Bacterial and Viral Diseases in Aquatic Animals

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Aquatic Animals".

Deadline for manuscript submissions: 31 January 2025 | Viewed by 23765

Special Issue Editor


E-Mail Website
Guest Editor
College of Veterinary Medicine, Sichuan Agricultural University, Ya'an, China
Interests: zoopathology; etiology; aquatic animals

Special Issue Information

Dear Colleagues,

The health of aquatic animals is a veterinary scientific field which is constantly evolving and increasing in complexity. In recent years, the emergence of new pathogeny caused serious harm to aquaculture, and the timely diagnosis of diseases according to pathogenesis, epidemiology, and pathology is very important. It is pivotal for an aquatic veterinary clinician to be pliant and open-minded. Fishing ground owners are becoming more and more demanding with regards to their own veterinarian, who must be updated on novel diagnostic technologies in order to provide an excellent service. The aim of this Special Issue is to publish original research papers, case studies, and review articles focusing on the latest advances in aquatic animals pathogenesis, epidemiology, and pathology. This Special Issue welcomes all experts and researchers that would like to present information in a concise, understandable, and logical format on the current state-of-the-art in aquatic animals veterinary medicine. You are invited to submit either an original research article or a review summarizing research on the pathogenesis, epidemiology, and pathology of aquatic animals. Articles highlighting and documenting any aspect of this field will be considered for publication.

Prof. Dr. Yi Geng
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Animals is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • bacterial diseases
  • viral diseases
  • pathogenesis
  • epidemiology and pathology

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (11 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

9 pages, 7743 KiB  
Communication
Natural Co-Infections of Aeromonas veronii and Yellow Catfish Calicivirus (YcCV) in Ascites Disease Outbreaks in Cultured Yellow Catfish: An Emerging Fish Disease in China
by Shuai Xu, Wenli Huang, Tao Zheng, Shan Jin, Zigong Wei and Bo Guan
Animals 2024, 14(22), 3289; https://doi.org/10.3390/ani14223289 - 15 Nov 2024
Viewed by 350
Abstract
Yellow catfish is one of the most important aquaculture species in China, with an annual output of 565,000 tons. Between May and July 2022, the farmed yellow catfish experienced an unusually high mortality rate in an aquaculture farm next to Futou Lake in [...] Read more.
Yellow catfish is one of the most important aquaculture species in China, with an annual output of 565,000 tons. Between May and July 2022, the farmed yellow catfish experienced an unusually high mortality rate in an aquaculture farm next to Futou Lake in Hubei, China. Diseased fish exhibited symptoms including ascites, skin ulcers, and bleeding in the head, oral cavity, and lower jaw base. Polymerase chain reaction (PCR) and sequence analyses confirmed the co-infection of Yellow Catfish Calicivirus (YcCV) and Aeromonas veronii in the diseased fish. Transmission electron microscopy exposed abundant virus particles within kidney and spleen cells, characterized by their spherical shape and approximate diameter of 35 nm. Historically, the ascites disease in yellow catfish has been predominantly attributed to bacterial infections over the past two decades. This study represents the first documentation of a correlation between the ascites disease of yellow catfish and the natural co-infection of YcCV and Aeromonas veronii. The findings suggest a possible synergistic interaction between YcCV and bacterial pathogens, potentially aggravating disease severity in yellow catfish aquaculture. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

