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1.
Arq. bras. med. vet. zootec. (Online) ; 71(5): 1609-1615, set.-out. 2019. tab
Artigo em Português | LILACS, VETINDEX | ID: biblio-1038678

RESUMO

Objetivou-se avaliar a ocorrência de Aeromonas spp. em peixes e amostras de água na região semiárida de Pernambuco e avaliar a frequência de aerolissina (aerA), enterotoxina citotóxica (act), enterotoxina citotônica (alt) e serina protease (ahp) nesses isolados. Foram analisados 70 peixes vivos e oito mortos com sinais clínicos de aeromoniose e 16 amostras de água. Aeromonas spp. foram identificadas por análises microbiológicas (provas bioquímicas) e molecular, usando-se primers específicos para a região 16S rRNA, e a distribuição dos quatro fatores de virulência (aerA, alt, act e ahp) foi investigada por ensaio de PCR. Cento e cinquenta e cinco (84,7%) isolados foram confirmados como Aeromonas spp. na análise molecular. Os genes de virulência mais frequentes foram act (53,55%) e aerA (51,61%). De acordo com o tipo de amostra, observou-se maior frequência do gene aerA (87,5% P=0,0474) em isolados de peixes mortos e a menor frequência do gene act (47,73% P=0,0002) em peixes vivos. Este estudo demonstrou a presença de aeromoniose no cultivo de tilápias em tanques-rede, nos municípios de Jatobá e Petrolândia, na região semiárida de Pernambuco. A detecção de aerA, act e alt pode ser utilizada na tipagem de virulência de Aeromonas spp.(AU)


The purpose of this study was to evaluate the occurrence of Aeromonas spp. from fishes and tilapia net-cage farm water in semi-arid regions of Pernambuco and to evaluate the frequency of the aerolysin (aerA), cytotoxic enterotoxin (act), cytotonic enterotoxin (alt) and serine protease (ahp) genes in Aeromonas isolates. 70 live and eight dead fish with aeromoniosis clinical signs and 16 water samples were analyzed. Aeromonas spp. isolated were identified by microbiological (biochemical evidence) and molecular analysis using specific primers for 16SrRNA region, while the distribution of four virulence factors, including aerA, alt, act and ahp, was investigated by PCR assay. One hundred fifty-five (84.7%) isolates were confirmed as Aeromonas spp. by molecular analysis. The most frequent virulence genes in isolates were act (53.55%) and aerA (51,61%). According to the kind of sample, the higher frequency of aerA gene (87.5% P= 0.0474) was observed in isolates from dead fish and the lowest frequency of act gene (47.73% P= 0.0002) from live fish. This study found the presence of aeromoniosis on tilapia farming in net-cages on Jatobá and Petrolândia counties in the semiarid Pernambuco region. The detection of aerA, act and alt can be used for virulence typing of Aeromonas spp. isolates.(AU)


Assuntos
Animais , Tilápia/microbiologia , Aeromonas/patogenicidade , Ciclídeos/microbiologia , Pesqueiros , Virulência
2.
Microb Pathog ; 135: 103612, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31252064

RESUMO

Emergence of antibiotic resistant bacteria has necessitated the drive to explore competent antimicrobial agents or to develop novel formulations to treat infections including Aeromonas hydrophila. The present study investigates the synergistic antibacterial effects of citrus flavonoid rutin and florfenicol (FF) against A. hydrophila in vitro and in vivo. Rutin is extracted and purified from Citrus sinensis peel through preparative HPLC and characterized through TLC, GC-MS and 1H and 13C NMR analyses. Though rutin did not display significant antibacterial activity, it modulated FF activity resulting in four-fold reduction in the MIC value for FF. The anti-biofilm potential of synergistic association of rutin and FF was validated by protein analysis, quantification of exopolysaccharide (EPS) and microscopy studies using sub-MIC doses. Besides antibacterial action, in vivo studies showed that Rutin/FF combination enhanced host immunity by improving blood cell count, anti-protease, and lysozyme activities as well as decreased the oxidative stress and the pathological changes of tilapia Oreochromis niloticus against A. hydrophila infection. No significant DNA damages or clastogenic effects were detected in tilapia challenged with A. hydrophila under Rutin/FF treatment. It is shown that an acute-phase Lipopolysaccharide binding protein (LBP) enhances the innate host defence against bacterial challenge. Semi quantitative RT-PCR and western blot results revealed the significant increase of LBP in the supernatant of tilapia monocytes/macrophages challenged with A. hydrophila upon treatment. The study findings substantiate that the combination of natural molecules with antibiotics may open up possibilities to treat MDR strains.


