
ST81 is among the common STs in this study. Two independent sub-lineages of ST81 strains are found. Furthermore, the presence of a high number of AMR genes and multiple mobile elements indicate a potential risk for transmission of ST81. Based on these results, a robust surveillance system is crucial for identifying outbreaks, tracking infection trends, and implementing timely interventions.
序列型（ST）81主要与核糖体分型（RT）369相关，是一种产毒素A阴性、产毒素B阳性的基因型，也是中国常见的序列型。此外，据报道ST81菌株对多种抗菌药物的耐药率最高。然而，鉴于ST81存在传播的可能性，对这类序列型的流行病学特征的研究仍然有限。
我们进行了一项基因组流行病学研究，以探讨2010年1月至2021年1月期间中国不同地区的五家三级医院中ST81的遗传特征。通过全基因组测序（WGS）对临床产毒菌株进行鉴定、多位点序列分型（MLST）分型、系统发育分析以及抗菌耐药基因（AMR）鉴定。
共分离出108株ST81临床菌株，并通过WGS成功进行了分析，结果表明这类序列型中携带AMR的分离株比例较高。此外，还检测到两种转座子，Tn916和Tn6189。我们发现所有ST81基因组密切相关，菌株之间的成对核心基因组单核苷酸多态性（cgSNP）距离平均为13个cgSNP（范围为0 - 425个cgSNP）。值得注意的是，通过贝叶斯分析，这些分离株被分为两个亚谱系（SL I和SL II），这表明两个亚谱系是独立出现的。需要注意的是，一些AMR（如A、F和B）和Tn916仅在SL I中检测到。
ST81是本研究中常见的序列型之一。发现了ST81菌株的两个独立亚谱系。此外，大量AMR基因和多种移动元件的存在表明ST81存在传播的潜在风险。基于这些结果，一个强大的监测系统对于识别疫情暴发、追踪感染趋势以及及时实施干预措施至关重要。
