Facultad de Quimico Farmacobiologia, Universidad Michoacana de San Nicolas de Hidalgo, Tzintzuntzan 173, Col. Matamoros, Morelia Michoacan 58240, Mexico.
Departamento de Microbiologia, Escuela Nacional de Ciencias Biologicas-Instituto Politecnico Nacional, Prolongacion Carpio y Plan de Ayala S/N, Col. Casco de Santo Tomas, Ciudad de Mexico 11340, Mexico.
J Food Prot. 2021 May 1;84(5):760-766. doi: 10.4315/JFP-20-286.
This study investigated the presence of nontuberculous mycobacteria (NTM) for the first time in two types of unpasteurized fresh cheese produced in the state of Michoacan, Mexico. We tested for this pathogen, along with the others, to broaden the study of microbiological quality in 60 samples of cheese, 30 fresh and 30 Adobera, which were collected from six artisanal cheese factories (ACFs). The hygienic conditions of these establishments and the practices of cheese manufacture were generally poor. Although Mycobacterium bovis was not detected, four cheese samples harbored NTM isolates. The four NTM isolates were identified using three molecular markers (hsp65, rrs, and rpoB genes) that corresponded to Mycolicibacterium fortuitum (n = 3) and Mycolicibacterium mageritense (n = 1). All 60 cheese samples analyzed had unsatisfactory microbiological quality according to the Mexican Official Guideline. Regarding fresh cheeses, all 30 samples analyzed were positive for aerobic mesophilic bacteria, total coliforms, fecal coliforms, and yeasts and molds. Escherichia coli and Staphylococcus aureus were present in 23 and 21 samples, respectively. Listeria monocytogenes was identified in a sample and was isolated from a bulk milk tank in the same ACF. With regard to Adobera cheeses, all samples were positive for aerobic mesophilic bacteria, total coliforms, fecal coliforms, yeasts and molds, and S. aureus. E. coli was isolated from 28 samples. Salmonella was isolated from a sample and from a wooden shovel used in the manufacture of the cheeses in the same ACF. Thus, the consumption of unpasteurized fresh cheese may represent a public health risk. Because of this, health authorities should enforce the legislation that forbids the processing of cheese with unpasteurized milk and encourage producers to follow good manufacturing practices from original ingredients, through the production process of the cheese, to its sale to assure a safe product.
本研究首次在墨西哥米却肯州生产的两种未经巴氏消毒的新鲜奶酪中发现了非结核分枝杆菌（NTM）。我们测试了这种病原体以及其他病原体，以扩大对 60 份奶酪样本（30 份新鲜奶酪和 30 份 Adobera）的微生物质量研究，这些样本均来自六个手工奶酪工厂（ACF）。这些工厂的卫生条件和奶酪生产工艺普遍较差。虽然未检测到牛分枝杆菌，但有 4 个奶酪样本含有 NTM 分离株。使用 3 个分子标记（hsp65、rrs 和 rpoB 基因）对 4 个 NTM 分离株进行鉴定，这些分离株分别对应于偶然分枝杆菌（Mycolicibacterium fortuitum，n=3）和马格利特分枝杆菌（Mycolicibacterium mageritense，n=1）。根据墨西哥官方指南，所有 60 个分析的奶酪样本的微生物质量均不令人满意。关于新鲜奶酪，所有 30 个分析的样本均呈需氧中温细菌、总大肠菌群、粪便大肠菌群和酵母和霉菌阳性。23 个样本中有大肠杆菌，21 个样本中有金黄色葡萄球菌。从同一 ACF 的一个批量牛奶罐中分离到一个样本中的单核细胞增生李斯特菌。关于 Adobera 奶酪，所有样本均呈需氧中温细菌、总大肠菌群、粪便大肠菌群、酵母和霉菌以及金黄色葡萄球菌阳性。从 28 个样本中分离到大肠杆菌。从同一 ACF 生产奶酪中使用的一个木铲中分离到一个样本中的沙门氏菌。因此，食用未经巴氏消毒的新鲜奶酪可能会带来公共卫生风险。为此，卫生当局应执行禁止使用未经巴氏消毒的牛奶加工奶酪的法规，并鼓励生产者从原始原料开始遵循良好的生产规范，通过奶酪的生产过程，直至销售，以确保产品安全。