Assuntos
Aeromonas hydrophila/efeitos dos fármacos , Doenças dos Peixes/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/veterinária , Rutina/farmacologia , Rutina/uso terapêutico , Tianfenicol/análogos & derivados , Aeromonas hydrophila/crescimento & desenvolvimento , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Biofilmes/efeitos dos fármacos , Citrus sinensis/química , Dano ao DNA/efeitos dos fármacos , Modelos Animais de Doenças , Combinação de Medicamentos , Sinergismo Farmacológico , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Doenças dos Peixes/patologia , Pesqueiros , Imunidade/efeitos dos fármacos , Imunomodulação , Índia , Testes de Sensibilidade Microbiana , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Rutina/imunologia , Tianfenicol/imunologia , Tianfenicol/farmacologia , Tianfenicol/uso terapêutico , Tilápia/microbiologia , Virulência/efeitos dos fármacos
3.
J Food Sci ; 84(6): 1487-1493, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31066925

RESUMO

This paper investigates the bacterial microbiota in tilapia fillets under cold (4 °C), iced (0 °C), and superchilled (-3 °C) storage conditions. At 4 °C, at least seven species/strains of Pseudomonas were detected in the fillets, five of which were dominant either at a certain stage or throughout the entire storage period. Shewanella was less dominant than Pseudomonas at 4 °C, while Serratia became dominant after 6 days storage at 4 °C. The microbiota in fillets stored at 0 and -3 °C were very similar and rarely changed during storage, yet differed greatly from the microbiota at 4 °C. Only two Pseudomonas species/strains grew at 0 and -3 °C, one of which was the most dominant. A Vibrionimonas sp. not found at 4 °C was found to be the second most dominant species at 0 and -3 °C. Shewanella and Psychrobacter were also present at 0 and -3 °C but were the minor genera. The most dominant strains at -3, 0, and 4 °C were separately isolated and subjected to full length 16S rDNA sequencing, which demonstrated that they were identical and were Pseudomonas fluorescens. The changes of the total bacterial count and TVBN value of the fillets inoculated with the isolated P. fluorescens were very similar to those of fillets with natural microbiota. This implies that P. fluorescens is the most important spoiler of tilapia fillets at -3, 0, or 4 °C. PRACTICAL APPLICATION: This research shows that fewer species of bacteria survive at 0 and -3 °C than those at 4 °C, while among these bacteria, the most important spoiler is P. fluorescens. This may provide some clues to extend the shelf life of tilapia fillets by taking some inhibitory measures targeted at P. fluorescens in the future.


Assuntos
Bactérias/isolamento & purificação , Armazenamento de Alimentos/métodos , Microbiota/fisiologia , Temperatura , Tilápia/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Carga Bacteriana , Temperatura Baixa , DNA Bacteriano/análise , DNA Ribossômico , Pseudomonas/classificação , Pseudomonas/genética , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Serratia/classificação , Serratia/genética , Serratia/isolamento & purificação , Fatores de Tempo
4.
Microb Pathog ; 131: 164-169, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30978428

RESUMO

Bacterial diseases are one of the major problems in freshwater fish culture and have been linked to significant losses and high mortality rate. In this study, Nile tilapia Oreochromis niloticus was infected by Providencia rettgeri to evaluate the oxidative stress and antioxidant responses in the fish tissues. Juvenile Nile tilapia was divided into two groups, as follow: control (uninfected) and experimentally infected with 100 µL of P. rettgeri suspension containing 2.4 × 107 viable cells/fish, and the liver and kidney tissues were collected on days 7 and 14 post-infection (PI). Liver and kidney ROS and lipid peroxidation levels were high in infected fish on day 14 PI compared to control group, while superoxide dismutase activity was lower in liver (days 7 and 14 PI) and kidney (day 14 PI) compared to their respective control groups. Liver and kidney antioxidant capacity against peroxyl radicals, non-proteic, and proteic thiols levels was lower in infected tilapia on day 14 PI compared to control group. Based on these results, P. rettgeri infection may elicit oxidative damage via increased ROS production, decreased ROS elimination and inhibits enzymatic and non-enzymatic antioxidant defense systems; which may contribute directly to disease pathophysiology of infected animals.


Assuntos
Antioxidantes/metabolismo , Ciclídeos/metabolismo , Doenças dos Peixes/metabolismo , Estresse Oxidativo , Providencia/patogenicidade , Animais , Brasil , Ciclídeos/imunologia , Ciclídeos/microbiologia , Modelos Animais de Doenças , Infecções por Enterobacteriaceae/imunologia , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/veterinária , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Interações Hospedeiro-Patógeno/fisiologia , Rim/metabolismo , Peroxidação de Lipídeos , Fígado/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tilápia/microbiologia
5.
Can J Microbiol ; 65(7): 522-529, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30921521

RESUMO

We carried out sequencing of samples cultivated in floating beds with different Chinese medicinal herbs (Control, Houttuynia cordata Thunb., Polygonum cuspidatum, and a combination of H. cordata with Ipomoea aquatica Forssk.; named groups A, B, C, D, respectively) to analyze changes in the composition of gut microbiota of tilapia feces. Fusobacteria (ranging from 49.0% to 73.3%), Firmicutes (12.3%-37.8%), and Proteobacteria (5.1%-23.0%) were found to be the most dominant phyla present in all samples. The operational taxonomic units and the Ace and Chao1 indices of groups A and D were significantly higher than those of group C. Polygonum cuspidatum decreased the species richness and diversity of microbial communities in tilapia intestinal feces. The phylum WCHB1-60, order Enterobacteriales, and genus Plesiomonas significantly decreased (in group A); the species Plesiomonas shigelloides significantly decreased (in groups B and C); and the genus Leucobacter significantly increased (in group D) when compared with the control. The relative abundance of the class Verrucomicrobiae (groups B vs C) significantly decreased. In the presence of I. aquatica, the phylum Bacteroidetes significantly decreased, while the genera Leucobacter and Pelotomaculum significantly increased. The ratio of Bacteroidetes to Firmicutes was significantly higher in groups B and C relative to the controls, while it decreased significantly in group D. The algae (i.e., Anabaena and Microcystis) and beneficial pathogenic bacteria decreased in groups C and D, respectively. In addition, Enterovibrio decreased in all treatment groups. The present data demonstrate that floating bed cultivation with Chinese medicinal herbs significantly alters the gut microbiota of tilapia, which may enhance its immune activity.


