Polymerase chain reaction-mediated genotyping of Hortaea werneckii, causative agent of tinea nigra.

The black yeast Hortaea werneckii is known to be a causative agent of human tinea nigra but is also found in the environment. Strains from dissimilar sources were studied by polymerase chain reaction fingerprinting of nuclear DNA, using primers annealing to repetitive and random sequences. The seven groups found correspond to those known from restriction fragment length polymorphism (RFLP) studies of the mitochondrial DNA of the same strains. Two main groups contained strains from human as well as from non-human sources. The human strains did not cluster, but were randomly distributed over several populations. It was concluded that these strains are not pathogenic. The factor common to both niches is a relatively high salt concentration.