ORCID Profile
0000-0002-0200-8132
Current Organisation
Tohoku University
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Publisher: Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences
Date: 30-09-2016
Publisher: Informa UK Limited
Date: 13-02-2022
Publisher: Wiley
Date: 05-2000
DOI: 10.1034/J.1600-0714.2000.290503.X
Abstract: Post-antifungal effect (PAFE) is defined as the suppression of growth that persists following limited exposure of fungi to antimycotics and subsequent removal of the drug. The fungal pathogen Candida albicans is the major aetiologic agent of oral candidosis, and the cell surface hydrophobicity (CSH) of this yeast is considered a critical factor contributing to its colonisation potential. As the concentration of topically prescribed antifungals reach sub-therapeutic levels at dosage intervals, the study of the polyene-induced PAFE and its impact on the CSH of oral C. albicans should be of clinical relevance. Hence the aims of this investigation were to measure the PAFE and CSH of 12 isolates of C. albicans following limited exposure (1 h) to nystatin and hotericin B and also to investigate the ultrastructural features of yeast cells following such antifungal exposure. The yeasts were exposed to sub-lethal concentrations of nystatin (x2 MIC) and hotericin B (x2 MIC) for a period of 1 h. Following subsequent removal of the drug, the PAFE and the CSH of the isolates were assessed by a turbidometric measurement of growth and a biphasic aqueous-hydrocarbon assay, respectively. The mean duration of PAFE of nystatin and hotericin B were 5.99 (+/-0.49) h and 8.73 (+/-0.93) h, respectively, while the reduction in CSH following exposure to these drugs were 17.32% (P<0.05 for 83% of the isolates) and 14.26% (P<0.05 for 66% of the isolates), respectively. On scanning electron microscopy the exposed cells were seen to undergo collapse of the internal cell membrane, leaving an intact cell wall, while a proportion of cells were deflated. Some cells showed intense puckering of the cell wall, resulting in a mulberry appearance. Taken together, these data elucidate additional mechanisms by which polyene antimycotics may operate in vivo to suppress candidal pathogenicity.
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.IJANTIMICAG.2009.03.008
Abstract: Biofilm formation involving profuse hyphal growth is a major characteristic of Candida spp. and confers higher antifungal resistance than its planktonic mode of growth. We investigated the antifungal susceptibility of Candida albicans and its hyphal mutants (Delta efg1/efg1, Delta cph1/cph1 and DeltaDelta cph1/cph1 efg1/efg1) to commonly used antifungals during planktonic, adhesion and biofilm modes of growth. The minimum inhibitory concentration (MIC) of each antifungal agent was determined for a lower inoculum (1x10(3) cells/mL) and higher inoculum (1x10(7) cells/mL) of planktonic Candida. Furthermore, MICs of C. albicans biofilms and adhesion modes of growth were determined with a standard XTT assay. Candida albicans in adhesion and biofilm modes of growth, but not in planktonic mode, were resistant to all five antifungal agents tested. Although Delta efg1/efg1 and DeltaDelta cph1/cph1 efg1/efg1 mutants formed less biofilm than wild-type C. albicans SC5314, they were similarly resistant to caspofungin. However, these mutants were more sensitive to hotericin B and nystatin than the wild-type. Adhesion per se confers increased resistance to antifungal agents, which is further pronounced in the biofilm mode of Candida. Filamentation does not appear to be a major determinant of the antifungal resistance in Candida biofilms.
Publisher: Bentham Science Publishers Ltd.
