J Vet Sci.  2024 Jul;25(4):e42. 10.4142/jvs.23286.

Genomic insights of S. aureus Microbiology associated with bovine mastitis in a high livestock activity region of Mexico

• Aguirre-Sánchez JR
• Campo NCd
• Medrano-Félix JA
• Martínez-Torres AO
• Chaidez C
• Querol-Audi J
• Campo NCd

• KMID: 2558447
• DOI: http://doi.org/10.4142/jvs.23286

Abstract

Importance
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.
Conclusion
and Relevance: 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.

Keyword

S. aureus; bovine mastitis; virulence factors; multi-resistant genes; genomics