Molecular Diagnosis of Two Major Implantation Mycoses: Chromoblastomycosis and Sporotrichosis

Abstract

Chromoblastomycosis and sporotrichosis are the two main implantation mycoses that are now recognized as fungal neglected tropical diseases (NTDs). Their laboratory diagnosis mainly relies on direct microscopy, histopathology, and identification of the fungus by culture. However, to be appropriately used, these techniques require mycological expertise that is not widely available and may be absent in peripheral health care facilities in endemic areas. In addition, they lack sensitivity and specificity, and the culture for isolation and identification can have a long time-to-results period. Molecular methods, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), have been developed in well-equipped reference laboratories. They greatly improve the rapidity and accuracy of diagnosis; in particular, for species identification. Recently, PCR and sequencing have paved the way for more user-friendly point-of-care tests, such as those based on LAMP or RCA technologies, which can be used in basic healthcare settings and even in field consultations.

Keywords: MALDI-TOF MS; PCR; chromoblastomycosis; isothermal PCR; molecular; sequencing; sporotrichosis.

Figure 1

Diagnostic techniques for chromoblastomycosis (CBM) and sporotrichosis (SPT). ITS: internal spacer; WGS: whole genome sequencing; LAMP: loop-mediated isothermal amplification; RCA: rolling circle amplification; MALDI-ToF MS: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.