Investigation of extramammary sources of Group B Streptococcus reveals its unusual ecology and epidemiology in camels

Seligsohn, D., Crestani, C., Gitahi, N., Lejon Flodin, E., Chenais, E. and Zadoks, R. N. (2021) Investigation of extramammary sources of Group B Streptococcus reveals its unusual ecology and epidemiology in camels. PLoS ONE, 16(12), e0252973. (doi: 10.1371/journal.pone.0252973) (PMID:34860840) (PMCID:PMC8641886)

Abstract

Camels are vital to food production in the drylands of the Horn of Africa, with milk as their main contribution to food security. A major constraint to camel milk production is mastitis, inflammation of the mammary gland. The condition negatively impacts milk yield and quality as well as household income. A leading cause of mastitis in dairy camels is Streptococcus agalactiae, or group B Streptococcus (GBS), which is also a commensal and pathogen of humans and cattle. It has been suggested that extramammary reservoirs for this pathogen may contribute to the occurrence of mastitis in camels. We explored the molecular epidemiology of GBS in camels using a cross-sectional study design for sample collection and phenotypic, genomic and phylogenetic analysis of isolates. Among 88 adult camels and 93 calves from six herds in Laikipia County, Kenya, GBS was detected in 20% of 50 milk samples, 25% of 152 nasal swabs, 8% of 90 oral swabs and 3% of 90 rectal swabs, but not in vaginal swabs. Per camel herd, two to four sequence types (ST) were identified using Multi Locus Sequence Typing (MLST). More than half of the isolates belonged to ST617 or its single-locus variant, ST1652, with these STs found across all sample types. Capsular serotype VI was detected in 30 of 58 isolates. In three herds, identical STs were detected in milk and swab samples, suggesting that extramammary sources of GBS may contribute to the maintenance and spread of GBS within camel herds. This needs to be considered when developing prevention and control strategies for GBS mastitis. The high nasal carriage rate, low recto-vaginal carriage rate, and high prevalence of serotype VI for GBS in camels are in stark contrast to the distribution of GBS in humans and in cattle and reveal hitherto unknown ecological and molecular features of this bacterial species.

• Item Type: Articles
• Additional Information: This study was funded by the Swedish Research Council [grant number VR2015_03583] (https://www.vr.se/) awarded to EC.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Zadoks, Professor Ruth and Crestani, Miss Chiara

Creator Roles

Crestani, C.: Formal analysis, Visualization, Writing – original draft, Writing – review and editing
Zadoks, R. N.: Supervision, Writing – review and editing

• Authors: Seligsohn, D., Crestani, C., Gitahi, N., Lejon Flodin, E., Chenais, E., and Zadoks, R. N.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Copyright Holders: Copyright © 2021 Seligsohn et al.
• First Published: First published in PLoS ONE 16(12): e0252973
• Publisher Policy: Reproduced under a Creative Commons License