Assuntos
Fallopia japonica , Microbioma Gastrointestinal , Houttuynia , Ipomoea , Tilápia/microbiologia , Animais , Bactérias/classificação , Bacteroidetes/isolamento & purificação , Fezes/microbiologia , Firmicutes/isolamento & purificação , Intestinos/microbiologia , Masculino , Microbiota , Proteobactérias/isolamento & purificação , Tilápia/crescimento & desenvolvimento
6.
Food Chem ; 275: 497-503, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30724225

RESUMO

This study develops a reliable radial basis function neural networks (RBFNNs) to estimate freshness for tilapia fillets stored under non-isothermal conditions by using optimal wavelengths from hyperspectral imaging (HSI). The results show that, for tilapia fillet stored at -3, 0, 4, 10, and 15 °C and non-isothermal conditions, total volatile basic nitrogen (TVB-N), total aerobic counts (TAC), and the K value increase whereas sensory scores decrease with increasing storage time. To simplify the models, nine optimal wavelengths were selected by using the successive projections algorithm (SPA), following which SPA-RBFNN models were built based on the selected wavelengths and the values of TVB-N, TAC, K, and sensory evaluations for tilapia fillets store isothermally. The ability of the models based on HSI to predict the freshness indicators were verified for tilapia fillets stored under non-isothermal conditions. HSI thus has an excellent potential for nondestructive determination of freshness in tilapia fillets.


Assuntos
Qualidade dos Alimentos , Armazenamento de Alimentos/métodos , Alimentos Marinhos , Temperatura , Tilápia , Animais , Nitrogênio/análise , Alimentos Marinhos/análise , Alimentos Marinhos/microbiologia , Tilápia/microbiologia
7.
BMC Microbiol ; 19(1): 21, 2019 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-30665355

RESUMO

BACKGROUND: Francisella noatunensis subsp. orientalis (Fno) is an emergent fish pathogen and the etiologic agent of piscine francisellosis. Besides persisting in the environment in both biofilm and planktonic forms, Fno is known to infect and replicate inside tilapia macrophages and endothelial-derived cells. However, the mechanism used by this emergent bacterium for intracellular survival is unknown. Additionally, the basis of virulence for Fno is still poorly understood. Several potential virulence determinants have been identified in Fno, including homologues of the recently described F. tularensis Type VI Secretion System (T6SS). In order to gain a better understanding of the role the putative Fno T6SS might play in the pathogenesis of piscine francisellosis, we performed transcriptional analysis of Fno T6SS gene-homologues under temperature, acidic, and oxidative stress conditions. RESULTS: Few transcriptional differences were observed at different temperatures, growth stages and pHs; however, a trend towards higher expression of Fno T6SS-homologue genes at 25 °C and under oxidative stress was detected when compared to those quantified at 30 °C and under no H2O2 (p < 0.05). CONCLUSIONS: Results from this study suggest that several of the F. tularensis T6SS-homologues may play an important role in the virulence of Fno, particularly when the bacterium is exposed to low temperatures and oxidative stress.


Assuntos
Francisella/genética , Francisella/patogenicidade , Regulação Bacteriana da Expressão Gênica , Sistemas de Secreção Tipo VI/genética , Fatores de Virulência/genética , Animais , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Concentração de Íons de Hidrogênio , Estresse Oxidativo/genética , Temperatura , Tilápia/microbiologia
8.
Prev Vet Med ; 162: 131-135, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30621892

RESUMO

Infection with Streptococcus agalactiae causes mortality and major economic losses in Nile tilapia (Oreochromis niloticus) farming worldwide. In Brazil, serotype strains Ia, Ib and III have been isolated in streptococcosis outbreaks, but serotype Ib is the most prevalent. Vaccination is considered an effective method to prevent economically-important diseases in aquaculture and has been associated with decreased use of antibiotics and improvements in fish survival. We developed a flexible partial-budget model to undertake an economic appraisal of vaccination against Streptococcus agalactiae in Nile tilapia farmed in net cages in large reservoirs. The model considers the benefits and costs that are likely to be associated with vaccination at the farm-level, in one production cycle. We built three epidemiological scenarios of cumulative mortality attributable to S. agalactiae (5%, 10%, and 20%, per production cycle) in a non-vaccinated farm. For each scenario, we applied a stochastic model to simulate the net return of vaccination, given a combination of values of "vaccine efficacy", "gain in feed conversion ratio", "feed price", "fish market price ", and "cost of vaccine dose". In the 20% cumulative mortality scenario, the net return would break-even (benefits ≥ costs) in at least 97.9% of interactions. Should cumulative mortality be lower than 10%, the profitability of vaccination would be more dependent on better feed conversion ratio. The inputs "feed price" and "cost of vaccine" had minor effects on the output, in all pre-vaccination mortality scenarios. Although our simulations are based on conservative values and consider uncertainty about the modeled parameters, we conclude that vaccination against S. agalactiae is likely to be profitable in Nile tilapia farms, under similar production conditions.


