Genomic insights of Klebsiella pneumoniae isolated from a native Amazonian fish reveal wide resistome against heavy metals, disinfectants, and clinically relevant antibiotics.

A multidrug-resistant CTX-M-15-producing Klebsiella pneumoniae (KpP1 strain) was isolated from a native Amazonian fish (Brachyplatystoma filamentosum) at the Brazilian Amazon. The strain was identified by MALDI-TOF. The genome was extracted, purified and a Nextera DNA Flex library was prepared and sequenced by Illumina platform. The sequenced genome was de novo assembled using Unicycler and in silico prediction accomplished by curated bioinformatics tools. The size of the genome is 5.6 Mb with 5715 genes. Whole-genome sequencing analysis revealed the presence of wide resistome, with genes conferring resistance to clinically relevant antibiotics, heavy metals and disinfectants. The KpP1 strain was assigned to the sequence type ST3827, KL111 (wzi113) and O3b locus. Native freshwater fish sold in wet markets of the Amazonian region could be an important vehicle for transmission of multidrug-resistant bacteria to humans. This study may give genomic insights on the spread of critical-priority WHO pathogens in a One Health context.

The Chelating Mineral on Organic Acid Salts Modulates the Dynamics and Richness of the Intestinal Microbiota of a Silver Catfish Rhamdia quelen.

The aim of this study was to evaluate the influence of the chelating mineral on propionic acid, calcium or sodium on the composition, dynamics and richness of the intestinal microbiota of a native silver catfish Rhamdia quelen through high-throughput sequencing (HTS). A total of 225 fish (8.43 ± 0.18 g) were distributed in tanks, 15 fish per tank in five groups with three replicates each: Control, Ca-propionate 0.25% (Ca0.25%) Ca-propionate 1% (Ca1%), Na-propionate 0.25% (Na0.25%) and Na-propionate 1% (Na1%). The feed was provided four times a day for 60 days. After experimental period, the fish were fasted for 24 h and the intestine was aseptically collected, pooled by treatment, and fixed in pure absolute ethanol for subsequent DNA extraction and HTS. The HTS showed that the supplementation of the propionic acid chelated to the mineral calcium or sodium in the different concentrations increased the operational taxonomic units and richness in comparison to control group. The main phyla found were Fusobacteria, Firmicutes, Proteobacteria and Bacteroides. Both the fusobacteria and the genus Cetobacterium, especially C. somerae, were positively modulated with Ca0.25% and Na1% supplementation. It can be emphasized that supplementation with calcium or sodium propionate at different concentrations changed the natural microbiota of R. quelen.

Detection of Pseudomonas sp. in pirarucu (Arapaima gigas): a case report in the Western Amazon / Detecção dePseudomonas sp.em pirarucu (Arapaima gigas): um relato de caso na Amazônia Ocidental

Pirarucu (Arapaima gigas) is one of the most important fish in Amazonian fish farming. However, information about its nutritional, zootechnical and microbiological aspects is still scarce. This is especially true for the juvenile phase due to high mortality rates caused by malnutrition, difficulties in food training, endo and ectoparasite infestations, which in turn lead to immunosuppression, favoring secondary bacterial infections that may be present due to various environmental factors (e.g., sudden temperature variations, water acidity and pollution of the aquatic environment) and the status of fish. The Pseudomonas sp. species studied in this work is part of the aquatic ecosystem and is considered a contaminant or invader because it infects a wide variety of aquatic species, including pirarucu. Given this assumption, the objective of the study was to report a case of Pseudomonas sp. in the viscera and dorsum of a juvenile pirarucu Arapaima gigas (SCHINZ, 1822) detected through bacteriological analysis. In the fish production chain in the Western Amazon, pirarucu is one of the most prominent fish species because of its high zootechnical performance in terms of weight gain and commercial value. However, one of the biggest obstacles in its production chain occurs during the juvenile phase, with high mortality rates caused by mainly bacterial infections, leading to economic