16 pages, 4821 KiB  
Article
Unveiling Insights into the Whole Genome Sequencing of Mycobacterium spp. Isolated from Siamese Fighting Fish (Betta splendens)
by Nguyen Dinh-Hung, Samuel Mwakisha Mwamburi, Ha Thanh Dong, Channarong Rodkhum, Watcharachai Meemetta, Nguyen Vu Linh, Hung N. Mai, Arun K. Dhar, Ikuo Hirono, Saengchan Senapin and Satid Chatchaiphan
Animals 2024, 14(19), 2833; https://doi.org/10.3390/ani14192833 - 1 Oct 2024
Viewed by 923
Abstract
This study aims to genomically elucidate six isolates of rapidly growing non-tuberculous mycobacteria (RGM) derived from Siamese fighting fish (Betta splendens). These isolates had previously undergone phenotypic and biochemical characterization, antibiotic susceptibility testing, and in vivo virulence assessment. Initial DNA barcoding [...] Read more.
This study aims to genomically elucidate six isolates of rapidly growing non-tuberculous mycobacteria (RGM) derived from Siamese fighting fish (Betta splendens). These isolates had previously undergone phenotypic and biochemical characterization, antibiotic susceptibility testing, and in vivo virulence assessment. Initial DNA barcoding using the 16S rRNA sequence assigned these six isolates to five different species, namely Mycobacterium chelonae (BN1983), M. cosmeticum (BN1984 and N041), M. farcinogenes (SNSK5), M. mucogenicum (BN1956), and M. senegalense (BN1985). However, the identification relied solely on the highest percent identity of the 16S rRNA gene, raising concerns about the taxonomic ambiguity of these species. Comprehensive whole genome sequencing (WGS) and extended genomic comparisons using multilocus sequence typing (MLST), average nucleotide identity (ANI), and digital DNA–DNA hybridization (dDDH) led to the reclassification of BN1985 and SNSK5 as M. conceptionense while confirming BN1983 as M. chelonae and BN1984 and N041 as M. cosmeticum. Notably, the analysis of the BN1956 isolate revealed a potential new species that is proposed here as M. mucogenicum subsp. phocaicum sp. nov. Common genes encoding “mycobacterial” virulence proteins, such as PE and PPE family proteins, MCE, and YrbE proteins, were detected in all six isolates. Two species, namely M. chelonae and M. cosmeticum, appear to have horizontally acquired T6SS-II (clpB), catalase (katA), GroEL (groel), and capsule (rmlb) from distantly related environmental bacteria such as Klebsiella sp., Neisseria sp., Clostridium sp., and Streptococcus sp. This study provides the first draft genome sequence of RGM isolates currently circulating in B. splendens and underscores the necessity of WGS for the identification and classification of mycobacterial species. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

16 pages, 2100 KiB  
Article
Genomic and Pathological Characterization of Acute Hepatopancreatic Necrosis Disease (AHPND)-Associated Natural Mutant Vibrio parahaemolyticus Isolated from Penaeus vannamei Cultured in Korea
by Ye Bin Kim, Seon Young Park, Hye Jin Jeon, Bumkeun Kim, Mun-Gyeong Kwon, Su-Mi Kim, Jee Eun Han and Ji Hyung Kim
Animals 2024, 14(19), 2788; https://doi.org/10.3390/ani14192788 - 26 Sep 2024
Viewed by 771
Abstract
Acute hepatopancreatic necrosis disease (AHPND) is one of the most important diseases in the global shrimp industry. The emergence of mutant AHPND-associated V. parahaemolyticus (VpAHPND) strains has raised concerns regarding potential misdiagnosis and unforeseen pathogenicity. In this study, we [...] Read more.
Acute hepatopancreatic necrosis disease (AHPND) is one of the most important diseases in the global shrimp industry. The emergence of mutant AHPND-associated V. parahaemolyticus (VpAHPND) strains has raised concerns regarding potential misdiagnosis and unforeseen pathogenicity. In this study, we report the first emergence of a type II (pirA, pirB+) natural mutant, VpAHPND (strain 20-082A3), isolated from cultured Penaeus vannamei in Korea. Phenotypic and genetic analyses revealed a close relationship between the mutant strain 20-082A3 and the virulent Korean VpAHPND strain 19-021-D1, which caused an outbreak in 2019. Detailed sequence analysis of AHPND-associated plasmids showed that plasmid pVp_20-082A3B in strain 20-082A3 was almost identical (>99.9%) to that of strain 19-021-D1. Moreover, strains 20-082A3 and 19-021-D1 exhibited the same multilocus sequence type (ST 413) and serotype (O1:Un-typeable K-serogroup), suggesting that the mutant strain is closely related to and may have originated from the virulent strain 19-021-D1. Similar to previous reports on the natural mutant VpAHPND, strain 20-082A3 did not induce AHPND-related symptoms or cause mortality in the shrimp bioassay. The emergence of a mutant strain which is almost identical to the virulent VpAHPND highlights the need for surveillance of the pathogen prevalent in Korea. Further investigations to elucidate the potential relationship between ST 413 and recent Korean VpAHPND isolates are needed. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

