Current Knowledge of Trichosporon spp. and Trichosporonosis

Abstract

SUMMARY Trichosporon spp. are basidiomycetous yeast-like fungi found widely in nature. Clinical isolates are generally related to superficial infections. However, this fungus has been recognized as an opportunistic agent of invasive infections, mostly in cancer patients and those exposed to invasive medical procedures. It is possible that the ability of Trichosporon strains to form biofilms on implanted devices, the presence of glucuronoxylomannan in their cell walls, and the ability to produce proteases and lipases are all factors likely related to the virulence of this genus and therefore may account for the progress of invasive trichosporonosis. Disseminated trichosporonosis has been increasingly reported worldwide and represents a challenge for both diagnosis and species identification. Phenotypic identification methods are useful for Trichosporon sp. screening, but only molecular methods, such as IGS region sequencing, allow the complete identification of Trichosporon isolates at the species level. Methods for the diagnosis of invasive trichosporonosis include PCR-based methods, Luminex xMAP technology, and, more recently, proteomics. Treating patients with trichosporonosis remains a challenge because of limited data on the in vitro and in vivo activities of antifungal drugs against clinically relevant species of the genus. Despite the mentioned limitations, the use of antifungal regimens containing triazoles appears to be the best therapeutic approach.

Trichosporon asahii causing nosocomial urinary tract infections in intensive care unit patients: genotypes, virulence factors and antifungal susceptibility testing

“…Consistent with previous studies (Colombo et al, 2011;Padhye et al, 2002;Rodriguez-Tudela et al, 2007), there were susceptible populations commonly associated with trichosporonosis in this study (Table 1). All 23 patients were from ICUs and elderly (¢75 years).…”

The development of animal infection models and antifungal efficacy assays against clinical isolates ofTrichosporon asahii,T. asteroidesandT. inkin

“…49,52 In this sense, and taking in account the modest results obtained with monotherapies in our study, and their scarce efficacy in clinical setting, the usage of combined therapies appears to be the most fitting strategy to improve the outcomes of disseminated Trichosporon infections. 2 The recent sequencing of T. asahii genome and the soon to become available genome sequences of other Trichosporon species (Goldman et al, forthcoming) will provide a powerful tool for the dissection of the molecular virulence mechanisms deployed by Trichosporon species, while facilitating the identification of novel fungal targets for antifungal therapies to treat this kind of infection. Subsequently, the combination G. mellonella and murine assays developed in the presented study will be useful for the study of Trichosporon virulence and the future improvement of antifungal strategies for controlling trichosporonosis.…”

“…Since these organisms are skilled at adhering to these devices and apt at forming biofilms, they are able to escape from antifungal drugs and host immune responses. 2,22 It has been speculated that the secretion of proteases and phospholipases are important virulence factors for scavenging nutrient inside the host. 23 These pathogens are also able to produce glucuronoxylomannan (GXM) in their cell walls, similarly to Cryptococcus neoformans 24,25 and it is possible this polysaccharide may help to attenuate phagocytosis by host immune cells.…”

“…can be found in soil, decomposing wood, air, rivers, lakes, seawater, cheese, scarab beetles, bird droppings, bats, pigeons, and cattle. 2 They belong to the human microbiome, as colonizers of the gastrointestinal and oral cavities, male perigenital skin (scrotal, perianal, and inguinal sites of the body) and temporarily inhabiting the respiratory tract and skin. [3][4][5][6][7][8][9][10][11][12] It is not clear how Trichosporonosis can be acquired, but the following possibilities can be envisaged: (i) poor hygiene, (ii) bathing in contaminated water, (iii) sexual transmission, (iv) hair humidity and the length of the scalp hair (more specifically in the case of acquiring white piedra), (v) gastrointestinal colonization and further translocation throughout the gut (deep-seated infections), and (vi) exogenously acquired through a percutaneously inserted intravascular catheter via colonized skin.…”

“…[13][14][15][16][17][18] In spite of the fact that Trichosporon spp are probably the second or third most common non-Candida yeast infections causing invasive disease in patients with hematological cancer, there are few reports related to virulence factors of this genus. 2,[19][20][21] The main causes of infection by invasive Trichosporon spp. are central and vesical venous catheters, and peritoneal catheter-related devices.…”