NASAL COLONIZATION BY GOLDEN-PIGMENTED COAGULASE-POSITIVE STAPHYLOCOCCUS SPP. IN DOMESTIC CATS IN THE PROVINCE OF ESPÍRITO SANTO, BRAZIL: ANTIMICROBIAL RESISTANCE PROFILES AND ONE HEALTH IMPLICATIONS

João Beraldi Passini de Castro, Samara Torres Gualhano, Bianca Magnelli Mangiavacchi,
Lígia Cordeiro Matos Faial, Clara dos Reis Nunes, Juliana Toledo Campos Arêas, Kelen Salaroli Viana,
Júlio Cesar dos Santos Boechat, Renato Mataveli Ferreira Filho, Paulo Roberto Blanco Moreira Norberg, Antonio Neres Norberg*

ABSTRACT

Staphylococci capable of producing golden-pigmented colonies, commonly associated with Staphylococcus aureus and other coagulase-positive species such as Staphylococcus pseudintermedius, are significant opportunistic pathogens in both veterinary and human medicine. This research aimed to determine the prevalence of such staphylococci in the nasal cavity of cats attended at a veterinary clinic in Bom Jesus do Norte, Province of Espírito Santo, Brazil, and to characterize their antimicrobial susceptibility profiles. Nasal swabs were collected from 45 clinically healthy cats that had not received antimicrobials in the preceding six months. Bacterial isolation, phenotypic identification, and antimicrobial susceptibility testing were performed according to EUCAST guidelines using the Kirby-Bauer disk diffusion method. Golden-pigmented, coagulase-positive Staphylococcus spp. were isolated from 15 cats (33.3% prevalence). Among these isolates, 66.6% (10/15) were resistant to cefoxitin, indicating methicillin resistance. Resistance to ampicillin and penicillin was observed in 93.3% of isolates, while macrolides, lincosamides, and chloramphenicol showed variable resistance. Notably, all isolates remained fully susceptible to ciprofloxacin, linezolid, tetracycline, and rifampicin. Network analysis of co-resistance patterns revealed a central cluster of β-lactam resistance tightly linked to other antimicrobial classes, consistent with a multidrug-resistant phenotype. These findings highlight the circulation of methicillin-resistant staphylococci in apparently healthy pet cats in the southern region of the Province of Espírito Santo, underscoring their potential role as reservoirs of antimicrobial resistance genes within the One Health framework. The high susceptibility to non-β-lactam antimicrobials supports their judicious use in empirical therapy, while the elevated resistance to methicillin prevalence calls for enhanced surveillance and antimicrobial stewardship in veterinary practice.

Keywords: Staphylococcus; methicillin-resistant; cats; antimicrobial resistance; nasal colonization; One Health.