Li Xiujun, Wang Duochun, Li Baisheng, Zhou Haijian, Liang Song, Ke Changwen, Deng Xiaoling, Kan Biao, Morris J Glenn, Cao Wuchun
a School of Public Health Shandong University, Wenhuaxi Road, Shandong 250012, People's Republic of China.
b Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, 155 Chang-Bai Street, Changping District, Beijing 102206, People's Republic of China.
Can J Microbiol. 2016 Feb;62(2):139-47. doi: 10.1139/cjm-2015-0443. Epub 2015 Nov 18.
Toxigenic isolates of Vibrio cholerae serogroups O1 and O139 from aquatic reservoirs are a key source for recurrent epidemics of cholera in human populations. However, we do not have an optimal understanding of the microbiology of the strains within these reservoirs, particularly outside of the time periods when there are active cholera cases in the surrounding community. The main objective of the present study was to identify and characterize V. cholerae O1 and O139 in the Pearl River Estuary at a time when active disease was not being identified, despite prior occurrence of epidemic cholera in the region. Water samples were collected at 24 sites in the research area at monthly intervals between 2007 and 2010, and screened for the presence of V. cholerae O1 and O139. All isolates were screened for the presence of ctxAB, ompW, toxR, and tcpA genes. Multilocus variable number tandem repeat analysis (MLVA) was used to assess possible relationships among strains. The results show that Vibrio cholerae O1 or O139 was isolated, on average, from 6.7% of the sites screened at each time point. All V. cholerae O1 and O139 isolates were ctxAB negative, and 37% were positive for tcpA. Isolation was most common in the oldest, most urbanized district compared with other districts, and was associated with lower pH. Despite year-to-year variability in isolation rates, there was no evidence of seasonality. MLVA of 27 selected isolates showed evidence of high genetic diversity, with no evidence of clustering by year or geographic location. In this region where cholera has been epidemic in the past, there is evidence of environmental persistence of V. cholerae O1 and O139 strains. However, environmental strains were consistently nontoxigenic, with a high level of genetic diversity; their role as current or future agents of human disease remains uncertain.
来自水体储库的霍乱弧菌O1群和O139群产毒株是人群中霍乱反复流行的关键来源。然而，我们对这些储库中菌株的微生物学了解并不完善，特别是在周边社区没有活跃霍乱病例的时间段之外。本研究的主要目的是在该地区曾发生过霍乱流行但当时未发现活跃病例时，鉴定和表征珠江口的霍乱弧菌O1群和O139群。2007年至2010年期间，每月在研究区域的24个地点采集水样，筛查霍乱弧菌O1群和O139群的存在情况。对所有分离株筛查ctxAB、ompW、toxR和tcpA基因的存在情况。采用多位点可变数目串联重复分析（MLVA）评估菌株之间可能的关系。结果显示，在每个时间点筛查的位点中，平均有6.7%分离出霍乱弧菌O1群或O139群。所有霍乱弧菌O1群和O139群分离株的ctxAB均为阴性，37%的tcpA为阳性。与其他地区相比，分离现象在最古老、城市化程度最高的地区最为常见，且与较低的pH值有关。尽管分离率逐年变化，但没有季节性证据。对27株选定分离株的MLVA显示出高度的遗传多样性，没有按年份或地理位置聚类的证据。在这个过去曾发生过霍乱流行的地区，有证据表明霍乱弧菌O1群和O139群菌株在环境中持续存在。然而，环境菌株始终不产毒，具有高度的遗传多样性；它们作为当前或未来人类疾病病原体的作用仍不确定。
