Caracterização de amostras de Cryptococcus neoformans e aspectos clínicos e epidemiológicos da criptococose de pacientes do Hospital de Clínicas de Uberlândia

Abstract

Cryptococcus is a yeast-like fungus, capsuled, which has the ability to infect and cause disease in a wide variety of hosts; is the causative agent of cryptococcosis, systemic disease, subacute or chronic, occurring before the AIDS epidemic was sporadic and usually associated with patients with low cellular immunity. Two species are the main pathogenic to humans: C. neoformans and C. gattii; generally C. neoformans cause disease in immunocompromised individuals, manifested as a disease in immunocompetent individuals generally have as C. gattii agent. The laboratory diagnosis of cryptococcosis is usually performed by microbiological examinations (direct and culture research) in various clinical specimens and also by serological methods (latex reaction). Molecular techniques may also be used, but still have limited application in clinical diagnostics. Treatment is with amphotericin B in the induction phase and with fluconazole in the phases of consolidation and maintenance. The objectives of this study were to investigate the phenotypic and molecular characteristics and determine the antifungal susceptibility of Cryptococcus neoformans isolated from samples from patients treated at Uberlândia Clinical Hospital in the 2004-2013 period; and also examine the demographic characteristics of the patients. The phenotypic characteristics have been studied through the use of conventional biochemical tests, such as melanin production and urease and sensitivity to canavanine; to have the molecular characteristics, conventional PCR reactions and research have been used in the URA-5 gene by PCR-RFLP. The antifungal susceptibility was performed either by disk diffusion technique and the dilution technique broth through VITEK ® 2 system. The demographic characteristics of patients suffering from cryptococcosis were studied by analyzing the records. Between 41 samples were stored Cryptococcus identified as C. neoformans. During molecular analysis it was found that 40 were C. neoformans var. grubii (VNI) and one was C. gattii (VGI). All strains were mating type . All isolates were susceptible to antifungals front tested by automated method of broth microdilution (Vitek ® 2, Biomerieux). Patients affected by cryptococcosis were mostly men 31-40 years old, coming from urban areas. The meningoencephalitis was the predominant form of the disease; most were immunocompromised, AIDS being the predominant underlying disease. Most of them receive appropriate treatment according to the proposed guidelines; however, 58% of patients progressed to death.

Cryptococcus neoformans: um fungo patogênico oportunista

“…As leveduras obtêm um crescimento melhor a 30 °C, enquanto sua termotolerância máxima é de 40 °C (Silva, 2020;Moretti, 2023). (Idnurm, 2005;Furtado, 2012;Aguiar, 2016).…”

“…Em relação à taxonomia, o gênero Cryptococcus é um eucarioto do Reino Fungi, pertencente à classe Tremellomicetes, família Tremellaceae (Aguiar, 2016). Quanto aos aspectos morfológicos, a variedade C. neoformans caracteriza-se por apresentar formato esférico ou ovalado, medindo de 2 a 8 µm de diâmetro, apresentando uma cápsula mucopolissacarídica, composta majoritariamente (90%) pela glucuronoxilomanana -GXM, medindo entre 5 a 30 µm (Zaragoza, Fries, Casadevall, 2003;Leal, 2006;Aguiar, 2016;Moretti, 2023). Além de sua cápsula, entre seus principais fatores de virulência estão a atividade urease, a produção de melanina e o desenvolvimento a 37 °C (Gomes et al, 2010;Kwon-Chung et al, 2014).…”