Resistencia antibiótica de genotipos de cepas de Salmonella spp de cerdos sacrificados en rastros del Estado de México

multiresistant salmonella serovar typhimurium strains are a worldwide problem in animal and human health. the aim of this study was to determine the frequency of some salmonella spp resistance genes (cmla/tetr, pse-1, tem, sip b/c) in strains isolated from pigs slaughtered at abattoirs in the estado de mexico. of 87 analyzed strains 22 (25.28%) had phenotypical resistance to chloramphenicol (30 μg), 15 (17.24%) to ampicillin (10 μg) and 54 (62.07%) to sulfamethoxazole (60 μg). the phenotypical and genotypical relation of the 87 strains was: of the 22 chloramphenicol resistant strains only 14 (63.63%) expressed the cmla/tetr resistance gene, and of the 65 strains non-resistant to chloramphenicol only 36 (55.38%) expressed the cmla/tetr resistance gene. regarding the 15 ampicillin resistant strains only 2 (13.33%) were carriers of the pse-1 gene and 7 (46.66%) presented the tem gene; both genes confer genotypical ampicillin resistance. of 72 non-resistant ampicillin strains, 11 (15.27%) carried the tem gene which confers ampicillin resistance. two salmonella strains (2.28%) belonged to phagotype dt104. strains not showing phenotypical resistance but carrying resistance genes have not been exposed to selection by competition, although they possess the mechanism to express such resistance.