Assuntos
Doenças dos Peixes/prevenção & controle , Infecções Estreptocócicas/veterinária , Vacinas Estreptocócicas/economia , Streptococcus agalactiae/imunologia , Tilápia/microbiologia , Animais , Aquicultura/economia , Brasil , Análise Custo-Benefício , Doenças dos Peixes/economia , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Modelos Econômicos , Infecções Estreptocócicas/economia , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/prevenção & controle , Vacinas Estreptocócicas/uso terapêutico
9.
J Food Prot ; 82(2): 256-261, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30677309

RESUMO

In this study, we investigated contamination rates and possible contamination routes of Salmonella in two typical tilapia sashimi processing plants in Taiwan. We found that the overall isolation rate was 5.0% ( n = 61), from a total of 1,218 samples collected in a year from different processing sections (freezing, scaling and bleeding, visceral removal, washing and disinfection, and packaging) and from different operating times (before processing and 3 and 6 h after processing began). In plant A, which is a relatively well-operated plant compared with plant B, Salmonella was only found in the freezing, scaling and bleeding, and visceral removal sections, with isolation rates ranging from 0 to 9.3%. No Salmonella was identified in the final ready-to-eat products at plant A. In plant B, Salmonella was found in all sections and in the final products, with isolation rates ranging from 4.6 to 36.1%. Regarding the processing times, the contamination rates increased significantly ( P < 0.05) 3 h after processing began in plant B. Among the isolates, 10 serotypes were detected, some of which are commonly observed in human salmonellosis cases in Taiwan, indicating a risk of zoonoses. However, only four isolates showed antimicrobial resistance in the current study. With molecular subtyping, we observed accumulated and persistent Salmonellae contamination patterns in plant B. These results suggest that inadequate sanitation impairs the foodborne pathogen control program in tilapia sashimi plants.


Assuntos
Contaminação de Alimentos/análise , Intoxicação Alimentar por Salmonella/prevenção & controle , Salmonella/isolamento & purificação , Tilápia , Animais , Eletroforese em Gel de Campo Pulsado , Microbiologia de Alimentos , Humanos , Salmonella/crescimento & desenvolvimento , Sorogrupo , Taiwan , Tilápia/microbiologia
10.
J Food Sci ; 84(2): 370-380, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30640981

RESUMO

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.


Assuntos
Corantes/análise , Leite/química , Alimentos Marinhos/análise , Compostos de Tritil/análise , Adsorção , Animais , Argentina , Peixes-Gato/microbiologia , China , Cromatografia Líquida/métodos , Corantes/isolamento & purificação , Contaminação de Alimentos/análise , Violeta Genciana/análise , Violeta Genciana/isolamento & purificação , Corantes de Rosanilina/análise , Corantes de Rosanilina/isolamento & purificação , Alimentos Marinhos/microbiologia , Espectrometria de Massas em Tandem/métodos , Tilápia/microbiologia , Compostos de Tritil/isolamento & purificação , Vietnã
11.
Fish Shellfish Immunol ; 86: 53-63, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30428393

RESUMO

The administration of probiotics during early ontogenetic stages can be an effective way to manipulate the gut microbiota of animals. Specifically, the administration of probiotics can enhance gut-colonization success and regulate the immune response. In this study, the effects of early contact with probiotic Lactococcus lactis subsp. lactis JCM5805 on the gut microbial assembly of larvae Nile tilapia were examined. The effects of JCM5805 on IFNα expression through the TLR7 and TLR9-dependent signal transduction pathway as well as larval disease resistance were studied. Three days postfertilization, embryos were randomly allocated into nine 30 L tanks with a concentration of 20 eggs L-1. Triplicate tanks were performed for each treatment. Treatments included a control group (C), a low probiotic concentration group (T1), where JCM5805 was added to the water at 1 × 104 cfu ml-1, and a high probiotic concentration group (T2), where JCM5805 was added to the water at 1 × 108 cfu ml-1. Probiotics were administered continuously for 15 days. qPCR was used to analyze transcript levels of the TLR7, TLR9, MyD88, IRF7 and IFNα genes using RNA extracted from whole embryos on day 5 and 10, and from the intestine of larvae on day 15. Transcription of these genes was also measured in the intestine, liver and spleen of larvae one month after the cessation of probiotic administration. The results showed that MyD88 and IRF7 were significantly elevated on days 5 and 10 in the T2 group. TLR9 and IFNα were also significantly elevated on days 5, 10 and 15 during probiotic application of T2 (P < 0.05). One month after the cessation of probiotics administration, no significant difference was observed in the expression of these genes (P > 0.05). The larvae were fed probiotics for 15 days and were infused with Streptococcus agalactiae strain WC1535 at a final concentration of 1 × 106 cfu ml-1. The survival rate of T2 was significantly higher than that of the C group (P < 0.05). Microbial characterization by Illumina HiSeq sequencing of 16S rRNA gene amplicons showed the significantly higher presence of JCM5805 in the guts of T2 after 15 days of probiotic continuous application. Although JCM5805 was below the detection level after the cessation of probiotic for 5 days, the gut microbiota of the exposed tilapia larvae in T2 remained clearly different from that of the control treatment after the cessation of probiotic administration. These data indicated that a high concentration of the probiotic strain JCM5805 upregulated the expression of IFNα via the TLR7/TLR9-Myd88 pathway and enhanced disease resistance of larvae. JCM5805 was only transiently detected and thus was not included in the stable larval microbiota. The early microbial exposure of tilapia larvae affects the gut microbiota at later life stages. However, whether the upregulation of related genes is related to the presence of JCM5805 strain in the intestine requires further verification.


