Susceptibility of Candida albicans to flucytosine when tested in different formulations of yeast nitrogen base broth

1986 ◽  
Vol 5 (3) ◽  
pp. 273-276
Author(s):  
John N. Galgiani ◽  
Carole A. Yturralde ◽  
Kris O. Dugger
Keyword(s):  
Candida Albicans ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base

scholarly journals Reversible fluconazole resistance in Candida albicans: a potential in vitro model.

1997 ◽  
Vol 41 (3) ◽  
pp. 535-539 ◽  
Author(s):  
H M Calvet ◽  
M R Yeaman ◽  
S G Filler
Keyword(s):  
Candida Albicans ◽  
Molecular Mechanisms ◽  
Rabbit Model ◽  
Serial Passage ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Fluconazole Resistance ◽  
Karyotypic Analysis

To study the development and potential mechanisms of antifungal resistance in relation to antifungal exposure, reversible fluconazole resistance was examined in vitro. Candida albicans ATCC 36082 blastospores were passed in liquid yeast nitrogen base medium containing either 4, 8, 16, or 128 micrograms of fluconazole per ml, and susceptibility testing was performed after each passage. High-level fluconazole resistance (50% inhibitory concentration, > 256 micrograms/ml) developed in the isolates after serial passage in medium containing 8, 16, or 128 micrograms of fluconazole per ml, but not in isolates passed in 4 micrograms of fluconazole per ml. Reduced susceptibility was noted within four to seven passages, which was equivalent to 14 to 19 days of exposure to the drug. However, all isolates returned to the susceptible phenotype after 8 to 15 passages in medium lacking the drug; thus, fluconazole resistance was reversible in vitro. In vivo, organisms retained the resistant phenotype after a single passage in the rabbit model of infective endocarditis. Restriction digest profiles and karyotypic analysis of the parent strain and selected fluconazole-resistant and -susceptible isolates from each group were identical. Investigations into the molecular mechanisms of this reversible resistance failed to reveal increased accumulation of mRNA for 14 alpha-demethylase, the target enzyme for fluconazole, or for the candidal multidrug transporters CDR1 and BENr. This process of continuous in vitro exposure to antifungal drug may be useful as a model for studying the effects of different antifungal agents and dosing regimens on the development of resistance and for defining the mechanism(s) of reversible resistance.

Delivery of Amphotericin B to Candida albicans by Using Biomachined Lab-on-a-Chip

2017 ◽  
Vol 30 ◽  
pp. 24-30 ◽  
Author(s):  
M. Hanif Nadhif ◽  
Yudan Whulanza ◽  
Jos Istiyanto ◽  
Boy M. Bachtiar
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Continuous Flow ◽  
Drug Testing ◽  
Lab On A Chip ◽  
Yeast Nitrogen Base ◽  
Mold Surface ◽  
Cnc Milling ◽  
Polydimethyl Siloxane ◽  
Nitrogen Base

This paper investigates the ability of biomachined lab-on-a-chip (LoC) to perform drug testing of Amphotericin B to the Candida albicans. The chip is made of polydimethyl siloxane (PDMS). Molds are patterned using CNC milling followed by biomachining. CNC milling process creates channel features on the bottom mold, while biomachining forms rough surface on the channels. After the molds are created, LoC can be manufactured using those molds. Hence, contour surface on LoC’s channels is also realized following the mold surface. Later, Candida albicans is seeded on the LoC’s channels for 24 and 48 hours with the continuous flow of Yeast Nitrogen Base (YNB) Sterile. Then, cell viability is tested using 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium (MTT).The result shows that C. albicans could adhere and grow in the LoC channels. Based on this result, drug testing is conducted in the presence and absence of Amphotericin B (Amp B) under two schemes: without (static) and with (dynamic) the continuous flow of YNB Sterile and Amp B. After 48 hour incubation period, C. albicans biofilm of 28.72 % is shown during dynamic scheme, whereas static scheme had C. albicans biofilm of 99.32 % indicating that the dynamic scheme provides a better efficacy compared to the static scheme.

scholarly journals Counter-Acting Candida albicans-Staphylococcus aureus Mixed Biofilm on Titanium Implants Using Microbial Biosurfactants

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2420
Author(s):  
Erica Tambone ◽  
Alice Marchetti ◽  
Chiara Ceresa ◽  
Federico Piccoli ◽  
Adriano Anesi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Candida Albicans ◽  
Metabolic Activity ◽  
Titanium Implants ◽  
Microbial Colonization ◽  
Total Biomass ◽  
Yeast Nitrogen Base ◽  
Biofilm Inhibition ◽  
Nitrogen Base ◽  
Primary Osteoblasts

