Phenotypic and genotypic study on antibiotic resistance and pathogenic factors of isolates from small ruminant mastitis milk in South of Italy (Sicily).

is the major cause of mastitis in small ruminants in the Mediterranean farms causing severe losses to dairy industry. Antibiotic treatment has been the most common approach to control these infections. Aim of this study was to investigate antimicrobial resistance (AMR), virulence factors and biofilm-related genes of 84 Sicilian strains of isolated from sheep and goats milk during two different periods δT (2006-2009) and δT (2013-2015). Kirby Bauer method and Polymerase Chain Reaction (PCR) were utilized to monitor AMR and related genes (). Moreover, toxin genes (, and ) and biofilm genes () were studied. Twenty-six isolates (30.9%) showed multidrug resistance. The two groups showed similar results with exception for higher values of resistance for tilmicosin and lower for sulfamethoxazole and vancomycin of the second group. gene was detected in one isolate. Tetracycline resistance was higher than 20%, with an increase in δT group. Toxin genes were found in 5 isolates (5.9%), belonging of δT group, while 57 of isolates (67.8%) showed biofilm related genes. The high presence of multi-resistant isolates suggests the need of more responsible use of antibiotic therapy for the control of these infections.