Susceptibility of clinical isolates of Cryptococcus neoformans to amphotericin B using time-kill methodology.

The in vitro activities of amphotericin B (AmB) were evaluated against 40 isolates of Cryptococcus neoformans using time-kill curves. The isolates were obtained from 20 AIDS patients with cryptococcal meningitis submitted to AmB therapy. Isolates were exposed in vitro to 1 microg/mL of AmB that represents a serum concentration of AmB, and the viable colony counts were determined over time. AmB exhibited fungicidal activity at 6 and 12 h for 70.6% of isolates, at 24 h for 7.3%, and at 48 h for 22% of isolates, respectively. This effect was not maximized when the test drug concentration was up to 4 times the AmB MIC for the isolates. Regrowth was observed in 17.5% of the isolates after fungicidal endpoint. With standard in vitro susceptibility testing, this tolerance phenomenon could not be assessed, and thus, these tests may underestimate the resistance of C. neoformans to AmB in vivo. AmB is the first-choice drug for the treatment of cryptococcosis in Brazil, and future studies using time-kill methodology are needed to estimate the predictive value of this test in the clinical failure.

Molecular diversity of serial Cryptococcus neoformans isolates from AIDS patients in the city of São Paulo, Brazil.

Despite highly active anti-retroviral therapy, cryptococcal meningoencephalitis is the second most prevalent neurological disease in Brazilian AIDS patients, being frequently a defining condition with several episodes. As knowledge of Cryptococcus neoformans isolates in the same episode is critical for understanding why some patients develop several episodes, we investigated the genotype characteristics of C. neoformans isolates in two different situations. By pulsed field gel electrophoresis and random amplified polymorphic DNA analysis, 54 isolates from 12 patients with AIDS and cryptococcosis were analyzed. Group 1 comprised 39 isolates from nine patients with a single episode and hospitalization. Group 2 comprised 15 isolates from three patients with two episodes and hospitalizations. Except for three patients from group 1 probably infected with a single C. neoformans isolate, the other nine patients probably were infected with multiple isolates selected in different collection periods, or the infecting isolate might have underwent mutation to adapt and survive the host immune system and/or the antifungal therapy. However, the three patients from group 2 presented genetic diversity among isolates collected in both hospitalizations, possibly having hosted the initial isolate in both periods. These data, emphasize that Cryptococcus diversity in infection can contribute to strategies of treatment and prevention of cryptococcosis.

Molecular diversity of serial Cryptococcus neoformans isolates from AIDS patients in the city of São Paulo, Brazil

Despite highly active anti-retroviral therapy, cryptococcal meningoencephalitis is the second most prevalent neurological disease in Brazilian AIDS patients, being frequently a defining condition with several episodes. As knowledge of Cryptococcus neoformans isolates in the same episode is critical for understanding why some patients develop several episodes, we investigated the genotype characteristics of C. neoformans isolates in two different situations. By pulsed field gel electrophoresis and random amplifield polymorphic DNA analysis, 54 isolates from 12 patients with AIDS and cryptococcosis were analyzed. Group 1 comprised 39 isolates from nine patients with a single episode and hospitalization. Group 2 comprised 15 isolates from three patients with two episodes and hospitalizations. Except for three patients from group 1 probably infected with a single C. neoformans isolate, the other nine patients probably were infected with multiple isolates selected in different collection periods, or the infecting isolate might have underwent mutation to adapt and survive the host immune system and/or the antifungal therapy. However, the three patients from group 2 presented genetic diversity among isolates collected in both hospitalizations, possibly having hosted the initial isolate in both periods. These data, emphasize that Cryptococcus diversity in infection can contribute to strategies of treatment and prevention of cryptococcosis.

AIDS-associated central nervous system cryptococcosis: a Brazilian case study.

In recent years the effect of HAART in patients with AIDS has been great at decreasing the incidence of opportunistic infections. Nonetheless, patients with AIDS living in developing countries still present with severe central nervous system cryptococcosis, with high mortality rates. The study of the clinical-epidemiological-laboratory aspects of the patients treated before the HAART era might be useful in an assessment of the impact of these drugs in the prognosis of cases.

Cryptococcus neoformans varieties isolated from patients with aids referred to a hospital of São Paulo city during 1996-1999

Cryptococcus neoformans é uma levedura capsulada que apresenta tropismo pelo sistema nervoso central causando meningoencefalite. É a micose mais freqüente em pacientes com AIDS, e é responsável pela alta morbidade e mortalidade. Há duas variedades: var. neoformans e var. gattii. C. neoformans var.neoformans está distribuído mundialmente e é comumente encontrado em fezes de aves, principalmente de pombo. C. neoformans var. gattii está geograficamente limitado a regiões tropicais e subtropicais e está associado a algumas espécies de árvores, principalmente, Eucalyptus sp. A proposta desse estudo foi de avaliar a prevalência das variedades de Cryptococcus neoformans isoladas de 452 amostras de líquido cefalorraquiano (LCR) provenientes de 183 pacientes com AIDS, internados no Instituto de Infectologia Emílio Ribas – São Paulo-SP, de 1996 a...

Cryptococcus neoformans is an encapsulated yeast that presents tropism for central nervous system, and causes meningoencephalitis. Cryptococcosis is the most frequent mycosis in patients with AIDS, and itis the cause of high morbidity and mortality. C. neoformans presents two varieties var. neoformans andvar. gattii. Cryptococcus neoformans var. neoformans has been world-wide isolated from avian feces, especially pigeon excreta. C. neoformans var. gattii is geographically restricted to tropical and subtropical regions, and it is associated with some trees species, mainly Eucalyptus sp. The proposal of this study was to evaluate the prevalence of Cryptococcus neoformans varieties isolated from 452 cerebrospinalfluid (CSF) samples from 183 patients with AIDS referred to the Instituto de Infectologia Emilio Ribas- São Paulo-SP, from 1996 to 1999. CSF samples were cultured on canavanine-glycine-bromothymolblue...

Cryptococcosis: a review of the brazilian experience for the disease

Cryptococcosis is a systemic mycosis caused by Cryptococcus neoformans. The disease occurs in patients with cellular immunodeficiency. The incidence of cryptococcosis arises with aids, and mycosis is one of the opportunistic infections that defines AIDS. After the HAART era the occurrence of cryptococcosis decreased all over the world, but it still continues to be a prevalent disease in Brazil. Thus, we consider this paper to be very important as a result of our reviewing of Brazilian literature regarding some relevant aspects of that disease.

Cryptococcosis: a review of the Brazilian experience for the disease.

Cryptococcosis is a systemic mycosis caused by Cryptococcus neoformans. The disease occurs in patients with cellular immunodeficiency. The incidence of cryptococcosis arises with aids, and mycosis is one of the opportunistic infections that defines AIDS. After the HAART era the occurrence of cryptococcosis decreased all over the world, but it still continues to be a prevalent disease in Brazil. Thus, we consider this paper to be very important as a result of our reviewing of Brazilian literature regarding some relevant aspects of that disease.