Invasive aspergillosis caused by cryptic species in transplant recipients: A review

The clinical and microbiological characteristics of invasive aspergillosis (IA) caused by cryptic Aspergillus species have not been well-defined in transplant settings. However, IA is among the most common mould infections in solid organ and hematopoietic stem cell transplant recipients. Among 55 causative isolates in the 53 reported cases, Aspergillus calidoustus, A. lentulus, A. tubingensis, and A. udagawae were the four most common causative cryptic Aspergillus species. Newer diagnostic modalities, such as matrix-assisted laser desorption ionization-time of flight mass spectrometry, may help diagnose these cryptic species. Of the 24 cases with detailed clinical information, 13 had antifungal breakthrough infections. The 12-week mortality rates of all 24 cases, 7 cases of A. calidoustus, and 7 cases of A. lentulus were 46%, 43%, and 43%, respectively. Based on antifungal susceptibility profiles obtained from previous studies, an empiric antifungal regimen such as liposomal amphotericin B with or without echinocandin is recommended for A. calidoustus. A combination of an anti-mould azole and liposomal amphotericin B with or without an echinocandin is suggested for A. lentulus and A. udagawae. Additionally, any one of voriconazole, isavuconazole, or posaconazole with or without liposomal amphotericin B with or without an echinocandin is indicated for A. tubingensis. Newer antifungal agents may have more significant activity against Aspergillus cryptic species.