Diagnosing invasive fungal diseases – limitations of microbiological diagnostic methods

BACKGROUND: Invasive fungal infections (IFD) are a principal cause of morbidity and mortality in immunosuppressed patients, with case fatality rates ranging from 30 - 80% in neutropenic patients. This results at least partly from difficulties in obtaining a reliable and early diagnosis. Conventional methods, for example culture-based methods, may be difficult and are often delayed. Serological tests such as the galactomannan enzyme immunoassay are at present most promising for diagnosing invasive aspergillosis; however, sensitivity and specificity vary within the studies. Similar data are shown for Aspergillus detection by polymerase chain reaction. OBJECTIVE: The aim of this article is to review classical and new diagnostic tools for the identification of invasive fungal infections and to summarize current limitations of these methods. CONCLUSION: The early diagnosis of IFD still remains a problem as existing tools lack sensitivity or specificity. Therefore, the combination of microscopy, culture-based methods, and serological and molecular techniques is necessary to allow early detection of IFD.