The Impact of Cultivation Media on the In Vitro Biofilm Biomass Production of Candida spp

PPZ1-TORC1 pathway mediates ferroptosis and antifungal resistance in Candida albicans

Candida albicans (C. albicans), a common fungal pathogen, is responsible for infections such as oral candidiasis. Given the widespread misuse of antifungal medications and the increasing resistance, it is critical to explore new strategies to eradicate C. albicans. This study investigates ferroptosis, a form of cell death previously underexplored in fungi, focusing on the role of the fungus-specific protein phosphatase Z1 (PPZ1) in regulating the target of rapamycin complex 1 (TORC1) pathway during tert-butyl hydroperoxide (t-BuOOH)-induced ferroptosis. We demonstrated that ferroptosis induced by t-BuOOH promoted the accumulation of iron-dependent lipid peroxides, leading to the death of C. albicans. Furthermore, PPZ1 deletion impairs TORC1 signaling, activates autophagy, increases sensitivity to ferroptosis following t-BuOOH exposure, and reduces resistance to various antifungal drugs. These findings reveal the role of the PPZ1-TORC1 pathway in ferroptosis and provide a theoretical basis for developing ferroptosis as a novel antifungal strategy to eradicate C. albicans. The potential combined application of ferroptosis and antifungal drugs is expected to improve the efficacy of treating fungal infections.

The appropriate nutrient conditions for methicillin-resistant Staphylococcus aureus and Candida albicans dual-species biofilm formation in vitro

Polymicrobial biofilms, the reason for most chronic wound infections, play a significant role in increasing antibiotic resistance. The in vivo effectiveness of the new anti-biofilm therapy is conditioned by the profound evaluation using appropriate in vitro biofilm models. Since nutrient availability is crucial for in vitro biofilm formation, this study is focused on the impact of four selected cultivation media on the properties of methicillin-resistant Staphylococcus aureus and Candida albicans dual-species biofilms. To reflect the wound environment, Tryptic soy broth, RPMI 1640 with and without glucose, and Lubbock medium were supplemented with different amounts of host effector molecules present in human plasma or sheep red blood cells. The study demonstrates that the Lubbock medium provided the most appropriate amount of nutrients regarding the biomass structure and the highest degree of tolerance to selected antimicrobials with the evident contribution of the biofilm matrix. Our results allow the rational employment of nutrition conditions within methicillin-resistant Staphylococcus aureus and Candida albicans dual-species biofilm formation in vitro for preclinical research. Additionally, one of the potential targets of a complex antibiofilm strategy, carbohydrates, was revealed since they are prevailing molecules in the matrices regardless of the cultivation media.

Synergistic antifungal effect of thiophene derivative as an inhibitor of fluconazole-resistant Candida spp. biofilms

Candida species resistant to fluconazole have raised concern in the scientific medical community due to high mortality in patients with invasive disease. In developing countries, such as Brazil, fluconazole is the most commonly used antifungal, and alternative treatments are expensive or not readily available. Furthermore, the occurrence of biofilms is common, coupled with their inherent resistance to antifungal therapies and the host's immune system, these microbial communities have contributed to making infections caused by these yeasts an enormous clinical challenge. Therefore, there is an urgent need to develop alternative medicines, which surpass the effectiveness of already used therapies, but which are also effective against biofilms. Therefore, the present study aimed to describe for the first time the antifungal and antibiofilm action of the derivative 2-amino-5,6,7,8-tetrahydro-4 H-cyclohepta[b]thiophene-3-isopropyl carboxylate (2AT) against clinical strains of Candida spp. resistant to fluconazole (FLZ). When determining the minimum inhibitory concentrations (MIC), it was found that the compound has antifungal action at concentrations of 100 to 200 µg/mL, resulting in 100% inhibition of yeast cells. Its synergistic effect with the drug FLZ was also observed. The antibiofilm action of the compound in subinhibitory concentrations was detected, alone and in association with FLZ. Moreover, using scanning electron microscopy, it was observed that the compound 2AT in isolation was capable of causing significant ultrastructural changes in Candida. Additionally, it was also demonstrated that the compound 2AT acts by inducing characteristics compatible with apoptosis in these yeasts, such as chromatin condensation, when visualized by transmission electron microscopy, indicating the possible mechanism of action of this molecule. Furthermore, the compound did not exhibit toxicity in J774 macrophage cells up to a concentration of 4000 µg/mL. In this study, we identify the 2AT derivative as a future alternative for invasive candidiasis therapy, in addition, we highlighted the promise of a strategy combined with fluconazole in combating Candida infections, especially in cases of resistant isolates.

