Qualidade microbiológica de tambaqui e pintado produzidos em viveiros escavados / Microbiological quality of tambaqui and pintado produced in excavated tanks

O presente trabalho teve como objetivo avaliar e quantificar S. aureus e presença ou ausência de salmonela em peixes frescos nativos provenientes de viveiros escavados localizados na Região Norte. Foram analisados 4 lotes de pintado e 4 lotes de tambaqui, com 4 amostras (peixes) em cada lote, onde o lote representava uma despesca em tanque escavado. As análises foram realizadas com kits da 3M mundialmente utilizados e recomendados pela Association of Official Analytical Chemists (AOAC). Os resultados demonstraram presença de salmonella em todos os lotes de tambaqui e em três lotes de pintado. Quanto à contagem de S. aureus, apenas uma amostra (peixe) apresentou acima do estabelecido, da espécie pintado.

Isolation of Saprolegnia aenigmatica oomycetes and protocol for experimental infection of pacu (Piaractus mesopotamicus) / Isolamento do oomiceto Saprolegnia aenigmatica e protocolo de infecção experimental em pacu (Piaractus mesopotamicus)

Successful disease treatment depends on molecular studies under indoor conditions with experimental infection protocols that facilitate understanding the disease and the drug`s efficacy. The internal transcribed spacer (ITS) region was sequenced from three isolates, which were identified as Saprolegnia aenigmatica. Subsequently, healthy fish were immunosuppressed with dexamethasone (1.2 mg kg-1) and descaled to the skin using a sharp scalpel. These individuals were isolated in individual aquariums maintained at 22°C. Individuals in one group were subcutaneously inoculated with 9,000 zoospores (DDZ treatment), a second group was exposed to oomycetes in water with three colonized baits (DDB), a third group was maintained in water without zoospores (DD), and a control group (C) consisted of healthy animals. After 48 and 96 hours, two animals from each group were euthanized for fungal reisolation. The fish from groups DD and C did not show clinical signs, and no oomycetes were isolated. The animals from the DDZ and DDB groups showed cotton-wool-like masses on the skin, and S. aenigmatica was re-isolated. Thus, for infection using zoospores or baits parasitized by S. aenigmatica, an immunosuppressor (dexamethasone) and a sharp scalpel can be used effectively to establish an experimental infection in P. mesopotamicus.

O sucesso do tratamento de uma enfermidade depende do estudo de moléculas em condições de laboratório por meio de protocolos de infecção experimental que viabilizam a compreensão da doença e da eficácia dos fármacos. Pela sequência ITS foram identificadas três cepas de Saprolegnia aenigmatica. Dessa forma, pacus sadios foram submetidos à imunossupressão com dexametasona (1,2 mg kg-1), esfoliados com auxílio de bisturi e distribuídos em aquários a 22ºC. Após este procedimento, um grupo de animais foi inoculado com 9.000 zoósporos/peixe subcutâneo (DEZ), a outro foram adicionadas três iscas colonizadas com o oomiceto na água (DEI), um terceiro grupo foi mantido sem contato com o oomiceto (DE) e um quarto grupo, de animais sadios, representaram o controle (C). Após 48 e 96h deste procedimento, foram eutanaziados animais de cada grupo para reisolamento. Os animais do grupo DE e C não apresentaram sinais clínicos e não foi reisolado o oomiceto. Porém, tanto os animais do grupo DEZ quanto como os animais do grupo DEI apresentaram micélio branco na pele e foi reisolado Saprolegnia aenigmatica. Assim, a infecção com zoósporos ou com iscas colonizadas por S. aenigmatica, com o uso de dexametasona e abrasivo epitelial são formas eficazes de infecção experimental em P. mesopotamicus.

