Geographical, Temporal and Host-Species Distribution of Potentially Human-Pathogenic Group B Streptococcus in Aquaculture Species in Southeast Asia

Wanna Sirimanapong; Nguyễn Ngọc Phước; Chiara Crestani; Swaine Chen; Ruth N Zadoks

doi:10.3390/pathogens12040525

Geographical, Temporal and Host-Species Distribution of Potentially Human-Pathogenic Group B Streptococcus in Aquaculture Species in Southeast Asia

Pathogens. 2023 Mar 28;12(4):525. doi: 10.3390/pathogens12040525.

Authors

Wanna Sirimanapong¹, Nguyễn Ngọc Phước², Chiara Crestani³, Swaine Chen⁴, Ruth N Zadoks⁵

Affiliations

¹ Veterinary Aquatic Animal Research Health Care Unit, Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand.
² Faculty of Fisheries, University of Agriculture and Forestry, Hue University, Hue City 53000, Vietnam.
³ Laboratory of Biodiversity and Epidemiology of Bacterial Pathogens, Institut Pasteur, 75015 Paris, France.
⁴ Infectious Diseases Group, Genome Institute of Singapore, Singapore 138672, Singapore.
⁵ Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Camden, NSW 2570, Australia.

Abstract

Group B Streptococcus (GBS) is a major pathogen of humans and aquatic species. Fish have recently been recognized as the source of severe invasive foodborne GBS disease, caused by sequence type (ST) 283, in otherwise healthy adults in Southeast Asia. Thailand and Vietnam are among the major aquaculture producers in Southeast Asia, with GBS disease reported in fish as well as frogs in both countries. Still, the distribution of potentially human-pathogenic GBS in aquaculture species is poorly known. Using 35 GBS isolates from aquatic species in Thailand collected from 2007 to 2019 and 43 isolates from tilapia collected in Vietnam in 2018 and 2019, we have demonstrated that the temporal, geographical, and host-species distribution of GBS ST283 is broader than previously known, whereas the distribution of ST7 and the poikilothermic lineage of GBS are geographically restricted. The gene encoding the human GBS virulence factor C5a peptidase, scpB, was detected in aquatic ST283 from Thailand but not in ST283 from Vietnam or in ST7 from either country, mirroring current reports of GBS strains associated with human sepsis. The observed distribution of strains and virulence genes is likely to reflect a combination of spill-over, host adaptation through the gain and loss of mobile genetic elements, and current biosecurity practices. The plastic nature of the GBS genome and its importance as a human, aquatic, and potentially foodborne pathogen suggests that active surveillance of GBS presence and its evolution in aquaculture systems may be justified.

Keywords: ST283; Streptococcus agalactiae; host-adaptation; zoonosis.

Grants and funding

The collaboration culminating in this study was funded by the Academy of Medical Sciences, UK, through a Global Challenges Research Fund (GCRF) Networking Grant (to N.N.P. and R.N.Z.); by the University of Glasgow’s GCRF Small Grants Fund, an initiative supported by an allocation of Global Challenges Research Fund from the Scottish Funding Council under agreement SFC/AN/10/2018 (to R.N.Z.); and by the University of Glasgow College of Medical, Veterinary and Life Sciences Doctoral Training Programme 2017–2021 (to C.C.). S.C. was supported by the National Medical Research Council, Ministry of Health, Singapore (grants NMRC/CIRG/1467/2017 and CIRG19NOV-0024); the Temasek Foundation Innovates through its Singapore Millennium Foundation Research Grant Programme; and the Genome Institute of Singapore (GIS)/Agency for Science, Technology and Research (A*STAR).