Molecular study of archival fungal strains isolated from cases of lacaziosis (Jorge Lobo's disease)

Abstract

Lacazia loboi, the aetiological agent of lacaziosis (Jorge Lobo's disease), is an uncultivated anomalous fungal microbe closely related to Paracoccidioides brasiliensis, both restricted Latin American Pathogens. Early reports suggesting that L. loboi had been isolated in pure culture from cases of lacaziosis, only added more confusion to the already confusing aetiology of this disease. These strains were later identified as unusual contaminants and some of them as P. brasiliensis. Recent phylogenetic analysis grouped L. loboi as the sister taxon to P. brasiliensis, thus it was postulated that the original P. brasiliensis strains recovered from cases of lacaziosis, could be the aetiological agent of the disease. Using molecular methodologies, we investigated the archival P. brasiliensis isolate No. 525 from a case of lacaziosis, as well as other archival isolates, identified earlier as common contaminants, all recovered from similar cases of the disease. Phylogenetic analysis, using the 18S small subunit rDNA sequences of these isolates showed that strain No. 525 was a typical P. brasiliensis isolate and the other studied strains were indeed contaminants. This study unequivocally indicates that the aetiological agent of lacaziosis is yet to be cultured. © 2007 The Authors.