Selection of autochtone probiotic for Astyanax bimaculatus / Seleção de probiótico autóctone para Astyanax bimaculatus

This study aimed to isolate native lactic acid bacteria of yellow tail lambari (Astyanax bimaculatus) and evaluate their effect on host microbiota and gut morphology, as well as survival after experimental challenge. The isolated bacterial strains were evaluated for their inhibition against pathogenic bacterial strains in vitro, and the strain with highest inhibitory ability was molecularly identified as Lactobacillus spp. For in vivo testing, eighty fish were distributed in ten tanks equipped with a recirculation system. The experimental units were divided into two treatments: fish fed with Lactobacillus spp. supplement and fish fed an unsupplemented diet (control). After 30 days, guts from three fish from each experimental unit were pooled for microbiological and histological analysis. The other five fish were inoculated with 2.1x104CFU.mL-1 of Aeromonas hydrophila to evaluate survival after 24h. Lambaris fed with the probiotic diet had a lower count of Vibrios spp., Pseudomonas spp. and Staphylococcus spp., and a higher count of lactic acid bacteria compared to control treatment, as well as, increased length, width and perimeter of intestinal villi, as well as higher survival rate (16.2%) after experimental challenge compared to the unsupplemented group. The results show that the Lactobacillus spp. used has effect probiotic for yellow tail lambari.(AU)

Este estudo objetivou isolar bactéria ácido-láctica nativa do lambari-do-rabo-amarelo (Astyanax bimaculatus) e seu efeito na microbiota e morfologia do trato digestório do hospedeiro, assim como a sobrevivência após um desafio experimental. As bactérias isoladas foram avaliadas quanto a suas inibições in vitro contra bactérias patogênicas; a cepa com maior capacidade de inibição foi identificada como Lactobacillus spp. Para o teste in vivo, 80 peixes foram distribuídos em 10 tanques equipados com sistema de recirculação. As unidades experimentais foram divididas em dois tratamentos: peixes alimentados com Lactobacillus spp. suplementado e peixes alimentados com dieta não suplementada (controle). Após 30 dias, foram coletados o trato intestinal de três peixes, por unidade experimental, para análises microbiológicas e histológicas. Outros cinco peixes foram inoculados com 2,1x104UFCmL-1 de Aeromonas hydrophila para se avaliar a sobrevivência após 24h. Lambaris alimentados com probiótico apresentaram menor contagem de Vibrios spp., Pseudomonas spp. e Staphylococcus spp., e maior de bactérias ácido-lácticas quando comparados com o tratamento controle, assim como aumento do comprimento, da largura e do perímetro das vilosidades intestinais e maior taxa de sobrevivência (16,2%,) após desafio experimental, em comparação com o grupo sem suplementação. Os resultados mostram que o Lactobacillus spp. possui efeito probiótico para o lambari-do-rabo-amarelo.(AU)

Mortalidade de tambacus (Colossoma macropomum x Piaractus mesopotamicus) infectados por Edwardsiella tarda / Mortality of tambacus (Colossoma macropomum x Piaractus mesopotamicus) infected by Edwardsiella tarda

O presente trabalho relata um surto de mortalidade de tambacus (Colossoma macropomum x Piaractus mesopotamicus) criados em tanques escavados da Fazenda-Escola da UCDB. Os peixes apresentaram sintomas clínicos de letargia, anorexia, aumento da produção de muco, nado desordenado e comportamento de buscar a superfície da água. Ao exame necroscópico de três peixes foram evidenciadas hemorragias nas nadadeiras e pele, opacidade de córnea, hemoperitôneo, distensão e repleção da vesícula biliar e congestão e hemorragia do tubo digestivo. O exame microbiológico dos materiais coletados das lesões dos tambacus foi positivo para a bactéria Edwardsiella tarda. A análise de qualidade de água indicou grande quantidade de fitoplânctons que proliferaram em função do excesso de matéria orgânica, caracterizando a eutrofização da água. Atribuiu-se a causa da morte dos tambacus à infecção oportunista pela E. tarda, favorecida pelo desequilíbrio devido ao excesso de matéria orgânica em suspensão na água. As mortes cessaram após a correção dos parâmetros da qualidade da água do tanque.

