Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 5 2026 10 05 818 827 Omolbanin Faryabi Department of Medical Parasitology & Mycology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran Elham Isaei Research Center of Tropical and Infectious Diseases, Kerman University of Medical Sciences, Kerman, Iran Samira Salari Department of Medical Parasitology & Mycology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran; Research Center of Tropical and Infectious Diseases, Kerman University of Medical Sciences, Kerman, Iran Seyed Amin Ayatollahi Mousavi Department of Medical Parasitology & Mycology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran; Research Center of Tropical and Infectious Diseases, Kerman University of Medical Sciences, Kerman, Iran Ehsan Salarkia Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran Mohammad Hossein Sobhanipoor Department of Laboratory Sciences, School of Medicine, Bam University of Medical Sciences, Bam, Iran Pooya Ghasemi Nejad Almani Department of Medical Parasitology & Mycology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran Alireza Izadi KUMSDepartment of Medical Parasitology & Mycology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran; Department of Medical Parasitology & Mycology, School of Medicine, Shahed University, Tehran, Iran 2025 07 30 2026 09 02 Background and Objectives: Candida albicans (C. albicans) is the most common cause of candidiasis in immunocompromised patients. Biofilm-associated Candida can lead to treatment complications and systemic infections. Materials and Methods: In this study, the antifungal activity of the cell-free supernatant (CFS) derived from Lactobacillus casei was assessed against C. albicans strains. To differentiate between pH- and H₂O₂-mediated effects and specific metabolite activity, all antifungal and antibiofilm assays were performed using CFS that had been neutralized to pH 7.0 and treated with catalase. Results: The ranges of minimum inhibitory concentration (MIC) and Half-maximal inhibitory concentration (IC50) for CFS were 7.81-62.5 and 95.1-159.6 µl/ml, respectively. Using corrected FICI criteria (synergy ≤ 0.5; additive > 0.5-1.0; indifference > 1.0-4.0), additive effects were observed in 50% of strains, synergy in 20% (including the standard strain PTCC 5027), and indifference in 30%. Conclusion: The results demonstrate that the CFS of L. casei exhibits promising in vitro antifungal and antibiofilm activity against C. albicans. When used in combination with nystatin, L. casei CFS showed additive or synergistic effects, suggesting its potential as an adjunctive agent for further investigation. However, these findings are preliminary, and in vivo studies and clinical assessments are necessary to validate the therapeutic potential of L. casei CFS in the management of oral candidiasis. https://ijm.tums.ac.ir/index.php/ijm/article/view/5678 https://ijm.tums.ac.ir/index.php/ijm/article/download/5678/1942