Assuntos
Microbioma Gastrointestinal/imunologia , Lactococcus lactis/fisiologia , Tilápia/crescimento & desenvolvimento , Tilápia/microbiologia , Animais , Regulação da Expressão Gênica no Desenvolvimento/imunologia , Probióticos , Distribuição Aleatória , Tilápia/imunologia , Transcriptoma
12.
Fish Shellfish Immunol ; 86: 635-640, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30528659

RESUMO

Vaccination is the most effective approach for prevention of infectious diseases in aquaculture. Although immersion vaccination is more applicable compared to in-feed/oral administration and injection, this method suffers from low potency as the efficiency of uptake of antigens through mucosal membranes is limited. In this study, we have successfully developed a mucoadhesive vaccine delivery system to enhance the efficacy of direct immersion vaccination against Flavobacterium columnare, the causative agent of columnaris disease in red tilapia. A formalin-killed negatively charged, bacterial cell suspension was used to prepare a mucoadhesive vaccine by electrostatic coating with positively charged chitosan. Our results demonstrate that the chitosan-complexed vaccine greatly increases its mucoadhesiveness, thus increasing the chances of vaccine uptake by the gill mucosa and improving the protection obtained against columnaris infection. The surface charge of the chitosan-complexed vaccine was altered from anionic to cationic after chitosan modification. Tilapia were vaccinated with the prepared chitosan-complexed vaccine by immersion. The challenge test was then carried out 30 and 60 days post vaccination, which resulted in a high level of mortalities in the non-vaccinated and uncomplexed vaccine groups. A high relative percentage survival (RPS) of vaccinated fish was noted with the mucoadhesive vaccine. Our results indicated that the naked vaccine failed to protect the fish from columnaris infection, which is consistent with the mucoadhesive assays performed during the study showing that the naked vaccine was unable to bind to mucosal surfaces. This system is therefore an effective method for immersion vaccination in order to deliver the antigen preparation to the mucosal surface membrane of the fish.


Assuntos
Vacinas Bacterianas/uso terapêutico , Doenças dos Peixes/prevenção & controle , Infecções por Flavobacteriaceae/veterinária , Polímeros/química , Tilápia/imunologia , Vacinação/métodos , Adesivos/química , Animais , Aquicultura , Vacinas Bacterianas/química , Quitosana/química , Infecções por Flavobacteriaceae/prevenção & controle , Flavobacterium , Brânquias/imunologia , Imersão , Membrana Mucosa/metabolismo , Eletricidade Estática , Propriedades de Superfície , Tilápia/microbiologia , Vacinas de Produtos Inativados/química , Vacinas de Produtos Inativados/uso terapêutico
13.
Fish Shellfish Immunol ; 86: 260-268, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30439500

RESUMO

Synbiotics, a synergistic combination of probiotics and prebiotics, are currently regarded as one of the most practical nutritional supplements in tilapia farms. In this study, the effect of supplementing the diet of red tilapia (Oreochromis spp.) with Jerusalem artichoke (Helianthus tuberosus) and Lactobacillus rhamnosus GG (LGG) was evaluated. Growth performance, serum biochemical parameters, intestinal morphology, goblet cell counts, immune parameters and protection against Aeromonas veronii challenge were determined. The results showed that fish fed with synbiotic-supplemented diets had a significantly higher (P < 0.05) feed conversion ratio (FCR), specific growth rate (SGR), and average daily gain (ADG) than fish fed with a control diet. The synbiotic-supplemented diet increased glucose, total protein and the total cholesterol levels. The absorptive area of the proximal and distal intestine of fish fed on the synbiotic diet was significantly higher (P < 0.05) than in those fed with probiotics (LGG), prebiotic-supplemented diets (JA), and the control diet. Goblet cell counts revealed that the numbers of acid mucous cells, neutral mucous cells and double-staining mucous cells of fish fed the synbiotic-supplemented diet (JA + LGG) were significantly higher (P < 0.05) in the proximal and distal intestine. Fish fed the synbiotic-supplemented diets also exhibited significantly higher (P < 0.05) lysozyme activity. The cumulative mortalities of fish fed with a synbiotic-supplemented diet were significantly lower than those of fish fed other diets. The results suggested the beneficial effect of JA and LGG synbiotic diet on growth performance and health status of red tilapia. Direct administration of JA and LGG in fish feed can be used as a practical nutritional supplement in red tilapia.


