ERAfrica Safe Dairy – Health hazards caused by bacteria in traditional African fermented dairy products: Food safety and epidemiology

Fermentation of dairy products plays an important role for extended shelf life, microbial safety and general nutrition, and in particular for the preparation of weaning food for children, and has a long tradition in many African regions. However the low quality of milk and uncontrolled and unhygienic fermentation processes lead to frequent contamination with foodborne pathogens, including Escherichia coli, Streptococcus agalactiae, Staphylococcus aureus and Listeria spp.

We have previously shown that traditional fermented dairy products (FDP) in different regions of Africa (Kenya, Somalia, Mali, Sudan, Côte d’Ivoire and Sahel area) are fermented by dairy adapted strains of Streptococcus infantarius subsp. infantarius (Sii). Functional analysis and comparative genomics also suggest adaptation to the dairy environment paralleling that of the Western dairy species Streptococcus thermophilus. Sii is a member of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) which has been associated with human and animal infections, including endocarditis, bacteremia and colonic cancer. Sii strains in FDP may represent a significant health risk to African populations who consume spontaneously fermented FDP.

In this project, we aim to investigate health risk of Sii isolated in African FDP by comparing with Sii strains isolated from infections to elucidate a possible epidemiologic link. The project is carried out in Kenya and Côte d’Ivoire. Epidemiologic data will be obtained through case-control study in regional hospitals in combination with the isolation of clinical Sii and SBSEC strains. Isolates will be genotypically characterized and screened for relevant pathogenic factors. We also aim to contribute to develop adapted technologies (e.g. starter culture, milk pretreatment) to enhance the quality and safety of traditional FDPs, and especially fermented weaning food for infants.

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