Trends in the epidemiology of opportunistic fungal infections: Predisposing factors and the impact of antimicrobial use practices

In the past decade, the frequency of opportunistic fungal infections has increased, and the spectrum of fungal pathogens has changed. The increasing number of susceptible hosts, the introduction of newer modalities for hematopoietic stem cell transplantation, the evolution of organ transplantation practices, the use of novel immunosuppressive agents, and current antimicrobial prophylactic strategies have likely contributed to the changing epidemiology of invasive mycoses. The introduction of azoles more than a decade ago has had a profound impact on curtailing candidal infections. However, a dramatic increase in azole-resistant Candida species and mold infections has been documented. The trends in time of onset, spectrum, and frequency of infections due to invasive molds and opportunistic yeasts are unique for different fungi and vary between subsets of immunocompromised hosts. This review discusses the implications of these trends for guiding judicious use of antimicrobial prophylactics and for unraveling the pathophysiological basis of fungal infections.