No abstract available.
Drug Resistance, Fungal* ; Fungi*

OBJECTIVETo observe the drug resistance and drug efflux pumps gene mRNA of Saccharomyces albicans, including CDR1 gene and MDR1 gene, at different stage of biofilm formation in chemostat, furthermore to analysis the relationship between the drug efflux pump gene expression and the biofilm related drug resistance.

METHODSTo form the mature biofilm in vitro in chemostat, then collect the biofilm strains at different development stages (2, 12, 24, 48 h) to semi-quantified mRNA amount of CDR1 gene and MDR1 gene by one step RT-PCR method. Using XTT reduction method to test the dynamic change of Saccharomyces albicans drug resistance in biofilm.

RESULTSAntifungal resistance of biofilm-grown cells increased conjunction with the biofilm maturation. Compared with earth stage of biofiom strains, the amount of CDR1 mRNA gene in mature biofilm strains increased, while MDR1 gene did not.

CONCLUSIONThere is positive correlation between drug resistance and biofilm maturation of Saccharomyces albicans. Biofilm related drug resistance appears to be partially associated with the upregulation of drug efflux pumps, although the variation is not shown coincidence. During the biofilm formation, CDR1 gene expression is actively up-regulated, but MDR1 gene expression is stable.

Antifungal Agents ; Biofilms ; Candida albicans ; Drug Resistance, Fungal ; Fluconazole ; Fungal Proteins ; Gene Expression Regulation, Fungal ; Membrane Transport Proteins ; Saccharomyces

Adult ; Aged ; Cross Infection ; microbiology ; Drug Resistance, Bacterial ; Drug Resistance, Fungal ; Humans ; Male ; Middle Aged ; Pneumoconiosis ; complications

Ethanol tolerance is related to the expression of multiple genes, and genome-based engineering approaches are much more efficient than manipulation of single genes. In this study, ultraviolet (UV) mutagenesis, dielectric barrier discharge (DBD) air plasma mutagenesis, and artificial transcription factor (ATF) technology were adopted to treat an industrial yeast strain S. cerevisiae Sc4126 to obtain mutants with improved ethanol tolerance. Mutants with high ethanol tolerance were obtained, and the ratio of positive mutants was compared. Among the three approaches, the rate of positive mutation obtained by ATF technology was 10- to 100-folds of that of the two other methods, with highest genetic stability, suggesting the ATF technology promising for rapid alteration of phenotypes of industry yeast strains for efficient ethanol fermentation.
Adaptation, Physiological ; drug effects ; Drug Resistance, Fungal ; genetics ; Ethanol ; pharmacology ; Fungal Proteins ; genetics ; metabolism ; Industrial Microbiology ; methods ; Mutagenesis ; Saccharomyces cerevisiae ; drug effects ; genetics ; growth & development

Candida species are frequently found in the normal microorganism of humans, which facilitates their encounter with most implanted biomaterials and host surfaces. Medical devices such as stents, prostheses, implants and various types of catheters have all been shown to support colonization and biofilm formation by Candida. Candida albicans remains the fungal species most commonly associated with biofilm formation and the increase in Candida infections in the last decades has almost paralleled the increase and widespread use of a broad range of medical implant devices, mainly in populations with impaired host defenses. The formation of C. albicans biofilms carries important clinical repercussions because of their increased resistance to antifungal therapy and the ability of cells within biofilms to withstand host immune defenses. Also, biofilm formation on medical devices can negatively impact the host by serving as a reservoir or source for future continuing infections. This review article aims to provide insights on various aspects of C. albicans biofilms, formation and structure, their role in pathogenesis and antifungal drug resistance.
Biocompatible Materials ; Biofilms ; Candida ; Candida albicans ; Catheters ; Colon ; Drug Resistance, Fungal ; Humans ; Prostheses and Implants ; Stents

The incidence of invasive fungal infection has increased worldwide along with the increasing population of high risk patients. Recently developed antifungal agents, such as second-generation triazoles and echinocandins, provide the potential to improve therapeutic options against invasive fungal infections. However, treatment of invasive fungal infections has been hampered by both intrinsic and acquired resistance to antifungal agents among many fungal pathogens. A better understanding of the clinical impact of antifungal resistance is important for selecting the proper antifungal agent in patients with systemic fungal infections. This article reviews the current situation with regard to intrinsic and acquired resistance of clinically significant yeasts and filamentous fungi against currently available antifungal agents.
Amphotericin B ; Antifungal Agents ; Azoles ; Drug Resistance, Fungal ; Echinocandins ; Fungi ; Humans ; Incidence ; Triazoles ; Yeasts

