Topical Lactobacillus applications for modulation of the vaginal and skin microbiota

Date: 25 March 2019

Venue: UAntwerpen, Stadscampus, Promotiezaal "De Grauwzusters" - Lange Sint-Annastraat 7 - 2000 Antwerpen (route: UAntwerpen, Stadscampus)

Time: 5:00 PM

Organization / co-organization: Department of Bioscience Engineering

PhD candidate: Eline Oerlemans

Principal investigator: Sarah Lebeer & Gilbert Donders

Short description: PhD defence Eline Oerlemans - Faculty of Science, Department of Bioscience Engineering


On and in our bodies, we carry a large collection of micro-organisms, often referred to as the microbiota. Although many associate bacteria and yeasts often with infection, the majority of the members of these microbial communities are harmless or even have a positive effect on our health. In various pathologies, the balance between the beneficial and the potentially harmful microorganisms is disturbed. In this thesis, we studied two vaginal and one dermatological pathologies and investigated whether supplementation of Lactobacillus strains, often associated with health promoting effects, could alleviate the studied conditions.

In a first experimental chapter, the composition and abundance of the microbiome of aerobic vaginitis is described. This underexplored vaginal condition is associated with severe symptoms and general health treats. Although the microbiota of its microbial counterpart, bacterial vaginosis, has been studied extensively, molecular analysis of the aerobic vaginitis microbiome has been lagging behind. In these two vaginal conditions, the microbiome deviates from the normally encountered abundance of healthy lactobacilli. In contrast, the microbiota in vulvovaginal candidosis, the focus of next experimental chapter, was previously suggested to remain relatively unchanged. However, because we hypothesized that the activity and functionality of the endogenous lactobacilli could be (temporarily) inhibited by the Candida infections, here, exogenous lactobacilli other than typical vaginal taxa were screened and selected for the development of a probiotic gel for vaginal use. The effect of this gel on the vaginal bacteriome and mycobiome was evaluated in a proof-of-concept clinical trial in patients with acute vulvovaginal candidosis.

As lactobacilli have been shown to hold probiotic potential in the vaginal conditions mentioned above and since we realized that our collection contained not enough endogenous Lactobacillus isolates, various lactobacilli were isolated from vaginal samples of the previous chapters. We evaluated relevant characteristics for application, such as growth speed and lack of antibiotic resistance genes, and possible beneficial functions, such as an antipathogenic effect on Streptococcus agalacticae, a vaginal pathobiont and important cause of neonatal infections.

In the last experimental chapter, we could show a clear association between vaginal lactobacilli and the Lactobacillus taxa found on the skin. In addition, a facial cream was developed containing live lactobacilli, which was developed with a reduction of acne symptoms as purpose. This chapter describes the selection of the Lactobacillus strains, the formulation of the cream and the microbiome of healthy controls and acne patients, before, during and after treatment with the cream.