Assuntos
Helianthus , Lactobacillus rhamnosus , Simbióticos/administração & dosagem , Tilápia/imunologia , Aeromonas veronii/imunologia , Ração Animal/análise , Animais , Aquicultura , Dieta/veterinária , Doenças dos Peixes/imunologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/imunologia , Intestinos/anatomia & histologia , Tilápia/crescimento & desenvolvimento , Tilápia/microbiologia
14.
Acta Sci Pol Technol Aliment ; 18(4): 413-425, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31930792

RESUMO

BACKGROUND: The production and commercialization of tilapia (Oreochromis niloticus) is fundamentally important to the semi-arid region of northeastern Brazil. In this region, one of the main forms of commercialization occurs in street markets (fairs). A high incidence of methicillin-resistant Staphylococcus aureus (MRSA) strains was previously detected in different food-related environments in Brazil. However, limited data is available about the presence of MRSA in street markets commercializing tilapias. In this study, we identified Staphylococcus aureus from tilapia and utensils used in the commercialization of tilapia in the street markets of a semi-arid Brazilian municipality and characterized the virulence potential of the isolates by analyzing their β-lactam resistance, intercellular adhesion and enterotoxin genes. METHODS: The study used samples from the 5 main markets in the city. Phenotypic tests to determine antimicrobial resistance, exopolysaccharide (EPS) production, the potential for biofilm formation and cell surface hydrophobicity were conducted on S. aureus isolates. The presence of antimicrobial resistance genes (mecA and blaZ), potential biofilm production genes (icaA and icaD) and enterotoxin (se) genes was investigated. RESULTS: Coagulase-positive staphylococci (CoPS) were detected in samples from all markets in discordance with the legal limits in force. Twelve isolates were confirmed to be S. aureus. Ten isolates demonstrated multidrug resistance (MDR). All isolates were able to produce EPS and form biofilms. Eight isolates exhibited strong hydrophobicity and six a high potential for biofilm formation. Twelve isolates were positive for mecA, blaZ, icaD and sed. CONCLUSIONS: Tilapia marketed in unsuitable conditions may be a vehicle for staphylococcal food poisoning and for the dissemination of MRSA to consumers. Additionally, the ability of the isolates to produce biofilms is an alert to the presence and persistence of these virulent microorganisms on utensils used for the commercial distribution of tilapia.


Assuntos
Microbiologia de Alimentos , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/patogenicidade , Tilápia/microbiologia , Animais , Aderência Bacteriana/genética , Biofilmes/crescimento & desenvolvimento , Brasil , Comércio , Utensílios de Alimentação e Culinária , DNA Bacteriano/análise , Farmacorresistência Bacteriana/genética , Enterotoxinas/genética , Doenças Transmitidas por Alimentos/microbiologia , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Testes de Sensibilidade Microbiana , Polissacarídeos Bacterianos/biossíntese , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/transmissão , Staphylococcus aureus/genética , Resistência beta-Lactâmica/genética
15.
J Food Prot ; 81(12): 1973-1981, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30457388

RESUMO

This study evaluated the microbiological safety of fresh Nile tilapia ( Oreochromis niloticus) from Kenyan fresh water fish value chains. One hundred seventy-six fish samples were analyzed. The microbial counts of hygiene indicators, total viable aerobic count (TVC), total coliforms, and fecal coliforms isolated by using culture techniques were enumerated, and microbial pathogens present in the fish samples were identified and characterized by using molecular methods. The diversity of bacterial isolates was determined by using the Shannon-Weaver diversity index. The mean of TVC in the samples was 4.44 log CFU/g. A comparison with the European Commission and International Commission on Microbiological Specifications for Foods standards showed two fish samples had counts above the 5.00 log CFU/g limit for TVC, and all the fish samples had total coliform and fecal coliform counts above 2.00 and 1.00 log CFU/g, respectively. Pathogenic strains, including Shiga toxin-producing and enteropathogenic Escherichia coli, Listeria monocytogenes, Yersinia enterocolitica, Klebsiella pneumoniae, and Salmonella enterica, were identified in the fish samples. The diversity of 1,608 bacterial isolates was higher in semiregulated chains than unregulated chains. The diversity was also high at the retail stage of the fish value chain. In conclusion, fresh Nile tilapia samples were above some of the set food safety standards and may be a source of foodborne pathogens. Further microbial risk assessment for detected pathogens is recommended to further support public health protection, taking into account growth, inactivation through cooking, processing, survival, and consumption.


Assuntos
Ciclídeos , Microbiologia de Alimentos , Tilápia , Animais , Contagem de Colônia Microbiana , Água Doce , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Positivas/isolamento & purificação , Quênia , Tilápia/microbiologia , Microbiologia da Água
16.
Chemosphere ; 213: 345-350, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30241078

RESUMO

Recently, Boron (B) contamination of aquatic ecosystem has received considerable critical attention due to its toxic effects at high concentrations on plants as well as animals. Previous studies on toxic effects of B have not dealt with DNA damages in blood and sperm cells of Nile tilapia (Oreochromis niloticus), together with blood parameters. This study consisted of two successive experiments purposes to determine these findings, including the median-lethal concentration (LC50) of B for Nile tilapia. In the first one, at 96 h, LC50 of B for Nile tilapia was 141.42 mg L-1 B. In the second one, Nile tilapia were treated with five elevated B concentrations (1, 5, 25, 50 and 100 mg L-1 B) and hematological, serum biochemical parameters, and DNA damages of Nile tilapia in these treatments were determined comparing with the control after 14 days of exposure. Hematological parameters (red blood cell count, hematocrit, and hemoglobin) were similar to each other in all groups while serum biochemical parameters (glucose, total protein, cholesterol, alkaline phosphatase, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase) in B treatments, especially in 50 and 100 mg L-1 B groups, were found significantly higher (P < 0.05). DNA fragmentation was detected in all blood cells in ≥25 mg L-1 B treatments, while all sperm cells in 100 mg L-1 B treatments. These results demonstrated the harmful effects of B at high concentration (50 and 100 mg L-1 B) on the DNA integrity of blood and sperm cells, and also the serum biochemical parameters.


