Antifungal susceptibility and genetic characterization of Cuban Cryptococcus strains

Illnait-Zaragozí M.T.


Objectives: Data on Cuban Cryptococcus spp. isolates with regard to susceptibility and molecular epidemiology are scarce. Here we report the results of 134 clinical isolates, 86 environmental isolates from pigeon guano and 196 environmental isolates from different plant species.
Method: Molecular patterns were analyzed by sizes of polymorphic fragments obtained by restriction enzymes (AFLP), detection of Aa, Aa, Da and Da alleles of STE20 locus by PCR, ITS1/5.8S/ITS2 and D1/D2 fragments sequencing, as well as the number of short repetitive fragments (STR) for which a set of nine primers were designed. Susceptibility to amphotericin B, five fluorocytosine, fluconazole, itraconazole, voriconazole, posaconazole and Isavuconazole by broth microdilution were also determined.
Results: All clinical isolates and 29.7% of all the environmental ones were molecularly identified as C. neoformans var. grubii MATa. C. heveaniensis was the prevalent species among the strains obtained from plants. STR was more discriminatory than AFLP showing that 70% of the environmental isolates were allocated into one group which contained only two clinical isolates. The remaining clinical isolates segregated over 10 genetically separate groups. In serial isolates from seven patients, STR patterns showed 14 distinctive profiles; in two patients recurrence was associated with genotypic identical isolates and the remainder exhibited genotypic differences from the initial infecting strain. Susceptibility testing showed no resistance to the studied antifungal drugs. The lowest MICs were found for the new drug Isavuconazole.
Conclusion: Our results suggest the presence of, so far unstudied, additional sources of infection in addition to pigeon guano. Infection with multiple genotypes as a mechanism of recurrence has been shown as well as the high potential of Isavuconazole as treatment for cryptococcal infection.

    • TIMM 5th (2013)