This study aimed to grow a fungal-bacterial mixed biofilm on medical-grade titanium and assess the ability of the biosurfactant R89 (R89BS) coating to inhibit biofilm formation. Coated titanium discs (TDs) were obtained by physical absorption of R89BS. Candida albicans-Staphylococcus aureus biofilm on TDs was grown in Yeast Nitrogen Base, supplemented with dextrose and fetal bovine serum, renewing growth medium every 24 h and incubating at 37 °C under agitation. The anti-biofilm activity was evaluated by quantifying total biomass, microbial metabolic activity and microbial viability at 24, 48, and 72 h on coated and uncoated TDs. Scanning electron microscopy was used to evaluate biofilm architecture. R89BS cytotoxicity on human primary osteoblasts was assayed on solutions at concentrations from 0 to 200 μg/mL and using eluates from coated TDs. Mixed biofilm was significantly inhibited by R89BS coating, with similar effects on biofilm biomass, cell metabolic activity and cell viability. A biofilm inhibition >90% was observed at 24 h. A lower but significant inhibition was still present at 48 h of incubation. Viability tests on primary osteoblasts showed no cytotoxicity of coated TDs. R89BS coating was effective in reducing C. albicans-S. aureus mixed biofilm on titanium surfaces and is a promising strategy to prevent dental implants microbial colonization.

scholarly journals Flow Cytometry Antifungal Susceptibility Testing of Pathogenic Yeasts other than Candida albicans and Comparison with the NCCLS Broth Microdilution Test

2000 ◽  
Vol 44 (10) ◽  
pp. 2752-2758 ◽  
Author(s):  
Rama Ramani ◽  
Vishnu Chaturvedi
Keyword(s):  
Flow Cytometry ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Broth Microdilution ◽  
Nitrogen Base ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT Candida species other than Candida albicansfrequently cause nosocomial infections in immunocompromised patients. Some of these pathogens have either variable susceptibility patterns or intrinsic resistance against common azoles. The availability of a rapid and reproducible susceptibility-testing method is likely to help in the selection of an appropriate regimen for therapy. A flow cytometry (FC) method was used in the present study for susceptibility testing ofCandida glabrata, Candida guilliermondii,Candida krusei, Candida lusitaniae,Candida parapsilosis, Candida tropicalis, andCryptococcus neoformans based on accumulation of the DNA binding dye propidium iodide (PI). The results were compared with MIC results obtained for amphotericin B and fluconazole using the NCCLS broth microdilution method (M27-A). For FC, the yeast inoculum was prepared spectrophotometrically, the drugs were diluted in either RPMI 1640 or yeast nitrogen base containing 1% dextrose, and yeast samples and drug dilutions were incubated with amphotericin B and fluconazole, respectively, for 4 to 6 h. Sodium deoxycholate and PI were added at the end of incubation, and fluorescence was measured with a FACScan flow cytometer (Becton Dickinson). The lowest drug concentration that showed a 50% increase in mean channel fluorescence compared to that of the growth control was designated the MIC. All tests were repeated once. The MICs obtained by FC for all yeast isolates except C. lusitaniae were in very good agreement (within 1 dilution) of the results of the NCCLS broth microdilution method. Paired ttest values were not statistically significant (P = 0.377 for amphotericin B; P = 0.383 for fluconazole). Exceptionally, C. lusitaniae isolates showed higher MICs (2 dilutions or more) than in the corresponding NCCLS broth microdilution method for amphotericin B. Overall, FC antifungal susceptibility testing provided rapid, reproducible results that were statistically comparable to those obtained with the NCCLS method.

scholarly journals Metabolic Engineering of Non-carotenoid-Producing Yeast Yarrowia lipolytica for the Biosynthesis of Zeaxanthin

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuxiao Xie ◽  
Shulin Chen ◽  
Xiaochao Xiong
Keyword(s):  
Yarrowia Lipolytica ◽  
Fold Increase ◽  
Genetically Engineered ◽  
Cell Factory ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Yeast Extract Peptone Dextrose ◽  
Dry Cell Weight ◽  
A Cell ◽  
Β Carotene

