Retrospective analysis of antimicrobial susceptibility testing illustrates the problem of resistant Staphylococcus species in cats in the northeastern United States.

Staphylococcus infections are a concern in both human and veterinary medicine due to their zoonotic potential, ability to cause a spectrum of diseases, and antimicrobial resistance (AMR). This study retrospectively analyzed AMR among 1278 Staphylococcus isolates obtained from cats over 15 years, primarily from the northeastern United States. Staphylococcus felis (26 %), Staphylococcus aureus (22 %), and Staphylococcus pseudintermedius (15 %) were the predominant species. The most common isolation sites were skin and soft tissue (52 %) and urinary tract (22 %). Resistance to at least one antimicrobial was seen in 54 % of isolates. S. pseudintermedius displayed the lowest proportion of susceptibility overall. Susceptibility was lowest overall to penicillin (48 %), followed by ampicillin (49 %) and erythromycin (62 %), while susceptibility was highest to vancomycin and rifampin (≥99 %). The overall prevalence of multidrug resistance was 19 %, most common among S. pseudintermedius isolates (46 %). Survival models revealed increased minimum inhibitory concentrations for several antimicrobials in 2018-2022 compared to 2008-2012. Compared to coagulase-negative staphylococcal species, S. pseudintermedius had higher MICs for β-lactams, fluoroquinolones, doxycycline, and trimethoprim-sulfamethoxazole. S. felis had the highest susceptibilities and lowest MICs. This study underscores the significance of AMR and MDR in feline medicine and One Health. The findings emphasize the need for vigilant AMR surveillance in veterinary practices and antimicrobial stewardship in companion animal medicine.