The arrangement of dual-species biofilms of Candida albicans and Issatchenkia orientalis can be modified by the medium: effect of Voriconazole

Both Candida albicans and Issatchenkia orientalis have been isolated from different types of infections over the years. They have the ability to form communities of microorganisms known as biofilms. It has been demonstrated that the medium employed in studies may affect the biofilm development. The aim of this study was to investigate the arrangement of dual-species biofilms of C. albicans and I. orientalis cultivated on either RPMI-1640 or Sabouraud Dextrose Broth (SDB), as well as the inhibitory effect of Voriconazole (VRC). For the experiments performed, ATCC strains were used, and yeast-mixed suspensions were inoculated in 96-well plates with either RPMI-1640 or SDB, in the presence or absence of VRC. The results were observed by counting the number of CFU obtained from scraping off the biofilms produced and plating the content on CHROMagar Candida medium. It was observed that for all conditions tested the medium chosen affected the arrangement of dual-species biofilms: when RPMI-1640 was used, there was a prevalence of C. albicans, while the opposite was noted when SDB was used. It could be suggested that the medium and environment could regulate interactions between both yeast species, including the response to different antifungal drugs.

Culture media influences Candida parapsilosis growth, susceptibility, and virulence

Introduction

Candida parapsilosis, a pathogenic yeast associated with systemic infections, exhibits metabolic adaptability in response to nutrient availability.

Methods

We investigated the impact of RPMI glucose supplemented (RPMId), TSB, BHI and YPD media on C. parapsilosis growth, morphology, susceptibility (caspofungin and amphotericin B), and in vivo virulence (Galleria mellonella) in planktonic and biofilm states.

Results

High-glucose media favors growth but hinders metabolic activity and filamentation. Media promoting carbohydrate production reduces biofilm susceptibility. Virulence differences between planktonic cells and biofilm suspensions from the same media shows that biofilm-related factors influence infection outcome depending on nutrient availability. Pseudohyphal growth occurred in biofilms under low oxygen and shear stress, but its presence is not exclusively correlated with virulence.

Discussion

This study provides valuable insights into the intricate interplay between nutrient availability and C. parapsilosis pathogenicity. It emphasizes the importance of considering pathogen behavior in diverse conditions when designing research protocols and therapeutic strategies.

The inhibitory effect of photodynamic therapy on dual-species biofilms of Candida albicans and Candida krusei can be determined by Candida albicans/Candida krusei ratio

Candida krusei and Candida albicans present the ability to form communities of microorganisms called biofilms. Biofilms can be composed of a single species or more and are an important virulence factor. The inhibition of C. albicans and C. krusei as well as of their dual-species biofilms by antimicrobial Photodynamic Therapy (aPDT) has been demonstrated. This study aimed to investigate the effect of aPDT, with TBO, on dual-species biofilms of C. albicans and C. krusei using different culture mediums, RPMI-1640 and Sabouraud-dextrose broth (SDB) to produce biofilms presenting different C. albicans/C. krusei ratio. Biofilms formed using RPMI-1640 presented a higher C. albicans/C. krusei ratio, however, biofilms formed using SDB presented a predominance of C. krusei. The metabolic activity of biofilms produced using RPMI-1640 was inhibited by aP (∼40%), while biofilms produced using SDB were not affected by aPDT. In addition, biofilm biomass was reduced in biofilms produced using RPMI-1640 and treated with aPDT (∼20%). The results demonstrated that aPDT reduces C. albicans development in dual-species biofilms with C. krusei. However, no effect could be observed on C. krusei, demonstrating that C. krusei, when present in the structure of dual-species biofilms can be resistant to aPDT.