O pirarucu (Arapaima gigas)é um dos peixes de maior interesse para piscicultura amazônica. No entanto, os conhecimentos sob os aspectos nutricional, zootécnico e microbiológico desse peixe ainda são escassos. Sobretudo, na fase juvenil, porque nessa fase ocorrem altas taxas de mortalidade porque são mais susceptíveis à desnutrição, dificuldades no treinamento alimentar, infestações por endo e ectoparasitas, que por sua vez, ocasionam imunossupressão, favorecendo infecções bacterianas secundárias que podem estar presentes em virtude de diversos fatores ambientais e estado imunológico dos peixes. São exemplos, variações bruscas de temperatura, acidez da água e poluição do ambiente aquático. A espécie Pseudomonas sp. estudada nesse trabalho faz parte do ecossistema aquático, sendo considerada como contaminante ou um invasor, porque infecta grande variedade de espécies aquáticas, inclusive o pirarucu. Diante do pressuposto, o objetivo do trabalho foi relatar o caso de detecção de Pseudomonas sp.em vísceras e dorso do pirarucu Arapaima gigas(SCHINZ, 1822) juvenil por meio de análise bacteriológica. Na cadeia produtiva do pescado na Amazônia Ocidental, o pirarucu é um dos peixes de destaque por ser uma espécie com alto desempenho zootécnico em ganho de peso e valor comercial. Porém, um dosmaiores empecilhos da cadeia produtiva se encontra na fase juvenil da espécie havendo altos índices de mortalidade ocasionados por infecções principalmente de origem bacteriana levando a percas econômicas a piscicultura. Neste estudo detectou-se Pseudomonas sp.em amostra de dorso e vísceras de pirarucu em uma piscicultura no município de Ouro Preto do Oeste, Rondônia, Brasil.

Detection of Pseudomonas sp. in pirarucu (Arapaima gigas): a case report in the Western Amazon / Detecção dePseudomonas sp.em pirarucu (Arapaima gigas): um relato de caso na Amazônia Ocidental

Pirarucu (Arapaima gigas) is one of the most important fish in Amazonian fish farming. However, information about its nutritional, zootechnical and microbiological aspects is still scarce. This is especially true for the juvenile phase due to high mortality rates caused by malnutrition, difficulties in food training, endo and ectoparasite infestations, which in turn lead to immunosuppression, favoring secondary bacterial infections that may be present due to various environmental factors (e.g., sudden temperature variations, water acidity and pollution of the aquatic environment) and the status of fish. The Pseudomonas sp. species studied in this work is part of the aquatic ecosystem and is considered a contaminant or invader because it infects a wide variety of aquatic species, including pirarucu. Given this assumption, the objective of the study was to report a case of Pseudomonas sp. in the viscera and dorsum of a juvenile pirarucu Arapaima gigas (SCHINZ, 1822) detected through bacteriological analysis. In the fish production chain in the Western Amazon, pirarucu is one of the most prominent fish species because of its high zootechnical performance in terms of weight gain and commercial value. However, one of the biggest obstacles in its production chain occurs during the juvenile phase, with high mortality rates caused by mainly bacterial infections, leading to economic

O pirarucu (Arapaima gigas)é um dos peixes de maior interesse para piscicultura amazônica. No entanto, os conhecimentos sob os aspectos nutricional, zootécnico e microbiológico desse peixe ainda são escassos. Sobretudo, na fase juvenil, porque nessa fase ocorrem altas taxas de mortalidade porque são mais susceptíveis à desnutrição, dificuldades no treinamento alimentar, infestações por endo e ectoparasitas, que por sua vez, ocasionam imunossupressão, favorecendo infecções bacterianas secundárias que podem estar presentes em virtude de diversos fatores ambientais e estado imunológico dos peixes. São exemplos, variações bruscas de temperatura, acidez da água e poluição do ambiente aquático. A espécie Pseudomonas sp. estudada nesse trabalho faz parte do ecossistema aquático, sendo considerada como contaminante ou um invasor, porque infecta grande variedade de espécies aquáticas, inclusive o pirarucu. Diante do pressuposto, o objetivo do trabalho foi relatar o caso de detecção de Pseudomonas sp.em vísceras e dorso do pirarucu Arapaima gigas(SCHINZ, 1822) juvenil por meio de análise bacteriológica. Na cadeia produtiva do pescado na Amazônia Ocidental, o pirarucu é um dos peixes de destaque por ser uma espécie com alto desempenho zootécnico em ganho de peso e valor comercial. Porém, um dosmaiores empecilhos da cadeia produtiva se encontra na fase juvenil da espécie havendo altos índices de mortalidade ocasionados por infecções principalmente de origem bacteriana levando a percas econômicas a piscicultura. Neste estudo detectou-se Pseudomonas sp.em amostra de dorso e vísceras de pirarucu em uma piscicultura no município de Ouro Preto do Oeste, Rondônia, Brasil.(AU)

