Frequency of clinically isolated strains of oral Candida species at Kagoshima University Hospital, Japan, and their susceptibility to antifungal drugs in 2006–2007 and 2012–2013

BACKGROUND: The isolation frequency and susceptibility to antifungal agents of oral Candida isolates from patients with oral candidiasis (OC) were compared between studies conducted in 2006–2007 and 2012–2013. METHODS: A total158 strains was isolated from 112 patients who visited Kagoshima University Hospital for the treatment of OC during the 14-month period from February 2012 and March 2013, and evaluated on the isolation frequency of each Candida strain and the susceptibility against antifungal drugs as compared to those evaluated in 2006–2007. RESULTS: There was a higher frequency of xerostomia as a chief complaint and of autoimmune disease in the 2012–2013 study than in the 2006–2007 study. More than 95% of Candida isolates were C. albicans and C. glabrata. In addition, the proportion of the latter increased from 12.3% in the 2006–2007 study to 23.4% in the 2012–2013 study, while the proportion of the former decreased from 86.2% to 72.8%, respectively. C. albicans was isolated in almost all patients, while C. glabrata was only isolated concomitantly with C. albicans. Minimal inhibitory concentrations (MICs) were not significantly different between groups with a few exceptions. Candida isolates, of which MICs surpassed break points, apparently increased for miconazole and itraconazole against C. glabrata in the 2012–2013 study, but this was not statistically significant. As a result, more cases of autoimmune disease, a greater number of C. glabrata isolates, and higher resistance to azoles were seen in the 2012–2013 study than in the 2006–2007 study. CONCLUSION: These data indicate that with recent increases in C. glabrata infection, a causative fungus of OC, and in C. glabrata resistance to azoles, caution is needed in the selection of antifungal drugs for the treatment of OC.