Zeaxanthin is vital to human health; thus, its production has received much attention, and it is also an essential precursor for the biosynthesis of other critical carotenoids such as astaxanthin and crocetin. Yarrowia lipolytica is one of the most intensively studied non-conventional yeasts and has been genetically engineered as a cell factory to produce carotenoids such as lycopene and β-carotene. However, zeaxanthin production by Y. lipolytica has not been well investigated. To fill this gap, β-carotene biosynthesis pathway has been first constructed in this study by the expression of genes, including crtE, crtB, crtI, and carRP. Three crtZ genes encoding β-carotene hydroxylase from different organisms were individually introduced into β-carotene-producing Y. lipolytica to evaluate their performance for producing zeaxanthin. The expression of crtZ from the bacterium Pantoea ananatis (formerly Erwinia uredovora, Eu-crtZ) resulted in the highest zeaxanthin titer and content on the basis of dry cell weight (DCW). After verifying the function of Eu-crtZ for producing zeaxanthin, the high-copy-number integration into the ribosomal DNA of Y. lipolytica led to a 4.02-fold increase in the titer of zeaxanthin and a 721% increase in the content of zeaxanthin. The highest zeaxanthin titer achieved 21.98 ± 1.80 mg/L by the strain grown on a yeast extract peptone dextrose (YPD)–rich medium. In contrast, the highest content of DCW reached 3.20 ± 0.11 mg/g using a synthetic yeast nitrogen base (YNB) medium to culture the cells. Over 18.0 g/L of citric acid was detected in the supernatant of the YPD medium at the end of cultivation. Furthermore, the zeaxanthin-producing strains still accumulated a large amount of lycopene and β-carotene. The results demonstrated the potential of a cell factory for zeaxanthin biosynthesis and opened up an avenue to engineer this host for the overproduction of carotenoids.

scholarly journals Correlation of Fluconazole MICs with Clinical Outcome in Cryptococcal Infection

2000 ◽  
Vol 44 (6) ◽  
pp. 1544-1548 ◽  
Author(s):  
A. I. Aller ◽  
E. Martin-Mazuelos ◽  
F. Lozano ◽  
J. Gomez-Mateos ◽  
L. Steele-Moore ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Maintenance Therapy ◽  
National Committee ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Cryptococcal Infection ◽  
Microdilution Method ◽  
Cryptococcal Disease ◽  
Fluconazole Therapy

ABSTRACT We have correlated the in vitro results of testing the susceptibility of Cryptococcus neoformans to fluconazole with the clinical outcome after fluconazole maintenance therapy in patients with AIDS-associated cryptococcal disease. A total of 28 isolates of C. neoformans from 25 patients (24 AIDS patients) were tested. The MICs were determined by the broth microdilution technique by following the modified guidelines described in National Committee for Clinical Standards (NCCLS) document M27-A, e.g., use of yeast nitrogen base medium and a final inoculum of 104 CFU/ml. The fluconazole MIC at which 50% of isolates are inhibited (MIC50) and MIC90, obtained spectrophotometrically after 48 h of incubation, were 4 and 16 μg/ml, respectively. Of the 25 patients studied, 4 died of active cryptococcal disease and 2 died of other causes. Therapeutic failure was observed in five patients who were infected with isolates for which fluconazole MICs were ≥16 μg/ml. Four of these patients had previously had oropharyngeal candidiasis (OPC); three had previously had episodes of cryptococcal infection, and all five treatment failure patients had high cryptococcal antigen titers in either serum or cerebrospinal fluid (titers, >1:4,000). Although 14 of the 18 patients who responded to fluconazole therapy had previously had OPC infections, they each had only a single episode of cryptococcal infection. It appears that the clinical outcome after fluconazole maintenance therapy may be better when the infecting C. neoformans strain is inhibited by lower concentrations of fluconazole for eradication (MICs, <16 μg/ml) than when the patients are infected with strains that require higher fluconazole concentrations (MICs, ≥16 μg/ml). These findings also suggest that the MICs determined by the modified NCCLS microdilution method can be potential predictors of the clinical response to fluconazole therapy and may aid in the identification of patients who will not respond to fluconazole therapy.

scholarly journals Cell Surface Engineering of a β-Galactosidase for Galactooligosaccharide Synthesis

