In-Vitro Archaeacidal Activity of Biocides against Human-Associated Archaea

Saber Khelaifia,Michel Drancourt,Jean Brunel Michel

doi:10.1371/journal.pone.0062738

Abstract

BackgroundSeveral methanogenic archaea have been detected in the human intestinal microbiota. These intestinal archaea may contaminate medical devices such as colonoscopes. However, no biocide activity has been reported among these human-associated archaea.MethodologyThe minimal archaeacidal concentration (MAC) of peracetic acid, chlorhexidine, squalamine and twelve parent synthetic derivatives reported in this study was determined against five human-associated methanogenic archaea including Methanobrevibacter smithii, Methanobrevibacter oralis, Methanobrevibacter arboriphilicus, Methanosphaera stadtmanae, Methanomassiliicoccus luminyensis and two environmental methanogens Methanobacterium beijingense and Methanosaeta concilii by using a serial dilution technique in Hungates tubes.Principal FindingsMAC of squalamine derivative S1 was 0.05 mg/L against M. smithii strains, M. oralis, M. arboriphilicus, M. concilii and M. beijingense whereas MAC of squalamine and derivatives S2–S12 varied from 0.5 to 5 mg/L. For M. stadtmanae and M. luminyensis, MAC of derivative S1 was 0.1 mg/L and varied from 1 to ≥10 mg/L for squalamine and its parent derivatives S2–S12. Under the same experimental conditions, chlorhexidine and peracetic acid lead to a MAC of 0.2 and 1.5 mg/L, respectively against all tested archaea.Conclusions/SignificanceSqualamine derivative S1 exhibited a 10–200 higher archaeacidal activity than other tested squalamine derivatives, on the majority of human-associated archaea. As previously reported and due to their week corrosivity and their wide spectrum of antibacterial and antifungal properties, squalamine and more precisely derivative S1 appear as promising compounds to be further tested for the decontamination of medical devices contaminated by human-associated archaea.

Highlights

An increasing number of methanogenic archaea are being found in the human microbiota [1]
It has been shown that purge used prior to colonoscopy, may not eliminate these particular methanogenic archaea: for instance, halophilic and methanogenic archaea M. smithii, M. stadtmanae, M. arboriphilicus and Methanosaeta concilii [12] were detected in colonic mucosal biopsies from patients who had received a purge [13]
All the positive control cultures of M. smithii, M. oralis, M. arboriphilicus, M. stadtmanae, M. luminyensis, M. beijingense and M. concilii incubated without biocide grew as expected with a methane production starting at day 3

Summary

Introduction

An increasing number of methanogenic archaea are being found in the human microbiota [1]. Since Miller and collaborators reported the isolation of methanogenic archaea Methanobrevibacter smithii [2] from human feces, new strains were recently identified. It has been shown that purge used prior to colonoscopy, may not eliminate these particular methanogenic archaea: for instance, halophilic and methanogenic archaea M. smithii, M. stadtmanae, M. arboriphilicus and Methanosaeta concilii [12] were detected in colonic mucosal biopsies from patients who had received a purge [13]. These human-associated archaea may contaminate any medical device soiled by feces such as colonoscopes. No biocide activity has been reported among these human-associated archaea

Methods

Results

Conclusion