Assuntos
Boro/efeitos adversos , Fragmentação do DNA/efeitos dos fármacos , Espermatozoides/química , Tilápia/microbiologia , Animais , Boro/química , Peixes , Masculino
17.
Appl Environ Microbiol ; 84(16)2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-29915111

RESUMO

Streptococcus agalactiae (group B Streptococcus [GBS]) causes disease in a wide range of animals. The serotype Ib lineage is highly adapted to aquatic hosts, exhibiting substantial genome reduction compared with terrestrial conspecifics. Here, we sequence genomes from 40 GBS isolates, including 25 isolates from wild fish and captive stingrays in Australia, six local veterinary or human clinical isolates, and nine isolates from farmed tilapia in Honduras, and compared them with 42 genomes from public databases. Phylogenetic analysis based on nonrecombinant core-genome single nucleotide polymorphisms (SNPs) indicated that aquatic serotype Ib isolates from Queensland were distantly related to local veterinary and human clinical isolates. In contrast, Australian aquatic isolates are most closely related to a tilapia isolate from Israel, differing by only 63 core-genome SNPs. A consensus minimum spanning tree based on core-genome SNPs indicates the dissemination of sequence type 261 (ST-261) from an ancestral tilapia strain, which is congruent with several introductions of tilapia into Australia from Israel during the 1970s and 1980s. Pangenome analysis identified 1,440 genes as core, with the majority being dispensable or strain specific, with non-protein-coding intergenic regions (IGRs) divided among core and strain-specific genes. Aquatic serotype Ib strains have lost many virulence factors during adaptation, but six adhesins were well conserved across the aquatic isolates and might be critical for virulence in fish and for targets in vaccine development. The close relationship among recent ST-261 isolates from Ghana, the United States, and China with the Israeli tilapia isolate from 1988 implicates the global trade in tilapia seed for aquaculture in the widespread dissemination of serotype Ib fish-adapted GBS.IMPORTANCEStreptococcus agalactiae (GBS) is a significant pathogen of humans and animals. Some lineages have become adapted to particular hosts, and serotype Ib is highly specialized to fish. Here, we show that this lineage is likely to have been distributed widely by the global trade in tilapia for aquaculture, with probable introduction into Australia in the 1970s and subsequent dissemination in wild fish populations. We report here the variability in the polysaccharide capsule among this lineage but identify a cohort of common surface proteins that may be a focus of future vaccine development to reduce the biosecurity risk in international fish trade.


Assuntos
Doenças Transmissíveis Importadas/veterinária , Evolução Molecular , Doenças dos Peixes/transmissão , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/genética , Tilápia/microbiologia , Aclimatação , Animais , Aquicultura , Doenças Transmissíveis Importadas/microbiologia , Doenças dos Peixes/microbiologia , Microbiologia de Alimentos , Genoma Bacteriano , Genótipo , Biologia Marinha , Filogenia , Polimorfismo de Nucleotídeo Único , Queensland , Sorogrupo , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/transmissão , Streptococcus agalactiae/isolamento & purificação , Streptococcus agalactiae/patogenicidade , Virulência , Fatores de Virulência
18.
Gene ; 672: 156-164, 2018 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-29906530

RESUMO

The success of the pathogenic bacteria is partly attributable to their ability to thwart host innate immune responses, which includes resisting the antimicrobial functions of macrophages. And reactive oxygen species (ROS) is one of the most effective antimicrobial components of macrophages to kill invading bacteria. Our previous studies found that Aeromonas hydrophila can survive in fish macrophages, which suggested that this bacterium might take fish macrophages as their shelters to resist drug killings and other immune damage. But how A. hydrophila survive in host macrophages remains unknown. Since KatG has been reported to have not only catalase activity but also peroxidase and peroxynitritase activity, the amino acid sequence and protein structure of KatG was analyzed in this study, the function of KatG in A. hydrophila survival in and escape from host macrophages was also carried out. The bioinformatics analysis displayed that KatG of A. hydrophila B11 showed >93% homologous to that of KatG in other Aeromonas. KatG of A. hydrophila was stable silenced by shRNA and RT-qPCR confirmed the expression of KatG in KatG-RNAi was significantly reduced. The survival rate of intracellular KatG-RNAi decreased by 80% compared to that of the wild type strain B11, while the intracellular ROS level of the macrophages that phagocytosed KatG-RNAi increased 65.9% when compared to that of the macrophages phagocytosed wild-type strain. The immune escape rate of A. hydrophila decreased by 85% when the expression of KatG was inhibited. These results indicated that (1) The amino acid sequence and protein structure of KatG of A. hydrophila is conserved; (2) KatG helped A. hydrophila to survive in fish macrophages by eliminating the harm of intracellular H2O2 and inhibiting intracellular ROS levels increased; (3) A small portion of intracellular A. hydrophila could escape from host macrophages for further infection, in this process KatG also played important role.


