Bhuyan Soubhagya K, Vairale Mohan G, Arya Neha, Yadav Priti, Veer Vijay, Singh Lokendra, Yadava Pramod K, Kumar Pramod
School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
Defence Research Laboratory, Tezpur, Assam, India.
Infect Genet Evol. 2016 Jun;40:352-356. doi: 10.1016/j.meegid.2015.11.029. Epub 2015 Dec 2.
Cholera is often caused when drinking water is contaminated through environmental sources. In recent years, the drastic cholera epidemics in Odisha (2007) and Haiti (2010) were associated with natural disasters (flood and Earthquake). Almost every year the state of Assam India witnesses flood in Brahamputra River valley during reversal of wind system (monsoon). This is often followed by outbreak of diarrheal diseases including cholera. Beside the incidence of cholera outbreaks, there is lack of experimental evidence for prevalence of the bacterium in aquatic environment and its association with cholera during/after flood in the state. A molecular surveillance during 2012-14 was carried out to study prevalence, strain differentiation, and clonality of Vibrio cholerae in inland aquatic reservoirs flooded by Brahamputra River in Assam. Water samples were collected, filtered, enriched in alkaline peptone water followed by selective culturing on thiosulfate bile salt sucrose agar. Environmental isolates were identified as V. cholerae, based on biochemical assays followed by sero-grouping and detailed molecular characterization. The incidence of the presence of the bacterium in potable water sources was higher after flood. Except one O1 isolate, all of the strains were broadly grouped under non-O1/non-O139 whereas some of them did have cholera toxin (CT). Surprisingly, we have noticed Haitian ctxB in two non-O1/non-O139 strains. MLST analyses based on pyrH, recA and rpoA genes revealed clonality in the environmental strains. The isolates showed varying degree of antimicrobial resistance including tetracycline and ciprofloxacin. The strains harbored the genetic elements SXT constins and integrons responsible for multidrug resistance. Genetic characterization is useful as phenotypic characters alone have proven to be unsatisfactory for strain discrimination. An assurance to safe drinking water, sanitation and monitoring of the aquatic reservoirs is of utmost importance for combating the impending epidemic threat in the flood affected areas. Further, the management of flood through multi-prong approaches and sustainable utilization of environmental resources would be effective in disease management.
霍乱通常是由于饮用水通过环境源受到污染而引起的。近年来，奥里萨邦（2007年）和海地（2010年）的严重霍乱疫情与自然灾害（洪水和地震）有关。几乎每年，在印度阿萨姆邦，当风系逆转（季风）时，布拉马普特拉河流域都会发生洪水。随后往往会爆发包括霍乱在内的腹泻疾病。除了霍乱疫情的发生率外，该邦缺乏关于该细菌在水生环境中的流行情况及其与洪水期间/之后霍乱关联的实验证据。2012年至2014年期间进行了分子监测，以研究阿萨姆邦被布拉马普特拉河淹没的内陆水库中霍乱弧菌的流行情况、菌株分化和克隆性。采集水样，过滤后在碱性蛋白胨水中富集，然后在硫代硫酸盐胆盐蔗糖琼脂上进行选择性培养。根据生化分析、血清分组和详细的分子特征鉴定环境分离株为霍乱弧菌。洪水过后，饮用水源中该细菌的存在发生率更高。除了一株O1分离株外，所有菌株都大致归类为非O1/非O139，而其中一些菌株确实含有霍乱毒素（CT）。令人惊讶的是，我们在两株非O1/非O139菌株中发现了海地ctxB。基于pyrH、recA和rpoA基因的多位点序列分型分析揭示了环境菌株中的克隆性。分离株表现出不同程度的抗菌耐药性，包括对四环素和环丙沙星的耐药性。这些菌株携带负责多药耐药性的遗传元件SXT 整合子和整合子。遗传特征鉴定很有用，因为仅靠表型特征已被证明不足以区分菌株。确保安全饮用水、卫生设施以及对水库的监测对于应对洪水受灾地区迫在眉睫的疫情威胁至关重要。此外，通过多管齐下的方法管理洪水以及可持续利用环境资源将有效地进行疾病管理。
