Oral Candida isolates in patients undergoing radiotherapy for head and neck cancer:: prevalence, azole susceptibility profiles and response to antifungal treatment

Oral pseudomembranous candidiasis and mucositis were assessed in 39 patients receiving a total dose of 39-70 Gy radiotherapy for head and neck cancer. Mucositis was scored using the Radiation Therapy Oncology Group criteria, and oral candidiasis was diagnosed on the basis of clinical evaluation and quantitative laboratory findings. Radiation-induced mucositis was observed in 9/39 patients. Only 3/39 patients discontinued radiotherapy due to acute severe mucosal effects. Candidiasis (colony-forming units 35 to greater than or equal to60/lesion) associated with mucositis was diagnosed in 30/39 patients: the most frequent aetiology of the infection was Candida albicans (n = 23), followed by Candida glabrata (n = 3), Candida krusei (n = 2), Candida tropicalis (n = 1) and Candida kefyr (n = 1). Patients with confirmed oral pseudomembranous candidiasis were treated with either fluconazole 200 mg/day or itraconazole 200 mg/day for 2 weeks. Clinical improvement and concomitant negative Candida cultures (mycologic cure) were the criteria determining a response to antifungal treatment. Etest revealed very low voriconazole MICs (0.004-0.125 mug/ml) for all isolates, and fluconazole resistance for eight C. albicans strains (MIC > 64 mug/ml) and for the C. krusei isolates (MIC > 32 mug/ml). The same strains showed itraconazole susceptibility dose dependence (MIC 0.5 mug/ml). Despite the itraconazole susceptible dose dependent MIC readings, all patients with oral pseudomembranous candidiasis caused by these strains responded to antifungal treatment with 200 mg/day itraconazole. Oral mycologic surveillance of patients undergoing radiotherapy for head and neck malignancies and susceptibility testing of isolates may be indicated in cases with mucositis-associated confirmed oral pseudomembranous candidiasis to ensure prompt administration of targeted antifungal treatment. On the basis of the low MIC values found, clinical evaluation of voriconazole is indicated for management of oral pseudomembranous candidiasis refractory to other azoles.