Occurrence, Geographic Distribution, and Antimicrobial Resistance Profiles of Staphylococcus aureus Isolated from Artisanal Fresh Goat Cheese Produced in the Altiplano Potosino Region, Mexico

Artisanal fresh goat cheese produced under traditional small-scale conditions may harbor antimicrobial-resistant pathogens. This study assessed the occurrence and geographic distribution of Staphylococcus aureus, characterized antimicrobial resistance, and explored the antibacterial activity of titanium dioxide (TiO2) against multidrug-resistant (MDR) isolates in the Altiplano Potosino region of Mexico. A total of 150 samples from 15 rural communities in seven municipalities were analyzed. Of 38 presumptive isolates, 24 were confirmed as S. aureus (16.0% of samples), occurring only in Charcas and Vanegas. Based on locality-level susceptibility profiles, 9 of 24 confirmed isolates (37.5%) were assigned an MDR phenotype involving macrolides, lincosamides, and aminoglycosides, with clindamycin resistance observed across all five positive localities. In exploratory assays, UV-C-activated TiO2 produced the largest inhibition zones and lowest viable counts. Viable counts were significantly lower under UV-C than under natural sunlight (p = 0.016), but not significantly different from darkness after Bonferroni adjustment (p = 0.073). These findings establish a regional baseline for S. aureus occurrence and antimicrobial resistance and provide preliminary evidence of measurable antibacterial activity of UV-C-activated TiO2 against MDR isolates.