Date: 11-2008
DOI: 10.2174/157016208786501445
Abstract: Oral candidosis (syn. Oral candidiasis OC), is a collective term given to a group of oral mucosal disorders caused by the fugal pathogen belonging to the genus Candida. The association of OC with the human immunodeficiency virus (HIV) infection has been known since the advent of the acquired immune deficiency syndrome (AIDS) pandemic. OC is one of the earliest manifestations of HIV disease in high risk in iduals not undergoing chemotherapy and is also a strong predictor of the subsequent risk of AIDS-related illness or death. With the advances in HIV therapy, such as highly active anti-retroviral therapy (HAART), the prevalence and presenting features of OC have changed in HIV-infected in iduals, especially those in industrialized countries. The presence of OC in "controlled" HIV-positive in iduals may be indicative of a patient nonadherence to therapy or possible failure. The factors contributing to the genesis of OC and its progression in these in iduals are poorly understood, but may include an interrelationship between HIV and Candida and/or a dysfunction in the local immunity, superimposed on weakened cell-mediated immunity and depletion of CD4 T cells. The dramatic increase in publications on this topic matches the increased importance and awareness of this opportunistic infection in HIV-infected in iduals. In this review we first address the epidemiologic and clinical features of OC in HIV-infected persons, followed by the current understanding of the pathogenesis of OC in the context of HIV infection with a concluding section on the current management concepts of OC.
Publisher: Springer Science and Business Media LLC
Date: 03-06-2020
DOI: 10.1186/S12903-020-01133-3
Abstract: The use of silver-formulation as microbicide to arrest dentinal caries is gaining popularity. The primary objective of the present appraisal was to systematically review the clinical (in vivo) applications and antimicrobial potential of silver-containing formulations in arresting dentinal caries. Our secondary aim was to sum up the available in vitro applications of silver-containing formulations against cariogenic microbes isolated from dentine lesions. Ovid MEDLINE, EBSCO host, Web of Science, and Cochrane Library databases was searched between January 2009–May 2019. In vivo: We observed conflicting evidence of antimicrobial efficacy of SDF on a erse array of microbial taxa present in carious dentine of primary and permanent teeth. Moreover, there is insufficient evidence on the application of AgNP-fluoride as an effective microbicidal against cariogens of dentine lesions. In vitro: We found a good evidence of microbicidal efficacy of silver diamine fluoride (SDF) on selective cariogenic microbes in human dentine model. Additionally, a good evidence was noted of in vitro application of silver nanoparticles (AgNPs) as a useful microbicidal against S. mutans adhesion, growth and subsequent biofilm formation in human dentine models. Taken together, in vitro evidence indicates the promising antimicrobial potential of silver-based formulations (SDF and nanosilver) against the predominant cariogenic flora, particularly from dentine lesions. Post-treatment clinical data of either the bactericidal and bacteriostatic effects of SDF or nanosilver are sparse. Furthermore, the current understanding of the specific size, concentration, antimicrobial mechanisms, and toxicological aspects of nano-silver compounds is inadequate to draw firm conclusions on their clinical utility.
Publisher: Elsevier BV
Date: 02-2010
Publisher: Microbiology Society
Date: 09-2011
Abstract: Biofilm formation is a major virulence attribute of Candida albicans and is directly associated with therapeutic failure. One method by which Candida acquires antifungal resistance is the expression of drug-resistance genes. This study aimed to evaluate the transcriptional regulation of several genes associated with antifungal resistance of C. albicans under planktonic, recently adhered and biofilm growth modes and in C. albicans biofilms in response to antifungal agents. Initially, the antifungal susceptibility of C. albicans cultures in different growth modes was evaluated by standard antifungal susceptibility testing. Next, to assess CDR1, CDR2, MDR1, ERG11, FKS1 and PIL1 expression, RNA was harvested from cells in each growth mode, and from biofilms after drug treatment, and subjected to quantitative real-time RT-PCR (qRT-PCR). Biofilm C. albicans was more resistant to antifungals than recently adhered cells and stationary-phase planktonic cultures. Transcriptional expression of CDR1, CDR2, MDR1, ERG11 and FKS1 was lower in recently adhered C. albicans than in the stationary-phase planktonic cultures. In contrast, PIL1 levels were significantly increased in recently adhered and biofilm modes of growth. The expression of MDR1 in biofilms greatly increased on challenge with hotericin B but not with the other drugs tested (P<0.01). ERG11 was significantly upregulated by ketoconazole (P<0.01). Caspofungin and hotericin B significantly upregulated FKS1 expression, whereas they significantly downregulated PIL1 expression (P<0.01). These results indicate that the expression of drug-resistance genes is associated with higher drug resistance of Candida biofilms, and lay a foundation for future large-scale genome-wide expression analysis.
No related grants have been discovered for Hiroshi Egusa.