Nationwide study of candidemia, antifungal use, and antifungal drug resistance in Iceland, 2000 to 2011

Abstract

Candidemia is often a life-threatening infection, with highly variable incidence among countries. We conducted a nationwide study of candidemia in Iceland from 2000 to 2011, in order to determine recent trends in incidence rates, fungal species distribution, antifungal susceptibility patterns, and concurrent antifungal consumption. A total of 208 infection episodes in 199 patients were identified. The average incidence during the 12 years was 5.7 cases/100,000 population/year, which was significantly higher than that from 1990 to 1999 (4.3/100,000/year; P = 0.02). A significant reduction in the use of blood cultures was noted in the last 3 years of the study, coinciding with the economic crisis in the country (P < 0.001). Age-specific incidence rates were highest among patients at the extremes of age, 20.7/100,000 for <1 year of age and 18.1/100,000 for >60 years, and varied by gender. Age-specific incidence among males >80 years old was 28.6/100,000/year, and it was 8.3/100,000/year for females in this age group (P = 0.028). The 30-day survival rate among adult patients remained unchanged compared to that from 1990 to 1999 (70.4% versus 69.5%, P = 0.97). Candida albicans was the predominant species (56%), followed by C. glabrata (16%) and C. tropicalis (13%). The species distribution remained stable compared to that from previous decades. Fluconazole use increased 2.4-fold from 2000 to 2011, with no increase in resistance. In summary, the incidence of candidemia in Iceland has continued to increase but may have reached a steady state, and no increase in antifungal drug resistance has been noted. Decreased use of blood cultures toward the end of the study may have influenced detection rates.

Fig 1

Incidence of candidemia in Iceland, 2000 to 2011. (A) Population-based incidence and the total number of blood cultures at the 2 university hospitals on an annual basis. The solid line represents the population-based incidence, whereas the gray columns depict the absolute number of blood culture sets, unadjusted for population size. (B) Annual age-specific incidence by age and gender.

Fig 2

Kaplan-Meier survival analysis for patients with candidemia in Iceland, 1990 to 2011 (P = 0.97, log-rank test). Survival analysis was performed for adult patients only (2000 to 2011, 189 cases). For comparison, previously published data from 1990 to 1999 in Iceland (105 cases) was included in the analysis.

Fig 3

Distribution of MICs of fluconazole for 124 Candida albicans bloodstream isolates cultured from 2000 to 2011 compared to 68 C. albicans bloodstream isolates cultured from 1990 to 1999 in Iceland. The MIC distribution did not vary significantly between the two time periods (P = 0.68).