Division of Bacteriology, Indian Council of Medical Research- National Institute of Cholera and Enteric Diseases (ICMR-NICED), P-33, Scheme-XM, CIT Road, Beliaghata, Kolkata, 700 010, India.
Curr Microbiol. 2024 Nov 4;81(12):443. doi: 10.1007/s00284-024-03939-8.
We present a novel report of abundance of halophilic Vibrio alginolyticus with thermotolerant and enterotoxigenic characteristics from community water system of an inland-focus of India causing diarrheal outbreak as an index pathogen. Though, Vibrio alginolyticus causing diarrhea after exposure to marine water and consumption of seafood was reported globally, its existence in non-saline drinking-water sources with pathogenic viability was unknown. A 'matched-pair-case-control' study identified the primary source of V. alginolyticus infection as 'tap-water' distributed by the municipality, used for drinking (MOR: 8.33; 95% CI 2.51-27.6) and household chores (MOR: 3.75; 95% CI 1.24-11.3). Cardinal toxin gene 'tdh' and other pathogenicity markers viz.tlh, vppC, toxR, VPI, T3SS1 and sxt were detected in V. alginolyticus isolates. Expression potential of the hemolytic genes are demonstrated by hemolysis assay and transcriptome analysis. Altogether 30.55% of isolates exhibited strong hemolytic potential in vitro. RT-PCR revealed uninterrupted virulence gene expression in outbreak strains under heat stress. Surprisingly, ~ 100% of V. alginolyticus from the outbreak focus were sensitive/partially sensitive to all group of antibiotics except β-lactums, carbapenem and quinolones. High drug-sensitivity suggested lack of previous human gut exposure and indicated a fresh dissemination from the environmental niche to the community domain. The maximum likelihood phylogeny depicted multiple clades in V. alginolyticus strains from Pan India sources. Isolated outbreak strains shared common ancestry with the strains from nearby riverine system, a source of 'drinking water' supplied to the affected community, confirming its environmental origin. V. alginolyticus, traditionally a fish-pathogen, is steadily gaining an emerging epidemiological relevance alongside other waterborne diarrheagenic bacteria and its 'thermotolerant' attribute poses additional threat under the canvas of climate change.
我们报告了一种新型的嗜盐性弧菌丰度，该菌具有耐热和肠毒性特征，来自印度内陆焦点的社区水系统，作为指示病原体引起腹泻暴发。尽管全球有报道称，暴露于海水和食用海鲜后会导致弧菌性腹泻，但在非咸饮用水源中存在具有致病性的弧菌是未知的。一项“配对病例对照”研究确定了弧菌感染的主要来源是市政供应的“自来水”，用于饮用（OR：8.33；95%CI 2.51-27.6）和家庭杂务（OR：3.75；95%CI 1.24-11.3）。在弧菌分离株中检测到主要毒素基因“tdh”和其他致病性标记物，如 tlh、vppC、toxR、VPI、T3SS1 和 sxt。溶血基因的表达潜能通过溶血试验和转录组分析得到证实。总共 30.55%的分离株在体外表现出强烈的溶血潜能。RT-PCR 显示在热应激下，暴发菌株的毒力基因表达不断。令人惊讶的是，来自暴发中心的约 100%的弧菌对所有抗生素组（除了β-内酰胺类、碳青霉烯类和喹诺酮类）敏感/部分敏感。高药敏性表明弧菌以前没有在人类肠道中暴露过，这表明它是从环境栖息地向社区领域传播的。最大似然系统发育树描绘了来自印度各地的弧菌菌株的多个进化枝。分离的暴发株与来自附近河流系统的菌株具有共同的祖先，该系统是供应给受影响社区的“饮用水”的来源，证实了其环境来源。弧菌，传统上是一种鱼类病原体，随着其他水源性腹泻病原菌的出现，其流行病学相关性稳步增强，其“耐热”特性在气候变化的背景下构成了额外的威胁。
