Department of Applied Microbiology and Biotechnology, Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology in Szczecin, 71-459-Szczecin, Poland.
Department of Applied Microbiology and Biotechnology, Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology in Szczecin, 71-459-Szczecin, Poland.
J Dairy Sci. 2020 Apr;103(4):3076-3081. doi: 10.3168/jds.2019-17574. Epub 2020 Feb 7.
Our objective was to assess the enterotoxigenic potential of coagulase-negative staphylococci (CNS) isolated from bovine milk in Poland. We analyzed CNS isolates collected from 133 bovine milk batches from dairy farms in the Western Pomerania district during 2 milking seasons. A total of 163 isolates were screened by multiplex/duplex PCR for the presence of 18 of 25 enterotoxin genes identified so far in Staphylococcus aureus. The CNS strains presumed to be potentially enterotoxigenic were identified at the species level based on MALDI-TOF mass spectrometry analysis. Based on the presence of an amplicon matching D, G, or O enterotoxin genes, we initially identified 32 of the 163 CNS isolates tested as potentially enterotoxigenic. However, only 8 of these strains were confirmed as such. All 8 of these CNS strains, identified as Staphylococcus haemolyticus, harbored the seg genes, a prerequisite for enterotoxin G production, but so far not connected with staphylococcal foodborne poisoning cases. None of the CNS bovine milk isolates tested was a potential producer of classical A to E staphylococcal enterotoxins. Results of our surveys revealed a low prevalence of enterotoxigenic CNS among the milk isolates from dairy farms in the Western Pomerania district, Poland, suggesting that they pose only a mild health risk in milk. In our opinion, confirmed formation of nonspecific amplicons leading to false-positive results excludes multiplex/duplex PCR as the sole method for assessing the enterotoxigenic potential of CNS.
我们的目的是评估从波兰牛奶奶中分离出的凝固酶阴性葡萄球菌（CNS）的肠毒素产生潜力。我们分析了在两个挤奶季节中从西波美拉尼亚地区的奶牛场收集的 133 批牛奶中分离出的 CNS 分离株。总共通过多重/双重 PCR 筛选了 163 株 CNS 分离株，以检测到目前为止在金黄色葡萄球菌中鉴定出的 25 种肠毒素基因中的 18 种。根据 MALDI-TOF 质谱分析，假定具有潜在肠毒性的 CNS 菌株在物种水平上进行鉴定。根据与 D、G 或 O 肠毒素基因匹配的扩增子的存在，我们最初鉴定出 163 株 CNS 分离株中的 32 株具有潜在肠毒性。然而，只有 8 株被证实如此。所有这 8 株 CNS 菌株被鉴定为溶血性葡萄球菌，均携带 seg 基因，这是肠毒素 G 产生的前提条件，但迄今为止与葡萄球菌食源性中毒病例无关。在所测试的 CNS 牛奶奶分离株中，没有一种是经典 A 至 E 型葡萄球菌肠毒素的潜在生产者。我们的调查结果表明，波兰西波美拉尼亚地区奶牛场牛奶分离株中肠毒性 CNS 的流行率较低，表明它们在牛奶中仅构成轻度健康风险。在我们看来，确认形成非特异性扩增子导致假阳性结果排除了多重/双重 PCR 作为评估 CNS 肠毒性潜力的唯一方法。
