DNA fingerprinting pattern and susceptibility to antifungal drugs in Cryptococcus neoformans variety grubii isolates from Barcelona city and rural environmental samples

Recognition of seven species in the Cryptococcus gattii/Cryptococcus neoformans species complex

Phylogenetic analysis of 11 genetic loci and results from many genotyping studies revealed significant genetic diversity with the pathogenic Cryptococcus gattii/Cryptococcus neoformans species complex. Genealogical concordance, coalescence-based, and species tree approaches supported the presence of distinct and concordant lineages within the complex. Consequently, we propose to recognize the current C. neoformans var. grubii and C. neoformans var. neoformans as separate species, and five species within C. gattii. The type strain of C. neoformans CBS132 represents a serotype AD hybrid and is replaced. The newly delimited species differ in aspects of pathogenicity, prevalence for patient groups, as well as biochemical and physiological aspects, such as susceptibility to antifungals. MALDI-TOF mass spectrometry readily distinguishes the newly recognized species.

Prevalence and antifungal susceptibility of Cryptococcus neoformans isolated from pigeon excreta in Chon Buri Province, Eastern Thailand

 The prevalence of cerebral meningitis caused by Cryptococcus neoformans in HIV-infected patients in Eastern Thailand is high. However, little is known about the occurrence of this pathogenic yeast in the environment of this region.  The aim of our study was to characterize the prevalence of C. neoformans, its serotypes and antifungal drug susceptibilities in environmental isolates from Chon Buri, Eastern Thailand.  C. neoformans was isolated from 10% of fifty pigeon excreta examined from this province. All C. neoformans isolates were of serotype A and although the isolates displayed slightly decreased susceptibility towards fluconazole, all tested sensitive to amphotericin B, fluconazole and itraconazole. This study is the first report of the occurrence of C. neoformans in pigeon excreta in eastern Thailand.

Microbiological characteristics of clinical isolates of Cryptococcus spp. in Bahia, Brazil: molecular types and antifungal susceptibilities

To determine the profiles of susceptibility to antifungal and the genotypes of clinical isolates of Cryptococcus in Bahia, Brazil, 62 isolates were collected from cases of meningitis in the period from 2006 to 2010. Their susceptibilities to fluconazole, itraconazole, amphotericin B and 5-flucytosine were determined by the broth microdilution technique described by the Clinical and Laboratory Standards Institute and genotyping of the URA5 gene was accomplished by restriction fragment length polymorphism. C. neoformans accounted for 79% of the identified yeast and C. gattii represented the remaining 21%. Evaluation of the genotypes determined that 100% of the C. gattii isolates belong to the VGII genotype, and 98% of the C. neoformans isolates belong to the VNI genotype. Determination of susceptibility revealed isolates resistant to fluconazole (4.8%), 5-flucytosine (1.6%) and amphotericin B (3.2%); the stratification of sensitivity results for each species showed significant differences in susceptibility to azoles. This study is the first to describe the susceptibility profiles of molecular and clinical isolates of Cryptococcus in Bahia, Brazil. The high percentage of C. gattii isolates belonging to the VGII genotype and its lower susceptibility to antifungal agents highlight the importance of knowing which species are involved in cryptococcal infections in northeastern Brazil.

[Urease activity in Cryptococcus neoformans and Cryptococcus gattii]

Urease is an enzyme considered one of the main virulence factors in Cryptococcus neoformans. Quantitative differences in urease production between C. neoformans and the new species Cryptococcus gattii have not been so far documented. Using a standardized method, 25 isolates of C. neoformans and 19 of C. gattii were seeded in Christensen urea broth medium for urease activity detection. Approximately, the 50% of activity of one unit of commercial jack beans urease (A550=0.215) was considered as a reference to classified the Cryptococcus in two cathegories, low (A550<0.215) or high (A550=or>0.215) urease producers. After 72 hours of incubation, 76% of C. neoformans and 15.8% of C. gattii strains were high urease producers (p=0.016). Based on these results, the species C. neoformans appeared as the highest urease producer. Other virulence factors should also be investigated to explain C. gattii pathogenicity.