Caracterización de β-lactamasas de espectro extendido en aislamientos clínicos colombianos de Salmonella enterica no tifoidea de 1997 a 2022

INTRODUCTION. Salmonella spp. is a zoonotic pathogen transmitted to humans through contaminated water or food. The presence of extended-spectrum β-lactamases is a growing public health problem because these enzymes are resistant to third and fourth generation cephalosporins. OBJECTIVE. To characterize extended-spectrum β-lactamases in Salmonella spp. isolates received by the acute diarrheal disease/foodborne disease surveillance program of the Grupo de Microbiología of the Instituto Nacional de Salud. MATERIALS AND METHODS. A total of 444 Salmonella spp. isolates, resistant to at least one of the cephalosporins, were obtained between January 1997 and June 2022. The extended- spectrum β-lactamases phenotype was identified by the double disk test. DNA extraction was carried out by the boiling method, and the ( bla ) CTX-M, ( bla ) SHV, and ( bla ) TEM genes were amplified by PCR. RESULTS. All the isolates were positive for the extended-spectrum β-lactamases test. The genes identified were: ( bla ) CTX-M + ( bla ) TEM (n=200), ( bla ) CTX-M (n=177), ( bla ) SHV(n=16), ( bla ) SHV + ( bla ) CTX-M (n=6), ( bla ) TEM (n=13) and ( bla ) SHV + ( bla ) CTX-M + ( bla ) TEM (n=3). Twenty-six isolates were negative for the evaluated genes. Positive extended-spectrum β-lactamases isolates were identified in Bogotá and 21 departments: Chocó, Magdalena, Meta, Bolívar, Casanare, Cesar, Córdoba, Quindío, Atlántico, Tolima, Cauca, Cundinamarca, Huila, Boyacá, Caldas, Norte de Santander, Risaralda, Antioquia, Nariño, Santander y Valle del Cauca. CONCLUSION. Resistance to third generation cephalosporins in Salmonella spp. isolates was mainly caused by ( bla ) CTX-M. Isolates were resistant to ampicillin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole (44 %; 197/444). The most frequent extended-spectrum β-lactamases-expressing serotypes were Salmonella Typhimurium and Salmonella Infantis.