Diversity and Antibiotic Resistance of Cultivable Bacteria in Bulk Tank Milk from Dairy Farms in Shandong Province, China

The study analyzed bacterial diversity and antimicrobial resistance (AMR) profiles in cow bulk tank milk from five dairy farms in Shandong Province, China. The results showed a high resistance rate to sulfadiazine (53.2%) and the lowest to levofloxacin (6.0%). 23% of isolates were multidrug-resistant. Nine resistance genes targeting seven antibiotic classes were identified, with sul1 and ant(4′)-Ia showing the highest detection rates. The findings suggest enhanced AMR surveillance, improved antibiotic stewardship, and targeted interventions to mitigate public health risks.