Aeromonas hydrophila infection in silver catfish causes hyperlocomotion related to stress.

Aeromonosis is a fish disease that leads to haemorrhagic septicaemia and high mortality. The detection of early behavioural changes associated to this disease could be helpful in anticipating the initiation of treatment, increasing the probability of success. The influence of this disease on the hypothalamic-pituitary-interrenal (HPI) axis and on the brain expression of heat shock proteins (HSP) is little known. Therefore, the aim of this study was to evaluate the effect of Aeromonas hydrophila infection on individual behaviour and brain expression of genes related to stress (slc6a2, hsp90, hspa12a, hsd20b, hsd11b2, crh) in silver catfish (Rhamdia quelen). Thirty fish were divided into healthy and infected groups. The fish of the infected group were inoculated intramuscularly with 50 µL of bacterial suspension (6.4 × 108 CFU/mL), while control animals received 50 µL of saline. On day five post-infection, animals were submitted to the novel tank test, euthanized, and the brain was collected for molecular analysis. Infected fish swam more in the unknown aquarium and presented an increase in brain expression of genes related to HSP (hspa12a) and the route of cortisol synthesis (crh) when compared to uninfected fish. Therefore, this disease causes hyperlocomotion related to stress.

Avaliação microbiológica de filés de surubim (Pseudoplatystoma spp) submetidos à defumação com alecrim / Microbiological evaluation of fillets of surubim (Pseudoplatystoma spp) submitted to defumation with rosemary

O objetivo foi avaliar a microbiota dos filés de surubim (Pseudoplatystoma spp.) submetidos à defumação com alecrim. Foram coletados fragmentos dos filés para cada etapa de avaliação (in natura, salmoura e defumação em 2, 4, e 6 horas). Da salga para a defumação houve uma redução, no qual, os microrganismos aeróbios mesófilos diminuíram de 1,4x105UFC/g para 1,8x104 UFC/g nos filés sem alecrim e 1,4x104 UFC/g nos filés com alecrim e na contagem de microrganismos aeróbios psicrotróficos foi observada redução de 1,9x105UFC/g para 7,8x104 UFC/g nos filés sem alecrim e 2,6x104 UFC/g nos filés com alecrim. Portanto, os filés adicionados de alecrim apresentaram queda constante e mais brusca na contagem bacteriana e resultou em uma boa redução da carga bacteriana.

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.

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.(AU)

Avaliação microbiológica de filés de surubim (Pseudoplatystoma spp) submetidos à defumação com alecrim / Microbiological evaluation of fillets of surubim (Pseudoplatystoma spp) submitted to defumation with rosemary

O objetivo foi avaliar a microbiota dos filés de surubim (Pseudoplatystoma spp.) submetidos à defumação com alecrim. Foram coletados fragmentos dos filés para cada etapa de avaliação (in natura, salmoura e defumação em 2, 4, e 6 horas). Da salga para a defumação houve uma redução, no qual, os microrganismos aeróbios mesófilos diminuíram de 1,4x105UFC/g para 1,8x104 UFC/g nos filés sem alecrim e 1,4x104 UFC/g nos filés com alecrim e na contagem de microrganismos aeróbios psicrotróficos foi observada redução de 1,9x105UFC/g para 7,8x104 UFC/g nos filés sem alecrim e 2,6x104 UFC/g nos filés com alecrim. Portanto, os filés adicionados de alecrim apresentaram queda constante e mais brusca na contagem bacteriana e resultou em uma boa redução da carga bacteriana.(AU)

Extracts of Hesperozygis ringens (Benth.) Epling: in vitro and in vivo antibacterial activity against fish pathogenic bacteria.

