摘要

尽管大多数巴西乳制品符合高技术标准，但牛奶生产存在质量问题，可能会降低最终产品质量。在生产和处理过程中，有几种微生物可能会污染牛奶。如果奶牛的抗菌药物使用仍未得到控制，食品中抗菌素抗性基因的水平转移可能会对食品生产商和乳品企业都特别关注。本研究集中于对米纳斯奶酪中假定的革兰氏阳性球菌以及分离的细菌中抗微生物和杀生物剂抗性基因的评估。处理7种不同的工业商标Minas奶酪（n = 35）的代表性样品用于选择性培养和分离革兰氏阳性球菌。所有分离的细菌通过16S rRNA基因的DNA测序鉴定。通过PCR筛选抗微生物剂抗性基因。总体而言，分离和鉴定了208株菌，分别为：粪肠球菌（47.6％），解大球菌（18.3％），屎肠球菌（11.5％），病例肠球菌（7.7％），溶血葡萄球菌（7.2％），金黄色葡萄球菌％），表皮葡萄球菌（2.9％）和海氏肠球菌（0.5％）。其中以blaZ（65.2％），msrA（60.9％），msrB（46.6％），linA（54.7％）为主的遗传标记mecA（78.0％）和smr（71.4％ ，aacA-aphD（47.6％）。根据巴西卫生法规，这些细菌不被认为是有害的污染物质，因此奶酪样品中含有抗菌素抗性标记的机会主义病原菌的发生是特别令人关注的。然而，它们是潜在的致病细菌，并且奶酪可被认为是可通过食物链，制造人员和消费者水平转移的抗微生物剂抗性基因的储库。

Although most Brazilian dairy products meet high technological standards, there are quality issues regarding milk production, which may reduce the final product quality. Several microbial species may contaminate milk during manufacture and handling. If antimicrobial usage remains uncontrolled in dairy cattle, the horizontal transfer of antimicrobial resistance genes in foodstuffs may be of particular concern for both food producers and dairy industry. This study focused on the evaluation of putative Gram positive cocci in Minas cheese and of antimicrobial and biocide resistance genes among the isolated bacteria. Representative samples of 7 different industrially trademarked Minas cheeses (n = 35) were processed for selective culture and isolation of Gram positive cocci. All isolated bacteria were identified by DNA sequencing of the 16S rRNA gene. Antimicrobial resistance genes were screened by PCR. Overall, 208 strains were isolated and identified as follows:Enterococcus faecalis (47.6%), Macrococcus caseolyticus (18.3%), Enterococcus faecium (11.5%), Enterococcus caseliflavus (7.7%), Staphylococcus haemolyticus(7.2%), Staphylococcus aureus (4.3%), Staphylococcus epidermidis (2.9%), andEnterococcus hirae (0.5%). The genetic markers mecA (78.0%) and smr (71.4%) were the most prevalent, but others were also detected, such as blaZ (65.2%),msrA (60.9%), msrB (46.6%), linA (54.7%), and aacA‐aphD (47.6%). The occurrence of opportunist pathogenic bacteria harboring antimicrobial resistance markers in the cheese samples are of special concern, since these bacteria are not considered harmful contaminating agents according to the Brazilian sanitary regulations. However, they are potentially pathogenic bacteria and the cheese may be considered a reservoir for antimicrobial resistance genes available for horizontal transfer through the food chain, manufacturing personnel and consumers.

https://onlinelibrary.wiley.com/doi/full/10.1111/1750-3841.14019