Aeromonas hydrophila in Rhamdia quelen: macroscopIc and microscopIc aspect of the lesions and antibiotic resistence profiles / Aeromonas hydrophila em Rhamdia quelen: aspectos macro e microscópico das lesões e perfil de resistência a antimicrobianos

With the intensification of fish culture in Rio Grande do Sul, the incidence and severity of pathologies increased significantly; fish raised under inappropriate management conditions are prone to stress related pathologies, such as that caused by Aeromonas hydrophila. Herein, the isolation, antibiotic sensibility and macroscopic and microscopic lesions caused by A. hydrophila are described. The identification of A. hydrophila was confirmed following inoculation on blood agar and biochemical assays. Macroscopic lesions were initially observed as ulcers in the caudal peduncle that became disseminated through the body and barbs, exposing muscle tissue. Histopathological lesions were characterized by degeneration, necrosis, hyperplasia, mononuclear cell infiltration and the presence of bacteria colonies. All samples of A. hydrophila were susceptible to chloramphenicol, polymyxin B, kanamycin, sulfonamides and neomycin; 81.25% of the samples were susceptible to doxycyclin and 18.75% had intermediate susceptibility. Cefoxitin was effective against 75% of the samples, but 18.75% of the samples had intermediate susceptibility and 6.25% were resistant. The susceptibility to erythromycin observed among 50% of the samples, but 31.25% and 18.75% of the samples has intermediate susceptibility or were completely resistant, respectively. Thus, to know the resistance profiles of the bacteria

Com a intensificação da piscicultura no Rio Grande do Sul verificou-se o aumento da incidência e severidade de várias doenças, entre elas a bacteriose causada por Aeromonas hydrophila com surtos associados com alterações das condições ambientais e/ou fatores estressantes. Amostras de jundiás (Rhamdia quelen) com suspeita de infecção por A. hydrophila foram encaminhadas ao LDPI-UPF (Laboratório de Diagnóstico e Pesquisa em Ictiopatologia da Universidade de Passo Fundo). As culturas foram sugestivas de Aeromonas sp. e confirmadas bioquimicamente como A. hydrophila. As lesões iniciaram-se com ulceração do pedúnculo caudal, evoluindo para descamação cutânea, formando-se lesões ulcerativas no corpo e barbilhões com exposição de musculatura. Microscopicamente, as principais alterações foram degeneração, necrose, hiperplasia, infiltrado mononuclear e presença de colônias bacterianas. Quanto à sensibilidade bacteriana aos antibióticos, os resultados indicaram que 100% das amostras isoladas foram sensíveis a nitrofurantoína, norfloxacina, tetraciclina, ampicilina e gentamicina e 93,75% ao cloranfenicol, polimixina B, kanamicina, sulfonamidas e neomicina. A doxiciclina teve 81,25% das amostras sensíveis e 18,75% com sensibilidade intermediária, a cefoxitina, 75% das amostras sensíveis, 18,75% intermediárias e 6,25 resistentes, enquanto a eritromicina demonstrou 50% de amostras sensíveis,

Aeromonas hydrophila in Rhamdia quelen: macroscopIc and microscopIc aspect of the lesions and antibiotic resistence profiles / Aeromonas hydrophila em Rhamdia quelen: aspectos macro e microscópico das lesões e perfil de resistência a antimicrobianos

With the intensification of fish culture in Rio Grande do Sul, the incidence and severity of pathologies increased significantly; fish raised under inappropriate management conditions are prone to stress related pathologies, such as that caused by Aeromonas hydrophila. Herein, the isolation, antibiotic sensibility and macroscopic and microscopic lesions caused by A. hydrophila are described. The identification of A. hydrophila was confirmed following inoculation on blood agar and biochemical assays. Macroscopic lesions were initially observed as ulcers in the caudal peduncle that became disseminated through the body and barbs, exposing muscle tissue. Histopathological lesions were characterized by degeneration, necrosis, hyperplasia, mononuclear cell infiltration and the presence of bacteria colonies. All samples of A. hydrophila were susceptible to chloramphenicol, polymyxin B, kanamycin, sulfonamides and neomycin; 81.25% of the samples were susceptible to doxycyclin and 18.75% had intermediate susceptibility. Cefoxitin was effective against 75% of the samples, but 18.75% of the samples had intermediate susceptibility and 6.25% were resistant. The susceptibility to erythromycin observed among 50% of the samples, but 31.25% and 18.75% of the samples has intermediate susceptibility or were completely resistant, respectively. Thus, to know the resistance profiles of the bacteria

