Search

An increasingly diverse array of clinically relevant animal models of candidiasis have been established that mimic both the immune perturbations of the host and tissue-specific features of candidiasis in humans. Cause-and-effect analysis of Candida host–pathogen interactions using these animal models has made a quantum leap forward in the genomic era, with the concurrent construction of C. albicans mutants with targeted mutations of putative virulence factors, the application of microarrays and other emerging technologies to comprehensively assess C. albicans gene expression in vivo, and construction of transgenic and knockout mice to simulate specific host immunodeficiencies. The opportunity to combine these powerful tools will yield an unprecedented wealth of new information on the molecular and cellular pathogenesis of candidiasis. [Copyright &y& Elsevier]

The availability of CD4C/HIV&supMutA; transgenic (Tg) mice expressing human immunodeficiency virus type 1 in immune cells and developing an AIDS-like disease has provided the opportunity to devise a model of mucosal candidiasis that closely mimics the clinical and pathologic features of candidal infection in human AIDS. After intraoral infection with Candida albicans, oral burdens were strikingly elevated in the Tg mice, compared with non-Tg littermates (P <.05), during primary infection, a 6-10-week carrier state, and a marked terminal outgrowth preceding death. The chronic carrier state was absent in the non-Tg mice because of clearing of C. albicans. Candida hyphae penetrated the epithelium of the oral cavity, esophagus, and cardial-atrium fold of the stomach, accompanied by a mononuclear cell infiltrate. Immunohistochemical analysis suggested that decreased frequencies of major histocompatibility complex class II-expressing cells, combined with reduced CD4&sup+; cells, may underlie the susceptibility to mucosal candidiasis in these Tg mice. [ABSTRACT FROM AUTHOR]

The small Ras-like GTPase Ran/Gsp1p is a highly conserved nuclear protein required for the nucleocytoplasmic trafficking of macromolecules. Recent findings suggest that the Ran/Gsp1p pathway may have additional roles in several aspects of nuclear structure and function, including spindle assembly, nuclear envelope formation, nuclear pore complex assembly and RNA processing. Here, we provide evidence that Gsp1p can regulate telomeric function in Saccharomyces cerevisiae. We show that overexpression of PRP20, encoding the Gsp1p GDP/GTP nuclear exchange factor, specifically weakens telomeric silencing without detectably affecting nucleocytoplasmic transport. In addition to this silencing defect, we show that Rap1p and Sir3p delocalize from their normal telomeric foci. Interestingly, Gsp1p was found to interact genetically and physically with the telomeric component Sir4p. Taken together, these results suggest that the GSP1 pathway could regulate proper telomeric function in yeast through Sir4p. [ABSTRACT FROM AUTHOR]

Abstract. A 6-year-old girl had a 7-month history of headaches and painful torticollis. A CT scan of the mastoids showed extensive bone destruction of the base of the skull and C-1. Biopsies of the retropharyngeal area and of the anterior aspect of C-1 were performed: histopathologic findings were suggestive of mycotic infection and cultures were positive for Candida albicans. The child was treated successfully with amphotericin B. The immunologic evaluation demonstrated the absence of myeloperoxidase in the neutrophils. [ABSTRACT FROM AUTHOR]

Objectives: Azole resistance among Aspergillus fumigatus isolates is a growing concern worldwide. Induction of mutations during azole therapy, environment-acquired mutations caused by azole fungicides and intrinsic resistance of cryptic Fumigati species all contribute to the burden of resistance. However, there is a lack of data in Canada on this emerging threat.Methods: To gain insights into the magnitude and mechanisms of resistance, a 14 year collection of Aspergillus section Fumigati comprising 999 isolates from 807 patients at a Montreal hospital was screened for azole resistance, and resistance mechanisms were investigated with the combined use of genome sequencing, 3D modelling and phenotypic efflux pump assays.Results: Overall azole resistance was low (4/807 patients; 0.5%). A single azole-resistant A. fumigatus sensu stricto strain, isolated from a patient with pulmonary aspergillosis, displayed efflux-pump-mediated resistance. Three patients were colonized or infected with azole-resistant cryptic Fumigati species (one Aspergillus thermomutatus, one Aspergillus lentulus and one Aspergillus turcosus). Evidence is presented that azole resistance is efflux-pump-mediated in the A. turcosus isolate, but not in the A. lentulus and A. thermomutatus isolates.Conclusions: Azole resistance is rare in our geographic area and currently driven by cryptic Fumigati species. Continued surveillance of emergence of resistance is warranted. [ABSTRACT FROM AUTHOR]

