Diversidade de espécies e do perfil de resistência a antimicrobianos de Enterococcus e Staphylococcus isolados de pequenos animais (cães e gatos)

Abstract

Bacteria of the genera Enterococcus and Staphylococcus are Gram-positive cocci frequently isolated from humans and animals, as they are part of the normal microbiota of different tissues and organs. However, some species within these bacterial genera (such as Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus pseudintermedius) are opportunistic and have pathogenic potential, being capable of causing more severe clinical manifestations in humans and companion animals (such as dogs and cats). Concerns are even greater when isolates are not susceptible to the main antibacterial agents and display multidrug resistance (MDR). The present study aimed to investigate the diversity of bacterial species and analyze the antibacterial resistance profile of isolates from sick and healthy animals that were preliminarily identified as Enterococcus spp. and Staphylococcus spp. These isolates were obtained from samples collected from domiciled dogs and cats. A total of 57 Enterococcus spp. clinical isolates and 78 Staphylococcus spp. isolates were obtained from the microbiota of different apparently healthy dogs (n = 95) and cats (n = 40) living in various cities in Rio Grande do Sul between 2016 and 2022. These isolates were maintained in culture collections and reanalyzed for traditional bacteriological identification, species detection by mass spectrometry (MALDI-TOF), and assessment of resistance to the main antibacterial agents used in small-animal clinical practice.Analysis of the 57 Enterococcus spp. isolates revealed the occurrence of only three species: E. faecium (39; 68.4%), E. faecalis (17; 29.8%), and E. avium (1; 1.8%). These isolates showed resistance to the following antibacterial agents: rifampicin (46; 80.7%), tetracycline and streptomycin (42; 73.7%), ampicillin and imipenem (41; 71.9%), erythromycin (39; 68.4%), gentamicin (38; 66.7%), ciprofloxacin (36; 63.2%), norfloxacin (32; 56.1%), nitrofurantoin (10; 17.5%), and chloramphenicol (9; 15.7%). An MDR profile was identified in 45 isolates (78.9%). The results of the evaluation of 78 isolates previously identified as staphylococci demonstrated that 68 (87.2%) were confirmed as Staphylococcus spp., including 26 (38.2%) classified as coagulase-positive staphylococci (CPS) and 42 (61.8%) as coagulase-negative staphylococci (CNS). 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. antimicrobial resistance (AMR) analyses demonstrated that 17 (25%) isolates showed sensitivity to all drugs tested 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 most frequently associated CoPS with AMR, including nine (45%) MDR and four (20%) MRS, while S. equorum was the predominant CoNS with antimicrobial resistance (AMR), highlighting nine (75%) cases of MDR and four (33.3%) of MRS. In conclusion, different species of Enterococcus spp. and Staphylococcus spp. are frequently found in the normal microbiota and/or infections of dogs and cats, and they exhibit varying levels of resistance to antibacterial agents. These findings highlight the importance of identifying and monitoring these microorganisms to improve understanding of their relevance in veterinary and human medicine, within the One Health framework. [resumo fornecido pelo autor]