RESUMO
In some pathogens, trehalose biosynthesis is induced in response to stress as a protection mechanism. This pathway is an attractive target for antimicrobials as neither the enzymes, Tps1, and Tps2, nor is trehalose present in humans. Accumulation of T6P in Candida albicans, achieved by deletion of TPS2, resulted in strong reduction of fungal virulence. In this work, the effect of T6P on Tps1 activity was evaluated. Saccharomyces cerevisiae, C. albicans, and Candida tropicalis were used as experimental models. As expected, a heat stress induced both trehalose accumulation and increased Tps1 activity. However, the addition of 125 µM T6P to extracts obtained from stressed cells totally abolished or reduced in 50 and 60 % the induction of Tps1 activity in S. cerevisiae, C. tropicalis, and C. albicans, respectively. According to our results, T6P is an uncompetitive inhibitor of S. cerevisiae Tps1. This kind of inhibitor is able to decrease the rate of reaction to zero at increased concentrations. Based on the similarities found in sequence and function between Tps1 of S. cerevisiae and some pathogens and on the inhibitory effect of T6P on Tps1 activity observed in vitro, novel drugs can be developed for the treatment of infectious diseases caused by organisms whose infectivity and survival on the host depend on trehalose.
Assuntos
Candida albicans/enzimologia , Candida tropicalis/enzimologia , Inibidores Enzimáticos/química , Glucosiltransferases/antagonistas & inibidores , Saccharomyces cerevisiae/enzimologia , Fosfatos Açúcares/química , Trealose/análogos & derivados , Candida albicans/patogenicidade , Candida tropicalis/patogenicidade , Candidíase/tratamento farmacológico , Candidíase/enzimologia , Inibidores Enzimáticos/farmacologia , Especificidade da Espécie , Fosfatos Açúcares/farmacologia , Trealose/química , Trealose/farmacologiaRESUMO
Over the past years, the incidence of yeast infections, especially candidiasis, has increased. It is known that birds, including cockatiels, harbor potentially pathogenic yeasts to human beings in their gastrointestinal tract. Thus, this work aims at determining the in vitro antifungal susceptibility and phospholipase activity of Candida spp. isolated from the gastrointestinal tract and stools of cockatiels. Sixty cockatiels were assessed and samples were collected from oral cavity, crop and cloaca and stools were collected from cages where birds were kept. Yeast species were identified according to morphological and biochemical characteristics. Amphotericin B, itraconazole and fluconazole were tested against 39 C. albicans; 12 C. tropicalis; 7 C. parapsilosis and 1 C. krusei, through broth microdilution test. These same isolates were also tested for phospholipase production, on egg yolk agar. For amphotericin B, itraconazole and fluconazole, MICs were 0.25-1 µg/mL, 0.03125 to ≥16 µg/mL and 0.5 to ≥64 µg/mL, respectively, and resistance to itraconazole and fluconazole was observed in 14 (35.89%) and 4 (10.26%) C. albicans isolates, respectively. All C. albicans were positive for phospholipase production, out of which 74.36% presented high enzymatic activity. Among non-albicans Candida species, 40% produced phospholipase. The results show that cockatiels might represent a hazard to human health, as sources of infections caused by resistant Candida spp., especially to immunocompromised individuals, children and elderly.
