The effect of cigarette smoking on the prevalence of oral candidiasis caused by Candida albicans and the expression of selected virulence genes among adults in Jordan.

Oral Candidiasis (OC) is considered one of the major fungal problems, and the infections are predominantly associated with habitual factors such as smoking. Candida albicans remains the most dominant species, and smoking has been shown to alter its virulence on a molecular level. This study aimed to assess the prevalence of OC among smokers and non-smokers in Jordan and to investigate factors crelated to Candida albicans incidence in oral samples involving smoking and evaluate the effect of cigarette smoke condensate on the expression level of selected virulence-related genes (HWP1, ALS3, ECE1, and TEC1). A total of 400 Jordanian volunteers (200 smokers and 200 non-smokers) were included in this study. Oral samples were collected using buccal swabs from participants recruited from different hospitals. Samples were cultured on Sabouraud Dextrose agar, YPD agar, and Candida species were phenotypically identified using chromogenic agar and the germ tube test. Molecular analysis was performed on C. albicans isolates were exposed to waterpipe smoke condensate under controlled experimental conditions, followed by RNA extraction, cDNA synthesis, and quantitative real-time PCR (RT-qPCR) to evaluate the expression levels of hyphae-associated genes. Results show that C. albicans was identified as the predominant species (82/400; 20.5%), while no fungal growth was observed in 276 samples (276/400; 69%). Among the 82 samples positive for C. albicans, the majority were obtained from smokers (70/82; 85.37%). A significantly higher prevalence of infection was observed among males (75.6%) compared to females (24.4%). Furthermore, exposure of C. albicans isolates to cigarette smoke condensate resulted in an upregulation of the HWP1 gene expression, indicating a potential role of smoking in enhancing virulence-associated gene expression. This study declared that smoking was related with a higher incidence of oral candidiasis and Candida albicans colonization compared with non-smoking. Besides, exposure to cigarette smoke condensate resulted in differential regulation of virulence-associated genes, characterized by high HWP1 expression and low ALS3, TEC1, and ECE1 expression. These results propose that smoking may cause increased oral candidiasis prevalence and altered virulence-related responses in Candida albicans under experimental conditions.