The pathogenicity of Cryptococcus neoformans is heterogeneous and is associated with the expression of virulence factors. This study aimed to correlate the pathogenicity of C. neoformans var. grubii in BALB/c mice with in vitro virulence factors, fluconazole minimal inhibitory concentrations (MICs) and molecular profiles, before and after animal passage. Ten environmental isolates and one ATCC strain of C. neoformans var. grubii mating type α were evaluated. Most isolates (91%) killed 50% or more of the infected animals by day 24 postinfection and were recovered from the lungs and brains of surviving animals on days 7 and 14 postinfection. The burden of yeast in the lungs was more variable than that in the brain. The differences in the expression of virulence factors (growth at 37ºC, presence and size of the capsule and production of melanin, urease, proteinase and phospholipase) by most isolates pre and postpassage in animals were not statistically significant. The fluconazole MICs in postpassaged lines differed by a one-dilution from the MIC of the corresponding prepassaged line for six isolates. Using molecular typing [polymerase chain reaction-fingerprinting with (GACA)4 and M13], eight isolates were identified as VNI and three as VNII. We concluded that different isolates with the same molecular and phenotypic profiles, including isolates that are markedly hypervirulent, span a wide range of virulence and there were no changes in virulence factors in the postpassaged lines when compared with the corresponding nonpassaged lines.

Neste estudo procedeu-se a avaliação da atividade antibacteriana e antifúngica dos extratos brutos de Alternanthera maritima (Amaranthaceae) planta in natura de duas coletas distintas e obtidos por cultura de células buscando-se averiguar a manutenção da atividade antimicrobiana dos extratos obtidos da planta in vivo e in vitro. A ação antibacteriana e antifúngica foi determinada pelo método de difusão em ágar (técnica do poço) utilizando-se trinta cepas de microrganismos indicadores (bactérias Gram-positivas e Gram-negativas, leveduras e dermatófitos). Todos os extratos obtidos com solventes orgânicos avaliados apresentaram-se bioativos com halos de inibição de 6 a 20 mm. Os extratos da planta in natura das duas coletas (Restinga de Marica (RJ), verão de 1995 e 1998) inibiram o desenvolvimento de diferentes microrganismos (bactérias, leveduras e dermatófitos). Os extratos obtidos da cultura de calos desenvolvidos em duas condições de cultivo diferentes, também se mantiveram bioativos. Assim, os resultados obtidos encorajam a realização de novos estudos com esta espécie vegetal para se determinar quais as substâncias presentes nos extratos e que contribuem para a atividade biológica, como também para entender seu mecanismo de ação e avaliar sua toxicidade, visando uma possível aplicação farmacêutica.

The aim of this study was to evaluate the antibacterial and antifungal activity of callus culture (two different hormonal combination culture medium) and adult plants (two collect) extracts from Alternanthera maritima (Amaranthaceae) investigating the maintenance of antimicrobial activity in vivo and in vitro. The antibacterial and antifungal activity was determined by the agar-well diffusion method against thirty strains of microorganisms including Gram-positive and Gram-negative bacteria, yeasts and dermatophytes. All the organic crude extracts studied were bioactive. Extracts of aerial parts and roots of adult plants collected during the same period of years of 1995 and 1998 (Restinga de Maricá (RJ), collect 1 and 2) inhibited the growth of several microorganisms (bacteria, yeasts and dermatophytes) with inhibition halo between 6 and 20 mm. Plant cell callus culture extracts obtained from two culture conditions were also bioactive. Thus, the positive results suggest that the A. maritima extracts should be further studied to determine the bioactive chemical compounds as well as to understand the possible mechanisms of action and evaluate their toxicity looking toward a pharmaceutical employment.