Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 17 2 2025 04 05 293 302 Masoumeh Sadat Hosseini Department of Microbial Biotechnology, Faculty of Basic Sciences and Advanced Technologies in Biology, University of Science and Culture, Tehran, Iran Masoumeh Navidinia Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sima Sadat Seyedjavadi Department of Mycology, Pasteur Institute of Iran, Tehran, Iran Mehdi Goudarzi Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Helia Rasouli Department of Biology, Islamic Azad University Science and Research Branch, Tehran, Iran Amir Mohsen Mahdavian Department Medical Laboratory Sciences, Students Research Committee, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Elina Rahimi Zamani Department Medical Laboratory Sciences, Students Research Committee, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2023 10 16 2024 11 27 Background and Objectives: The azole antifungals are the most frequent class used to treat Candida infections. It is essential to elucidate the potential of natural compounds as an alternative in eliminating Candida albicans (C. albicans). Therefore, in the present study, the antagonistic effect of Pseudomonas aeruginosa toxins on azole antifungal resistance in C. albicans species was investigated. Materials and Methods: In this study, 28 C. albicans species with azole antifungal resistance were obtained from patients at Shohadaye Tajrish Hospital. The effect of toxins, such as phenazine, pyocyanin, pyoverdine, and fluorescein, was examined on C. albicans species. The antifungal activity of these toxins against C. albicans spp. was determined using methods such as minimal inhibitory concentration (MIC90), radial diffusion assay (RDA), and detection of reactive oxygen species (ROS). Results: The prevalence of C. albicans strains in urinary catheters, surgical wounds, respiratory tracts, blood, and standard strains was 46.3%, 21.4%, 25%, 7.14%, and 3.57%, respectively. The MIC values were reported as 32 µg/ml for phenazine, and 128 µg/ml for pyoverdine, pyocyanin, and fluorescein. The results showed that phenazine exhibited higher inhibitory effects against C. albicans isolated from clinical samples compared to the other toxins. After exposure to phenazines (20 µg/ml), 65-70% of yeast cells of C. albicans spp. showed rhodamine 123 fluorescence, indicating high intracellular reactive oxygen species (ROS) production. Conclusion: The antifungal effect of different toxins in C. albicans spp. may be due to ROS-mediated apoptotic death. The results suggest that phenazine has high potential in controlling C. albicans. This natural compounds are a potential alternative for eliminating this yeast. https://ijm.tums.ac.ir/index.php/ijm/article/view/4447 https://ijm.tums.ac.ir/index.php/ijm/article/download/4447/1769