Diagnosis of invasive fungal infections: Culture and antifungal susceptibility tests

Abstract

Despite recent advances in diagnostic and therapeutic approaches and increasing options, the incidence of invasive fungal infections is rising with the increase in the number of immunosuppressed patients. Culture is accepted as the gold standard for diagnosis of fungal infections. Despite rapid advances in molecular and serological methods in recent years, culture is still extremely important because it allows for antifungal susceptibility testing. Resistance to antifungal drugs can be seen naturally in some species of fungi or can be acquired as a result of extensive usage of antifungals in clinical practice or agriculture. Furthermore, it is very important to identify the agent at the species or complex level in order to interpret the results of the antifungal susceptibility tests correctly. Antifungal susceptibility tests should be performed in the routine laboratories, when the fungus is isolated from a sterile body site such as blood and cerebrospinal fluid, when a reported resistance to the isolated species is expected, and when there is a risk of acquired resistance in patients who do not respond to treatment. In conclusion, the identification of fungal diseases by conventional culture methods is indispensable as it permits a species-level identification and antifungal susceptibility testing, despite being time-consuming and requirement of an experienced staff to interpret the results.