2011, Number 4
Antibiotic resistance of Salmonella spp strain genotypes isolated from pigs slaughtered at abattoirs in the Estado de Mexico
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ABSTRACTMultiresistant 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.
HIRD D, HERNÁNDEZ AJ, WILLIAMS JJ, RODRÍGUEZ BJC, SEGURA CJC. Medidas de asociación epidemiológica. Memorias del V Curso Internacional Teórico-Práctico en Epidemiología; 2000 noviembre 27 – diciembre 1; Mérida (Yucatán) México. Mérida (Yucatán) México: Facultad de Medicina Veterinaria y Zootecnia. Universidad Autónoma de Yucatán, 2000: 19-27.