Com a intensificação da piscicultura no Rio Grande do Sul verificou-se o aumento da incidência e severidade de várias doenças, entre elas a bacteriose causada por Aeromonas hydrophila com surtos associados com alterações das condições ambientais e/ou fatores estressantes. Amostras de jundiás (Rhamdia quelen) com suspeita de infecção por A. hydrophila foram encaminhadas ao LDPI-UPF (Laboratório de Diagnóstico e Pesquisa em Ictiopatologia da Universidade de Passo Fundo). As culturas foram sugestivas de Aeromonas sp. e confirmadas bioquimicamente como A. hydrophila. As lesões iniciaram-se com ulceração do pedúnculo caudal, evoluindo para descamação cutânea, formando-se lesões ulcerativas no corpo e barbilhões com exposição de musculatura. Microscopicamente, as principais alterações foram degeneração, necrose, hiperplasia, infiltrado mononuclear e presença de colônias bacterianas. Quanto à sensibilidade bacteriana aos antibióticos, os resultados indicaram que 100% das amostras isoladas foram sensíveis a nitrofurantoína, norfloxacina, tetraciclina, ampicilina e gentamicina e 93,75% ao cloranfenicol, polimixina B, kanamicina, sulfonamidas e neomicina. A doxiciclina teve 81,25% das amostras sensíveis e 18,75% com sensibilidade intermediária, a cefoxitina, 75% das amostras sensíveis, 18,75% intermediárias e 6,25 resistentes, enquanto a eritromicina demonstrou 50% de amostras sensíveis,

Chronic exposure to sub-lethal concentration of a glyphosate-based herbicide alters hormone profiles and affects reproduction of female Jundiá (Rhamdia quelen).

This work was carried out to verify the effect of a glyphosate-based herbicide on Jundiá hormones (cortisol, 17ß-estradiol and testosterone), oocyte and swim-up fry production. Earthen ponds containing Jundiá females were contaminated with glyphosate (3.6mg/L); blood samples were collected from eight females from each treatment immediately before, or at 1, 10, 20, 30 and 40 days following contamination. A typical post-stress rise in cortisol levels was observed at the 20th and 40th days following exposure to glyphosate. At the 40th day, 17ß-estradiol was decreased in the exposed females. A similar number of oocytes were stripped out from females from both groups; however, a lower number of viable swim-up fry were obtained from the herbicide exposed females, which also had a higher liver-somatic index (LSI). The results indicate that the presence of glyphosate in water was deleterious to Rhamdia quelen reproduction, altering steroid profiles and egg viability.

The color of illumination affects the stress response of jundiá (Rhamdia quelen, Quoy & Gaimard, Heptapteridae)

This paper provides the first data about physiological responses to stress in jundiá (Rhamdia quelen) exposed to different light colours. Jundiá is a species for fish production in the southern part of South America - and suitable for any region with a temperate or subtropical climates. In order to develop a light management for jundiá fingerlings during indoor maintenance and to understand the relationship between welfare and light colour in the jundiá, fingerlings were exposed to white, blue and green light. At the 10th day of light exposure an acute stressor was imposed. One hour after the application of the stressor, fish were sampled. Stress was assessed by means of cortisol determination. Our results show that green light seems to be the worst alternative to illuminate jundiá indoor experimentation facilities, or even fish transportation. The results also suggests that colour affects the stress response of jundia, and may be usefull for the management of this species.