Antimicrobial resistance in Salmonella Enteritidis isolated from clinical and environmental broiler chickens and breeders broiler

The antimicrobial resistance of Salmonella Enteritidis strains isolated from clinical and environmental poultry samples in the Southern Brazil during the years of 1999, 2000 and 2001 was evaluated. Among the 79 isolated samples, 64 (81%) were resistant to at least one of the antimicrobial agents tested, showing 22 different resistance patterns. Tetracycline showed the highest percentage (64,5%) of resistance among the antimicrobial agents used. Resistance to drugs at different levels was found as the following: ampicillin (1.2%), kanamycin (1.2%), ciprofloxacin (2.5%), enrofloxacin (8.8%), gentamicin (21.5%), streptomycin (20.2%), nitrofurantoin (26.6%), and nalidixic acid (30.4%). None of the S. Enteritidis strains were resistant to chloramphenicol, norfloxacin, and polimycin B. Among the 64 S. Enteritidis strains that showed resistance, 43 (67.2%) were resistant to two or more antimicrobial agents. Twenty-one (32.8%) strains were resistant to only one of the antimicrobial agents, 14 to tetracycline, three to nalidixic acid, three to nitrofurantoin, and one to gentamycin. These antimicrobial resistance levels suggest a high occurrence of tetracycline resistant S. Enteritidis strains and resistance to two or more antimicrobial agents