AIMS: This study investigated the in vitro antibacterial activity of Hesperozygis ringens (Benth.) Epling leaf extracts against fish pathogenic bacteria, as well as the in vivo activity of the most active extract in silver catfish (Rhamdia quelen) experimentally infected with Aeromonas hydrophila. Moreover, the chemical composition of the extract used in the survival assay was evaluated. METHODS AND RESULTS: Only hexane extract (HEHR) showed in vitro antibacterial activity (MIC and MBC ranging from 1600 to 3200 µg ml-1 ) against clinical isolates of A. hydrophila, Raoultella ornithinolytica and Citrobacter freundii, obtained from naturally infected silver catfish, and A. hydrophilaATCC 7966. The major compound of the volatile fraction of HEHR was determined as pulegone. HEHR promoted a 93·33% relative survival rate of silver catfish experimentally infected with A. hydrophila 7 days after a single therapeutic bath at 30 mg l-1 , while florfenicol at 4 mg l-1 , which promoted a 60% relative survival rate. CONCLUSIONS: The antibacterial activity of H. ringens (Benth.) Epling leaf extracts seems to be related to phytochemicals of apolar character, since HEHR promoted better survival rate of infected animals than florfenicol. SIGNIFICANCE AND IMPACT OF THE STUDY: The HEHR has potential to be used in the control and treatment of bacterial infections in organic aquaculture.

Analysis of Triphenylmethane Dye Residues and their Leuco-Forms in Frozen Fish by LC-MS/MS, Fish Microbial Quality, and Effect of Immersion in Whole Milk on Dye Removal.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and used to quantify crystal violet (CV), leucocrystal violet (LCV), malachite green (MG), leucomalachite green (LMG), and brilliant green (BG) residues in frozen fish (121 samples) from various countries, in order to detect the use of prohibited antibiotic dyes in fish for human consumption. The microbial quality of the fish was also assessed along with the effectiveness of a simple treatment with whole fat milk to reduce the levels of CV and LCV contamination. CV and LCV were the only two residues detected. They were found in farmed Pangasius (0.362 to 41.34 µg/kg and 0.178 to 10.58 µg/kg, respectively) and Tilapia (1.24 to 9.48 µg/kg and 1.29 to 2.81 µg/kg). Based on aerobic plate count (APC), 74%, 59%, and 55% of the samples of Tilapia fillets (from China) and Pangasius fillets (United Arab Emirates and Vietnam), and 100% and 50% of the skin samples of Hake (Argentina and U.S.A.) were of unacceptable microbial quality (APC > 107 cfu/g). Human pathogens, namely Escherichia coli, Staphylococcus aureus, and Vibrio spp., were detected in most fish. A significant reduction in CV and LCV concentrations by more than a third was achieved after immersing Pangasius and Tilapia fillets in whole fat milk for 120 minutes. These findings support the necessity of regular inspections and monitoring of CV and other antibiotic dye residues in fish, along with routine assessments of fish microbial quality, in order to protect public health. PRACTICAL APPLICATION: The described LC-MS/MS method can be used to rapidly and simultaneously quantify antibiotic dye residues in frozen fish. CV and LCV were detected in farmed Pangasius and Tilapia fillets and their concentrations was reduced by more than one third after immersing the fillets in whole milk for 120 min, a treatment which is not intended to replace safe fish farming practices upstream to artificially lower the level of banned dyes in fish. The findings support the necessity of regular inspections and monitoring of CV and other antibiotic dye residues in fish, along with assessments of fish microbial quality, to protect public health.

