Epidemiology of oral yeast colonization and infection in patients with hematological malignancies, head neck and solid tumors

Background: The aim of this study was to investigate the epidemiology of oral yeast colonization and infection amongst cancer patients. Methods: Patients with solid tumor, head-neck cancer or hematological malignancy were recruited into the study. Demographic data on age, gender, type of cancer, preceding treatment with antibiotics, anti-fungal agents, chemotherapy, radiation or surgery and presence of dentures were recorded on admission. Oral examination and microbial swabs were obtained and yeast culture, identification and antifungal susceptibility performed. Results: Oral yeast colonization was prevalent in 56.8% (227/400) of all cancer patients and 18.9% (43/227) of those had clinical and microbiological evidence of infection. The incidence of oral candidiasis in yeast colonized patients was highest in head neck cancer (29.2%) followed by hematological malignancies (20.5%) and solid tumor (17%) patients. Age and dentures were identified as independent risk factors associated with yeast carriage. Candida albicans was the dominant (74%) species (497.5 per 1000 cancer admissions) followed by C. glabrata (11.5%), C. tropicalis (2.6%), C. krusei (2.6%) and C. parapsilosis (1.9%). The overall resistance to azoles was 28.2% (75/266). Resistance to specific drugs was seen for fluconazole (4.5%), itraconazole (11.7%), ketoconazole (11.3%), voriconazole (0.75%) and caspofungin (41.1%) but none to amphotericin B or nystatin. Conclusions: The highest incidence of oral candidiasis amongst cancer patients was seen in head neck cancers. The majority of infections were caused by C. albicans but almost one third of patients harbored non-C. albicans strains such as C. glabrata which were often more resistant to anti-fungal agents.