Ortigosa M, Irigoyen A, Urdin M, García S, Ibañez F C, Torre P
Dpto. Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadia, Pamplona 31006, Navarra, Spain.
Int J Food Microbiol. 2008 Jul 15;125(2):146-52. doi: 10.1016/j.ijfoodmicro.2008.03.035. Epub 2008 Apr 8.
Enterococci are a ubiquitous group and are natural constituents of the intestinal flora of nearly all animals and humans and can reach high levels in a variety of farmhouse cheeses. The purpose of this study was to determine the origin of the different enterococcal strains present in cheeses at different stages of ripening by typing the enterococci isolated from the raw milk, the cheeses, the cheesemaking environment, and from the faecal matter of the ewes and humans associated with cheese production. The potential presence of vancomycin-resistant enterococci (VRE) at all stages of the process and in the cheeses was also considered. The study was carried out at two separate cheesemaking dairy plants, and samples of the ewes' faeces, the shepherds' and cheesemakers' stools, teat cups, vat, brine, holding tank milk, vat milk, and the cheeses after brining and after 1, 15, and 60 days of ripening were collected. Cheesemaking procedures at the two plants were similar, yet the enterococcal levels and species observed differed at all the sample collection points, though E. faecalis predominated in all the milk and cheese samples. The traceability study performed for the species E. faecalis present at all the sample collection points suggested that the cheesemaker and the cheesemaking equipment were the source of the enterococci in the cheeses, though other possible non-faecal sources remain to be determined. VanC1 and vanC2/C3 enterococcal strains were isolated from the ovine faeces, teat cup, brine, and vat samples at cheesemaking dairy plant A, while only two vanC2/C3 strains were isolated from ovine faeces samples at dairy plant B. No VRE strains were detected in any of the milk or cheese samples.
肠球菌是一类广泛存在的菌群，几乎是所有动物和人类肠道菌群的天然组成部分，并且在各种农家奶酪中含量很高。本研究的目的是通过对从生牛奶、奶酪、奶酪制作环境以及与奶酪生产相关的母羊和人类粪便中分离出的肠球菌进行分型，来确定处于不同成熟阶段的奶酪中不同肠球菌菌株的来源。同时还考虑了该过程所有阶段以及奶酪中耐万古霉素肠球菌（VRE）的潜在存在情况。该研究在两家独立的奶酪制作乳品厂进行，收集了母羊粪便、牧羊人和奶酪制作工人的粪便、奶杯、发酵桶、盐水、储奶罐牛奶、发酵桶牛奶以及腌制后和成熟1天、15天及60天后的奶酪样本。两家工厂的奶酪制作程序相似，但在所有样本采集点观察到的肠球菌水平和种类有所不同，不过粪肠球菌在所有牛奶和奶酪样本中占主导地位。对所有样本采集点存在的粪肠球菌进行的溯源研究表明，奶酪制作工人和奶酪制作设备是奶酪中肠球菌的来源，尽管其他可能的非粪便来源仍有待确定。在奶酪制作乳品厂A的羊粪便、奶杯、盐水和发酵桶样本中分离出了VanC1和VanC2/C3肠球菌菌株；而在乳品厂B，仅从羊粪便样本中分离出了两株VanC2/C3菌株。在任何牛奶或奶酪样本中均未检测到VRE菌株。
