ANTIBIOTIC RESISTANCE PROFILES OF S. AUREUS PATHOTYPES ISOLATED IN A COMMERCIAL RABBIT FARM IN ITALY

The breeding of meat rabbits is an important sector in the livestock industry in Italy and antibiotics are often used to control bacterial diseases. The focus of this study was to describe antibiotic resistance profiles’ distribution among Methicillin-sensitive Staphylococcus aureus (MSSA) population isolated in a rabbit farm. Out of a total of 592 methicillin-sensitive S. aureus strains (n = 552 from healthy skin and n = 40 from lesions), isolated from 400 rabbits of different age reared in a commercial medium-sized intensive breeding farm in Central Italy and from 3 farm-workers, a sample of 96 S. aureus, was randomly selected.Antimicrobial susceptibility tests (AST) for 16 antibiotics and molecular analyses (spa-typing) were carried out. Many categorical variables were used to perform statistical analysis, some related to the animals (rabbit’s ID, age category, site of sampling), and others to bacteria (spa-type). According to spa-typing and resistance profiles towards veterinary and human antibiotics, 26 pathotypes were identified. Association between pathotypes and animal categories (p = 0.019), and sampling sites (p = 0.001) were observed, while no association was found with lesions (p = 0.128). Two multidrug-resistant (MDRs) pathotypes, belonged to t2802 spa-type, were isolated from both farmers and rabbits. The 92.3% of pathotypes were MDRs and associated with age categories and adult and breeding rabbits. The highest resistance was observed against the classes of Tetracyclines, Macrolides, Glycopeptides in both animal and human S. aureus strains, while almost all were susceptible to Penicillins, according to the limited use of β-lactams in the farm. The number of resistances to antibiotic-classes increased with the time spent in the farm environment, which coincided with animal category. Strains carrying a higher number of resistances were the most represented in the farm. As expected, the selective pressure exerted by antibiotics use acted lowering susceptibility to various drug categories.