Detection of candidaemia in patients with and without underlying haematological disease

Abstract

Diagnosing candidaemia remains difficult despite the development of new diagnostics. We report a direct comparison of three different blood-culture systems and four indirect tests. One hundred and fourteen episodes either with haematological disease and fever despite antibacterials, or with documented invasive candidiasis, were enrolled prospectively. Clinical, para-clinical information and surveillance cultures were obtained. Blood culture was performed using conventional blood-culture bottles, mycosis bottles, and the Isolator 10 lysis centrifugation system. Serum D-arabinitol/L-arabinitol (DA/LA) ratios were determined by gas chromatography mass spectrometry. Antigen, mannan-antigen (Ag) and anti-mannan antibody (Ab) were detected by CandTec, Platelia Candida Ag ELISA and Candida AB/AC/AK kits, respectively. Episodes were classified as proven (n = 24), probable (n = 14), possible (n = 52) or unlikely (n = 24) invasive candidiasis. Candidaemia involved C. albicans (17), C. albicans + C. glabrata (3), C. tropicalis (1) and yeast (1). Mycosis bottles yielded two additional positives and the conventional blood culture yielded one positive not identified by other blood-culture methods. Considering proven and unlikely episodes, respectively, sensitivity and specificity were as follows: mannan-Ag and/or anti-mannan Ab: 83.3%, 78.3%; DA/LA ratio: 41.7%, 86.4%; and CandTec Candida Ag: 66.6%, 70.8%. Lowering the cut-off values to mannan-Ag 0.10 ng/mL and anti-mannan Ab 4 AU/mL, the values were: 100%, 73.9%. Applying the DA/LA ratio to only patients with haematological neutropenia the values were: 75%, 90.5%. Fungal blood culture allowed slightly improved detection of candidaemia. The best indirect test performance was obtained from combined mannan-Ag and anti-mannan Ab detection, especially with lower cut-offs. DA/LA ratio appears to be useful in the context of haematological neutropenia.