Citrobacter freundii infection in silver catfish (Rhamdia quelen): Hematological and histological alterations.

Citrobacter freundii is a fish pathogen known for its ability to cause injury and high mortality. There have been no studies reporting the effect of this bacterium on hematological parameters and internal organ histology in silver catfish (Rhamdia quelen). Therefore, the aim of this study is to evaluate the hematological and histopathological effects of an experimentally induced C. freundii infection in silver catfish. Twenty fish were divided into healthy and infected groups. The fish of the infected group were inoculated intramuscularly with 100 µL of bacterial suspension (6.4 × 108 CFU mL-1), while healthy control animals received 100 µL of sterile saline. On day 18 post-infection, blood and tissues (cephalic kidneys, livers, and spleens) were collected for histological analysis. The infected animals presented high mortality, as well as hematological and histological changes. In relation to hematology, the infected fish presented aregenerative anemia, protein loss, leukopenia with neutropenia, lymphocytosis, and leukoblastosis. Regarding histology, there was liver degeneration, decrease in the amount of renal hematopoietic tissue, and the presence of melanomacrophage centers (MMCs) in the spleen and cephalic kidney of infected fish. In summary, these alterations may contribute to disease pathophysiology, contributing to high mortality of affected fish.

Antibacterial potential of phytochemicals alone or in combination with antimicrobials against fish pathogenic bacteria.

AIMS: This study investigated the antibacterial activity of five phytochemicals (carvacrol, citral, eugenol, linalool and thymol) alone or in combination with florfenicol or oxytetracycline against bacteria isolated from silver catfish (Rhamdia quelen). We also analysed the potential of these compounds to inhibit biofilm formation and haemolysis caused by the bacteria. METHODS AND RESULTS: Bacteria were tested with antimicrobials to calculate the multiple antibiotic resistances. The checkerboard assay was used to evaluate a putative synergy between five phytochemicals and antimicrobials against the strains isolated. The biofilm formation inhibition assay was performed with phytochemicals and antimicrobials, and the haemolysis inhibition assay was performed with the phytochemicals. Carvacrol, eugenol and thymol were the most effective phytochemicals. Three combinations (linalool with florfenicol or oxytetracycline against Aeromonas hydrophila and citral with oxytetracycline against Citrobacter freundii) demonstrated synergy in the checkerboard assay. All phytochemicals inhibited biofilm formation and haemolysis activity. CONCLUSION: The tested phytochemicals showed satisfactory activity against fish pathogenic bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The phytochemicals did not present antagonistic interactions with the antimicrobials, allowing their combined use, which may contribute to a decrease in the use of conventional drugs and their residues in aquatic environment.

Citrobacter freundii impairs the phosphoryl transfer network in the gills of Rhamdia quelen: Impairment of bioenergetics homeostasis.

The precise coupling of spatially separated intracellular adenosine triphosphate (ATP)-producing and ATP-consuming, catalyzed by creatine kinase (CK), adenylate kinase (AK), and pyruvate kinase (PK), is a critical process in the bioenergetics of tissues with high energy demand, such as the branchial tissue. The effects of Citrobacter freundii infection on gills remain poorly understood, limited only to histopathological studies. Thus, the aim of this study was to evaluate whether experimental infection by C. freundii impairs the enzymes of the phosphoryl transfer network in gills of silver catfish (Rhamdia quelen). The CK (cytosolic and mitochondrial) and AK activities decreased in infected compared to uninfected animals, while the PK activity did not differ between groups. The gill histopathology of infected animals revealed extensive degeneration with fusion and necrosis of secondary lamellae, detachment of superficial epithelium, aneurysm, vessel congestion and inflammatory process. Based on these evidences, the inhibition and absence of an efficient communication between CK compartments caused the impairment of the branchial bioenergetics homeostasis, which was not compensated by the augmentation on branchial AK activity in an attempt to restore energy homeostasis. In summary, these alterations contribute to disease pathogenesis linked to branchial tissue in animals infected with C. freundii.

