Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.
West African Centre for Cell Biology of Infectious Pathogens, University of Ghana Legon, Legon, Accra, Ghana.
PLoS One. 2020 Jul 10;15(7):e0236016. doi: 10.1371/journal.pone.0236016. eCollection 2020.
Cholera remains a major global public health threat and continuous emergence of new Vibrio cholerae strains is of major concern. We conducted a molecular epidemiological study to detect virulence markers and antimicrobial resistance patterns of V. cholerae isolates obtained from the 2012-2015 cholera outbreaks in Ghana. Archived clinical isolates obtained from the 2012, 2014 and 2015 cholera outbreaks in Ghana were revived by culture and subjected to microscopy, biochemical identification, serotyping, antibiotic susceptibility testing, molecular detection of distinct virulence factors and Multi-Locus Variable-Number of Tandem-Repeat Analysis (MLVA). Of 277 isolates analysed, 168 (60.6%) were confirmed to be V. cholerae and 109 (39.4%) isolates constituted other bacteria (Escherichia coli, Aeromonas sobria, Pseudomonas aeruginosa, Enterobacter cloacae and Enterococci faecalis). Serotyping the V. cholerae isolates identified 151 (89.9%) as Ogawa, 3 (1.8%) as Inaba and 14 (8.3%) as non-O1/O139 serogroup. The O1 serogroup isolates (154/168, 91.7%) carried the cholera toxin ctxB gene as detected by PCR. Additional virulence genes detected include zot, tcpA, ace, rtxC, toxR, rtxA, tcpP, hlyA and tagA. The most common and rare virulence factors detected among the isolates were rtxC (165 isolates) and tcpP (50 isolates) respectively. All isolates from 2014 and 2015 were multidrug resistant against the selected antibiotics. MLVA differentiated the isolates into 2 large unique clones A and B, with each predominating in a particular year. Spatial analysis showed clustering of most isolates at Ablekuma sub-district. Identification of several virulence genes among the two different genotypes of V. cholerae isolates and resistance to first- and second-line antibiotics, calls for scaleup of preventive strategies to reduce transmission, and strengthening of public health laboratories for rapid antimicrobial susceptibility testing to guide accurate treatment. Our findings support the current WHO licensed cholera vaccines which include both O1 Inaba and Ogawa serotypes.
霍乱仍然是全球主要的公共卫生威胁，新出现的霍乱弧菌菌株引起了极大关注。我们进行了一项分子流行病学研究，以检测 2012 年至 2015 年加纳霍乱疫情中分离的霍乱弧菌的毒力标记物和抗生素耐药模式。从加纳 2012 年、2014 年和 2015 年霍乱疫情中获得的存档临床分离株通过培养复苏，并进行显微镜检查、生化鉴定、血清分型、抗生素敏感性试验、不同毒力因子的分子检测和多位点可变串联重复分析 (MLVA)。在分析的 277 株分离物中，168 株（60.6%）确认为霍乱弧菌，109 株（39.4%）分离物构成其他细菌（大肠杆菌、索氏气单胞菌、铜绿假单胞菌、阴沟肠杆菌和粪肠球菌）。对霍乱弧菌分离物进行血清分型，确定 151 株（89.9%）为 Ogawa 型，3 株（1.8%）为 Inaba 型，14 株（8.3%）为非 O1/O139 血清群。通过 PCR 检测，发现 O1 血清群分离物（154/168，91.7%）携带霍乱毒素 ctxB 基因。检测到的其他毒力基因包括 zot、tcpA、ace、rtxC、toxR、rtxA、tcpP、hlyA 和 tagA。在分离物中最常见和最罕见的毒力因子分别是 rtxC（165 株）和 tcpP（50 株）。2014 年和 2015 年的所有分离物对所选抗生素均呈多药耐药。MLVA 将分离物分为 2 个大型独特克隆 A 和 B，每个克隆在特定年份占优势。空间分析显示，大多数分离物在 Ablekuma 分区聚类。在两种不同基因型的霍乱弧菌分离物中发现了几种毒力基因，并对一线和二线抗生素产生耐药性，这呼吁扩大预防策略以减少传播，并加强公共卫生实验室以进行快速抗生素敏感性测试，以指导准确治疗。我们的研究结果支持当前世界卫生组织许可的霍乱疫苗，其中包括 O1 Inaba 和 Ogawa 血清型。
