Epidemiology of Emerging Fungi and Fungi-like Organisms

Abstract

Over the past several decades, rare and unusual fungi have been reported increasingly as agents of infection in humans and animals. This increased frequency of unusual fungal infections may be related in part to increasing numbers of patients with immunosuppression, as well as increased opportunities for environmental exposure to the organisms. In addition, the advent of better diagnostic modalities has aided in the identification of unusual organisms. This review discusses the epidemiology of emerging and unusual fungi and other pathogens causing fungal-like infection.

Infection Due to Non-Candidal Yeasts

“…Infections due to Trichosporon may be classified as superficial or deep. Disseminated infections are increasingly recognized in the compromised host over the past decade and are frequently fatal [1][2][3][4][5][6]. One of the first reported cases of disseminated disease was described in a 39 year-old female with lung cancer who subsequently developed a brain abscess [8].…”

“…Because of the fact that Saccharomyces species have a tendency to be nonpathogenic, the decision to attribute a causal role to S. cerevisiae is difficult [2][3][4][5][6]. Diagnostic difficulty occurs when the organism is recovered from body sites that may be colonized by Saccharomyces, especially in the absence of symptoms of infection.…”

“…This is generally done via a histopathologic examination. S. cerevisiae readily grows from blood culture bottles and on Sabouraud dextrose media [2][3][4][5][6]34].…”

“…Most experts advocate removing the focus of infection, whether it is an indwelling or tunneled intravenous catheter and the concurrent use of antifungal agents [36]. In vitro susceptibility studies reveal that S. cerevisiae, when compared to C. albicans isolates, are less susceptible to most antifungals, including azoles [1][2][3][4][5]26] (Table 9.3). Although clinical trials have not been conducted and in vitro susceptibility assays are not standardized, Saccharomyces species appear to be susceptible to most antifungals including amphotericin B, 5-flucytosine, ketoconazole, clotrimazole, miconazole, and terconazole [1][2][3][4][5]26] (Table 9.4).…”

“…Most yeast organisms are of low virulence and generally require significant alterations or reductions in host defenses prior to tissue invasion. Recently, however, because of the increased population of immunocompromised patients, the frequency of invasive infections due to yeasts as well as the number of organisms causing disease continues to grow [1][2][3][4][5][6] (Table 9.1).…”