Background. Neonatal invasive candidiasis (IC) presenting in the first week of life is less common and less well described than later-onset IC. Risk factors, clinical features, and disease outcomes have not been studied in early-onset disease (EOD, ⩽7 days) or compared to late-onset disease (LOD, >7 days). Methods. All extremely low birth weight (ELBW, <1000 g) cases with IC and controls from a multicenter study of neonatal candidiasis enrolled from 2001 to 2003 were included in this study. Factors associated with occurrence and outcome of EOD in ELBW infants were determined. Results. Forty-five ELBW infants and their 84 matched controls were included. Fourteen (31%) ELBW infants had EOD. Birth weight <750 g, gestation <25 weeks, chorioamnionitis, and vaginal delivery were all strongly associated with EOD. Infection with Candida albicans, disseminated disease, pneumonia, and cardiovascular disease were significantly more common in EOD than in LOD. The EOD case fatality rate (71%) was higher than in LOD (32%) or controls (15%) (P = .0001). The rate of neurodevelopmental impairment and mortality combined was similar in EOD (86%) and LOD (72%), but higher than in controls (32%; P = .007). Conclusions. ELBW infants with EOD have a very poor prognosis compared to those with LOD. The role of perinatal transmission in EOD is supported by its association with chorioamnionitis, vaginal delivery, and pneumonia. Dissemination and cardiovascular involvement are common, and affected infants often die. Empiric treatment should be considered for ELBW infants delivered vaginally who have pneumonia and whose mothers have chorioamnionitis or an intrauterine foreign body. [ABSTRACT FROM AUTHOR]

Background The tissue-signaling cytokines IL-17 and IL-22 are critical to host defense against oral Candida albicans infection, by their induction of oral antimicrobial peptide expression and recruitment of neutrophils. Mucosal Th17 cells which produce these cytokines are preferentially depleted in HIV-infected patients. Here, we tested the hypothesis that defective IL-17- and IL-22-dependent host responses to C. albicans determine the phenotype of susceptibility to oropharyngeal candidiasis (OPC) in transgenic (Tg) mice expressing HIV-1. Results Naïve CD4+ T-cells and the differentiated Th1, Th2, Th17, Th1Th17 and Treg lineages were all profoundly depleted in cervical lymph nodes (CLNs) of these Tg mice. However, naive CD4+ cells from Tg mice maintained the capacity to differentiate into these lineages in response to polarizing cytokines in vitro. Expression of Il17, Il22, S100a8 and Ccl20 was enhanced in oral mucosal tissue of non-Tg, but not of Tg mice, after oral infection with C. albicans. Treatment of infected Tg mice with the combination of IL-17 and IL-22, but not IL- 17 or Il-22 alone, significantly reduced oral burdens of C. albicans and abundance of Candida hyphae in the epithelium of tongues of infected Tg mice, and restored the ability of the Tg mice to up-regulate expression of S100a8 and Ccl20 in response to C. albicans infection. Conclusions These findings demonstrate that defective IL-17- and IL-22-dependent induction of innate mucosal immunity to C. albicans is central to the phenotype of susceptibility to OPC in these HIV transgenic mice. [ABSTRACT FROM AUTHOR]

