Transmission of an azole-resistant isogenic strain of Candida albicans among human immunodeficiency virus-infected family members with oropharyngeal candidiasis.
(57/3054)
We report transmission of an azole-resistant, isogenic strain of Candida albicans in a human immunodeficiency virus (HIV)-infected family of two children with symptomatic oropharyngeal candidiasis and a mother with asymptomatic colonization over a 5-year period. These findings were confirmed by three different molecular epidemiology methods: interrepeat PCR, Southern hybridization with a C. albicans repetitive element 2 probe, and electrophoretic karyotyping. This study contributes to an evolving understanding of the mode of transmission of C. albicans, particularly in children, and underscores the importance of monitoring specimens from family members of HIV-infected patients. (+info)
Rapid recruitment of late endosomes and lysosomes in mouse macrophages ingesting Candida albicans.
(58/3054)
Candida albicans is an important opportunistic pathogen, whose interaction with cells of the immune system, in particular macrophages (MO), is poorly understood. In order to learn more about the nature of the infectious mechanism, internalisation of Candida albicans was studied in mouse MO by confocal immunofluorescence and electron microscopy in comparison with latex beads of similar size, which were coated with mannosyl-lipoarabinomannan (ManLAM) to target the MO mannose receptor (MR). Uptake of Candida yeasts had characteristics of phagocytosis, required intact actin filaments, and depended on the activity of protein kinase C (PKC). Candida phagosomes rapidly attracted lysosome-associated membrane protein (Lamp)-rich vacuoles, indicative of fusion with late endosomes and lysosomes. Rapid recruitment of late endosomes and lysosomes could be observed regardless of heat-inactivation or serum-opsonisation of Candida, but did not follow binding of the mannosylated-beads to MO, which suggest that this phenotype is not MR-specific. The yeasts developed germ tubes within phagolysosomes, distended their membranes and escaped, destroying the non-activated MO. The filamentous form of Candida could penetrate intact MO even when phagocytosis was blocked, and also attracted Lamp-rich organelles. Inhibition of lysosomal acidification and associated lysosomal fusion reduced germ tube formation of Candida within the phagolysosomes. These data suggest that rapid recruitment of late endocytic/lysosomal compartments by internalizing C. albicans favours survival and virulence of this pathogen. (+info)
Safety and efficacy of multilamellar liposomal nystatin against disseminated candidiasis in persistently neutropenic rabbits.
(59/3054)
The activity of liposomal nystatin (L-Nys) against subacute disseminated candidiasis was investigated in persistently neutropenic rabbits. Antifungal therapy was administered for 10 days starting 24 h after intravenous inoculation of 10(3) blastoconidia of Candida albicans. Responses to treatment were assessed by the quantitative clearance of the organism from blood and tissues. Treatments consisted of L-Nys at dosages of 2 and 4 mg/kg of body weight/day (L-Nys2 and L-Nys4, respectively) amphotericin B deoxycholate at 1 mg/kg/day (D-AmB), and fluconazole at 10 mg/kg/day (Flu). All treatments were given intravenously once daily. Compared to the results for untreated but infected control animals, treatment with L-Nys2, L-Nys4, D-AmB, and Flu resulted in a significant clearance of the residual burden of C. albicans from the kidney, liver, spleen, lung, and brain (P < 0.0001 by analysis of variance). When the proportion of animals infected at at least one of the five tissue sites studied was evaluated, a dose-dependent response to treatment with L-Nys was found (P < 0.05). Compared to D-AmB-treated rabbits, mean serum creatinine and blood urea nitrogen levels at the end of therapy were significantly lower in animals treated with L-Nys2 (P < 0.001) and L-Nys4 (P < 0.001 and P < 0.01, respectively). L-Nys was less nephrotoxic than conventional amphotericin B and had dose-dependent activity comparable to that of amphotericin B for the early treatment of subacute disseminated candidiasis in persistently neutropenic rabbits. (+info)
Comparison of four methods for DNA typing of clinical isolates of Candida glabrata.