Berberine inhibits Candida albicans growth by disrupting mitochondrial function through the reduction of iron absorption

AIMS

This study aimed to investigate whether berberine (BBR) can inhibit the iron reduction mechanism of Candida albicans, lowering the iron uptake of the yeast and perhaps having antimicrobial effects.

METHODS AND RESULTS

We determined that BBR may cause extensive transcriptional remodeling in C. albicans and that iron permease Ftr1 played a crucial role in this process through eukaryotic transcriptome sequencing. Mechanistic research showed that BBR might selectively inhibit the iron reduction pathway to lower the uptake of exogenous iron ions, inhibiting C. albicans from growing and metabolizing. Subsequent research revealed that BBR caused significant mitochondrial dysfunction, which triggered the process of mitochondrial autophagy. Moreover, we discovered that C. albicans redox homeostasis, susceptibility to antifungal drugs, and hyphal growth are all impacted by the suppression of this mechanism by BBR.

CONCLUSIONS

The iron reduction mechanism in C. albicans is disrupted by BBR, which disrupts mitochondrial function and inhibits fungal growth. These findings highlight the potential promise of BBR in antifungal applications.

The Arylamidine T-2307 as a Novel Treatment for the Prevention and Eradication of Candida tropicalis Biofilms

Candida tropicalis is an emerging pathogen with a high mortality rate due to its virulence factors, including biofilm formation, that has important repercussions on the public health system. The ability of C. tropicalis to form biofilms, which are potentially more resistant to antifungal drugs and the consequent increasing antimicrobial resistance, highlights an urgent need for the development of novel antifungal. The present study analyzed the antibiofilm capacity of the arylamidine T-2307 on two strains of Candida tropicalis. Antimicrobial activity and time-killing assays were performed to evaluate the anticandidal effects of T-2307, the antibiofilm ability on biomass inhibition and eradication was evaluated by the crystal violet (CV) method. Furthermore, in Galleria mellonella infected larvae an increased survival after pre-and post- treatment with T-2307 was observed. The MTT test was used to determine the viability of immortalized human prostate epithelial cells (PNT1A) after exposure to different concentrations of T-2307. Levels of interleukin IL-4, IL-8, IL-10 were quantified after Candida infection of PNT1A cells and treatment. Active doses of T-2307 did not affect the viability of PNT1A cells, and drug concentrations of 0.005 or 0.01 µg mL^-1 inhibited the secretion of inflammatory cytokines. Taken together, these results provide new information on T-2307, indicating this drug as a new and promising alternative therapeutic option for the treatment of Candida infections.

Evaluation of the biofilm life cycle between Candida albicans and Candida tropicalis

Candida tropicalis is an emergent pathogen with a high rate of mortality associated with its biofilm formation. Biofilm formation has important repercussions on the public health system. However, little is still known about its biofilm life cycle. The present study analyzed the biofilm life cycle of Candida albicans and C. tropicalis during various timepoints (24, 48, 72, and 96 h) through biomass assays, colony-forming unit (CFU) counting, and epifluorescence and scanning electron microscopies. Our results showed a significant difference between C. albicans and C. tropicalis biofilms in each biomass and viability assay. All-time samples in the biomass and viability assays confirmed statistical differences between the Candida species through pairwise Wilcoxon tests (p < 0.05). C. albicans demonstrated a lower biomass growth but reached nearly the same level of C. tropicalis biomass at 96 h, while the CFU counting assays exhibited a superior number of viable cells within the C. tropicalis biofilm. Statistical differences were also found between C. albicans and C. tropicalis biofilms from 48- and 72-h microscopies, demonstrating C. tropicalis with a higher number of total cells within biofilms and C. albicans cells with a superior cell area and higher matrix production. Therefore, the present study proved the higher biofilm production of C. tropicalis.