Background This multicenter prospective study of invasive candidiasis (IC) was carried out to determine the risk factors for, incidence of, clinical and laboratory features, treatment and outcome of IC in infants of birth weight <1250 g. Methods Neonates <1250 g with IC and their matched controls (2:1) were followed longitudinally and descriptive analysis was performed. Survivors underwent neurodevelopmental assessment at 18 to 24 months corrected age. Neurodevelopmental impairment (NDI) was defined as blindness, deafness, moderate to severe cerebral palsy, or a score <70 on the Bayley Scales of Infant Development 2nd edition. Multivariable analyses were performed to determine risk factors for IC and predictors of mortality and NDI. Results Cumulative incidence rates of IC were 4.2%, 2.2% and 1.5% for birth-weight categories <750 g, <1000 g, <1500 g, respectively. Forty nine infants with IC and 90 controls were enrolled. Necrotizing enterocolitis (NEC) was the only independent risk factor for IC (p = 0.03). CNS candidiasis occurred in 50% of evaluated infants, while congenital candidiasis occurred in 31%. Infants with CNS candidiasis had a higher mortality rate (57%) and incidence of deafness (50%) than the overall cohort of infants with IC. NDI (56% vs. 33%; p = 0.017) and death (45% vs. 7%; p = 0.0001) were more likely in cases than in controls, respectively. IC survivors were more likely to be deaf (28% vs. 7%; p = 0.01). IC independently predicted mortality (p = 0.0004) and NDI (p = 0.018). Conclusion IC occurred in 1.5% of VLBW infants. Preceding NEC increased the risk of developing IC. CNS candidiasis is under-investigated and difficult to diagnose, but portends a very poor outcome. Mortality, deafness and NDI were independently significantly increased in infants with IC compared to matched controls. [ABSTRACT FROM AUTHOR]

Objectives In this study, we developed a nanoparticulate nystatin formulation and performed a comparative evaluation against a commercial nystatin preparation of its in vitro and in vivo antifungal activities. Methods A nystatin nanosuspension was prepared from a commercially available suspension by wet-media milling. The nanosuspension was characterized for particle size by laser diffraction and assayed for content by HPLC. Its in vitro activity was evaluated against Candida albicans strains SC5314 and LAM-1 (12.5–5000 μg/mL) using an agar plate assay and its in vivo efficacy was evaluated using a murine model of oral candidiasis. Briefly, DBA/2 mice were immunosuppressed with cortisone acetate, orally infected with C. albicans strain LAM-1, and treated for 14 days with conventional nystatin suspension, nystatin nanosuspension or saline control. Efficacy endpoints were oral fungal burden, mouse survival and organ histopathology. A single-dose pharmacokinetic study was also performed. Results The median particle size of the nystatin suspension was reduced from 6577 to 137 nm. The HPLC assay demonstrated a nystatin content of 98.7% ± 0.8% of the label claim. In vitro activity was superior to that of the conventional nystatin suspension at 100–5000 μg/mL concentrations. Beginning on day 3 of treatment, lower oral burdens of C. albicans were found in the nanosuspension group compared with the suspension and control groups. Mouse survival was also superior in the nanosuspension group. No systemic absorption was observed. Conclusions Taken together, these data reveal that nanonization of nystatin provides a novel approach to enhancing its efficacy in the treatment of oral candidiasis. [ABSTRACT FROM PUBLISHER]

The interaction of Cryptococcus neoformans with phagocytic cells of the innate immune system is a key step in disseminated disease leading to meningoencephalitis in immunocompromised individuals. Transcriptional profiling of cryptococcal cells harvested from cell culture medium or from macrophages found differential expression of metabolic and other functions during fungal adaptation to the intracellular environment. We focused on the ACL1 gene for ATP-citrate lyase, which converts citrate to acetyl- CoA, because this gene showed elevated transcript levels in macrophages and because of the importance of acetyl- CoA as a central metabolite. Mutants lacking ACL1 showed delayed growth on medium containing glucose, reduced cellular levels of acetyl- CoA, defective production of virulence factors, increased susceptibility to the antifungal drug fluconazole and decreased survival within macrophages. Importantly, acl1 mutants were unable to cause disease in a murine inhalation model, a phenotype that was more extreme than other mutants with defects in acetyl- CoA production (e.g. an acetyl- CoA synthetase mutant). Loss of virulence is likely due to perturbation of critical physiological interconnections between virulence factor expression and metabolism in C. neoformans. Phylogenetic analysis and structural modelling of cryptococcal Acl1 identified three indels unique to fungal protein sequences; these differences may provide opportunities for the development of pathogen-specific inhibitors. [ABSTRACT FROM AUTHOR]

