Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jun;44(6):747-756.
doi: 10.1111/jfd.13296. Epub 2020 Dec 3.

Phenotype, genotype and pathogenicity of Streptococcus agalactiae isolated from cultured tilapia (Oreochromis spp.) in Taiwan

Chiranan Sudpraseart  1 , Pei-Chi Wang  1   2   3 , Shih-Chu Chen  1   2   3   4
Affiliations

Phenotype, genotype and pathogenicity of Streptococcus agalactiae isolated from cultured tilapia (Oreochromis spp.) in Taiwan

Chiranan Sudpraseart et al. J Fish Dis. 2021 Jun.

Abstract

Tilapia (Oreochromis spp.) is globally used as an aquaculture fish species due to its high growth rate and disease resistance. However, it faces an increased risk of streptococcosis. Streptococcus agalactiae, also known as group B streptococcus (GBS), is the most important tilapia pathogen in Asia. Studies of Str. agalactiae infection in Taiwan are still unclear. Thus, this study aimed to explore the phenotype, genotype and pathogenicity of Str. agalactiae isolated from cultured tilapia in Taiwan in 2016-2018. The analysis revealed that 85% of the strains displayed β-haemolysis and 15% showed γ-haemolysis, with the same capsule level, and were positive for the CAMP test. The Rapid ID 32 Strep test showed a similarity of Rapid ID 32 Strep is more than 99.5% to GBS. Genotypic distribution by molecular serotyping detected only serotype Ia from all isolates, despite the regional differences. Pulsed-field gel electrophoresis (PFGE) was categorized into 3 and 10 clusters by restriction enzymes SmaI and ApaI, respectively. Virulence genes and antimicrobial resistance genes presented the same profile in all isolates. The challenge test with 106 CFU/fish (LD50 ), administered intraperitoneally, showed that the β-haemolysis strains had a higher mortality rate than γ-haemolysis, although they were from the same cluster from PFGE, year and region.

Keywords: Streptococcus agalactiae; PFGE; cultured tilapia; genotype; pathogenicity; phenotype.

PubMed Disclaimer

References

REFERENCES

    1. Azmai, M. N. A., & Saad, M. (2011). Streptococcosis in tilapia (Oreochromis niloticus): A review. Journal of Tropical Agricultural Science, 34, 195-206.
    1. Brochet, M., Couvé, E., Zouine, M., Vallaeys, T., Rusniok, C., Lamy, M. C., Buchrieser, C., Trieu-Cuot, P., Kunst, F., Poyart, C., & Glaser, P. (2006). Genomic diversity and evolution within the species Streptococcus agalactiae. Microbes and Infection, 8(5), 1227-1243. https://doi.org/10.1016/j.micinf.2005.11.010
    1. Brodeur, B. R., Boyer, M., Charlebois, I., Hamel, J., Couture, F., Rioux, C. R., & Martin, D. (2000). Identification of Group B Streptococcal Sip Protein, which elicits cross-protective immunity. Infection and Immunity, 68(10), 5610-5618. https://doi.org/10.1128/IAI.68.10.5610-5618.2000
    1. Chen, M., Wang, R., Luo, F.-G., Huang, Y., Liang, W.-W., Huang, T., Lei, A.-Y., Gan, X.-L., & Li, L.-P. (2015). Streptococcus agalactiae isolates of serotypes Ia, III and V from human and cow are able to infect tilapia. Veterinary Microbiology, 180, 129-135. https://doi.org/10.1016/j.vetmic.2015.07.033
    1. Chen, S. L. (2019). Genomic insights into the distribution and evolution of Group B Streptococcus. Frontiers in Microbiology, 10, 1447. https://doi.org/10.3389/fmicb.2019.01447

LinkOut - more resources