(60/3054)
A series of 35 isolates of Candida glabrata from 29 subjects (five AIDS patients and 24 HIV-seronegative individuals) was typed by electrophoretic karyotyping (EK), restriction fragment length polymorphism (RFLP) analysis, random amplification of polymorphic DNA (RAPD) and inter-repeat PCR (IR-PCR). The rank order of discriminatory ability among the four methods was as follows: EK (25 DNA types) > RAPD (19 DNA types) > IR-PCR (14 DNA types) > RFLP (4 DNA types). A composite DNA type was defined for each of the strains as the combination of types obtained by the four molecular methods. A total of 32 DNA types was obtained by this procedure; each individual harboured their own specific isolate (DNA type). Neither source of isolation nor HIV status was associated with a given DNA type. In three of five cases, initial and relapse isolates from individual patients were assigned to the same DNA type. These findings indicate that EK is the most useful method for the investigation of inter-strain variations within this Candida species. (+info)
Fas-FasL costimulation modulates the production of proinflammatory cytokines, and MRL/lpr mice, which lack a functional Fas molecule, produce more proinflammatory cytokines. This study found that Fas-FasL interactions are involved in host defense against lethal infection with Candida albicans. Macrophages of MRL/lpr mice produced significantly more tumor necrosis factor and interleukin-1 after stimulation with C. albicans than did control MRL+/+ macrophages. Mortality of Fas-deficient mice with disseminated candidiasis was significantly lower than control animals' because of decreased fungal load and inhibition of the formation of invasive hyphae in their organs. Increased recruitment of neutrophils at the infection site appeared to be responsible for these effects. In contrast, phagocytosis and killing of C. albicans by neutrophils of MRL/lpr and MRL+/+ mice was similar. Absence of Fas-FasL interactions leads to increased cytokine production after C. albicans stimulation, protecting mice against disseminated candidiasis. (+info)
Evidence for a general-purpose genotype in Candida albicans, highly prevalent in multiple geographical regions, patient types and types of infection.
(62/3054)
Epidemiological studies, using the probe Ca3, have shown that in a given patient population a single cluster of genetically related Candida albicans isolates usually predominates. The authors have investigated whether these local clusters are part of a single group, geographically widespread and highly prevalent as an aetiological agent of various types of candidiasis. An unrooted neighbour-joining tree of 266 infection-causing C. albicans isolates (each from a different individual) from 12 geographical regions in 6 countries was created, based on genetic distances generated by Ca3 fingerprinting. Thirty-seven per cent of all isolates formed a single genetically homogeneous cluster (cluster A). The remainder of isolates were genetically diverse. Using the maximum branch length within cluster A as a cut-off, they could be divided into 37 groups, whose prevalence ranged between 0.3% and 9%. Strains from cluster A were highly prevalent in all but one geographical region, with a mean prevalence across all regions of 41%. When isolates were separated into groups based on patient characteristics or type of infection, strains from cluster A had a prevalence exceeding 27% in each group, and their mean prevalence was 43% across all patient characteristics. These data provide evidence that cluster A constitutes a general-purpose genotype, which is geographically widespread and acts as a predominant aetiological agent of all forms of candidiasis in all categories of patients surveyed. (+info)
A multicopper oxidase gene from Candida albicans: cloning, characterization and disruption.
(63/3054)
A multicopper oxidase gene from the human pathogenic yeast Candida albicans was isolated and characterized. An open reading frame of 1872 bp, designated CaFET3, was identified, encoding a predicted protein of 624 amino acids and a molecular mass of 70.5 kDa. The identity between the deduced amino acid sequences of CaFET3 and the Saccharomyces cerevisiae FET3 gene is 55%. CaFET3 was localized on chromosome 6. A null mutant (fet3delta/fet3delta) was constructed by sequential gene disruption. Unlike the C. albicans SC5314 wild-type strain the fet3delta mutant was unable to grow in low-iron medium. The lack of growth of a S. cerevisiae fet3delta mutant in iron-limited medium was compensated by transformation with CaFET3. The null mutant strain showed no change in pathogenicity compared with the wild-type strain in the mouse model of systemic candidiasis. (+info)
A novel copper-binding protein with characteristics of a metallothionein from a clinical isolate of Candida albicans.
(64/3054)
It is known that clinical isolates of Candida albicans exhibit a high level of resistance to copper salts, although the molecular basis of this resistance is not clear. To investigate this, a novel copper-binding protein was purified from a clinical isolate of C. albicans. The protein was extracted from yeast cells after an induction period of 10 h in a copper-containing suspension medium. It was further purified by size-exclusion chromatography, ultrafiltration and reverse-phase HPLC. All protein fractions were analysed for their protein and copper contents. The copper/protein ratio increased steadily throughout the purification process; the most highly purified fraction showed a 210-fold increase compared to the whole-cell extract, with a recovery of 0.03%. The molecular mass of the protein was 10,000 Da and a reconstitution study using the purified apoprotein suggested that the equivalent extent of Cu(I) binding was approximately 14 mol eq. The amino-terminal segment of the copper-binding protein revealed three Cys-Xaa-Cys motifs, which is typical of a metallothionein (MT), and showed significant homology with mammalian MTs with respect to the positions of the cysteine residues. This is the first report of the isolation of a copper-binding protein from C. albicans. (+info)