13 pages, 1483 KiB  
Article
Development of Monoclonal Antibody against PirB and Establishment of a Colloidal Gold Immunochromatographic Assay for the Rapid Detection of AHPND-Causing Vibrio
by Xuan Dong, Jingmei Xie, Liying Wang, Xuan Li, Haoyu Lou, Guohao Wang and Jie Huang
Animals 2024, 14(11), 1600; https://doi.org/10.3390/ani14111600 - 29 May 2024
Viewed by 893
Abstract
Acute hepatopancreatic necrosis disease (AHPND) poses a significant threat to shrimp aquaculture worldwide, necessitating the accurate and rapid detection of the pathogens. However, the increasing number of Vibrio species that cause the disease makes diagnosis and control more difficult. This study focuses on [...] Read more.
Acute hepatopancreatic necrosis disease (AHPND) poses a significant threat to shrimp aquaculture worldwide, necessitating the accurate and rapid detection of the pathogens. However, the increasing number of Vibrio species that cause the disease makes diagnosis and control more difficult. This study focuses on developing a monoclonal antibody against the Photorhabdus insect-related (Pir) toxin B (PirB), a pivotal virulence factor in AHPND-causing Vibrio, and establishing a colloidal gold immunochromatographic assay for the enhanced early diagnosis and monitoring of AHPND. Monoclonal antibodies targeting PirB were developed and utilized in the preparation of colloidal-gold-labeled antibodies for the immunochromatographic assay. The specificity and sensitivity of the assay were evaluated through various tests, including antibody subclass detection, affinity detection, and optimal labeling efficiency assessment. The developed PirB immunochromatographic test strips exhibited a good specificity, as demonstrated by the positive detection of AHPND-causing Vibrio and negative results for non-AHPND-causing Vibrio. The study highlights the potential of the developed monoclonal antibody and immunochromatographic assay for the effective detection of AHPND-causing Vibrio. Further optimization is needed to enhance the sensitivity of the test strips for improved practical applications in disease prevention and control in shrimp aquaculture. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

11 pages, 1316 KiB  
Article
Development of a Melting Curve-Based Triple Eva Green Real-Time PCR Assay for Simultaneous Detection of Three Shrimp Pathogens
by Xuan Dong, Yujin Chen, Haoyu Lou, Guohao Wang, Chengyan Zhou, Liying Wang, Xuan Li, Jingfei Luo and Jie Huang
Animals 2024, 14(4), 592; https://doi.org/10.3390/ani14040592 - 11 Feb 2024
Viewed by 4718
Abstract
Infections with Enterocytozoon hepatopenaei (EHP), infectious hypodermal and hematopoietic necrosis virus (IHHNV), and Decapod iridescent virus 1 (DIV1) pose significant challenges to the shrimp industry. Here, a melting curve-based triple real-time PCR assay based on the fluorescent dye Eva Green was established for [...] Read more.
Infections with Enterocytozoon hepatopenaei (EHP), infectious hypodermal and hematopoietic necrosis virus (IHHNV), and Decapod iridescent virus 1 (DIV1) pose significant challenges to the shrimp industry. Here, a melting curve-based triple real-time PCR assay based on the fluorescent dye Eva Green was established for the simultaneous detection of EHP, IHHNV, and DIV1. The assay showed high specificity, sensitivity, and reproducibility. A total of 190 clinical samples from Shandong, Jiangsu, Sichuan, Guangdong, and Hainan provinces in China were evaluated by the triple Eva Green real-time PCR assay. The positive rates of EHP, IHHNV, and DIV1 were 10.5%, 18.9%, and 44.2%, respectively. The samples were also evaluated by TaqMan qPCR assays for EHP, DIV1, and IHHNV, and the concordance rate was 100%. This illustrated that the newly developed triple Eva Green real-time PCR assay can provide an accurate method for the simultaneous detection of three shrimp pathogens. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

