ABSTRACT

The recent emergence of LA-MRSA and their identification in people in contact with livestock has increased their importance for dairy sector and has led to the need to check MRSA presence in dairy foods. Therefore, a total of 285 dairy food samples were analyzed for the presence of MRSA. The 285 samples included raw milk (50 samples), traditional cheeses consisting of white-pickled cheese (50 samples) and Tulum cheese (50 samples), yogurt (25 samples), butter (25 samples), traditional clotted cream (20 samples), pastry cream (50 samples), and traditional Maras ice-cream (15 samples). The isolation procedure of S. aureus followed the EN/ISO 6888–1 (01/2004) method. Out of 99 presumptive isolates, 27 S. aureus isolate were identified by both MALDI-TOF MS and PCR. Overall, 15 out of 285 samples (5.26%) were contaminated by S. aureus; however, mean contamination level of S. aureus between different types of foods was observed as the highest in pastry creams with 6.4 × 10³ CFU/g No S. aureus was isolated in yogurt, butter, traditional clotted cream, and traditional Maras ice-cream samples. Strains with MRSA characteristics were investigated by real-time PCR (RTiPCR)-targeting mecA and mecC genes. Out of 27 S. aureus strains, 4 strains carried one gene [mecA gene in 2 strains, isolated from raw milk (sample no: 27) and a White-pickled cheese (sample no: 46); 2 strains carried mecC gene, isolated from two different pastry creams (sample no: 33 and 44)], and only a strain isolated from a pastry cream (sample no: 21) harbored both mecA and mecC genes. None of the strains from Tulum cheeses were positive with either mec genes. This study revealed the relationship of MRSA with raw milk and traditional artisanal dairy products. Extra preventive measures to avoid MRSA-contaminated dairy foods must be applied as their consumption poses a potential risk to public health.

摘要

最近出现的 LA-MRSA 及其在与牲畜接触的人中的识别增加了它们对乳制品行业的重要性，并导致需要检查乳制品中 MRSA 的存在。因此，共分析了 285 个乳制品样品中 MRSA 的存在。285个样品包括生牛奶（50个样品）、由白腌制奶酪（50个样品）和Tulum奶酪（50个样品）组成的传统奶酪、酸奶（25个样品）、黄油（25个样品）、传统凝块奶油（20个样品） 、糕点奶油（50 个样品）和传统 Maras 冰淇淋（15 个样品）。金黄色葡萄球菌的分离程序遵循 EN/ISO 6888–1 (01/2004) 方法。在 99 个推定分离株中，27 个金黄色葡萄球菌通过 MALDI-TOF MS 和 PCR 鉴定分离株。总体而言，285 个样本中有 15 个（5.26%）被金黄色葡萄球菌污染；然而，观察到不同类型食物之间金黄色葡萄球菌的平均污染水平在糕点奶油中最高，为 6.4 × 10 ³ CFU/g酸奶、黄油、传统凝块奶油和传统 Maras 冰淇淋中未分离出金黄色葡萄球菌奶油样品。通过实时 PCR (RTiPCR) 靶向mecA和mecC基因研究具有 MRSA 特征的菌株。在 27株金黄色葡萄球菌中，有 4 株携带一个基因 [ mecA2株基因，从生奶（样品编号：27）和白腌奶酪（样品编号：46）中分离；2 株携带mecC基因，从两种不同的糕点奶油中分离（样品编号：33 和 44）]，只有从糕点奶油（样品编号：21）中分离出的菌株含有mecA和mecC基因。图卢姆奶酪中没有任何菌株对mec基因呈阳性。该研究揭示了 MRSA 与生奶和传统手工乳制品的关系。必须采取额外的预防措施来避免受 MRSA 污染的乳制品，因为它们的食用会对公众健康构成潜在风险。