Therapeutic Challenges of Non- Aspergillus Invasive Mold Infections in Immunosuppressed Patients

Abstract

While Aspergillus spp. remain the major cause of invasive mold infections in hematologic cancer patients and transplant recipients, other opportunistic molds, such as Mucorales, Fusarium, and Scedosporium spp. are increasingly encountered in an expanding population of patients with severe and prolonged immunosuppression. High potential for tissue invasion and dissemination, resistance to multiple antifungals and high mortality rates are hallmarks of these non-Aspergillus invasive mold infections (NAIMIs). Assessment of drug efficacy is particularly difficult in the complex treatment scenarios of NAIMIs. Specifically, correlation between in vitro susceptibility and in vivo responses to antifungals is hard to assess, in view of the multiple, frequently interrelated factors influencing outcomes, such as pharmacokinetic/pharmacodynamic parameters determining drug availability at the site of infection, the net state of immune suppression, delay in diagnosis, or surgical debulking of infectious foci. Our current therapeutic approach of NAIMIs should evolve toward a better integration of the dynamic interactions between the pathogen, the drug and the host. Innovative concepts of experimental research may consist in manipulating the host immune system to induce a specific antifungal response or targeted drug delivery. In this review, we discuss the challenges in the management of NAIMIs and provide an update about the latest advances in diagnostic and therapeutic approaches.

Keywords: Fusarium; Lomentospora; Mucor; Rhizopus; Scedosporium; amphotericin B; azole; fusariosis; isavuconazole; mucormycosis; posaconazole; scedosporiosis; voriconazole.

FIG 1

Factors affecting antifungal activity: comparison of in vitro versus in vivo conditions.

FIG 2

In vitro antifungal activity of antifungal drugs against non-Aspergillus molds. The in vitro activity of the different antifungal drugs against a given pathogenic mold is classified in four different categories: active (white), intermediate (gray), inactive (black), or variable (hatched).