Infecção por Streptococcus agalactiae em rãs touro (Lithobates catesbeianus) cultivadas em sistema inundado

Abstract

Raniculture, like all animal production activities, generates products of commercial interest. The production of cultivated frogs mainly generates frog meat, a product known worldwide for its nutritional properties, such as proteins of high biological value, low fat content, good concentration of minerals and hypoallergenicity. In addition to meat, by-products from the production of bull frogs (Lithobates catesbeianus) such as mechanically separated meat, have also gained commercial prominence. Bacteria of the genus Streptococcus spp. are considered important pathogens to aquaculture worldwide. The aim of this study were identify the cause of massive mortality, in a flooded intensive system of breeding bull frogs. The main clinical signs presented by the animals were erratic swimming, anorexia, abdominal and limb edema, corneal opacity and lateral curvature of the body, leading to the clinical suspicion of streptococcosis. Thirteen animals were collected during the period from January to June 2019 that showed clinical signs of the disease. After macroscopic evaluation of the organs during necropsy, samples of the brain, heart, liver, lung and ascitic liquids were collected aseptically. 26 isolates were obtained, of which 42.30% brain, 23.07% heart, 15.38% liver, 11.53% lung and 7.69% ascitic fluid. All isolates were characterized as Gram positive cocci, catalase and oxidase negative. These samples were analyzed using the MALDI-TOF technique and identified as Streptococcus agalactiae Bacteria of the genus Streptococcus spp. can be found in the natural microbiota from the skin of cultivated frogs, and can be pathogenic in favorable situations, such as in rearing systems with high stocking density. The pathogen Streptococcus agalactiae, is common in fish, being responsible for high mortality rates in intensive farming systems. This is the first report of Streptococcus agalactiae described in bullfrogs, causing mortality and economic losses.