Diagnosis and management of invasive fungal infections due to non-Aspergillus moulds

Abstract

Invasive fungal infection (IFI) due to moulds other than Aspergillus are a significant cause of morbidity and mortality. Non-Aspergillus mould (NAM) infections appear to be on the increase due to an ever-expanding population of immunocompromised hosts. In this review, Mucorales, Scedosporium species, Lomentospora prolificans and Fusarium species are examined in detail, and the microbiology, risk factors, diagnosis and treatment of emerging NAMs such as Paecilomyces variotti, Purpureocillium lilacinum and Rasamsonia are summarized. The challenges in diagnosis are emphasized and the emerging importance of molecular methods is discussed. Treatment of IFI due to NAMs is a multi-pronged and multi-disciplinary approach. Surgery, correction of underlying risk factors, and augmentation of the host immune response are as important as antifungal therapy. Many of these NAMs are intrinsically resistant to the currently licensed antifungal agents, so selection of therapy needs to be guided by susceptibility testing. There are new antifungal agents in development, and these have the potential to improve the efficacy and safety of antifungal treatment in the future. Ongoing research is required to fully delineate the epidemiology of NAM infections, and to develop better diagnostic tools and treatments so that outcomes from these infections can continue to improve.

Figure 1.

CT scan image (axial view) of a reverse halo sign. This is defined as a central area of ground-glass opacification surrounded by a denser peripheral area of consolidation. Courtesy of Professor Samantha Ellis, Department of Radiology, Alfred Health, Melbourne.

Figure 2.

Rhizopus microsporus showing dispersed hyphae/stolon structure. Low objective view. Prepared using adhesive tape method and stained with lactophenol blue. Courtesy of Professor Wieland Meyer, Westerdijk Fungal Biodiversity Institute and Ms Krystyna Maszewska, Dr Catriona Halliday, Mr Alex Khan, Mr Tsung-Yu Pai and Ms Georgia Clementine Wunderlich, Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, NSW, Australia.

Figure 3.

Single-forming anelloconidia of Scedosporium apiospermum attached to conidiophore, showing anellations (arrow) leading to the truncated base of the anelloconidia. Stained using lactophenol blue under coverslip. Courtesy of Professor Wieland Meyer, Westerdijk Fungal Biodiversity Institute and Ms Krystyna Maszewska, Dr Catriona Halliday, Mr Alex Khan, Mr Tsung-Yu Pai and Ms Georgia Clementine Wunderlich, Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, NSW, Australia.

Figure 4.

Top of Scedosporium apiospermum colony after 4 days of growth at 27°C on Sabouraud dextrose agar. Courtesy of Professor Wieland Meyer, Westerdijk Fungal Biodiversity Institute and Ms Krystyna Maszewska, Dr Catriona Halliday, Mr Alex Khan, Mr Tsung-Yu Pai and Ms Georgia Clementine Wunderlich, Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, NSW, Australia.

Figure 5.

Histological specimen showing pigmented hyphae of Lomentospora prolificans. Grocott–Gömöri methenamine silver stain. ×100 magnification. Courtesy of Professor Catriona McLean, Anatomical Pathology, Alfred Health, Melbourne, Australia.

Figure 6.

Histological specimen showing pigmented hyphae of Fusarium. Grocott–Gömöri methenamine silver stain. ×100 magnification. Courtesy of Professor Catriona McLean, Anatomical Pathology, Alfred Health, Melbourne, Australia.

Figure 7.

Banana- or canoe-shaped macroconidia of Fusarium solani can be observed forming on a short phialide/conidiophore (arrow). Prepared using adhesive tape method and stained using lactophenol blue. Courtesy of Professor Wieland Meyer, Ms Krystyna Maszewska, Dr Catriona Halliday, Mr Alex Khan, Mr Tsung-Yu Pai and Ms Georgia Clementine Wunderlich, Westerdijk Fungal Biodiversity Institute and Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, NSW, Australia.