Investigating the Sharing of Staphylococcus spp. Between Dogs and Their Owners: A Comparative Study from Two Italian Veterinary Teaching Hospitals

Animal health is a key pillar of the One Health framework, which emphasizes the interconnectedness of humans, animals, and the environment. Staphylococcus spp., common commensals of skin and mucosa, are clinically important due to their virulence factors and increasing antimicrobial resistance. This cross-sectional study aimed to isolate and characterize Staphylococcus spp. from dogs and their owners and to assess correlations within their nasal microbiota. Nasal swabs were collected from at least 100 dog–owner pairs at two Veterinary Teaching Hospitals located in Northern (Turin Province) and Southern (Naples Province) Italy. In both study areas, S. pseudintermedius was the most common species in dogs. Among owners, S. epidermidis was predominant in Naples, while S. epidermidis and S. aureus were most frequent in Turin. A subset of 54 dog–owner pairs sharing the same Staphylococcus species (42 from Turin and 12 from Naples; in total 108 isolates) was included in this analysis, with a focus on antimicrobial patterns. S. aureus was the species most frequently shared between dogs and owners, followed by S. epidermidis, with no significant differences between the two sites. In particular, methicillin resistance (phenotypically inferred) was detected in 16.7% of isolates in Turin (19.0% in dogs; 14.3% in owners) and 41.7% of isolates in Naples (33.3% in dogs; 50.0% in owners). Multidrug resistance was detected in 34.3% of paired isolates overall, with a higher prevalence in Naples (58.3%) compared to Turin (27.4%). No significant association emerged between biofilm production and multidrug resistance (MDR). Overall, these findings suggest possible species sharing between dogs and owners, while biofilm formation did not predict MDR.