Perfil de resistência a antimicrobianos de Salmonella spp. isoladas de carcaças de frango de corte

Abstract

Salmonella spp. is one of the main causes of foodborne bacterial infections, particularly associated with gastroenteritis linked to the consumption of chicken meat, as it is an important reservoir for the microorganism. The prevalence of multidrug-resistant Salmonella spp. in animal-derived food has significantly increased, representing a growing public health concern. The objectives of this study were to identify strains of Salmonella spp. isolated from visibly contaminated or non-contaminated chicken carcasses, evaluating their antimicrobial resistance profile as well as the production of β-lactamase enzymes, and determining whether these characteristics correlate with the presence of visible contamination on the carcass. Sixty fresh chicken carcasses were collected after automatic evisceration, with 30 showing visible gastrointestinal contamination and 30 without visible contamination. The search for Salmonella spp. was conducted according to ISO 6579-1 methodology, and the identification of colonies was performed using MALDI ToF mass spectrometry, which identified 48 samples of Salmonella spp. that were cryopreserved in the microbiological collection of the Department of Technology and Inspection of Animal Origin Products at the School of Veterinary Medicine of the Federal University of Minas Gerais. Antimicrobial resistance was analyzed by the disk diffusion method, according to the Clinical and Laboratory Standards Institute, as well as tests to verify the presence of β-lactamase enzymes. Serotyping was conducted according to the White-Kauffmann-Le Minor scheme. In addition to descriptive statistical analysis, Fisher's Exact Test and Chi-square tests were also used. In this study, 50 % (n=24) of the serotypes were identified as Minnesota, and all exhibited multidrug resistance and production of ESBL (extended-spectrum betalactamase) and AmpC, highlighting their ability to resist multiple classes of antimicrobials and their potential to spread resistance mechanisms in clinical settings and food. All isolates classified as multidrug-resistant (n=25) showed 100 % resistance to amoxicillin/clavulanic acid, cephalothin, sulfamethoxazole-trimethoprim, and tetracycline. However, they demonstrated 100 % sensitivity to chloramphenicol, fosfomycin, gentamicin, and meropenem. Resistance to ciprofloxacin, significantly correlated with multidrug resistance (p<0,05), indicates that the use of fluoroquinolones may promote the acquisition of resistance to other classes. No correlation was found between carcass contamination and serotype, resistance profile, multidrug resistance, and the presence of ESBL and AmpC enzymes. The results of this study revealed a wide diversity of Salmonella spp. serotypes, with a focus on S. Minnesota, which exhibited a significant multidrug resistance profile in all evaluated strains, alongside the production of ESBL and AmpC enzymes. The comparison between contaminated and non-contaminated carcasses with gastrointestinal content demonstrates the fragility of using visual observation of contamination as an indicator of the presence of the pathogen.