15 pages, 10505 KiB  
Article
The cAMP Receptor Protein (CRP) of Vibrio mimicus Regulates Its Bacterial Growth, Type II Secretion System, Flagellum Formation, Adhesion Genes, and Virulence
by Ziqi Tian, Fei Xiang, Kun Peng, Zhenyang Qin, Yang Feng, Bowen Huang, Ping Ouyang, Xiaoli Huang, Defang Chen, Weimin Lai and Yi Geng
Animals 2024, 14(3), 437; https://doi.org/10.3390/ani14030437 - 29 Jan 2024
Cited by 2 | Viewed by 1561
Abstract
Vibrio mimicus is a serious pathogen in aquatic animals, resulting in significant economic losses. The cAMP receptor protein (CRP) often acts as a central regulator in highly pathogenic pathogens. V. mimicus SCCF01 is a highly pathogenic strain isolated from yellow catfish; the crp [...] Read more.
Vibrio mimicus is a serious pathogen in aquatic animals, resulting in significant economic losses. The cAMP receptor protein (CRP) often acts as a central regulator in highly pathogenic pathogens. V. mimicus SCCF01 is a highly pathogenic strain isolated from yellow catfish; the crp gene deletion strain (Δcrp) was constructed by natural transformation to determine whether this deletion affects the virulence phenotypes. Their potential molecular connections were revealed by qRT-PCR analysis. Our results showed that the absence of the crp gene resulted in bacterial and colony morphological changes alongside decreases in bacterial growth, hemolytic activity, biofilm formation, enzymatic activity, motility, and cell adhesion. A cell cytotoxicity assay and animal experiments confirmed that crp contributes to V. mimicus pathogenicity, as the LD50 of the Δcrp strain was 73.1-fold lower compared to the WT strain. Moreover, qRT-PCR analysis revealed the inhibition of type II secretion system genes, flagellum genes, adhesion genes, and metalloproteinase genes in the deletion strain. This resulted in the virulence phenotype differences described above. Together, these data demonstrate that the crp gene plays a core regulatory role in V. mimicus virulence and pathogenicity. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

15 pages, 32555 KiB  
Article
The Infection Properties of Trionyx sinensis Hemorrhagic Syndrome Virus and the Antiviral Effect of Curcumin In Vivo
by Jinbiao Jiao, Jiayun Yao, Feng Lin, Xuemei Yuan, Lei Huang, Jing Chen, Xianqi Peng, Haiqi Zhang and Shengqi Su
Animals 2023, 13(23), 3665; https://doi.org/10.3390/ani13233665 - 27 Nov 2023
Viewed by 1367
Abstract
Trionyx sinensis hemorrhagic syndrome virus (TSHSV) is an aquatic arterivirus causing a high mortality rate for T. sinensis (Chinese soft-shelled turtle), but the detailed infection properties of TSHSV are unclear, and no effective treatment is available. In this study, cell culture and histopathology [...] Read more.
Trionyx sinensis hemorrhagic syndrome virus (TSHSV) is an aquatic arterivirus causing a high mortality rate for T. sinensis (Chinese soft-shelled turtle), but the detailed infection properties of TSHSV are unclear, and no effective treatment is available. In this study, cell culture and histopathology were performed to elucidate the infection properties of TSHSV. Furthermore, the anti-TSHSV and immune-enhancing effects of curcumin were evaluated using survival statistics, qPCR, and tissue immunofluorescence. The results demonstrated that TSHSV could proliferate in the spleen cell line of T. sinensis, leading to cytopathic effects. TSHSV damaged the livers, kidneys, and lungs, characterized by cell disintegration and hyperemia. Curcumin at 250 mg/kg improved the survival of T. sinensis, and significantly reduced the viral load in the spleens, kidneys, and lungs. Moreover, curcumin inhibited the mRNA expression of immune-related genes, RSAD2, IFN-γ, and TNF-α (p < 0.05). In conclusion, these results imply that TSHSV is pathogenic to the spleen cell line, liver, spleen, kidney, and lung of T. sinensis. Curcumin effectively inhibits TSHSV and modulates the immune function of T. sinensis, so it holds promise as a means to prevent TSHSV. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

