Reappraisal of the serum (1→3)-β-D-glucan assay for the diagnosis of invasive fungal infections -: A study based on autopsy cases from 6 years

Background. The prevalence of invasive fungal infection is increasing. An effective diagnostic test is required to identify and treat them successfully. Methods. All autopsy records at our hospital for the period from January 2000 through December 2004 were reviewed for cases of invasive fungal infection. The diagnostic efficacy of a serum (1 -> 3)-beta-D-glucan (beta-glucan) assay was examined using only those cases in which patients had been tested for fungal infection within 2 weeks before death. Results. Of 456 autopsies, 54 (11.8%) involved cases of invasive fungal infection. Leukemias were the most frequent underlying disease (in 52% of cases of invasive fungal infection), and Aspergillus species was the most frequent pathogen detected (in 70%). Of the 54 patients with invasive fungal infection, 41 had beta-glucan testing performed within 2 weeks before death, as did 63 patients without invasive fungal infection; 48 of 54 patients with invasive fungal infection had a blood culture performed. The sensitivity and specificity of the beta-glucan test for the detection of invasive fungal infection were 95.1% and 85.7%, respectively, with a cutoff value of 30 pg/mL; 85.4% and 95.2%, respectively, with a cutoff value of 60 pg/mL; and 78.0% and 98.4%, respectively, with a cutoff value of 80 pg/mL. The sensitivity of blood culture testing was 8.3%. With a prevalence of 11.8%, the positive and negative predictive values for the beta-glucan test were 47.1% and 99.2%, respectively, with a cutoff of 30 pg/mL; 70.4% and 98.0%, respectively, with a cutoff of 60 pg/mL; and 86.7% and 97.1%, respectively, with a cutoff of 80 pg/mL. During the 6-year period studied, of 21 patients with fungus-positive blood cultures that were preceded or followed by a beta-glucan test within 2 weeks, 4 had negative beta-glucan test results (beta-glucan level, <30 pg/mL), and 17 had positive results (beta-glucan level, >60 pg/mL); the concordance between culture results and beta-glucan test results was 81.0%. Contrary to the general belief, 5 of 6 cases of cryptococcemia were associated with high serum beta-glucan levels. Conclusion. The beta-glucan test is an effective diagnostic tool for invasive fungal infection.