Molecular analysis of 311Cryptococcus neoformansisolates from a 30-month ECMM survey of cryptococcosis in Europe

Abstract

During a European Confederation of Medical Mycology (ECMM) prospective survey of cryptococcosis in Europe (from July 1997 to December 1999) 655 cases were reported from 17 countries; 565 of the completed questionnaires were evaluable. Cryptococcosis was associated with HIV infection in 77% of cases (range 57.5-94%). Assessment of the laboratory data highlighted the lack of defined standard procedures for the diagnosis of cryptococcosis: the antigen test was not usually used for screening, the disease was mainly recognised when meningitis occurred (65% of patients) and, with the exception of a few cases, the extent of the infection was not investigated. Cryptococcus neoformans was the etiological agent in all of the cases except for six caused by C. gattii and four by other Cryptococcus species. A total of 311 C. neoformans strains were serotyped by Crypto Check latex agglutination, genotyped by PCR-fingerprinting using the (GACA)4 oligonucleotide as a single primer, and their mating type was determined by PCR of the STE20 alleles. Serotype A was the most represented (51% of the isolates), followed by serotype D (30%) and serotype AD (19%). PCR-fingerprinting analysis significantly increased the percentage of hybrid strains to 30%, as 6% of the serotype A and 28% of the serotype D isolates were of the VN3 or VN4 hybrid genotype. In addition, the mating type determinations revealed the MATa serotype A allele in one haploid strain and 28 hybrids, and hybrid isolates with a single mating type (four Aalpha and two Dalpha) were also identified. This is the first prospective survey to be carried out in Europe which has attempted to investigate the epidemiology of cryptococcosis and the population structure of C. neoformans, and the results obtained thus far show the widespread involvement of AD hybrid strains in C. neoformans infections.

Extensive Genetic Diversity within the Dutch Clinical Cryptococcus neoformans Population

“…neoformans has been poorly studied. From the few available studies it is known that serotype D isolates are more prevalent in Europe (27,43). In the current study, only 12% of the clinical isolates were serotype D (Table 3).…”

“…When patients with a known immune status were considered, the percentage of HIV-positive patients was 62.8%, which is similar to data from other European studies. A French study showed that 77% (n ϭ 177) of the patients with cryptococcosis were HIV infected (17); in a cohort of 77 Austrian, German, and Swiss patients this was 68% (n ϭ 52) (40), a Spanish study observed 87% (n ϭ 48) (20), and a 30-month European survey reported 77% (n ϭ 435) of HIV-positive patients (43). In the current study, 18 (7.6%) patients were found to have no underlying disease or any other predisposing factors, such as corticosteroid treatment.…”

“…However, in Italy, 71% of the C. neoformans isolates were found to be serotype D (41). A European survey observed that a large proportion of the 311 C. neoformans isolates were serotype D (30%) and serotype AD (19%) (43). A higher proportion of infections caused by C. neoformans var.…”

Evolutionary Role of Interspecies Hybridization and Genetic Exchanges in Yeasts

“…Note that a novel C. neoformans ϫ C. gattii hybrid strain of serotype AB caused a lethal infection in a Canadian AIDS patient (21). Other hybrids of serotypes A and D were recently identified and studied at the molecular level (3,31,108,116,223). While most isolates of serotypes A and D are haploid, AD strains are diploid or aneuploid.…”

Correlation of Genotype and In Vitro Susceptibilities of Cryptococcus gattii Strains from the Pacific Northwest of the United States

“…While C. neoformans has a global distribution and is primarily associated with soil contaminated by bat or bird guano (19), C. gattii was until recently thought to be largely confined to tropical and subtropical regions, such as Australia and New Zealand, where it has been found primarily in association with Eucalyptus trees (11). C. gattii has also been isolated from clinical specimens from numerous other parts of the world, including Mexico, parts of Latin America, Europe, southern California, Hawaii, India, and Africa (15,19,25,30).…”