Non-culture-based diagnostic methods for the diagnosis of invasive candidiasis: are they helpful to clinicians?

ABSTRACT

Invasive candidiasis in immune-compromised patients is associated with high attributable mortality. Early detection of candidemia and accurate identification of Candida species are essential pre-requisites for improved prognosis. Since clinical presentation is non-specific and blood culture-based methods lack sensitivity, detection of immunological and molecular markers has provided an alternative for early diagnosis of invasive candidiasis. Serial estimations of these biomarkers have also proved useful to initiate pre-emptive therapy in suspected patients before clinical signs appear and to monitor response to therapy. Antigen-based methods include detection of beta-D-glucan [panfungal marker] and Candida mannan [genus-specific marker]. Detection of both, Candida mannan and anti-mannan antibodies has higher sensitivity. While false positive / negative results remain a problem, these markers provide a useful adjunct to the diagnosis if performed in select patient population. Recent advances have also been made in nucleic acid-based detection methods. A commercial real-time PCR assay [Light Cycler Septi Fast] for detection of clinically important Candida spp. in blood specimens within six hours is now available. Molecular methods have also resulted in speciesspecific identification of yeast isolates within an hour. While these advances aid in early and specific diagnosis of candidemia and invasive candidiasis, further evaluation of these approaches in different clinical settings is also needed