Microbiota in vitro modulated with polyphenols shows decreased colonization resistance against Clostridioides difficile but can neutralize cytotoxicity

Aleksander Mahnic,Jennifer M Auchtung,Nataša Poklar Ulrih,Robert A Britton,Maja Rupnik

doi:10.1038/s41598-020-65253-0

Abstract

While the knowledge on gut microbiota - C. difficile interactions has improved over the years, the understanding of the underlying mechanisms providing colonization resistance as well as preventative measures against the infection remain incomplete. In this study the antibiotic clindamycin and polyphenol extracts from pomegranate and blueberries were used individually and in combination to modulate fecal microbial communities in minibioreactor arrays (MBRA). Modulated communities were inoculated with C. difficile (ribotype 027). Subsequent 7-day periodical monitoring included evaluation of C. difficile growth and activity of toxins TcdA and TcdB as well as analysis of MBRA bacterial community structure (V3V4 16 S metagenomics). Polyphenols affected multiple commensal bacterial groups and showed different synergistic and antagonistic effects in combination with clindamycin. Exposure to either clindamycin or polyphenols led to the loss of colonization resistance against C. difficile. The successful growth of C. difficile was most significantly correlated with the decrease in Collinsella and Lachnospiraceae. Additionally, we demonstrated that Clostridium sporogenes decreased the activity of both C. difficile toxins TcdA and TcdB. The feature was shown to be common among distinct C. sporogenes strains and could potentially be applicable as a non-antibiotic agent for the alleviation of C. difficile infection.

Highlights

Clostridioides difficile infection (CDI) is a toxin mediated inflammation leading to diarrhoea and colitis, most commonly occurring in the hospital environment
A prior study using the minibioreactor arrays (MBRA) system reported the decrease or disappearance of certain Clostridiales members including Faecalibacterium during the growth under similar continuous culture conditions, in this case Akkermansia successfully grew in the system[24]
Most noteworthy we found bacterial groups which were decreased after the exposure to clindamycin alone but were unaffected when polyphenolic extracts (PE) were used in combination with clindamycin

Summary

Introduction

Clostridioides difficile infection (CDI) is a toxin mediated inflammation leading to diarrhoea and colitis, most commonly occurring in the hospital environment. Polyphenols are secondary plant metabolites found in abundance in food including different fruits, vegetables, seeds and herbs as well as in drinks such as coffee, tea and wine[13] They are currently extensively researched because of their anti-oxidant and anti-inflammatory properties[14], and exhibit beneficial effects on commensal www.nature.com/scientificreports bacterial groups while inhibiting the growth of potential pathogens, including C. difficile[15,16]. Both blueberry and pomegranate extracts used in this study were previously reported to promote the growth of gut commensal bacteria and inhibit potential pathogens[17,18,19] or modulate gut community towards beneficial outcomes[20,21,22]. The in vitro system (MBRA) used in this study was previously shown to be suitable for studies concerning C. difficile – microbiota interactions[23]

Objectives

Methods

Results

Conclusion