Antibiotic Resistance ofSalmonellaspp. Isolated from Shrimp Farming Freshwater Environment in Northeast Region of Brazil

Abstract

This study investigated the presence and antibiotic resistance ofSalmonellaspp. in a shrimp farming environment in Northeast Region of Brazil. Samples of water and sediments from two farms rearing freshwater-acclimatedLitopenaeus vannameiwere examined for the presence ofSalmonella. Afterwards,Salmonellaisolates were serotyped, the antimicrobial resistance was determined by a disk diffusion method, and the plasmid curing was performed for resistant isolates. A total of 30 (16.12%) of the 186 isolates were confirmed to beSalmonellaspp., belonging to five serovars:S. serovar Saintpaul,S. serovar Infantis,S. serovar Panama,S. serovar Madelia, andS. serovar Braenderup, along with 2 subspecies:S. entericaserovar houtenae andS. entericaserovar enterica. About twenty-three percent of the isolates were resistant to at least one antibiotic, and twenty percent were resistant to at least two antibiotics. Three strains isolated from water samples (pond and inlet canal) exhibited multiresistance to ampicillin, tetracycline, oxytetracycline, and nitrofurantoin. One of them had a plasmid with genes conferring resistance to nitrofurantoin and ampicillin. The incidence of bacteria pathogenic to humans in a shrimp farming environment, as well as their drug-resistance pattern revealed in this study, emphasizes the need for a more rigorous attention to this area.