The prognosis for persons with
invasive fungal infections has improved over the past 2 decades because of the development of new diagnostic tools, a better understanding of the epidemiology and prognostic factors of these
infections, and the availability of new
antifungal agents. Nevertheless, antifungal
therapy failure is still a substantial clinical problem. When this occurs, the clinician is tempted to attribute therapeutic failure to specific drug resistance and then to change
therapy or add another antifungal drug to the regimen. However, other factors may play an even greater role in antifungal
therapy failure, such as host factors, low concentration of the drug at the site of
infection,
drug toxicities, wrong diagnosis, and misdiagnosis of failure because of the occurrence of
immune reconstitution inflammatory syndrome. In this review, we discuss the differential diagnosis and management of antifungal
therapy failure in
invasive mycoses, to help clinicians appreciate the meaning of primary antifungal
therapy failure.