16 pages, 2092 KiB  
Article
Isolation, Identification, and Pathogenicity of Vibrio gigantis Retrieved from European Seabass (Dicentrarchus labrax) Farmed in Türkiye
by Sevdan Yilmaz, Süheyla Karataş, Terje Marken Steinum, Mert Gürkan, Dilek Kahraman Yilmaz and Hany M. R. Abdel-Latif
Animals 2023, 13(22), 3580; https://doi.org/10.3390/ani13223580 - 20 Nov 2023
Cited by 4 | Viewed by 1673
Abstract
In this study, V. gigantis strain C24 was isolated from cases of winter mortalities of hatchery-reared European seabass (Dicentrarchus labrax) broodstock in Türkiye. The first mortalities were reported in September 2016 and occurred annually in early autumn/late winter until the end [...] Read more.
In this study, V. gigantis strain C24 was isolated from cases of winter mortalities of hatchery-reared European seabass (Dicentrarchus labrax) broodstock in Türkiye. The first mortalities were reported in September 2016 and occurred annually in early autumn/late winter until the end of February 2019, when 15% of accumulated mortality was recorded. Diseased moribund fish exhibited general septicemic signs, including dermal ulcerations with hemorrhagic margins, distended abdomens, and hemorrhages below the pectorals, pelvic fins, and at the operculum. Postmortem findings showed congestion in several internal organs, hemorrhagic ascitic fluid, and congested prolapsed anal openings. The representative bacterial isolate V. gigantis strain C24 was characterized as Gram-negative, motile, nitrite-producing, and as vibrio static agent O/129-sensitive. The full-length 16S rRNA sequence (Accession No. ON778781) and gyrB gene sequence (Accession No. ON792326) of the C24 strain showed high similarity to V. gigantis strains. Moreover, the whole-genome average nucleotide identity (ANI) values (ANI > 97.7%) against four V. gigantis strains above the species demarcation limit unambiguously identified the C24 isolate as a member of this species. A preliminary virulence-gene analysis showed that the V. gigantis isolate C24 encoded at least three exotoxins, including two aerolysins and a thermolabile hemolysin. The experimental infection showed that the C24 isolate exhibited low to moderate virulence in experimentally infected European seabass juveniles. Interestingly, antimicrobial susceptibility testing revealed that the C24 isolate was susceptible to nalidixic acid, ciprofloxacin, and several other antibiotics but resistant to tilmicosin, kanamycin, streptomycin, and ampicillin. To our knowledge, this study is the first to report that V. gigantis could be considered an emerging bacterial pathogen in Türkiye, and it may threaten the international European seabass production. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

15 pages, 2535 KiB  
Article
The Assembly Process of Free-Living and Particle-Attached Bacterial Communities in Shrimp-Rearing Waters: The Overwhelming Influence of Nutrient Factors Relative to Microalgal Inoculation
by Yikai Shi, Xuruo Wang, Huifeng Cai, Jiangdong Ke, Jinyong Zhu, Kaihong Lu, Zhongming Zheng and Wen Yang
Animals 2023, 13(22), 3484; https://doi.org/10.3390/ani13223484 - 11 Nov 2023
Cited by 1 | Viewed by 1260
Abstract
The ecological functions of bacterial communities vary between particle-attached (PA) lifestyles and free-living (FL) lifestyles, and separately exploring their community assembly helps to elucidate the microecological mechanisms of shrimp rearing. Microalgal inoculation and nutrient enrichment during shrimp rearing are two important driving factors [...] Read more.
The ecological functions of bacterial communities vary between particle-attached (PA) lifestyles and free-living (FL) lifestyles, and separately exploring their community assembly helps to elucidate the microecological mechanisms of shrimp rearing. Microalgal inoculation and nutrient enrichment during shrimp rearing are two important driving factors that affect rearing-water bacterial communities, but their relative contributions to the bacterial community assembly have not been evaluated. Here, we inoculated two microalgae, Nannochloropsis oculata and Thalassiosira weissflogii, into shrimp-rearing waters to investigate the distinct effects of various environmental factors on PA and FL bacterial communities. Our study showed that the composition and representative bacteria of different microalgal treatments were significantly different between the PA and FL bacterial communities. Regression analyses and Mantel tests revealed that nutrients were vital factors that constrained the diversity, structure, and co-occurrence patterns of both the PA and FL bacterial communities. Partial least squares path modeling (PLS-PM) analysis indicated that microalgae could directly or indirectly affect the PA bacterial community through nutrient interactions. Moreover, a significant interaction was detected between PA and FL bacterial communities. Our study reveals the unequal effects of microalgae and nutrients on bacterial community assembly and helps explore microbial community assembly in shrimp-rearing ecosystems. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

