Phenotypic changes in group B streptococci grown in the presence of the polyols, erythritol, sorbitol and mannitol

Maram Hulbah,Matthew A Croxen,Gregory J Tyrrell

doi:10.1186/s12866-021-02208-z

Maram Hulbah, Matthew A Croxen + Show 1 more

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https://doi.org/10.1186/s12866-021-02208-z

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Journal: BMC microbiology	Publication Date: May 13, 2021
Citations: 1	License type: open-access

Affiliation: Taif University, University of Alberta

Abstract

BackgroundGroup B streptococci (GBS) are important neonatal bacterial pathogens that can cause severe invasive disease in the newborn. It is thought that in many cases of invasive neonatal GBS disease, the bacteria ascend the vagina into the uterus and infect the amniotic fluid surrounding the fetus. Important constituents of this environment include the polyols or sugar alcohols of which erythritol, sorbitol and mannitol are examples. The aim of our study was to investigate the effect of polyols on GBS grown in media containing these sugar alcohols.ResultsGBS incubated in varying concentrations of polyols (erythritol, sorbitol or mannitol) did not display any significant enhancement or inhibition of bacterial growth. However, growth of GBS in the presence of erythritol significantly increased the surface expression of GBS-PGK (a plasminogen binding protein) 1.25 to 1.5-fold depending on the erythritol concentration and significantly enhanced the survival in human blood 3X to 18X depending on the concentration of polyol used. Interestingly, GBS grown in 1% erythritol significantly increased invasion by the bacteria of HeLa cells (epithelial cell line) (150% vs 100%) however, at higher concentrations (2% or 4% of polyol) the number of CFUs was significantly reduced (55-75% vs 100%) suggesting higher concentrations of polyols may inhibit invasion. Erythritol also increased GBS hemolytic activity as well as enhancing biofilm formation 1.4X to 3.3X depending on the concentration of polyol used.ConclusionsGBS grown in the presence of polyols alters the bacteria’s phenotype resulting in changes associated with GBS virulence. This effect was greatest for the polyol erythritol.

Highlights

Group B streptococci (GBS) are important neonatal bacterial pathogens that can cause severe invasive disease in the newborn
Expression of Phosphoglycerate kinase (PGK) on the surface of GBS-S19 treated with polyols We have previously shown that GBS can express PGK on its surface in addition to intracellular expression [28]
GBS-S19 cultured in the presence of 1, 2%, or 4% erythritol significantly increased surface expression of GBS phosphoglycerate kinase (GBS-PGK) (1.25 to 1.5fold) compared to growth without erythritol (p = 0.003, p = 0.012, p = 0.014) (Fig. 2)

Summary

Introduction

Group B streptococci (GBS) are important neonatal bacterial pathogens that can cause severe invasive disease in the newborn. It is thought that in many cases of invasive neonatal GBS disease, the bacteria ascend the vagina into the uterus and infect the amniotic fluid surrounding the fetus. Important constituents of this environment include the polyols or sugar alcohols of which erythritol, sorbitol and mannitol are examples. Hulbah et al BMC Microbiology (2021) 21:145 naturally from fruits and can be commercially produced [7,8,9] Due to their lower caloric content compared to sugars, polyols are added to food, candies and chewing gum [10]. Polyols have been suggested to have preventive properties against caries and several studies have shown that polyols can decrease polysaccharide-producing oral streptococci glass surface adhesion and biofilm formation [12,13,14,15,16,17,18,19]

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