Production of E,E-farnesol (FOH) and biofilm formation were studied under various conditions in 56 strains of eight Candida spp. FOH production differed significantly not only between Candida spp. but within Candida albicans strains as well. FOH concentrations and biofilm formation were the highest for C albicans.Candida albicans is a major human fungal pathogen, causing both superficial and invasive tissue infections. The ability of C. albicans to form biofilms on medical devices has a profound impact on its capacity to cause human disease. C. albicans and other members of the genus Candida are able to grow in different forms as budding yeast, pseudohyphae, and true hyphae, which is called dimorphism (1,8). This transition from yeast to hyphal growth can be induced by various conditions (2, 25). Progression to a mature biofilm is dependent on cell adhesion, extracellular matrix production, and the yeast-to-hypha transition in C. albicans (2, 3). However, biofilm development in non-C. albicans Candida spp. (NCAC) is not well understood.Suppression of biofilm formation in C. albicans may be achieved by quorum-sensing molecules (5). E,E-Farnesol (FOH) has been reported to inhibit the induction of hyphal growth and biofilm formation in C. albicans (10,11). In this study, FOH secretion by C. albicans and eight NCAC was examined under various culture conditions. In addition, the development of biofilms was studied. Finally, the correlation between FOH secretion and biofilm formation was analyzed for all of the isolates studied.We studied 56 strains of eight Candida species (Table 1). All isolates were cultivated in RPMI 1640 medium with or without the addition of 10% fetal calf serum (FCS) at 37°C for 24 h under continuous rotation at 125 rpm. Two milliliters of sterile filtered (0.45 m) culture supernatant was extracted with 5 ml n-hexane-ethanol (90:10, vol/vol) and derivatized with 9-anthroylnitrile as previously described (13). Quantification was done with n-butanol as an internal standard (50 ng added to each sample). Reverse-phase high-performance liquid chromatography was done with a YMC Hydrosphere C 18 column (5 m, 150 by 2.1 mm [inside diameter]). A linear gradient of acetonitrile-water (85% to 100% over 20 min) was used as the mobile phase. Standard concentrations ranged from 0.004 M to 40 M FOH. Detection, determination of recovery, and calculations were performed as previously described (4, 13). The development of biofilms by all of the Candida spp. was studied according to Krom et al. (6), with minor differences such as using 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate sodium salt instead of 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide. In addition to visual reading at 450 nm, optical density was measured at 405 nm for data validation (15). All tests were done twice and analyzed with the two-tailed paired Student t test comparing 0 and 10% FCS cultivations (significance was set at a P value of Յ0.05).The quantification and...
Diseases caused by Candida species are an increasing problem. Candida species are associated with high overall mortality, due to a variety of virulence factors such as the yeast-to-hyphal switch and proteolytic enzymes. The phenomenon of microbial communication known as quorum sensing also seems to play an important role. The main characteristics of the quorum-sensing molecule E ,E -farnesol are well known for C. albicans. The present study focused on two questions. One of them concerned the secretion of E ,E -farnesol by C. albicans and involved a close examination of the effect of the medium (serum) and the origin of the isolates used. The second one dealt with the activity of E ,E -farnesol in non-C. albicans species, such as C. tropicalis and C. parapsilosis, e.g. its impact on biofilm formation and growth. Under serum conditions, C. albicans produced up to 58% more E ,E -farnesol at 37• C than at 30• C. The growth of all isolates was reduced and delayed by the administration of E ,Efarnesol. Of all Candida species, C. tropicalis isolates were most strongly affected by the addition of E ,E -farnesol. Biofilm formation on polystyrene was affected by E ,Efarnesol treatment in all non-C. albicans species and C. albicans. E ,E -farnesol exerts its main effect by altering the metabolic activity and growth inhibition of treated Candida species. The results obtained indicate that the presence of E ,E -farnesol in the environment not only regulates the morphology of the Candida species but also affects its fitness. In this regard, the secretion of E ,E -farnesol might provide an advantage for members of the microbial community.
Resveratrol is a natural stilbene synthesised by plants. This compound has been shown to inhibit the growth of Candida albicans TIMM 1768 efficiently. Till date, no information is available for other Candida species. The evaluation of the antimicrobial activity of resveratrol was analysed by the inhibition of the growth and metabolism assays. Our data indicate that resveratrol is not effective against Candida albicans and non-C. albicans species (C. dubliniensis, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei) in vitro. The potential candidacidal activity could not be confirmed.
Two Candida albicans isolates were collected from a HIV-positive patient with recurrent oropharyngeal candidosis (OPC). One isolate was taken during the first episode of oral candidosis [fluconazole susceptible (FLU-S), minimal inhibitory concentration (MIC) = 0.25 mg l(-1) ] and the second after the patient developed refractory OPC and resistance to fluconazole (FLU-R, MIC = 64 mg l(-1)). Both isolates were clonally identical. Different in vitro studies were carried out to assess putative virulence factors of both isolates. Gene expressions of efflux pumps and CSH1 were determined as well as adherence to human epithelial cells, determination of proteinase secretion and biofilm formation activity. Virulence was studied using a disseminated mouse model. All mice challenged with the FLU-S isolate survived the experiment when FLU was given. However, when FLU was absent, the mortality of the FLU-S isolate was higher than that of the FLU-R isolate with no mice surviving the experiment. In vitro studies showed pronounced growth rates of the FLU-S isolate and a more intense biofilm-building activity compared with the FLU-R isolate. The FLU-R isolate highly up-regulated MDR1 and CSH1. This isolate also adhered stronger to the epithelial cell line. The results showed that FLU-S and FLU-R isolates exhibit different virulence factors, which enable the survival of both isolates in adapted environments.
Five methods were compared, using conventional PCR, for the isolation of DNA from Aspergillus fumigatus conidia from 1-3-mL samples of whole blood. A lower detection threshold of Aspergillus conidia was achieved using 3-mL rather than 1-mL samples with three of five methods tested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.