14 pages, 3411 KiB  
Article
Edwardsiella tarda in Tambaqui (Colossoma macropomum): A Pathogenicity, Antimicrobial Susceptibility, and Genetic Analysis of Brazilian Isolates
by Francisco Yan Tavares Reis, Victória Pontes Rocha, Peter Charrie Janampa-Sarmiento, Henrique Lopes Costa, Renata Catão Egger, Naísa Cristine Passos, Carlos Henrique Santos de Assis, Sarah Portes Carneiro, Ágna Ferreira Santos, Brendhal Almeida Silva, Fernanda Alves Dorella, Márcia Pimenta Leibowitz, Ronald Kennedy Luz, Felipe Pierezan, Sílvia Umeda Gallani, Guilherme Campos Tavares and Henrique César Pereira Figueiredo
Animals 2023, 13(18), 2910; https://doi.org/10.3390/ani13182910 - 14 Sep 2023
Cited by 3 | Viewed by 2274
Abstract
Edwardsiella tarda is a crucial pathogenic bacterium in tropical aquaculture. This bacterium was recently isolated from tambaqui (Colossoma macropomum), a commercially important fish species in Brazil. This study assessed the antimicrobial susceptibility, pathogenicity, and genetic diversity of the tambaqui-derived E. tarda [...] Read more.
Edwardsiella tarda is a crucial pathogenic bacterium in tropical aquaculture. This bacterium was recently isolated from tambaqui (Colossoma macropomum), a commercially important fish species in Brazil. This study assessed the antimicrobial susceptibility, pathogenicity, and genetic diversity of the tambaqui-derived E. tarda isolates. Fourteen bacterial isolates isolated from tambaqui were identified as E. tarda by using matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry and dnaJ gene sequencing. Antimicrobial susceptibility tests were conducted against seven drugs using the disc diffusion assay. The pathogenicity test conducted by intraperitoneal injection of 2.4 × 107 colony-forming units (CFU) fish−1 of E. tarda (ED38-17) into tambaqui juveniles eventually revealed that neither clinical signs nor death were present. However, splenomegaly and whitish areas in the spleen and kidneys were observed. The histological investigation also revealed granulomatous splenitis, nephritis, and hepatitis occurring internally. Repetitive extragenic palindromic-PCR fingerprinting separated the 14 isolates into three genetic groups. The antibiogram revealed that all E. tarda isolates were wild-type (WT) to florfenicol (FLO), norfloxacin (NOR), neomycin (NEO), erythromycin (ERY), and oxytetracycline (OXY); however, some were non-wild-type to sulfamethoxazole/trimethoprim (7.1%) and amoxicillin (21.4%). Therefore, through experimental infection, E. tarda ED38-17 could induce pathogenic effects in C. macropomum. Additionally, three distinct genetic types were found, and the E. tarda isolates were WT to FLO, NOR, NEO, ERY, and OXY. These findings raise awareness of a bacteria causing unseen lesions, a pathogen that will potentially impact tambaqui aquaculture in the future. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Show Figures

Figure 1

Review

Jump to: Research

32 pages, 576 KiB  
Review
Streptococcosis a Re-Emerging Disease in Aquaculture: Significance and Phytotherapy
by Hien Van Doan, Mehdi Soltani, Alexandra Leitão, Shafigh Shafiei, Sepideh Asadi, Alan J. Lymbery and Einar Ringø
Animals 2022, 12(18), 2443; https://doi.org/10.3390/ani12182443 - 16 Sep 2022
Cited by 21 | Viewed by 6372
Abstract
Streptococcosis, particularly that caused by S. iniae and S. agalactiae, is a major re-emerging bacterial disease seriously affecting the global sustainability of aquaculture development. Despite a wide spread of the disease in aquaculture, few studies have been directed at assessing the in [...] Read more.
Streptococcosis, particularly that caused by S. iniae and S. agalactiae, is a major re-emerging bacterial disease seriously affecting the global sustainability of aquaculture development. Despite a wide spread of the disease in aquaculture, few studies have been directed at assessing the in vitro antagonistic activity and in vivo efficacy of medicinal herbs and other plants against streptococcal agents. Most in vitro studies of plant extractives against S. iniae and S. agalactiae have found antibacterial activity, but essential oils, especially those containing eugenol, carvacrol or thymol, are more effective. Although essential oils have shown better anti-streptococcal activity in in vitro assays, in vivo bioassays require more attention. The extracts examined under in vivo conditions show moderate efficacy, increasing the survival rate of infected fish, probably through the enhancement of immunity before challenge bioassays. The available data, however, lack dosage optimization, toxicity and bioavailability assays of a specific plant or its bioactive compound in fish organs; hence, it is difficult to judge the validation of clinical efficacy for the prevention or treatment of fish streptococcosis. Despite the known bioactive compounds of many tested plants, few data are available on their mode of action towards streptococcal agents. This review addresses the efficacy of medicinal plants to fish streptococcosis and discusses the current gaps. Full article
(This article belongs to the Special Issue Bacterial and Viral Diseases in Aquatic Animals)
Back to TopTop