Aeromonas caviae alters the activities of ecto-enzymes that hydrolyze adenine nucleotides in fish thrombocytes.

It is recognized that the purinergic system, through the activities of ectonucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-5'-nucleotidase (E-5'-nucleotidase), and ecto-adenosine deaminase (E-ADA), is involved in the regulation and modulation of the physiological and pathological events linked to hemostasis. This occurs due to the role of adenosine diphosphate (ADP) in the activation and recruitment of platelets, and the role of adenosine (Ado) in the inhibition of platelet activation. Thus, here we aimed to evaluate whether Aeromonas caviae infection impairs the ecto-enzymes of the purinergic system in fish thrombocytes and the involvement of this system in the hemorrhagic septicemia. The total number of fish thrombocytes decreased in infected animals compared to uninfected animals. Regarding the ecto-enzymes of the purinergic system, the E-NTPDase and E-5'-nucleotidase activities increased in infected animals compared to uninfected animals, while the E-ADA activity decreased. These findings show that adenine nucleotide hydrolysis is modified in the thrombocytes of fish experimentally infected with A. caviae, which impairs the coagulation process due the excessive hydrolysis of ADP, a molecule linked with activation and recruitment of thrombocytes at the site of vascular injury, and augmentation on Ado levels, a molecule linked with inhibitory effects on platelet activation and aggregation. In summary, the purinergic system might contribute to the occurrence of hemorrhagic frames in fish infected with A. caviae.

Microbiological condition of the catfish Sciades herzbergii from Bacanga Lagoon, northeastern Brazil / Qualidade microbiológica do bagre Sciades herzbergii capturado na Laguna do Bacanga, nordeste do Brasil

Fishing in Bacanga Lagoon supplements the income or even guarantees the survival of several families that live in this river basin on Maranhão Island (São Luís), which is densely populated and shows signs of water pollution. The present study aimed to assess the quality of recently captured catfish Sciades herzbergii, through microbiological analyses of muscles. In general, the samples of Bacanga Lagoon showed higher coliform values than those observed in fish collected in the control area (Pau Deitado, Paço do Lumiar, state of Maranhão). Samples collected in January showed a high content of total coliforms and coliforms at 45oC, which suggests a relationship between microbial contamination and the rainy season. Escherichia coli was the most abundant bacteria species in the samples from Bacanga Lagoon. The results showed poor sanitary conditions of the Bacanga Lagoon and demonstrated fecal contamination of the fish captured due to the high amount of untreated efluents discharged in the lagoon.

A pesca na laguna do Bacanga é uma atividade que garante o sustento e complementação de renda para diversas famílias que habitam nessa bacia hidrográfica da Ilha do Maranhão (São Luís) densamente ocupada e com sinais de poluição de suas águas. O trabalho objetivou avaliar a qualidade do bagre Sciades herzbergii através de análises microbiológicas do músculo de peixes recém-capturados. No geral, as amostras do Bacanga apresentaram valores de coliformes significativamente maiores que os observados nos peixes coletados na área controle (Pau Deitado, Paço do Lumiar, MA). Amostras coletadas nos meses de janeiro apresentaram elevada quantidade de coliformes totais e coliformes a 45oC sugerindo relação da contaminação microbiana com o período de chuvas, sendo que Escherichia coli foi a espécie mais abundante nas amostras do Bacanga. Os resultados indicaram as péssimas condições sanitárias da laguna do Bacanga e demostraram a contaminação de origem fecal nos peixes capturados em função do elevado volume de efluentes lançados sem tratamento na laguna.

