Journal of Antimicrobial Agents

Isolation and Antimicrobial Susceptibility of Salmonella Typhimurium and Salmonella Enteritidis in Fecal Samples from Animals

Abstract

López-Martín JI, González-Acuña D, García CA, and Carrasco LO

Salmonella enterica is a microorganism with high zoonotic potential, distributed worldwide, having more than 2,610 identified serovars and affecting different animal species, both production and wildlife animals. Objective: Prevention of human salmonellosis requires prior monitoring of Salmonella in animals. In this study. Salmonella enterica serovars from different animal origins were isolated and their antimicrobial susceptibility was determined.
Methods: A total of 2193 samples from different origins (feces of cattle, sheep, horses, pigs, dog, chickens and seagulls and chicken eggs) were analyzed for bacterial typing and antimicrobial susceptibility was studied by the Kirby-Bauer method including 9 antibacterial agents (florfenicol, amoxicillin, ceftiofur, gentamicin, oxytetracycline, trimethoprim/sulfamethoxazole, enrofloxacine, ampicillin and cefoperazone) and MIC50 and MIC90 for 6 of them were determined.
Results: A 4.38% serovar isolation (n = 96), including 6 S. Typhimurium (6.25%) from equine cattle and pig feces, 19 S. Enteritidis (19.79%) from seagulls and pigs and 71 other serovars, was obtained from the various animal origins. Serovar S. Typhimurium showed high resistance to oxytetracycline and gentamicin by the Kirby-Bauer method and a MIC90 of 512 μg.mL-1 for oxytetracycline and trimethoprim/sulfamethoxazole antibiotics. By the diffusion method, serovar S. Enteritidis was resistant to trimethoprim/sulfamethoxazole and its MIC90 was 256 μg.mL-1 for oxytetracycline. The 32% of Salmonella isolates showed multi-resistance, 2 strains, isolated from pigs (one S. Typhimurium and one S. Enteritidis serovars), showed resistance to 5 antimicrobials tested.
Conclusion: The constant release of these serovars to the environment, reaching also animal food, is a permanent potential risk for public health, turning into a first priority the establishment of control and antibiotic therapy strategies.