Assuntos
Aeromonas hydrophila/imunologia , Proteínas de Bactérias/genética , Catalase/genética , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Macrófagos/microbiologia , Aeromonas hydrophila/enzimologia , Aeromonas hydrophila/genética , Sequência de Aminoácidos , Animais , Células Cultivadas , Doenças dos Peixes/imunologia , Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Técnicas de Silenciamento de Genes , Infecções por Bactérias Gram-Negativas/imunologia , Infecções por Bactérias Gram-Negativas/microbiologia , Evasão da Resposta Imune , Macrófagos/imunologia , Viabilidade Microbiana , Modelos Moleculares , Estrutura Terciária de Proteína , Espécies Reativas de Oxigênio/metabolismo , Tilápia/imunologia , Tilápia/microbiologia
19.
Fish Shellfish Immunol ; 80: 624-630, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29886137

RESUMO

The animal intestine provides a competitive environment for the microbiota. Successful colonization by pathogens requires sensing chemical signals to regulate the expression of virulence genes. Some bacteria rely on a two-component chemical signal transduction system, named FusKR, to regulate virulence genes expression by intestinal fucose. Here we construct the fucP gene deletion strain prove FucP regulation of the T3SS in E. tarda. The result showed that the mutant strain had down-regulated significantly the gene expression of FusKR and T3SS compared to the wild-type strain (P < 0.05). This mutant strain significantly increased LD50 in zebrafish compared to the wild-type strain (P < 0.05), and significantly decreased penetration and motility in mucin than the wild-type strain (P < 0.05). Meanwhile, tilapia infected with mutant strain show significantly reduced E. tarda adherence and colonization than those infected with the wild-type strain (P < 0.05). Fish infected with EIB202 and ΔfucP showed significantly higher (P < 0.05) gene expression of IL-1ß, TNF-α, IFN-γ, TGF-ß and HSP-70 in head kidney than fish treated with PBS in the whole observed period; however CPP-3 did not show significant differences (P > 0.05) in all groups. Fish infected with EIB202 showed significantly higher (P < 0.05) gene expression of TGF-ß in head kidney than fish treated with ΔfucP in the whole observed period; however other cytokines did not show significant differences (P > 0.05) in the whole observed period. In addition, Fish infected with EIB202 showed significantly higher (P < 0.05) gene expression of IL-1ß, TNF-α and TGF-ß in spleen than fish treated with ΔfucP in the whole observed period, however IFN-γ, CPP-3, and HSP-70 did not show significant differences (P > 0.05) in the whole observed period. Although the gene expression of cytokines was induced similarly by both strains, all results indicate that the fucP gene deletion down-regulates the key gene expression of FucKR and T3SS, reduces the pathogenicity of E. tarda in fish, particularly decreases inducing the gene expression of TGF-ß in the head kidney and IL-1ß, TNF-α and TGF-ß in the spleen.


Assuntos
Proteínas de Bactérias/genética , Citocinas/imunologia , Edwardsiella tarda/patogenicidade , Infecções por Enterobacteriaceae/imunologia , Doenças dos Peixes/imunologia , Tilápia/imunologia , Fatores de Virulência/genética , Animais , Citocinas/genética , Edwardsiella tarda/genética , Infecções por Enterobacteriaceae/genética , Infecções por Enterobacteriaceae/veterinária , Doenças dos Peixes/genética , Expressão Gênica , Baço/imunologia , Tilápia/microbiologia
20.
Microb Pathog ; 122: 39-45, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29859291

RESUMO

Streptococcus agalactiae (S. agalactiae, GBS) infection has caused significant economic loss in the tilapia aquaculture, which is one of the most important commercial fish worldwide. Among the 10 serotypes of GBS, serotypes Ia, Ib, II and III were epidemic in tilapia while serotype IX has never been found in tilapia before. In this study, 80 strains isolated from moribund tilapia in China were identified as GBS. All the isolates have been classified as serotype III or serotype IX of GBS. Unexpectedly, the serotype IX has never been reported in fish, but it was epidemic in mammals. Antimicrobial resistance results showed that serotype IX but not III was resistant to streptomycin and erythromycin. Artificial infection results showed that both serotypes could cause serious pathological injuries in the infected tissues of tilapia. Furthermore, serotype IX instead of serotype III, mainly infected the brain of tilapia. The results will shed a new light on the epidemic and pathogenicity of GBS, and will pave a new way for the prevention of Streptococcosis in tilapia.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Doenças dos Peixes/microbiologia , Doenças dos Peixes/patologia , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/efeitos dos fármacos , Tilápia/microbiologia , Animais , Encéfalo/microbiologia , Encéfalo/patologia , China , Eritromicina/farmacologia , Sorogrupo , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/patologia , Streptococcus agalactiae/classificação , Streptococcus agalactiae/isolamento & purificação , Streptococcus agalactiae/patogenicidade , Estreptomicina/farmacologia
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