BACKGROUND: Echinocandins are a new class of antifungal agents with potent in vitro and in vivo activities against Aspergillus species. We investigated the in vitro activity of caspofungin and micafungin against Korean clinical Aspergillus isolates. MATERIALS AND METHODS: A total of 100 clinical isolates of Aspergillus species (32 A. fumigatus, 26 A. flavus, 22 A. niger and 20 A. terreus) were tested. The susceptibilities of caspofungin, micafungin, amphotericin B and itraconazole were established by means of the Clinical and Laboratory Standards Institute (CLSI) M38-A microdilution methods. The results for caspofungin and micafungin were evaluated by using the end points of minimum inhibitory concentrations (MIC) and minimum effective concentration (MEC, the lowest concentration that produces short and aberrant hyphal branchings microsopically). RESULTS: The MEC ranges of caspofungin and micafungin against 100 isolates of Aspergillus species were 0.06 to 0.5 microgram/mL and < or =0.03 microgram/mL, respectively. For both echinocandins, MIC values showed similar ranges to MEC in most isolates of Aspergillus spp., but caspofungin and micafungin MIC increased to >16 microgram/mL unexpectedly, in 5% (5/100) and 4% (4/100) of isolates, respectively, which resulted in the loss of a consistent correlation between the two endpoint readings. The MEC50 of all Aspergillus isolates for caspofungin and micafungin were 0.25 and < or =0.03 /mL, respectively, and the MIC50 for amphotericin B and itraconazole were 0.5 and 0.25 microgram/mL, respectively. There were no species-related differences in caspofungin and micafungin MECs for Aspergillus species. CONCLUSION: This data demonstrates excellent in vitro activity of echinocandins against clinical strains of Aspergillus species.
Amphotericin B ; Antifungal Agents ; Aspergillus* ; Drug Resistance, Fungal ; Echinocandins* ; Itraconazole ; Microbial Sensitivity Tests ; Niger ; Reading

BACKGROUND: Echinocandins are a new class of antifungal agents with potent in vitro and in vivo activities against Aspergillus species. We investigated the in vitro activity of caspofungin and micafungin against Korean clinical Aspergillus isolates. MATERIALS AND METHODS: A total of 100 clinical isolates of Aspergillus species (32 A. fumigatus, 26 A. flavus, 22 A. niger and 20 A. terreus) were tested. The susceptibilities of caspofungin, micafungin, amphotericin B and itraconazole were established by means of the Clinical and Laboratory Standards Institute (CLSI) M38-A microdilution methods. The results for caspofungin and micafungin were evaluated by using the end points of minimum inhibitory concentrations (MIC) and minimum effective concentration (MEC, the lowest concentration that produces short and aberrant hyphal branchings microsopically). RESULTS: The MEC ranges of caspofungin and micafungin against 100 isolates of Aspergillus species were 0.06 to 0.5 microgram/mL and < or =0.03 microgram/mL, respectively. For both echinocandins, MIC values showed similar ranges to MEC in most isolates of Aspergillus spp., but caspofungin and micafungin MIC increased to >16 microgram/mL unexpectedly, in 5% (5/100) and 4% (4/100) of isolates, respectively, which resulted in the loss of a consistent correlation between the two endpoint readings. The MEC50 of all Aspergillus isolates for caspofungin and micafungin were 0.25 and < or =0.03 /mL, respectively, and the MIC50 for amphotericin B and itraconazole were 0.5 and 0.25 microgram/mL, respectively. There were no species-related differences in caspofungin and micafungin MECs for Aspergillus species. CONCLUSION: This data demonstrates excellent in vitro activity of echinocandins against clinical strains of Aspergillus species.
Amphotericin B ; Antifungal Agents ; Aspergillus* ; Drug Resistance, Fungal ; Echinocandins* ; Itraconazole ; Microbial Sensitivity Tests ; Niger ; Reading

The incidence of invasive fungal infection has increased worldwide along with the increasing population of high risk patients. Recently developed antifungal agents, such as second-generation triazoles and echinocandins, provide the potential to improve therapeutic options against invasive fungal infections. However, treatment of invasive fungal infections has been hampered by both intrinsic and acquired resistance to antifungal agents among many fungal pathogens. A better understanding of the clinical impact of antifungal resistance is important for selecting the proper antifungal agent in patients with systemic fungal infections. This article reviews the current situation with regard to intrinsic and acquired resistance of clinically significant yeasts and filamentous fungi against currently available antifungal agents.
Amphotericin B ; Antifungal Agents ; Azoles ; Drug Resistance, Fungal ; Echinocandins ; Fungi ; Humans ; Incidence ; Triazoles ; Yeasts

BACKGROUNDThe cytochrome P450 lanosterol 14alpha-demethylase (Erg11p) encoded by ERG11 gene is the primary target for azole antifungals. Changes in azole affinity of this enzyme caused by amino acid substitutions have been reported as a mechanism of azole antifungal resistance. This study aimed to investigate the relationship between amino acid substitutions in Erg11p from fluconazole resistant Candida albicans (C. albicans) isolates and their cross-resistance to azoles.

METHODSMutations in ERG11 gene were screened in 10 clinical isolates of fluconazole resistant C. albicans strains. DNA sequence of ERG11 was determined by PCR based DNA sequencing.

RESULTSIn the 10 isolates, 19 types of amino acid substitutions were found, of which 10 substitutions (F72S, F103L, F145I, F198L, G206D, G227D, N349S, F416S, F422L and T482A) have not been reported previously. Mutations in ERG11 gene were detected in 9 isolates of fluconazole resistant C. albicans, but were not detected in 1 isolate.

CONCLUSIONSAlthough no definite correlation was found between the type of amino acid substitutions in Erg11p and the phenotype of cross-resistance to azoles, the substitutions F72S, F145I and G227D in our study may be highly associated with resistance to azoles because of their special location in Erg11p.

Antifungal Agents ; pharmacology ; Candida albicans ; drug effects ; genetics ; Cytochrome P-450 Enzyme System ; genetics ; Drug Resistance, Fungal ; Fluconazole ; pharmacology ; Fungal Proteins ; genetics ; Microbial Sensitivity Tests ; Mutation