Antimicrobial Susceptibility Patterns of Staphylococcus spp. Isolates from Mastitic Cases in Romanian Buffaloes from Western Romania

Mastitis is defined as mammary gland inflammation and is one of the most common and economically significant diseases affecting dairy cows. Bacteria are the most frequently reported agents responsible for mastitis, while other pathogens are often overlooked due to insufficient routine investigation. Incomplete diagnoses can result in inappropriate antimicrobial treatments, treatment failures, antimicrobial resistance, the spread of pathogens, and the recurrence of mastitis. <b>Background/Objectives</b>: This study aimed to investigate the presence of <i>Staphylococcus</i> spp. associated with Romanian buffalo mastitis on dairy farms in Western Romania via a bacteriological analysis of mastitis milk and determine antimicrobial susceptibility profiles. <b>Methods</b>: Bacterial culture was performed according to the guidelines described by the National Mastitis Council. Vitek 2 Compact systems (Bio Mérieux, France), with the GP ID cards, were used to confirm the species of the isolates. Antibiotic susceptibility testing was conducted by utilizing Vitek^® 2 preset antimicrobial card AST-GP79 Gram-positive Livestock WW. <b>Results</b>: Of all the milk samples (<i>n</i> = 115) analyzed, 83 were positive for <i>Staphylococcus</i> spp. (72.17%) and were evaluated for their antimicrobial susceptibility profiles. The most common microorganism found was <i>S. aureus</i> (<i>n</i> = 46; 55.42%), followed by <i>S. hyicus</i> (<i>n</i> = 28; 33.73%) and <i>S. schleiferi</i> (<i>n</i> = 9; 10.84%). These pathogens demonstrated significant resistance to the tetracycline, neomycin, benzylpenicillin, and erythromycin. <b>Conclusions</b>: Current control measures for mastitis caused by <i>S. aureus</i> are ineffective. A better understanding of the virulence factors in Romanian buffalo-adapted strains of <i>S. aureus</i>, their pathogenesis, and host immunological responses is essential for developing effective and sustainable non-antibiotic control tools such as vaccines, prophylactic therapies, and other innovative approaches.