2009 ◽  
Vol 75 (18) ◽  
pp. 5938-5942 ◽  
Author(s):  
Yumei Li ◽  
Lili Lu ◽  
Hongmei Wang ◽  
Xiaodong Xu ◽  
Min Xiao
Keyword(s):  
Cell Surface ◽  
Surface Engineering ◽  
Yeast Cells ◽  
Penicillium Expansum ◽  
Yeast Nitrogen Base ◽  
Gene Encoding ◽  
Nitrogen Base ◽  
Reading Frame ◽  
Acid Protein ◽  
Casamino Acids

ABSTRACT A novel gene encoding transglycosylating β-galactosidase (BGase) was cloned from Penicillium expansum F3. The sequence contained a 3,036-bp open reading frame encoding a 1,011-amino-acid protein. This gene was subsequently expressed on the cell surface of Saccharomyces cerevisiae EBY-100 by galactose induction. The BGase-anchored yeast could directly utilize lactose to produce galactooligosaccharide (GOS), as well as the by-products glucose and a small quantity of galactose. The glucose was consumed by the yeast, and the galactose was used for BGase expression, thus greatly facilitating GOS synthesis. The GOS yield reached 43.64% when the recombinant yeast was cultivated in yeast nitrogen base-Casamino Acids medium containing 100 g/liter initial lactose at 25°C for 5 days. The yeast cells were harvested and recycled for the next batch of GOS synthesis. During sequential operations, both oligosaccharide synthesis and BGase expression were maintained at high levels with GOS yields of over 40%, and approximately 8 U/ml of BGase was detected in each batch.

scholarly journals EFFECT OF NIGELLA SATIVA SEED EXTRACT ON THE VIABILITY OF CANDIDA GLABRATA

2019 ◽  
pp. 84-87
Author(s):  
FARAH DIBA ◽  
RATNA FARIDA ◽  
SRI REDJEKI
Keyword(s):  
Candida Glabrata ◽  
Nigella Sativa ◽  
Artificial Saliva ◽  
Positive Control ◽  
Negative Control ◽  
Seed Extract ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Common Opportunistic Infection ◽  
Yeast Nitrogen Base Medium

Objective: Candidiasis is a common opportunistic infection of the oral cavity caused by a yeast-like fungus called Candida. Candida glabrata is thesecond most frequently isolated species from this condition, after Candida albicans. This study aimed to evaluate the effect of Nigella sativa (blackcumin), known to possess antifungal properties, on the viability of C. glabrata.Methods: C. glabrata was added to a 96-microwell plate that was coated with artificial saliva and exposed to various concentrations (6.25%, 12.5%,25%, and 50%) of N. sativa seed extract; amphotericin B (250 mg/mL) was used as the positive control and 200 μL of yeast nitrogen base medium asthe negative control. The viability percentage of C. glabrata was determined by MTT assay.Results: The results showed that the viability values of C. glabrata were lower after exposure to the N. sativa seed extract when compared with thenegative control.Conclusion: The viability of Candida glabrata was decreased with increasing concentrations of the extract.

scholarly journals Saccharide sources do not influence the biofilm formation in Scedosporium/Lomentospora species

2020 ◽  
Vol 1 ◽  
Author(s):  
Thaís Pereira de Mello ◽  
Marta Helena Branquinha ◽  
André Luis Souza dos Santos
Keyword(s):  
Biofilm Formation ◽  
Culture Media ◽  
Yeast Nitrogen Base ◽  
Human Pathogens ◽  
Nitrogen Base ◽  
Opportunistic Fungi ◽  
Abiotic Surfaces ◽  
Resistance Patterns ◽  
Almost All ◽  
Glucose Supplementation

Abstract Scedosporium and Lomentospora species are ubiquitous saprophytic filamentous fungi that emerged as human pathogens with impressive multidrug-resistance profile. The ability to form biofilm over several biotic and abiotic surfaces is one of the characteristics that contributes to their resistance patterns against almost all currently available antifungals. Herein, we have demonstrated that Scedosporium apiospermum, Scedosporium minutisporum, Scedosporium aurantiacum and Lomentospora prolificans were able to form biofilm, in similar amounts, when conidial cells were incubated in a polystyrene substrate containing Sabouraud medium supplemented or not with different concentrations (2%, 5% and 10%) of glucose, fructose, sucrose and lactose. Likewise, the glucose supplementation of culture media primarily composed of amino acids (SCFM, synthetic cystic fibrosis medium) and salts (YNB, yeast nitrogen base) did not modulate the biofilm formation of Scedosporium/Lomentospora species. Collectively, the present data reinforce the ability of these opportunistic fungi to colonize and to build biofilm structures under different environmental conditions.

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