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* These authors contributed equally
The significance of petite colonies in Candida spp. drug resistance has not been fully explored. Antimicrobial photodynamic therapy (aPDT) offers a promising strategy against drug-resistant fungal infections. This study demonstrates that rose bengal-mediated aPDT effectively deactivates Candida glabrata and induces petite colonies, presenting a unique procedure.
Facing a 40% mortality rate in candidemia patients, drug-resistant Candida and their petite mutants remain a major treatment challenge. Antimicrobial photodynamic therapy (aPDT) targets multiple fungal structures, unlike antibiotics/antifungals, potentially thwarting resistance. Traditional methods for inducing petite colonies rely on ethidium bromide or fluconazole, which can influence drug susceptibility and stress responses. This study investigated the application of green light (peak 520 nm) and rose bengal (RB) photosensitizer to combat a drug-resistant Candida glabrata isolate. The findings revealed that aPDT treatment significantly inhibited cell growth (≥99.9% reduction) and effectively induced petite colony formation, as evidenced by reduced size and loss of mitochondrial redox indicator staining. This study provides initial evidence that aPDT can induce petite colonies in a multidrug-resistant C. glabrata strain in vitro, offering a potentially transformative approach for combating resistant fungal infections.
Fungal infections, particularly those caused by Candida albicans and increasingly drug-resistant Candida glabrata, pose a serious global threat1. These infections can be deadly, especially for hospitalized patients and those with weakened immune systems. Rising antifungal resistance threatens the control of invasive candidiasis, a severe fungal infection with high mortality, especially from Candida albicans2. Resistant strains hinder effective treatment, potentially increasing both complexity and death rates. In Alameda County, California, USA, C. glabrata has become the most prevalent....
1. Culturing of C. glabrata
NOTE: A multidrug-resistant C. glabrata (C2-1000907) that is resistant to most antifungal agents, including fluconazole, is used for the experiments. The experimental conditions may need to be adapted to the specific strain, as variations may exist among different strains. All experiments used log-phase Candida grown at 25 °C (mimicking natural infection) for consistency. C. glabrata's lack of hyphae simplifies quan.......
The data is presented as the mean with ± standard error and was obtained from three independent experiments, with at least triplicates in each group. Experimental data, including colony counts, OD600 measurements, and TTC staining results, were graphed and statistically analyzed using graphing and statistical software (see Table of Materials). One-way ANOVA or t-test was used to analyze the data, and a p-value <0.05 was considered significant. Scanning was performed .......
This study unveils PDT as the first reported method to induce petite colony formation in Candida, surpassing the established effects of ethidium bromide and fluconazole. This novel observation necessitates further exploration to unravel its implications for both fungal eradication by decreasing virulence and the emergence of resistance mechanisms.
RB-mediated PDT effectively inhibits the growth of C. glabrata, suggesting a potential alternative treatment approach for Candida infection.......
This work has received funding from the Ministry of Science and Technology, Taiwan [MOST 110-2314-B-006-086-MY3], National Cheng Kung University [K111-B094], [K111-B095], National Cheng Kung University Hospital, Taiwan [NCKUH-11204031], [NCKUMCS2022057].
....Name | Company | Catalog Number | Comments |
0.22 μm filter | Merck, Taipei, Taiwan | Millex, SLGVR33RS | |
1.5 mL microfuge tube | Neptune, San Diego, USA | #3745 | |
20% Triphenyltetrazolium chloride (TTC) | Sigma-Aldrich, MO, USA | T8877 | |
5 mL polypropylene round bottom tube | Corning, AZ, USA | 352059 | |
5 mL round-bottom tube with cell strainer cap | Corning, AZ, USA | Falcon, #352235 | |
96-well plate | Alpha plus, Taoyuan Hsien, Taiwan | #16196 | |
Agar | BRS, Tainan, Taiwan | AG012 | |
Blank disk | Advantec, Tokyo, Japan | 49005040 | |
Centrifuge | Eppendorf, UK | 5415R | |
Ethidium bromide solution | Sigma-Aldrich, MO, USA | E1510 | |
Fluconazole, 2 mg/mL | Pfizer, NY, USA | BC18790248 | |
GraphPad Prism | GraphPad Software | Version 7.0 | |
Green light emitting diode (LED) strip | Nanyi electronics Co.,Ltd, Tainan, Taiwan | 5050 | Excitation wave: 500~550 nm |
Low Temperature. shake Incubators | Yihder, Taipei, Taiwan | LM-570D (R) | |
Mouth care cotton swabs | Good Verita Enterprise, Taipei, Taiwan | 161357 | |
Muller Hinton II agar | BD biosciences, California, USA | 211438 | |
Multimode microplate reader | Molecular Devices | SpectraMax i3x | |
OD600 spectrophotometer | Biochrom, London, UK | Ultrospec 10 | |
Rose Bengal | Sigma-Aldrich, USA | 330000 | stock concentration 40 mg/mL = 4%, prepare in PBS, stored at 4 °C |
Sterilized glass tube | Sunmei, Tainan, Taiwan | AK45048-16100 | |
Yeast Extract Peptone Dextrose Medium | HIMEDIA, India | M1363 |
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