RESUMO
The increasing prevalence of multi-drug resistant (MDR) Escherichia coli in distinct ecological niches, comprising water sources and food-producing animals, such as fish species, has been widely reported. In the present study, quinolone-resistant E. coli isolates from Arapirama gigas, a major fish species in the Brazilian Amazon rivers and fish farms, were characterized regarding their antimicrobial susceptibility, virulence, and genetic diversity. A total of forty (40) specimens of A. gigas, including 20 farmed and 20 wild fish, were included. Thirty-four quinolone-resistant E. coli isolates were phenotypically tested by broth microdilution, while resistance and virulence genes were detected by PCR. Molecular epidemiology and genetic relatedness were analyzed by MLST and PFGE typing. The majority of isolates were classified as MDR and detected harboring blaCTX-M, qnrA and qnrB genes. Enterotoxigenic E. coli pathotype (ETEC) isolates were presented in low prevalence among farmed animals. MLST and PFGE genotyping revealed a wide genetic background, including the detection of internationally spread clones. The obtained data point out A. gigas as a reservoir in Brazilian Amazon aquatic ecosystems and warns of the interference of AMR strains in wildlife and environmental matrices.
RESUMO
In fish farmings, diseases can be reduced by using immunostimulants. The aim of this study was to evaluate the immunostimulant potential of Mentha piperita in tambaqui fed with 0, 0.5, 1.0 and 1.5% of oil per kg of commercial fish feed. The fish were inoculated with Aeromonas hydrophila to challenge them. Hematological and biochemical parameters were determined after 30 days of feeding and seven days after the challenge. There was no mortality and M. piperita oil did not influence fish production parameters. However, blood hemoglobin concentration (Hb) increased in the fish fed with 0.5 and 1.5% of oil per kg of diet; albumin increased in those fed with 1.0%; cholesterol increased in all groups with oil; and triglycerides increased in those fed with 0.5%. After the bacterial challenge, the fish showed decreases in Hb when fed with diet enriched with 1.5% oil per kg of diet, in mean corpuscular volume with 1.0% and in mean corpuscular hemoglobin concentration with 0 and 1.5%. Protein levels increased in groups with 0 and 1.5% of oil and albumin when fed with 0 and 1.0%; cholesterol levels increased in the control group; and high levels of triglycerides were observed in the groups with 0, 0.5 and 1.5%. Thus, M. piperita essential oil promoted hematological alterations in tambaqui and can be recommended in diets containing up to 1.0% per kg, because of the minimal physiological modifications caused. However, additional studies are necessary to obtain more information regarding to the physiological effects of this immunostimulant.
Em pisciculturas, doenças podem ser minimizadas com o uso de imunoestimulantes. O objetivo deste estudo foi avaliar o potencial imunoestimulante do óleo essencial de Mentha piperita na dieta de tambaqui com dietas contendo 0; 0,5; 1,0; 1,5% de inclusão do óleo por kg de ração comercial para peixes. Os tambaquis foram desafiados com a bactéria Aeromonas hydrophila. Hematologia e bioquímica dos tambaquis foram determinados após 30 dias de alimentação e sete dias do desafio. Não houve mortalidade dos peixes durante o experimento, sendo que o óleo não influenciou os parâmetros produtivos dos peixes. Entretanto, a concentração de hemoglobina (Hb) aumentou em peixes alimentados com 0,5 e 1,5% de óleo por kg de dieta; a albumina aumentou em 1,0%; o colesterol aumentou em todos os grupos com óleo; e triglicérides em 0,5% por kg de dieta. Após desafio bacteriano ocorreram diminuições da Hb nos peixes alimentados com 1,5% de óleo; do volume corpuscular médio com 1,0%; e da concentração de hemoglobina corpuscular média com 0 e 1,5%. Níveis aumentados de proteína nos grupos 0 e 1,5%; da albumina em 0 e 1,0%; do colesterol no controle; e dos triglicérides em 0, 0,5 e 1,5% de óleo na dieta. Assim o óleo essencial de M. piperita na dieta promoveu alterações hematológicas e pode ser recomendado seu uso em inclusões de até 1,0% por kg da dieta de tambaqui, devido às mínimas alterações fisiológicas causadas. Entretanto, estudos adicionais são necessários, de modo a obter informações sobre os efeitos fisiológicos deste imunoestimulante.
