Serotype, mating type and ploidy of Cryptococcus neoformans strains isolated from patients in Brazil

Serotype, mating type and ploidy of 84 strains of Cryptococcus neoformans isolated from 61 AIDS and 23 non-AIDS patients admitted in a tertiary teaching hospital in Sõo Paulo, Brazil were examined. Among 61 strains isolated from AIDS patients, 60 strains were var. grubii (serotype A). Only one strain was var. gattii (serotype B). No var. neoformans (serotype D) was found. Among 23 strains isolated from non-AIDS patients, 15 were var. grubii (serotype A) and the remaining 8 were var. gattii, all of which were serotype B. Seventy-three of the 75 serotype A strains were the heterothallic alpha type (MATalpha) and the remaining 2 were untypable (asexual). Most of the MATalpha strains (69/73) were haploid and the remaining 4 strains were diploid. Similarly, both of the 2 asexual strains among the 75 serotype A strains were haploid. There were no alpha-mating type (MATalpha) strains among the 84 isolates. All of the 8 var. gattii strains were serotype B and haploid. Among a total of 84 strains tested, neither serotype AD nor serotype D were found. Neither triploid nor tetraploid were found. These results suggest that the serological, sexual and ploidy characteristics in C. neoformans strains isolated from AIDS patients in Sõo Paulo were rather simple, whereas strains isolated from non-AIDS patients presented serotype A and B with predominance of serotype A

Chlamydospore formation by Paracoccidioides brasiliensis mycelial form

O papel do conteúdo nutritivo do meio de cultura e de oxigênio na produçäo de clamidósporos pela fase micelial do Pracoccidioides brasiliensis foi investigado. Quatro cepas do fungo (18, Bt4, 1183, Pb9) foram cultivadas, a 25-C, em meio sólido rico e pobre em nutrientes. As cepas 18 e 1183 foram também cultivadas em anerobiose em atmosfera de nitrogênio. A cepa 18 produziu grande número de clamidósporos terminais e intercalares após 7-10 dias de cultura em meio sólido pobre em nutrientes (agar 2%, com dextrose e polipeptona 0,1%). As outras três cepas produziram número significativamente menor de esporos. A cepa 18 näo produziu clamidósporos quando cultivada em dois meios ricos em nutrientes (infusäo de cérebro e coraçäo, e agar destrose de batata). A incubaçäo anaeróbica da cepa 18 em atmosfera de nitrogênio apresentou pequeno crescimento micelial com a presença de numerosos clamidósporos. A nivel ultraestrutural, os clamidósporos apresentam um ou mais núcleos e numerosas mitocôndrias, indicativos de potencial para posterior desenvolvimento. Assim, os esporos produziram gemulaçäo múltipla 1 dia após incubaçäo a 35-C. Os resultados demonstraram que, sob condiçöes ambientais adversas, a fase micelial do P. brasiliensis produz clamidósporos em curto período de tempo. É possível que o fungo encontre condiçöes semelhantes no solo, produzindo os esporos, que poderiam desempenhar papel na propagaçäo da paracoccidioidomicose