An outbreak of mortality of tambacus (Colossoma macropomum x Piaractus mesopotamicus) cultivated in dug tanks at UCDB was reported. Animals had clinical surface symptoms of lethargy, anorexia, increased mucus production, cluttering and swimming toward the water. Macroscopic examination of three fishes showed hemorrhages of the fins and skin, corneal opacity, hemoperitoneum, gallbladder distension and repletion, congestion and hemorrhages of the digestive tract. Water quality analysis indicated large amounts of phytoplankton that proliferated as a result of the excessive organic matter causing eutrophication of the water. The microbiological examination of tambacus lesions revealed the presence of the bacterium Edwardsiella tarda. The cause of the tambacus death was attributed to opportunistic infection by E. tarda, favored by the imbalance due to the intense organic matter in suspended in the water. Deaths stopped after the correction of the water quality parameters.

Evaluating the elimination of Brazilian entomopathogenic Bacillus by non-target aquatic species: an experimental study.

Ecotoxicity tests are key to predict environmental hazards resulting from chemical and biological pesticides in non-target species. In order to assess the effects of microbial pesticides it is important to determine if they cause infection in test organisms. At present the microbial elimination rate or clearance is not included in ecotoxicological regulatory protocols. This study evaluated the elimination of Bacillus thuringiensis and Bacillus sphaericus from fish and snails, after 30 days' exposure to commercial formulations of such entomopathogens. Data obtained showed that in clean water the tendency to eliminate microbial agents from the body of the exposed organisms is gradual over time but after 7 days the fish and snails were free of the two tested Bacillus spp.

Acute aerocystitis in Piaractus mesopotamicus: participation of eicosanoids and pro-inflammatory cytokines.

A total of 360 pacus (Piaractus mesopotamicus) were used to study vascular permeability (VP) and inflammatory cell component (CC) in induced aerocystitis in P. mesopotamicus through inoculation of inactivated Aeromonas hydrophila, and the effect of steroidal and nonsteroidal anti-inflammatory drugs. It was observed that after inoculation of A. hydrophila, the maximum VP occurred 180 min post-stimulus (MPS). Pretreatment with anti-inflammatory drugs inhibited VP, and the inhibitory effect of dexamethasone was seen earlier than the effects caused by meloxicam and indomethacin. Inoculation of the bacterium caused a gradual increase in the accumulation of cells, which reached a maximum 24 h post-stimulus (HPS). Pretreatment with dexamethasone, indomethacin and meloxicam reduced the accumulation of lymphocytes, thrombocytes, granulocytes and macrophages. There was no significant difference between the different doses of the drugs tested. The results suggest that eicosanoids and pro-inflammatory cytokines participate in chemical mediation in acute inflammation in pacus.

First description of ColE-type plasmid in Aeromonas spp. carrying quinolone resistance (qnrS2) gene.

AIMS: Isolation and full sequence analysis of ColE-type plasmid, which carries the qnrS2 gene. METHODS AND RESULTS: Quinolone resistance (qnrS2) gene-carrying plasmids were isolated from Aeromonas sobria and Aeromonas hydrophila strains, and plasmid sequencing was achieved by a primer-walking approach. The total sizes of these plasmids (pAQ2-1 and pAQ2-2) were 6900 bp and 6903 bp, respectively, and they were 99·1% identical to each other. The genes (oriV and repA) for plasmid replication were organized similar to the corresponding genes in the ColE2-type plasmids, pAsa3 and pAsa1, isolated from Aeromonas salmonicida subsp. salmonicida, but the gene (mobA) for mobilization was homologue to ColE1-type plasmid (pAsa2) from Aer. salmonicida subsp. salmonicida. Additionally, the qnrS2 gene was part of a mobile insertion cassette element in the plasmid. CONCLUSIONS: Two plasmids were assumed to be the same plasmid, and this identification of a plasmid-mediated qnrS2 gene from the two different strains underlines a possible diffusion of these resistance determinants in an aquaculture system. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first finding of the ColE-type plasmid carrying the qnrS2 gene.