Genomic analysis of group B Streptococcus from milk demonstrates the need for improved biosecurity: a cross-sectional study of pastoralist camels in Kenya

Seligsohn, D., Crestani, C., Forde, T. L. , Chenais, E. and Zadoks, R. N. (2021) Genomic analysis of group B Streptococcus from milk demonstrates the need for improved biosecurity: a cross-sectional study of pastoralist camels in Kenya. BMC Microbiology, 21, 217. (doi: 10.1186/s12866-021-02228-9) (PMID:34281509) (PMCID:PMC8287776)

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Abstract

Background: Streptococcus agalactiae (Group B Streptococcus, (GBS)) is the leading cause of mastitis (inflammation of the mammary gland) among dairy camels in Sub-Saharan Africa, with negative implications for milk production and quality and animal welfare. Camel milk is often consumed raw and presence of GBS in milk may pose a public health threat. Little is known about the population structure or virulence factors of camel GBS. We investigated the molecular epidemiology of camel GBS and its implications for mastitis control and public health. Results: Using whole genome sequencing, we analysed 65 camel milk GBS isolates from 19 herds in Isiolo, Kenya. Six sequence types (STs) were identified, mostly belonging to previously described camel-specific STs. One isolate belonged to ST1, a predominantly human-associated lineage, possibly as a result of interspecies transmission. Most (54/65) isolates belonged to ST616, indicative of contagious transmission. Phylogenetic analysis of GBS core genomes showed similar levels of heterogeneity within- and between herds, suggesting ongoing between-herd transmission. The lactose operon, a marker of GBS adaptation to the mammary niche, was found in 75 % of the isolates, and tetracycline resistance gene tet(M) in all but two isolates. Only the ST1 isolate harboured virulence genes scpB and lmb, which are associated with human host adaptation. Conclusions: GBS in milk from Kenyan camel herds largely belongs to ST616 and shows signatures of adaptation to the udder. The finding of similar levels of within- and between herd heterogeneity of GBS in camel herds, as well as potential human-camel transmission highlights the need for improved internal as well as external biosecurity to curb disease transmission and increase milk production.

Item Type:Articles
Additional Information:This study was funded by the Swedish Research Council [grant number VR2015_03583].
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Zadoks, Professor Ruth and Forde, Dr Taya and Crestani, Miss Chiara
Authors: Seligsohn, D., Crestani, C., Forde, T. L., Chenais, E., and Zadoks, R. N.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:BMC Microbiology
Publisher:BioMed Central
ISSN:1471-2180
ISSN (Online):1471-2180
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in BMC Microbiology 21: 217
Publisher Policy:Reproduced under a Creative Commons License

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