Abstract：
OBJECTIVE: Bovine mastitis, predominantly associated with gram-positive Staphylococcus aureus, poses a significant threat to dairy cows, leading to a decline in milk quality and volume with substantial economic implications.
OBJECTIVE: This study investigated the incidence, virulence, and antibiotic resistance of S. aureus associated with mastitis in dairy cows.
METHODS: Fifty milk-productive cows underwent a subclinical mastitis diagnosis, and the S. aureus strains were isolated. Genomic DNA extraction, sequencing, and bioinformatic analysis were performed, supplemented by including 124 S. aureus genomes from cows with subclinical mastitis to enhance the overall analysis.
RESULTS: The results revealed a 42% prevalence of subclinical mastitis among the cows tested. Genomic analysis identified 26 sequence types (STs) for all isolates, with Mexican STs belonging primarily to CC1 and CC97. The analyzed genomes exhibited multidrug resistance to phenicol, fluoroquinolone, tetracycline, and cephalosporine, which are commonly used as the first line of treatment. Furthermore, a similar genomic virulence repertoire was observed across the genomes, encompassing the genes related to invasion, survival, pathogenesis, and iron uptake. In particular, the toxic shock syndrome toxin (tss-1) was found predominantly in the genomes isolated in this study, posing potential health risks, particularly in children.
CONCLUSIONS: These findings underscore the broad capacity for antibiotic resistance and pathogenicity by S. aureus, compromising the integrity of milk and dairy products. The study emphasizes the need to evaluate the effectiveness of antibiotics in combating S. aureus infections.
OBJECTIVE: This study investigated the incidence, virulence, and antibiotic resistance of S. aureus associated with mastitis in dairy cows.
METHODS: Fifty milk-productive cows underwent a subclinical mastitis diagnosis, and the S. aureus strains were isolated. Genomic DNA extraction, sequencing, and bioinformatic analysis were performed, supplemented by including 124 S. aureus genomes from cows with subclinical mastitis to enhance the overall analysis.
RESULTS: The results revealed a 42% prevalence of subclinical mastitis among the cows tested. Genomic analysis identified 26 sequence types (STs) for all isolates, with Mexican STs belonging primarily to CC1 and CC97. The analyzed genomes exhibited multidrug resistance to phenicol, fluoroquinolone, tetracycline, and cephalosporine, which are commonly used as the first line of treatment. Furthermore, a similar genomic virulence repertoire was observed across the genomes, encompassing the genes related to invasion, survival, pathogenesis, and iron uptake. In particular, the toxic shock syndrome toxin (tss-1) was found predominantly in the genomes isolated in this study, posing potential health risks, particularly in children.
CONCLUSIONS: These findings underscore the broad capacity for antibiotic resistance and pathogenicity by S. aureus, compromising the integrity of milk and dairy products. The study emphasizes the need to evaluate the effectiveness of antibiotics in combating S. aureus infections.
摘要：
目标：牛乳腺炎，主要与革兰氏阳性金黄色葡萄球菌相关，对奶牛构成重大威胁，导致牛奶质量和数量下降，具有重大的经济影响。
目的：本研究调查了发病率，毒力,与奶牛乳房炎相关的金黄色葡萄球菌的抗生素耐药性。
方法：50头产奶奶牛接受了亚临床乳腺炎诊断，分离金黄色葡萄球菌菌株。基因组DNA提取,测序,测序并进行了生物信息学分析，通过包括来自患有亚临床乳腺炎的奶牛的124个金黄色葡萄球菌基因组来补充,以增强总体分析。
结果：结果显示，受试母牛的亚临床型乳腺炎患病率为42%。基因组分析确定了所有分离株的26种序列类型（ST），墨西哥STs主要属于CC1和CC97。分析的基因组表现出对苯酚的多药耐药性，氟喹诺酮,四环素,和头孢菌素,通常用作治疗的第一线。此外，在整个基因组中观察到类似的基因组毒力库，包括与入侵有关的基因，生存,发病机制，和铁的吸收。特别是,中毒性休克综合征毒素（tss-1）主要在本研究中分离出的基因组中发现，构成潜在的健康风险，特别是在儿童中。
结论：这些发现强调了金黄色葡萄球菌对抗生素耐药性和致病性的广泛能力，损害牛奶和乳制品的完整性。该研究强调需要评估抗生素在对抗金黄色葡萄球菌感染中的有效性。
目的：本研究调查了发病率，毒力,与奶牛乳房炎相关的金黄色葡萄球菌的抗生素耐药性。
方法：50头产奶奶牛接受了亚临床乳腺炎诊断，分离金黄色葡萄球菌菌株。基因组DNA提取,测序,测序并进行了生物信息学分析，通过包括来自患有亚临床乳腺炎的奶牛的124个金黄色葡萄球菌基因组来补充,以增强总体分析。
结果：结果显示，受试母牛的亚临床型乳腺炎患病率为42%。基因组分析确定了所有分离株的26种序列类型（ST），墨西哥STs主要属于CC1和CC97。分析的基因组表现出对苯酚的多药耐药性，氟喹诺酮,四环素,和头孢菌素,通常用作治疗的第一线。此外，在整个基因组中观察到类似的基因组毒力库，包括与入侵有关的基因，生存,发病机制，和铁的吸收。特别是,中毒性休克综合征毒素（tss-1）主要在本研究中分离出的基因组中发现，构成潜在的健康风险，特别是在儿童中。
结论：这些发现强调了金黄色葡萄球菌对抗生素耐药性和致病性的广泛能力，损害牛奶和乳制品的完整性。该研究强调需要评估抗生素在对抗金黄色葡萄球菌感染中的有效性。
