Are two Cryptococcus neoformans strains epidemiologically linked?

The aim of this study was to standardize a method to determine whether two strains of Cryptococcus neoformans could be considered epidemiologically li nked. We hypothesized that strains isolated from the same patient were epid emiologically linked and that those isolated from different patients were u nrelated. We used 17 environmental isolates and 97 clinical isolates from 3 1 patients diagnosed with cryptococcosis (1 to 1 I isolates per patient). U sing the plasmid pCnTel-1-labeled probe CENTEL, ne were able to differentia te some unrelated strains that yielded the same hybridization profile with the C, neoformans middle-repetitive-element CNRE-1 probe. The genetic dista nces separating the strains isolated from the same patient and those separa ting the strains isolated from different patients were estimated, and the r esults obtained with the two probes were compared. Analysis of the results enabled the calculation of tno Dice coefficient limits defining the zones c ontaining the pairs of linked strains and the pairs of unrelated strains, a s well as an intermediate uncertainty zone for which it was not possible to establish whether the pairs of strains were linked.