Microbiological condition of the catfish Sciades herzbergii from Bacanga Lagoon, northeastern Brazil / Qualidade microbiológica do bagre Sciades herzbergii capturado na Laguna do Bacanga, nordeste do Brasil

Fishing in Bacanga Lagoon supplements the income or even guarantees the survival of several families that live in this river basin on Maranhão Island (São Luís), which is densely populated and shows signs of water pollution. The present study aimed to assess the quality of recently captured catfish Sciades herzbergii, through microbiological analyses of muscles. In general, the samples of Bacanga Lagoon showed higher coliform values than those observed in fish collected in the control area (Pau Deitado, Paço do Lumiar, state of Maranhão). Samples collected in January showed a high content of total coliforms and coliforms at 45oC, which suggests a relationship between microbial contamination and the rainy season. Escherichia coli was the most abundant bacteria species in the samples from Bacanga Lagoon. The results showed poor sanitary conditions of the Bacanga Lagoon and demonstrated fecal contamination of the fish captured due to the high amount of untreated efluents discharged in the lagoon.(AU)

A pesca na laguna do Bacanga é uma atividade que garante o sustento e complementação de renda para diversas famílias que habitam nessa bacia hidrográfica da Ilha do Maranhão (São Luís) densamente ocupada e com sinais de poluição de suas águas. O trabalho objetivou avaliar a qualidade do bagre Sciades herzbergii através de análises microbiológicas do músculo de peixes recém-capturados. No geral, as amostras do Bacanga apresentaram valores de coliformes significativamente maiores que os observados nos peixes coletados na área controle (Pau Deitado, Paço do Lumiar, MA). Amostras coletadas nos meses de janeiro apresentaram elevada quantidade de coliformes totais e coliformes a 45oC sugerindo relação da contaminação microbiana com o período de chuvas, sendo que Escherichia coli foi a espécie mais abundante nas amostras do Bacanga. Os resultados indicaram as péssimas condições sanitárias da laguna do Bacanga e demostraram a contaminação de origem fecal nos peixes capturados em função do elevado volume de efluentes lançados sem tratamento na laguna.(AU)

Xanthine oxidase activity affects pro-oxidative and pro-inflammatory profiles in spleen of silver catfish experimentally infected with Aeromonas caviae.

Several pieces of evidence have linked the involvement of xanthine oxidase (XO), a source of uric acid and reactive oxygen species (ROS), to pro-oxidative and pro-inflammatory effects observed during bacterial fish diseases. Thus, the aim of this study was to evaluate whether upregulation of splenic XO activity contributes to disease pathogenesis of Aeromonas caviae infection, as well as whether it may be considered a pathway involved in ROS and nitric oxide (NO) production. XO activity increased in the spleen of infected animals, as did the splenic levels of uric acid, ROS and metabolites of nitric oxide (NOx), compared to the uninfected control group. Based on this evidence, upregulation of splenic XO activity induces pro-oxidant and pro-inflammatory profiles in the spleen of fish infected by A. caviae due to excessive formation of uric acid. Moreover, excessive uric acid induces the release of pro-inflammatory mediators, such as ROS and NOx, which contribute to disease pathophysiology. In summary, upregulation of XO activity may be considered a pathway involved in ROS and NOx production.

Streptococcus agalactiae impairs cerebral bioenergetics in experimentally infected silver catfish.

It is becoming evident that bacterial infectious diseases affect brain energy metabolism, where alterations of enzymatic complexes of the mitochondrial respiratory chain and creatine kinase (CK) lead to an impairment of cerebral bioenergetics which contribute to disease pathogenesis in the central nervous system (CNS). Based on this evidence, the aim of this study was to evaluate whether alterations in the activity of complex IV of the respiratory chain and CK contribute to impairment of cerebral bioenergetics during Streptococcus agalactiae infection in silver catfish (Rhamdia quelen). The activity of complex IV of the respiratory chain in brain increased, while the CK activity decreased in infected animals compared to uninfected animals. Brain histopathology revealed inflammatory demyelination, gliosis of the brain and intercellular edema in infected animals. Based on this evidence, S. agalactiae infection causes an impairment in cerebral bioenergetics through the augmentation of complex IV activity, which may be considered an adaptive response to maintain proper functioning of the electron respiratory chain, as well as to ensure ongoing electron flow through the electron transport chain. Moreover, inhibition of cerebral CK activity contributes to lower availability of ATP, contributing to impairment of cerebral energy homeostasis. In summary, these alterations contribute to disease pathogenesis linked to the CNS.