Evaluation of noninvasive methods for the diagnosis of fungal endocarditis.

ABSTRACT

Fungal endocarditis (FE) is an uncommon disease with a high risk of morbidity and mortality. Here, we evaluated the different methods for diagnosing this infection. Cardiac valve, vegetation, and embolic materials obtained during surgery were examined for fungal infections by direct smear and culture. At least two blood samples were inoculated at the bedside into BACTEC medium. Galactomannan, mannan Ag enzyme-linked immunosorbent assay, and real-time polymerase chain reaction (PCR) assay were performed with serum samples. Of 25 patients with suspected infective endocarditis (IE), 8 were found to have proven FE according to the direct culture results. The etiologic agents were Aspergillus niger (three cases), A. flavus (two cases), A. fumigatus (one case), and Candida albicans (two cases). Blood culture was positive in only 1 case. The sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios of the results from the galactomannan test were 83.3%, 84.2%, 62.5%, 94.1%, 5.3, and 0.2; these same values, obtained from real-time PCR, were 87.5%, 94.4%, 87.5%, 94.4%, 15.6, and 0.14, respectively. Because mannan antigen was positive in samples from only one patient, we opted not to calculate the sensitivity. However, the specificity value in 23 cases without IE caused by Candida spp. was 100%. Based on our results, both the galactomannan test and real-time PCR can serve as reliable, noninvasive tests for the diagnosis of FE, compared with culture, which is considered to be the gold standard.