Diversity and Antimicrobial Resistance of Staphylococci Isolated from Healthy Dogs and Cats in Southern Brazil

Staphylococcus spp. are potential pathogens classified into more than 50 species, frequently presenting antimicrobial resistance (AMR) to several drugs. The present study aimed to identify the Staphylococcus species and their AMR in staphylococci isolated from healthy companion animals (pets) in southern Brazil. A total of 78 presumptive Staphylococcus sp. isolates (from 48 dogs and 30 cats) were obtained in a period of five years (2018–2022). All isolates were analyzed by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-ToF) and tested with a panel of antimicrobials frequently used in pet treatment in Brazil. The results demonstrated that 68 isolates were identified as Staphylococcus spp., including 26 (38.2%) classified as coagulase-positive staphylococci (CoPS) and 42 (61.8%) as coagulase-negative staphylococci (CoNS). CoPS included S. pseudintermedius (n = 20; 29.4%), S. aureus (n = 3; 4.4%), and S. schleiferi (n = 2; 2.9%), while CoNS were S. equorum (n = 12; 17.6%), S. felis (n = 7; 10.3%), S. sciuri (n = 8; 11.8%), S. simulans (n = 4; 5.9%), S. epidermidis (n = 1; 1.5%), S. haemolyticus (n = 1; 1.5%), S. saprophyticus (n = 1; 1.5%), and S. xylosus (n = 1; 1.5%). The remaining eight isolates were identified as Staphylococcus spp. AMR analyses demonstrated that 17 (25%) isolates presented susceptibility to all tested drugs, and 51 (75%) to one or more antimicrobials. Twenty-four (35.6%) isolates were multidrug resistant (MDR), and 13 (19.1%) were methicillin-resistant staphylococci (MRS). S. pseudintermedius was the CoPS most frequently with AMR, including nine (45%) MDR and four (20%) MRS, while S. equorum was the predominant CoNS with AMR, highlighting nine (75%) MDR and four (33.3%) MRS. The Staphylococcus species diversity identified here highlights the importance of studying the microorganisms circulating in healthy companion animals and their characteristics concerning pathogenicity and AMR.