Salmonella spp. e Escherichia coli em ambientes de cultivo de camarão (Litopenaeus vannamei) no Estado do Ceará

Abstract

Bacteria of fecal origin, such as Escherichia coli and Salmonella, are frequently isolated from freshwater or marine waters, originating economic problems to the cultivation of aquatic organisms for human consumption. Another concerning factor is the growing resistance to antibiotics in the aquatic environment, due to its indiscriminate use for both human and animal prophylaxis. This considered, the following research aims at monitoring the presence of enteric bacteria (E. coli and Salmonella spp.) in areas of two freshwater acclimated shrimp (Litopenaeus vannamei) cultivation farms in Jaguaruana-CE, establishing antimicrobials resistance patterns. Sediment and water samples were gathered from ponds and nearby water streams from each farm. The estimated number of E. coli from both the pond and the main river samples were similar in all sources. Two hundred sixty-five (265) strains suspected of E. coli were isolated, 50 (18.87%) of those suspicions were confirmed by biochemical tests. Among the 186 strains suspected of Salmonella, 30 (16.13%) belong to the genus, with five different serovars: S. ser. Saintpaul, S. ser. Infantis, S. ser. Panama, S. ser. Madelia, S. ser. Braenderup, S. enterica subsp. Houtenae and S. enterica subsp. enterica. Physicochemical parameters (temperature, pH and salinity) did not have any influence on the isolation of E. coli or Salmonella strains. There was no relation between the E. coli MPN and Salmonella isolation among the analyzed samples. Resistance to TET, AMP and OTC was observed in 32% of the E. coli strains, where half of this percentage presented a plasmid-related phenotype. Resistance to TET, OTC, AMP and NIT was observed in 16.67% of the Salmonella strains. Only NIT resistance was considered of plasmid origin. Concerning TET and OTC, the E. coli isolates presented a MIC of 32 µg mL-1 and MBC of >128 µg mL-1; whereas the MIC and MBC for TET, OTC and NIT in the Salmonella strains were 64 µg mL-1 and >12,800 µg mL-1, respectively. According to the analysis of the genotypic profiles from the Salmonella isolates, it was not possible to determine the dispersion pattern of its serovars in the environment. The presence of pefA and invA genes was independent from both the serovar and environmental origin of the isolates.