Challenges in culture-negative cases of Madurella mycetomatis: A case report re-accentuating PCR as an essential diagnostic tool

Identifying novel drugs with new modes of action for neglected tropical fungal skin diseases (fungal skinNTDs) using an Open Source Drug discovery approach

INTRODUCTION

The three fungal skin neglected tropical diseases (NTD) mycetoma, chromoblastomycosis and sporotrichosis currently lack prioritization and support to establish drug discovery programs in search for novel treatment options. This has made the efforts to identify novel drugs for these skinNTDs fragmented.

AREAS COVERED

To help escalate the discovery of novel drugs to treat these fungal skinNTDs, the authors have prepared an overview of the compounds with activity against fungal skinNTDs by analyzing data from individual drug discovery studies including those performed on the Medicines for Malaria Venture (MMV) open access boxes.

EXPERT OPINION

The authors were unable to identify studies in which causative agents of all three skinNTDs were included, indicating that an integrated approach is currently lacking. From the currently available data, the azoles and iodoquinol were the only compounds with activity against causative agents from the three different fungal skinNTDs. Fungal melanin inhibition enhanced the activity of antifungal agents. For mycetoma, the fenarimols, aminothiazoles and benzimidazole carbamates are currently being investigated in the MycetOS initiative. To come to a more integrated approach to identify drugs active against all three fungal skinNTDs, compounds made in the MycetOS initiative could also be explored for chromoblastomycosis and sporotrichosis.

The genus Madurella: Molecular identification and epidemiology in Sudan

Eumycetoma (mycotic mycetoma) is the fungal form of mycetoma, a subcutaneous infection occurring in individuals living in endemic areas of the disease. The Sudan is hyperendemic for mycetoma, with the highest incidence being reported from Gezira State, Central Sudan. The present study was conducted at the Gezira Mycetoma Center and aimed to determine the cause of black-grain eumycetoma in the state and describe its epidemiology. Black-grain specimens were collected during the surgical operation and direct detection of the causative agent was performed using M. mycetomatis species-specific PCR and ITS PCR followed by sequencing. Black-grain was reported from 93.3% of all confirmed mycetoma cases (n = 111/119), with a prevalence in young males. Of the 91 samples subjected to direct PCR, 90.1% (n = 82) gave positive results. The predominant species (88.2%) was Madurella mycetomatis. One sample was identified as M. fahalii, one as M. tropicana, and one matched the phytopathogenic species Sphaerulina rhododendricola. The highest endemic zones were Southern Gezira (76.6%) and Northern Sinnar (23.4%). The study confirmed that direct molecular detection on grains provides rapid and specific diagnosis of agents of eumycetoma.

Eumycetoma is a neglected fungal disease endemic in Africa, India, and Latin America. Black-grain eumycetoma is the most common type in Africa and is mainly caused by Madurella spp. The Sudan, and in particular Gezira State, central Sudan is hyperendemic for black-grain eumycetoma. Patients with this type of mycetoma are treated with surgery in combination with antifungal therapy. In this study, we collected surgical biopsies from patients attending Gezira Mycetoma Center to directly identify the etiology of black-grain eumycetoma in this state. We also studied the epidemiology of the disease based on the demography of the patients’ population. Our result showed that the highest endemic regions were Southern Gezira (76.6%) and Northern Sinnar (23.4%). By applying direct PCR and sequencing we confirmed that the most common etiology of the disease is Madurella mycetomatis (88.2%). In addition, we found one case of M. fahalii and the first Sudanese case of M. tropicana and Sphaerulina rhododendricola.