Risk factors for the carriage of Streptococcus infantarius subspecies infantarius isolated from African fermented dairy products

Abstract

Streptococcus infantarius subsp. infantarius (Sii) has been identified as predominant lactic acid bacteria in spontaneously fermented dairy products (FDPs) in sub-Saharan Africa including Côte d'Ivoire. However, Sii belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC). Most SBSEC members are assumed to be involved as opportunistic pathogens in serious diseases in both humans and animals. A population-based cross-sectional survey, including 385 participants was conducted in Korhogo, northern Côte d'Ivoire, to identify risk factors for Sii fecal carriage, including consumption of local FDPs. A structured questionnaire was used to gather participant's socio-demographic and economic characteristics, their relation to livestock and dietary habits. In addition, fresh stool and milk samples were collected. The identification of Sii was done using a SBSEC-specific PCR assay targeting 16S rRNA and groEL genes. The overall prevalence of SBSEC and Sii carriage was 23.2% (confidence interval CI 95% = 18.9–27.5) and 12.0% (CI 95% = 8.4–15.5) for stool, respectively. Prevalence of Sii was significantly higher in consumers of artisanal butter compared with non-consumers (57.1% vs 10.1%, odds ratio OR: 11.9, 95% CI: 3.9–36.6), as well as in persons handling livestock (OR = 3.9; 95% CI = 1.6–9.3) and livestock primary products (OR = 5.7; 95% CI = 2.3–14.3). The closer contact with livestock was a risk factor for Sii fecal carriage. Sii strains were isolated from fresh and fermented milk products with a prevalence of 30.4% and 45.4%, respectively. Analysis of Sii population structure through the SBSEC multi locus sequence typing assay revealed a close relationship across human and dairy isolates, possibly linked to a Kenyan human isolate. All these outcomes underline the interest of in-depth investigations on the ecology, potential reservoirs and pathways of contamination by Sii at the human-animal-environment interface in comparison to yet to be collected data from Europe, Asia and the Americas to further elucidate the various roles of Sii.

Colonization Ability and Impact on Human Gut Microbiota of Foodborne Microbes From Traditional or Probiotic-Added Fermented Foods: A Systematic Review

“…More specifically, the overall fecal carriage rate of the foodborne microbe Streptococcus infantarius subsp. infantarius (Sii) in consumers of local dairy foods was similar to that of non-consumers, but significantly higher prevalence was found in consumers of artisanal butter, as well as in persons handling livestock and livestock primary products ( 89 ). The study by van de Pol et al observed that Methanobrevibacter smithii , which was also detected in the milk consumed by the subjects, could be recovered in the feces of almost all of the recruited children (78.2%), indicating that consumption of multiple different dairy products might be associated with increased presence of M. smithii in the gut ( 102 ).…”

“…In addition, 3 studies applied other molecular techniques such as T-RFLP, RAPD-PCR, and DGGE. Finally, 1 of the studies applied the Streptococcus bovis / Streptococcus equinus complex (SBSEC)-specific PCR assay on colonies isolated on selective media, with primers targeting the 16S rDNA and groEL genes ( 89 ).…”

Traditional milk transformation schemes in Côte d’Ivoire and their impact on the prevalence of Streptococcus bovis complex bacteria in dairy products

“…The finding of high overall prevalence of SBSEC strains in spontaneously FDP and unfermented milk samples adds the area of Korhogo in northern Côte d'Ivoire to the places of confirmed Sii and SBSEC presence in West Africa in addition to Mali and Abidjan area of Côte d'Ivoire [9,10]. This high overall prevalence might contribute to livestock and livestock primary product contact and rural habitat as indicators for Sii faecal carriage in humans [19]. Given the transhumant populations and cross-border trade in northern Côte d'Ivoire, this supports the postulated hypothesis of an even wider distribution of Sii across sub-Saharan Africa [1].…”

“…However, the close relationship of certain West African dairy Sii with East African human strains and for some strains also with human blood isolates requires enhanced knowledge of Sii prevalence, population structure and potential reservoirs particularly in West Africa [18]. The identification of close contact with livestock and livestock primary products as well as rural habitats as indicators for faecal carriage of Sii in humans [19] raises interest in the prevalence of Sii in the traditional milk transformation schemes and the production processes associated with them.…”

Characterization of Lactic Acid Bacteria in Pecorino DI Farindola Cheese and Manufacturing with a Lacticaseibacillus Paracasei Autochthonous Culture

“…L. garviae, Streptococcus infantarius and S. lutetiensis, that can cause infections in humans 82 [41,42] but can carry beneficial characters and be devoid of virulence traits at the strain 83 level [43,44].…”