A study from cows with mastitis was performed and Staphylococcus aureus was the predominant pathogen in 46.4 % among 153 studied strains from 276 milk samples of infected cows. Antibiotic resistance of 71 S. aureus isolates was determined in order to search resistant strains to antibiotics of clinical interest, as well as to determine their degree of multi-resistance. It was found that 60% of the S. aureus strains presented resistance to β-lactams, but none to oxacillin, teicoplamin or vancomycin. On the other hand, with the aim of reducing the use of current antibiotics and their associated resistance, a new formulation was introduced. The antimicrobial compounds (P22-P32), demonstrated to be effective in 55% of the 76 mastitis cases studied. The use of P22-P32 reduced the number of somatic cell to less than 300,000 SCC/mL-1 in 75.2 % of milk samples analyzed, normalizing the milk quality, fat and lactose levels and increasing the volume of production in 10.1 %.
mastitis; Staphylococcus aureus; antibiotic resistance; infection reduction
