Detection of candida albicans virulence genes isolated from periodontitis patients in salah al-din city

Abstract

Background: Candida albicans is an opportunistic fungal pathogen increasingly implicated in oral infections including periodontitis. Its virulence is partly attributed to adhesion proteins encoded by the ALS1 and HWP1 genes. This study aimed to isolate and characterise C. albicans from periodontitis patients and detect key virulence genes associated with pathogenicity.

Objective: To isolate and identify C. albicans from periodontal swab samples using microscopy, culture, and molecular methods, and to determine the prevalence of ALS1 and HWP1 virulence genes among confirmed isolates.

Methods: A total of 75 clinical swab samples were collected from patients aged 5–55 years diagnosed with periodontitis at Salah al-Din General Hospital and affiliated outpatient dental clinics, Iraq, between October 2024 and January 2025. Samples were subjected to direct microscopic examination, culture on Sabouraud's Dextrose Agar (SDA) and CHROMagar, and biochemical testing (urease assay). Genomic DNA was extracted from confirmed colonies, and polymerase chain reaction (PCR) was performed to detect ALS1 and HWP1 virulence genes. Haemolytic activity was assessed and analysed statistically.

Results: Direct microscopy identified 55 positive samples (73%). Culture on SDA yielded 40 positive isolates (53%), with 35 samples (47%) showing no growth. All 75 samples (100%) were confirmed as C. albicans by combined diagnostic methods. PCR analysis revealed the ALS1 gene in 18 of 25 confirmed isolates (72%) and the HWP1 gene in 15 of 25 isolates (60%). Haemolysin production varied significantly among isolates (p = 0.0006).

Conclusion: C. albicans was identified in a substantial proportion of periodontitis patients. The high prevalence of ALS1 (72%) and HWP1 (60%) virulence genes among isolates suggests that these adhesion-related proteins contribute significantly to periodontal infection pathogenesis. Inclusion of molecular virulence profiling in clinical mycological assessment may improve understanding of fungal involvement in periodontal disease.