Use of DNA Sequencing Analysis To Confirm Fungemia Due to Trichosporon dermatis in a Pediatric Patient

Abstract

This is the first reported case of human disease caused by Tricosporon dermatis, an organism recently transferred to the genus Trichosporon from Cryptococcus and now confirmed to be a human pathogen. CASE REPORTA 13-month-old male with a history of autoimmune enteropathy developed a fever of unknown origin (FUO) and malaise. The patient was the product of a full-term uncomplicated pregnancy and delivery. At 9 days of life he had a rotavirus infection and subsequently developed a malabsorption-dysmotility syndrome. The etiology of his enteropathy was unknown, but it was suspected to be autoimmune. He had been on immunosuppressant therapy, including prednisolone and tacrolimus; and his caloric needs had been maintained with total parenteral nutrition through a central venous catheter (CVC) since his first month of life. Numerous bacterial line infections had required catheter replacement, and at the time of this presentation he had a Broviac catheter in place in his right internal jugular vein. His physical examination was notable for rhinitis with a temperature of 101.0°F, and the differential diagnosis for his FUO included viral illness versus bacterial line infection. The patient had a normal total white blood cell count of 5.01 ϫ 10 6 per liter, with relative lymphopenia (5%) and neutrophilia (73%). Following the collection of blood samples for microbiologic analysis, the patient was started on intravenous vancomycin therapy.The blood specimens were taken from both the central line and a peripheral vein and were inoculated into BACTEC Plus Aerobic/F culture vials and processed in a blood culture system (BACTEC 9240 fluorescent series instruments; BD Diagnostic Systems, Sparks, MD). Growth was detected in the blood cultures after 48 h, with gram-positive organisms and yeast observed by microscopic examination. Subcultures were performed onto Trypticase soy sheep blood agar, which grew a coagulase-negative Staphylococcus, and CHROMagar, which produced mucoid mauve-colored colonies at 30°C after 24 h of incubation. Microscopic examination of subcultures grown on cornmeal agar revealed hyphae with the formation of arthroconidia and lateral and terminal blastoconidia (Fig. 1). The organism was found to be urease positive on Christensen's urea and displayed robust growth on Mycosel agar containing 0.01% cycloheximide. Urease positivity and cycloheximide resistance combined with the macroscopic and microscopic morphologies of the organism were consistent with the characteristics of Trichosporon spp. Further biochemical analysis with the VITEK 1 and 2 systems (bioMerieux, Inc., Durham, NC) identified Trichosporon mucoides with excellent confidence levels and t indices of 1.0 and 96.55, respectively. A second blood sample obtained 3 days after the initial sample was obtained, as well as a third sample obtained 8 days later, were again positive for T. mucoides. Based upon the initial colony morphology, which resembled a Candida sp. (especially Candida glabrata), a fluconazole susceptibility test was performed by the Cli...

Molecular Identification and Susceptibility ofTrichosporonSpecies Isolated from Clinical Specimens in Qatar: Isolation ofTrichosporon dohaenseTaj-Aldeen, Meis & Boekhout sp. nov

“…The genus Trichosporon now comprises 36 species. The number of Trichosporon species causing disseminated disease is expanding; T. asteroides, T. loubieri, and T. dermatis have recently been shown to cause disseminated trichosporonosis (25,33,38,55). Trichosporon has been reported to be the most common cause of nonCandida yeast infections in patients with hematological malignancies, and the infections were associated with high mortality rates, despite antifungal therapy (59).…”

“…Although uncommon, pathogenic species of this genus have been reported increasingly, mostly in patients with malignant diseases (3,6,9,10,11,20,32,44,47,48,63,77), neonates (18,56,84), a bone marrow transplant recipient (22), a solid organ transplant recipient (50), and patients with human immunodeficiency virus (34,35,46). Trichosporon has also been reported to cause fungemia (5,9,25,29,30,33,53,62). Members of the genus Trichosporon have occasionally been implicated as nail pathogens (16,28,74) and in subcutaneous infections (66).…”

“…The formation of blastoconidia was also investigated using these media. Growth at different temperatures (25,30,35,37,40, and 42°C) was evaluated using inoculated YPGA slants placed in incubators at the appropriate temperatures. The nutritional requirements, fermentative capabilities, reactions to diazonium blue B, and urease activities of the yeast strains were assessed according to the work of Yarrow (83).…”

Bloodstream Infections Due to Trichosporon spp.: Species Distribution, Trichosporon asahii Genotypes Determined on the Basis of Ribosomal DNA Intergenic Spacer 1 Sequencing, and Antifungal Susceptibility Testing

“…For instance, it has been mentioned in the literature that an isolate identified by molecular methods as Trichosporon dermatis was mistakenly identified as Trichosporon mucoides when Vitek Systems 1 and 2 (BioMérieux, France) were used (16). Furthermore, Ahmad et al (1) reported that four isolates previously identified by Vitek 2 as Trichosporon asahii were identified as Trichosporon asteroides by molecular techniques.…”

An Unusual Case of Nosocomial Trichosporon asahii Fungemia in a Patient with Tuberculous meningitis

“…Trichosporonosis is recognized as one of the emerging opportunistic mycosis in tertiary care hospitals, worldwide (8,9). These non-Candida yeasts present varied clinical manifestations ranging from superficial infections to severe life threatening invasive diseases in the immunocompromised host (10).…”