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Research article - Peer-reviewed, 2021

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

Seligsohn, Dinah; Crestani, Chiara; Gitahi, Nduhiu; Flodin, Emelie Lejon; Chenais, Erika; Zadoks, Ruth N.

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.

Published in

PLoS ONE
2021, volume: 16, number: 12, article number: e0252973
Publisher: PUBLIC LIBRARY SCIENCE

Authors' information

Seligsohn, Dinah
National Veterinary Institute (SVA)
Seligsohn, Dinah
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Crestani, Chiara
University of Glasgow
Gitahi, Nduhiu
University of Nairobi
Lejon Flodin, Emelie
Uppsala Veterinärmottagning
Chenais, Erika
National Veterinary Institute SVA
Zadoks, Ruth N.
University of Sydney
Zadoks, Ruth N.
University of Glasgow

UK√Ą Subject classification

Clinical Science

Publication Identifiers

DOI: https://doi.org/10.1371/journal.pone.0252973

URI (permanent link to this page)

https://res.slu.se/id/publ/116209