Assuntos
Doenças das Aves/microbiologia , Candida/efeitos dos fármacos , Candida/enzimologia , Candidíase/veterinária , Cacatuas , Gastroenteropatias/veterinária , Fosfolipases/metabolismo , Anfotericina B/farmacologia , Animais , Antifúngicos/farmacologia , Doenças das Aves/tratamento farmacológico , Doenças das Aves/enzimologia , Brasil , Candida/isolamento & purificação , Candidíase/tratamento farmacológico , Candidíase/enzimologia , Candidíase/microbiologia , Fezes/microbiologia , Fluconazol/farmacologia , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/enzimologia , Gastroenteropatias/microbiologia , Itraconazol/farmacologia , Testes de Sensibilidade Microbiana/veterinária , Estatísticas não Paramétricas , Zoonoses/microbiologiaRESUMO
Candida albicans secretes various hydrolytic enzymes which are considered to be an integral part in the pathogenesis. However, the role of lipases is far from being completely understood and the direct effects of these fungal enzymes during the host-pathogen interaction remain to be established. We recently isolated and characterized an extracellular C. albicans lipase (CaLIP), and demonstrated the ability of this fungal enzyme to interact directly with macrophages (Mvarphi) and hepatocytes and to operate as a virulence factor. Herein, we explored the effects of CaLIP on Mvarphi functions such as oxidative burst and l-arginine metabolism. The study was performed in cells with different activation status: normal-resting Mvarphis and Mvarphis primed in vivo or in vitro with C. albicans. The ability of this fungal factor to modulate the above-mentioned parameters was dependent on cells status, dose, and microenvironment, where the interaction took place. These results constitute a new finding in the biology of candidiasis and could illustrate an additional evolutive advantage for the fungus in the framework of the bidirectional host-pathogen interaction.
Assuntos
Arginina/metabolismo , Candida albicans/patogenicidade , Lipase/metabolismo , Macrófagos/metabolismo , NADPH Oxidases/metabolismo , Animais , Arginase/metabolismo , Candida albicans/enzimologia , Candidíase/enzimologia , Candidíase/metabolismo , Candidíase/microbiologia , Feminino , Interações Hospedeiro-Patógeno , Humanos , Lipase/farmacologia , Ativação de Macrófagos , Macrófagos/efeitos dos fármacos , Macrófagos/enzimologia , Óxido Nítrico Sintase Tipo II/biossíntese , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
Yeast infections are common in immunocompromised patients, although emerging species have been changing the epidemiological profile. The ability to secrete proteinases has been associated with pathogenicity within the genus Candida. This study had the aims of diagnosing yeast infections in immunocompromised patients and evaluating the virulence of the etiological agents, based on a proteinase secretion assay using bovine serum albumin as a substrate. Out of a total of 104 patients studied, 19 presented episodes of yeast infection. The respiratory tract (63.2%), followed by the urinary tract (10.5%), were the most common sites of infection. Candida albicans, Candida parapsilosis, Candida tropicalis and emerging species such as Candida krusei and Candida guilliermondii were isolated. Five isolates of Candida parapsilosis and one of Candida albicans and Candida guilliermondii exhibited high enzymatic activity. We conclude that enzymatic characterization of Candida isolates may be a useful prognostic marker, especially among immunocompromised individuals, since yeast infections in such patients are generally serious.
Assuntos
Candida/enzimologia , Candidíase/enzimologia , Peptídeo Hidrolases/biossíntese , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Candida/classificação , Candida/patogenicidade , Candidíase/imunologia , Candidíase/microbiologia , Bovinos , Feminino , Humanos , Hospedeiro Imunocomprometido , Masculino , Pessoa de Meia-Idade , Virulência , Adulto JovemRESUMO
Infecções por leveduras são freqüentes em imunocomprometidos, contudo espécies emergentes têm alterado o perfil epidemiológico. A habilidade de secretar proteases tem sido associada à patogenicidade do gênero Candida. Esta pesquisa teve como objetivos diagnosticar leveduroses em pacientes imunocomprometidos e avaliar a virulência dos agentes etiológicos baseado em teste de secreção de protease utilizando soro de albumina bovina como substrato. Do total de 104 pacientes estudados, 19 apresentaram episódios de leveduroses. O trato respiratório (63,2 por cento), seguido pelo trato urinário (10,5 por cento) foram os locais mais comuns de infecção. Candida albicans, Candida parapsilosis, Candida tropicalis e espécies emergentes como Candida krusei e Candida guilliermondii foram isoladas. Cinco isolados de Candida parapsilosis e um de Candida albicans e Candida guilliermondii exibiram alta atividade enzimática. Concluímos que a caracterização enzimática de isolados de Candida pode ser um útil marcador prognóstico, especialmente em imunocomprometidos, uma vez que leveduroses nestes pacientes são geralmente graves.
