Phage Therapy Is Effective against Infection by Mycobacterium ulcerans in a Murine Footpad Model

Gabriela Trigo,Joana Azeredo,Alexandra G Fraga,Adhemar Longatto-Filho,Jorge Pedrosa,António G Castro,Teresa G Martins,Christian Johnson

doi:10.1371/journal.pntd.0002183

Abstract

BackgroundBuruli Ulcer (BU) is a neglected, necrotizing skin disease caused by Mycobacterium ulcerans. Currently, there is no vaccine against M. ulcerans infection. Although the World Health Organization recommends a combination of rifampicin and streptomycin for the treatment of BU, clinical management of advanced stages is still based on the surgical resection of infected skin. The use of bacteriophages for the control of bacterial infections has been considered as an alternative or to be used in association with antibiotherapy. Additionally, the mycobacteriophage D29 has previously been shown to display lytic activity against M. ulcerans isolates.Methodology/Principal findingsWe used the mouse footpad model of M. ulcerans infection to evaluate the therapeutic efficacy of treatment with mycobacteriophage D29. Analyses of macroscopic lesions, bacterial burdens, histology and cytokine production were performed in both M. ulcerans-infected footpads and draining lymph nodes (DLN). We have demonstrated that a single subcutaneous injection of the mycobacteriophage D29, administered 33 days after bacterial challenge, was sufficient to decrease pathology and to prevent ulceration. This protection resulted in a significant reduction of M. ulcerans numbers accompanied by an increase of cytokine levels (including IFN-γ), both in footpads and DLN. Additionally, mycobacteriophage D29 treatment induced a cellular infiltrate of a lymphocytic/macrophagic profile.Conclusions/SignificanceOur observations demonstrate the potential of phage therapy against M. ulcerans infection, paving the way for future studies aiming at the development of novel phage-related therapeutic approaches against BU.

Highlights

Buruli Ulcer (BU), caused by Mycobacterium ulcerans, is an emerging, devastating skin disease reported in more than 30 countries, mainly in West Africa [1,2]
Standard treatment of BU patients consists of a combination of the antibiotics rifampicin and streptomycin for 8 weeks
The use of bacterial viruses for the control of bacterial infections has been considered as an alternative or a supplement to antibiotic chemotherapy

Summary

Introduction

Buruli Ulcer (BU), caused by Mycobacterium ulcerans, is an emerging, devastating skin disease reported in more than 30 countries, mainly in West Africa [1,2]. Since 2004, the World Health Organization (WHO) recommends the treatment of BU with a combination of rifampicin and streptomycin (RS) [11]. This treatment presents several limitations: (i) it does not resolve extensive lesions (as a result, surgery is the only alternative) [12]; (ii) the long period of administration of streptomycin by muscular injection demands skilled personnel; (iii) it is associated with adverse side effects [13,14] leading to poor compliance; and (iv) importantly, it may lead to the occurrence of paradoxical reactions associated with the worsening of the lesion and/or the appearance of new lesions [14,15,16,17,18]. Buruli Ulcer (BU) is a neglected, necrotizing skin disease caused by Mycobacterium ulcerans. The World Health Organization recommends a combination of rifampicin and streptomycin for the treatment of BU, clinical management of advanced stages is still based on the surgical resection of infected skin. The mycobacteriophage D29 has previously been shown to display lytic activity against M. ulcerans isolates

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