Microbiological quality of high-demand foods from three major cities in Ecuador

Bacterial foodborne diseases are one of the most important public health issues worldwide but in Ecuador reports on the microbiological quality of foods are scarce. In this study, a total of 450 traditional food samples including bolon, encebollado, sauces, ceviche, fruit juices, fruit salads, cheese, raw chicken and ground beef were collected from popular markets in the cities of Guayaquil, Quito and Cuenca. Samples were assessed for microbiological quality using both culture dependent and culture independent techniques. Populations of total aerobic bacteria, total coliforms, fecal coliforms and E. coli were examined by plate count. Representative colonies from each culture were further identified using biochemical tests and sequencing of the 16S rRNA gene. For the culture independent analysis, bacterial DNA was extracted from food samples and submitted to next generation sequencing (NGS) of the v3-v4 region of 16S rDNA. By using culture dependent techniques, high prevalence of opportunistic and true pathogens including E. coli, Klebsiella pneumoneae, Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and Shigella flexneri was observed.Other potential pathogens were identified by NGS, including Clostridium spp.., Vibrio spp.., Helicobacter spp.., Campylobacter spp.., among others but no E. coli, Salmonella spp.. or Listeria spp. were detected. This is the first report on the microbiological quality of food from Ecuador.

细菌性食源性疾病是全球最重要的公共卫生问题之一，但在厄瓜多尔，关于食品微生物质量的报告却极为罕见。在本研究中，共收集了450份传统食品样本，包括博隆、恩塞巴尔多、酱料、生鱼片、果汁、水果沙拉、奶酪、生鸡肉和碎牛肉，这些样本均来自瓜亚基尔、基多和昆卡等城市的繁华市场。样本的微生物质量通过依赖和独立于培养的技术进行评估。通过平板计数法检查了总需氧菌、总大肠菌群、粪便大肠菌群和埃希氏菌的数量。通过对每个培养的代表性菌落进行生化测试和16S rRNA基因测序，进一步鉴定了菌落。对于独立于培养的分析，从食品样本中提取了细菌DNA，并将其提交给16S rDNA的v3-v4区域的下一代测序（NGS）。通过依赖培养的技术，观察到包括埃希氏菌、肺炎克雷伯菌、沙门氏菌、单核细胞增生李斯特菌、金黄色葡萄球菌和福氏菌在内的机会性病原体和真病原体的高发病率。通过NGS识别了其他潜在病原体，包括梭菌属、弧菌属、幽门螺杆菌、弯曲菌属等，但未检测到埃希氏菌、沙门氏菌或李斯特菌。这是关于厄瓜多尔食品微生物质量的首次报告。