Anatomopathological characterization and etiology of lesions on Nile tilapia fillets (Oreochromis niloticus) caused by bacterial pathogens

Ferreira, Jair Alves; Leal, Carlos Augusto Gomes; Oliveira, Thaís Ferreira de; Nascimento, Karla Alvarenga; Macêdo, Juliana Targino Silva Almeida e; Pedroso, Pedro Miguel Ocampos

doi:10.1016/j.aquaculture.2020.735387

Cited by 5 publications

(3 citation statements)

References 19 publications

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“…Francisellosis is responsible for large economic losses, as severe outbreaks can result in mortalities of up to 95% (Chern & Chao, 1994; Colquhoun & Duodu, 2011). Additionally, granulomas characterized by central necrosis and the presence of melanomacropahges in adults’ muscles, macroscopically described as black spots, caused by francisellosis are reported to result in the condemnation of fillets at slaughterhouses (Junior et al, 2020; Mauel et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Administration of dehydrated oxytetracycline effectively reduces francisellosis mortality in Nile tilapia

Favero

Facimoto

Chideroli

et al. 2021

Aquaculture Research

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Francisellosis is a disease responsible for severe economic losses in aquaculture. Currently, this disease is controlled via biosecurity measures and treatment of affected batches. In this study, tilapia juveniles were challenged with Francisella orientalis via immersion and fed with oxytetracycline‐medicated feed, at 100 mg kg fish−1 and 200 mg kg fish−1, under prophylactic and therapeutic strategies for 16 and 15 days respectively. All doses and treatment strategies reduced the fish mortality. The detection of the pathogen from the spleen was lower in the treated groups. Histopathology analysis showed that challenged fish that received the highest dosage presented fewer granuloma in their spleens and less inflammatory infiltrate in their livers than untreated fish. Fish that received the prophylactic treatment, regardless of the dose, presented fewer granuloma in their livers than untreated fish. Fish treated with 100 mg kg fish−1 had better scores for hepatocyte accumulations than fish treated with the higher dosage. Furthermore, 20% of the unchallenged fish that received the higher dosage presented mild inflammatory infiltrate in their livers. No differences were observed in the serum hepatocyte lesion enzyme quantifications. The results indicate that oxytetracycline‐medicated feed is safe, even at the higher dose, and effective at controlling francisellosis in tilapia.

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Section: Introductionmentioning

confidence: 99%

“…Additionally, granulomas characterized by central necrosis and the presence of melanomacropahges in adults' muscles, macroscopically described as black spots, caused by francisellosis are reported to result in the condemnation of fillets at slaughterhouses (Junior et al, 2020;Mauel et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Administration of dehydrated oxytetracycline effectively reduces francisellosis mortality in Nile tilapia

Favero

Facimoto

Chideroli

et al. 2021

Aquaculture Research

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“…In the last decade, tilapia production increased from 150,000 to over 400,000 tonnes, making Brazil the fourth major Nile tilapia producer in the world, behind China, Indonesia and Egypt (FAO, 2021; IBGE, 2020; Peixe BR, 2021). However, this sector is being negatively impacted by bacterial diseases (Assane, Prada Mejia, et al, 2021; Chideroli et al, 2017; Delphino et al, 2019; Junior et al, 2020; Sebastião, Furlan, Hashimoto, & Pilarski, 2015; Sebastião, Pilarski, Kearney, & Soto, 2017) and the lack of effective therapies (Assane, de Sousa, et al, 2021; de Oliveira, Queiroz, Teixeira, Figueiredo, & Leal, 2018). According to Tavares-Dias and Martins (2017), in Brazil, the annual loss to the inland aquaculture sector due to parasitic and bacterial diseases is estimated to be USD 84 million.…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity, virulence, antimicrobial resistance genes, and antimicrobial susceptibility of group BStreptococcus(GBS) linked to mass mortalities of cultured Nile tilapia in Brazil

Assane

Neto

Ferreira

et al. 2022

Preprint

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Streptococcus agalactiae, group B Streptococcus (GBS), is the main bacterial pathogen of cultured Nile tilapia in many countries and causes extensive deaths in all stages of the farming cycle throughout the year. This study investigated the genetic diversity, virulence, presence of antibiotic resistance genes and antimicrobial susceptibility of 72 GBS linked to mass mortalities of cultured Nile tilapia in Brazil. Isolate identity was confirmed by morphological, biochemical and molecular analyses. Capsular serotype, multi-locus sequence typing (MLST) allelic profiles and putative pathogenic factors were identified by polymerase chain reaction (PCR), gel electrophoresis, sequencing and molecular analyses of different genes. The presence of antimicrobial resistance genes and antimicrobial susceptibility to florfenicol (FFC), oxytetracycline (OTC), thiamphenicol (TAP) and their combination were evaluated by PCR, followed by gel electrophoresis, and broth microdilution antimicrobial susceptibility testing, respectively. All clinical isolates studied were confirmed to be GBS, one from serotype III (IA2022) and 71 from serotype Ib, suggesting that serotype Ib was the most prevalent strain between 2011 and 2016 in the south and southern and southeastern regions of Brazil. Eight different allelic profiles were identified for the first time, being adhP-52, pheS-2, atr-31, glnA-4, sdhA-2, tkt-19 the most predominant. Between one (glcK) and three (adhP and glnA) alleles were present at each locus. All strains, except IA2022, showed a partial gene deletion event on the glcK gene. The surface protein Rib and hypervirulent GBS adhesin BibA were detected in all strains, except for 18P, which was negative for rib. On the other hand, α and β antigens of the C protein were only detected in IA2022. All antimicrobials showed high minimum inhibitory concentration (MIC ≥ 16 ug/mL) values against several strains with negative results for resistance genes. Despite indifference and antagonism being the most predominant activities in all combinations evaluated, the record of synergism, including in a strain with a resistance gene and phenotypic resistance, suggests that combination therapy can have therapeutic efficacy when well planned. The combination involving OTC and TAP or FFC is a likely candidate for improving the treatment of streptococcosis using combination therapy, even for strains showing phenotypic and genotypic resistance to OTC. This study provides pertinent data on pathogenic GBS genetic diversity, virulence, the presence of antibiotic resistance genes and antimicrobial susceptibility, which may be useful in the development of effective vaccines and therapeutic strategies for the prevention and control of streptococcosis in aquaculture farms.

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Meta-analyses indicate that dietary probiotics significantly improve growth, immune response, and disease resistance in tilapia

Saba,

Yasin,

Azmai

2024

Aquacult Int

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Anatomopathological characterization and etiology of lesions on Nile tilapia fillets (Oreochromis niloticus) caused by bacterial pathogens

Cited by 5 publications

References 19 publications

Administration of dehydrated oxytetracycline effectively reduces francisellosis mortality in Nile tilapia

Administration of dehydrated oxytetracycline effectively reduces francisellosis mortality in Nile tilapia

Genetic diversity, virulence, antimicrobial resistance genes, and antimicrobial susceptibility of group BStreptococcus(GBS) linked to mass mortalities of cultured Nile tilapia in Brazil

Meta-analyses indicate that dietary probiotics significantly improve growth, immune response, and disease resistance in tilapia

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