To comprehensively assess the in vivo expression of Candida albicans hydrolytic enzyme genes during oropharyngeal candidiasis (OPC), a controlled sequential analysis of the temporal expression of individual members of the SAP (secretory aspartyl proteinase) gene family and PLB1 (phospholipase B) in a murine model of OPC was conducted. Acute infections in intact C3H and DBA/2 mice were terminated by clearance of C. albicans within 7 days after oral inoculation, but transgenic (Tg) mice expressing human immunodeficiency virus type 1 were persistently colonized until a final outgrowth before death. In contrast to the sustained expression of other SAP genes and PLB1, SAP7 and SAP8 were conspicuously distinguished by their transient expression in both intact and Tg mice. SAP5 and SAP9 were most strongly expressed throughout the course of infection in the Tg mice. These findings indicate that expression of individual members of the C. albicans SAP gene family is differentially regulated during experimental OPC. [ABSTRACT FROM AUTHOR]

Studies Candida albicans secretory aspartyl proteinase 2 and its expression in Saccharomyces cerevisiae. Transformation of Saccharomyces cerevisiae and Candida albicans; Characterization of C. albicans strains; Results of the study.

Background: This multicenter prospective study of invasive candidiasis (IC) was carried out to determine the risk factors for, incidence of, clinical and laboratory features, treatment and outcome of IC in infants of birth weight <1250 g.Methods: Neonates <1250 g with IC and their matched controls (2:1) were followed longitudinally and descriptive analysis was performed. Survivors underwent neurodevelopmental assessment at 18 to 24 months corrected age. Neurodevelopmental impairment (NDI) was defined as blindness, deafness, moderate to severe cerebral palsy, or a score <70 on the Bayley Scales of Infant Development 2nd edition. Multivariable analyses were performed to determine risk factors for IC and predictors of mortality and NDI.Results: Cumulative incidence rates of IC were 4.2%, 2.2% and 1.5% for birth-weight categories <750 g, <1000 g, <1500 g, respectively. Forty nine infants with IC and 90 controls were enrolled. Necrotizing enterocolitis (NEC) was the only independent risk factor for IC (p=0.03). CNS candidiasis occurred in 50% of evaluated infants, while congenital candidiasis occurred in 31%. Infants with CNS candidiasis had a higher mortality rate (57%) and incidence of deafness (50%) than the overall cohort of infants with IC. NDI (56% vs. 33%; p=0.017) and death (45% vs. 7%; p=0.0001) were more likely in cases than in controls, respectively. IC survivors were more likely to be deaf (28% vs. 7%; p=0.01). IC independently predicted mortality (p=0.0004) and NDI (p=0.018).Conclusion: IC occurred in 1.5% of VLBW infants. Preceding NEC increased the risk of developing IC. CNS candidiasis is under-investigated and difficult to diagnose, but portends a very poor outcome. Mortality, deafness and NDI were independently significantly increased in infants with IC compared to matched controls. [ABSTRACT FROM AUTHOR]

We previously reported that CD4C/human immunodeficiency virus (HIV)Nef transgenic (Tg) mice, expressing Nef in CD4+ T cells and cells of the macrophage/dendritic cell (DC) lineage, develop a severe AIDS-like disease, characterized by depletion of CD4+ T cells, as well as lung, heart, and kidney diseases. In order to determine the contribution of distinct populations of hematopoietic cells to the development of this AIDS-like disease, five additional Tg strains expressing Nef through restricted cell-specific regulatory elements were generated. These Tg strains express Nef in CD4+ T cells, DCs, and macrophages (CD4E/HIVNef); in CD4+ T cells and DCs (mCD4/HIVNef and CD4F/HIVNef); in macrophages and DCs (CD68/HIVNef); or mainly in DCs (CD11c/HIVNef). None of these Tg strains developed significant lung and kidney diseases, suggesting the existence of as-yet-unidentified Nef-expressing cell subset(s) that are responsible for inducing organ disease in CD4C/HIVNef Tg mice. Mice from all five strains developed persistent oral carriage of Candida albicans, suggesting an impaired immune function. Only strains expressing Nef in CD4+ T cells showed CD4+ T-cell depletion, activation, and apoptosis. These results demonstrate that expression of Nef in CD4+ T cells is the primary determinant of their depletion. Therefore, the pattern of Nef expression in specific cell population(s) largely determines the nature of the resulting pathological changes. [ABSTRACT FROM AUTHOR]