Antimicrobial resistance of coagulase-negative Staphylococcus isolated from the external ear canal of healthy cats in Talca, Chile, South América: Preliminary results

Background: The microbiota of the external ear of cats comprises different types of bacteria that can change due to intrinsic or extrinsic factors. Coagulase-negative Staphylococcus (CoNS) is predominant in the external ear of cats. Antibiotic-resistant CoNS associated with infectious pathologies has been reported in humans. The presence of antibiotic-resistant CoNS acting as reservoirs in the ears of healthy cats could represent a zoonotic risk. This has not yet been studied in Talca, Chile. Aim: This study aimed to determine the antimicrobial susceptibility of CoNS strains obtained from the external ear of healthy cats in Talca, Chile, as a possible zoonotic risk. Methods: Ear swabs were obtained from 31 healthy cats. Bacterial culture and morphological analysis were performed on the samples. MALDI-TOF was used to identify CoNS strains, which were tested against a panel of 11 antibiotics using the Kirby-Bauer disk diffusion method. Fisher’s exact test was used to determine the association between the epidemiological variables of the patients and the antimicrobial susceptibility of CoNS strains. Results: Nine CoNS strains were isolated from the ear of seven healthy cats (prevalence 22.58%). Staphylococcus simulans and Staphylococcus felis were the main species identified. Antimicrobial resistance was observed in 55.5% of the strains, mainly to oxacillin. Resistance to more than two antibiotics was observed in 22.2% of the strains. No association was found between the epidemiological variables of the patients and the antimicrobial susceptibility of the CoNS strains. Conclusion: The ears of healthy cats can act as a reservoir for antibiotic-resistant CoNS, with a potential risk of transmission to humans. These preliminary results are the first to be reported in Talca, Chile.