Yeast infections are common in immunocompromised patients, although emerging species have been changing the epidemiological profile. The ability to secrete proteinases has been associated with pathogenicity within the genus Candida. This study had the aims of diagnosing yeast infections in immunocompromised patients and evaluating the virulence of the etiological agents, based on a proteinase secretion assay using bovine serum albumin as a substrate. Out of a total of 104 patients studied, 19 presented episodes of yeast infection. The respiratory tract (63.2 percent), followed by the urinary tract (10.5 percent), were the most common sites of infection. Candida albicans, Candida parapsilosis, Candida tropicalis and emerging species such as Candida krusei and Candida guilliermondii were isolated. Five isolates of Candida parapsilosis and one of Candida albicans and Candida guilliermondii exhibited high enzymatic activity. We conclude that enzymatic characterization of Candida isolates may be a useful prognostic marker, especially among immunocompromised individuals, since yeast infections in such patients are generally serious.
Assuntos
Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Bovinos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Candida/enzimologia , Candidíase/enzimologia , Peptídeo Hidrolases/biossíntese , Candida/classificação , Candida/patogenicidade , Candidíase/imunologia , Candidíase/microbiologia , Hospedeiro Imunocomprometido , Virulência , Adulto JovemRESUMO
Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the prevalent systemic mycosis in Latin America, paracoccidioidomycosis. We present here a survey of expressed genes in the yeast pathogenic phase of P. brasiliensis. We obtained 13,490 expressed sequence tags from both 5' and 3' ends. Clustering analysis yielded the partial sequences of 4,692 expressed genes that were functionally classified by similarity to known genes. We have identified several Candida albicans virulence and pathogenicity homologues in P. brasiliensis. Furthermore, we have analyzed the expression of some of these genes during the dimorphic yeast-mycelium-yeast transition by real-time quantitative reverse transcription-PCR. Clustering analysis of the mycelium-yeast transition revealed three groups: (i) RBT, hydrophobin, and isocitrate lyase; (ii) malate dehydrogenase, contigs Pb1067 and Pb1145, GPI, and alternative oxidase; and (iii) ubiquitin, delta-9-desaturase, HSP70, HSP82, and HSP104. The first two groups displayed high mRNA expression in the mycelial phase, whereas the third group showed higher mRNA expression in the yeast phase. Our results suggest the possible conservation of pathogenicity and virulence mechanisms among fungi, expand considerably gene identification in P. brasiliensis, and provide a broader basis for further progress in understanding its biological peculiarities.
Assuntos
Candida albicans/genética , Candidíase/genética , Etiquetas de Sequências Expressas , Regulação Fúngica da Expressão Gênica/genética , Genoma Fúngico , Paracoccidioides/genética , Paracoccidioidomicose/genética , Sequência de Bases/genética , Candida albicans/enzimologia , Candida albicans/patogenicidade , Candidíase/enzimologia , Candidíase/fisiopatologia , DNA Complementar/análise , DNA Complementar/genética , Enzimas/biossíntese , Enzimas/genética , Regulação Enzimológica da Expressão Gênica/genética , Humanos , Micélio/enzimologia , Micélio/genética , Micélio/crescimento & desenvolvimento , Paracoccidioides/enzimologia , Paracoccidioides/patogenicidade , Paracoccidioidomicose/enzimologia , Paracoccidioidomicose/fisiopatologia , RNA Mensageiro/genéticaRESUMO
Five species of edible mushrooms, Lentinula edodes, Pleurotus ostreatus, Pholiota nameko, Macrolepiota bonaerensis and Agaricus blazei, were tested for their potential to inhibit the in vitro growth of the pathogenic yeast Candida albicans. Only L. edodes had a fungistatic effect on this human pathogen. The inhibitory compound was produced intra and extracellularly in submersed L. edodes culture, and was also present in fresh and dehydrated mushroom basidiocarps. The fungistatic compound was heat sensitive and lost activity after 72 hours.