Autopsy case of disseminated Trichosporon inkin infection identified with molecular biological and biochemical methods

Invasive Trichosporon Infection: a Systematic Review on a Re-emerging Fungal Pathogen

Objectives: This review aimed to better depict the clinical features and address the issue of therapeutic management of Trichosporon deep-seated infections.

Methods: We comprehensively reviewed the cases of invasive Trichosporon infection reported in the literature from 1994 (date of taxonomic modification) to 2015. Data from antifungal susceptibility testing (AST) studies were also analyzed.

Results: Two hundred and three cases were retained and split into four groups: homeopathy (n = 79), other immunodeficiency conditions (n = 41), miscellaneous (n = 58) and newborns (n = 25). Trichosporon asahii was the main causative species (46.7%) and may exhibit cross-resistance to different antifungal classes. The unfavorable outcome rate was at 44.3%. By multivariate analysis, breakthrough infection (OR 2.45) was associated with unfavorable outcome, whilst the use of an azole-based therapy improved the prognosis (OR 0.16). Voriconazole-based treatment was associated with favorable outcome in hematological patients (73.6 vs. 41.8%; p = 0.016). Compiled data from AST demonstrated that (i) T. asahii exhibits the highest MICs to amphotericin B and (ii) voriconazole has the best in vitro efficacy against clinical isolates of Trichosporon spp.

Conclusions:Trichosporon infection is not only restricted to hematological patients. Analysis of compiled data from AST and clinical outcome support the use of voriconazole as first line therapy.

Subcutaneous Infection Associated with Trichosporon ovoides: A Case Report and Review of Literature

Trichosporon species are opportunistic yeasts which can cause infections, especially in immunocompromised patients. This is a report of Trichosporon ovoides that caused subcutaneous infection in a patient with underlying ischemic heart disease. The identification of fungal isolate was confirmed by PCR sequencing of ITS and large subunit regions in rRNA gene. In vitro susceptibility study showed that the isolate was susceptible to amphotericin B, fluconazole and voriconazole, and resistant to caspofungin, anidulafungin and itraconazole. The lesion improved after treatment with oral fluconazole and topical miconazole.

What Has Been Learned from Postmortem Studies?

Infectious and noninfectious pulmonary diseases are commonly found on postmortem autopsy studies in patients with hematological malignancy. Despite the technological advances in diagnostic testing and imaging modalities, obtaining an accurate clinical diagnosis remains difficult and often not possible until autopsy. Major diagnostic discrepancies between clinical premortem diagnoses and postmortem autopsy findings have been reported in these patients. The most common missed diagnoses are due to opportunistic infections and cardiopulmonary complications. These findings underscore the importance of enhanced surveillance, monitoring and treatment of infections and cardiopulmonary disorders in these patients. Autopsies remain important in determining an accurate cause of death and for improved understanding of diagnostic deficiencies, as well as for medical education and quality assurance.

Trichosporon inkin Esophagitis: An Uncommon Disease in a Patient with Pulmonary Cancer

Trichosporon species are usually opportunistic pathogens. Here, we present a case of esophagitis caused by T. inkin in a 54-year-old woman with pulmonary cancer and severe neutropenia in whom the susceptibility profile of the isolate against azoles and polyenes was verified. The patient was diagnosed with esophagitis grade I of Wilcox, presenting scattered whitish plaques and exudates in upper two-thirds of the esophageal mucosa. Antifungal therapy involving oral fluconazole (150 mg/day for 14 days) was ineffective. In vitro, the isolate showed no resistance to this azole and sensitivity to amphotericin B. Since T. inkin is of growing importance as an agent of invasive infections in immunocompromised patients, we stress that the diagnosis of esophagitis by this species should be followed by an assessment of the therapeutic sensitivity of the strain involved.

Differential diagnosis of trichosporonosis using conventional histopathological stains and electron microscopy

AIMS

Although Trichosporon is a causative pathogen of white piedra and summer-type hypersensitivity pneumonitis, fatal disseminated trichosporonosis cases have recently been increasing. However, Trichosporon is often confused with other fungi, especially Candida, in pathological specimens. The aim was to determine the utility of histopathological stains and electron microscopy for diagnosing trichosporonosis.

METHODS AND RESULTS

Autopsy cases of trichosporonosis, candidiasis, aspergillosis and cryptococcosis were investigated using histopathological stains and electron microscopy. Using Grocott's method, Trichosporon was weakly detected compared with other fungi. In contrast, diluted periodic acid methenamine silver (PAM) stain clearly enhanced the intensity of staining of Trichosporon compared with Candida. Furthermore, Alcian blue and colloidal iron stains predominantly detected Trichosporon. Electron microscopy after staining with diluted PAM demonstrated that Trichosporon has a variety of hyphal sizes and laminar deposition of rough silver granules, whereas Candida has uniform pseudohyphae and fine granules. The average diameter and population area of the granules were significantly higher in Trichosporon compared with Candida (P<0.01). Meanwhile, the laminar structure was preserved in the cell walls of Trichosporon without silver stains, whereas a low-density structure was observed in Candida.

CONCLUSIONS

Histopathological staining patterns and electron microscopic findings can facilitate the diagnosis of trichosporonosis.

Trichosporon mycotoxinivorans, a novel respiratory pathogen in patients with cystic fibrosis

This report describes the molecular epidemiology, in vitro susceptibility, colonial and microscopic morphologies, and biochemical features of Trichosporon mycotoxinivorans, a newly recognized pathogen that appears to have a propensity for patients with cystic fibrosis. The index patient died with histologically documented Trichosporon pneumonia complicating cystic fibrosis. This is also the first report of disease caused by a Trichosporon species in a nontransplant patient with cystic fibrosis. As T. mycotoxinivorans has not previously been recognized as a respiratory pathogen, the significance of its recovery from sputum samples was not initially appreciated. Genetic analysis of archived clinical samples found three additional cases of T. mycotoxinivorans infection which had previously been identified as other members of the genus. An additional isolate of T. mycotoxinivorans was identified from a clinical sample on initial testing. Three of these four cases were also patients with cystic fibrosis. All isolates had MICs at 48 h of amphotericin B of > or = 1 microg/ml and of echinocandins of > or = 16 microg/ml, but they displayed various susceptibilities to the triazoles. In summary, Trichosporon mycotoxinivorans is a newly recognized human pathogen that is associated with cystic fibrosis.

Morphological and biochemical characterization of the aetiological agents of white piedra

The Trichosporon genus is constituted by many species, of which Trichosporon ovoides and Trichosporon inkin are the causative agents of white piedra. They can cause nodules in genital hair or on the scalp. At present, Brazilian laboratory routines generally do not include the identification of the species of Trichosporon genus, which, although morphologically and physiologically distinct, present many similarities, making the identification difficult. The aim of this study was to identify the aetiological agents at the species level of white piedra from clinical specimens. Therefore, both the macro and micro morphology were studied, and physiological tests were performed. Trichosporon spp. was isolated from 10 clinical samples; T. ovoides was predominant, as it was found in seven samples, while T. inkin was identified just in two samples. One isolate could not be identified at the species level. T. inkin was identified for the first time as a white piedra agent in the hair shaft on child under the age of 10.

Molecular identification and susceptibility of Trichosporon species isolated from clinical specimens in Qatar: isolation of Trichosporon dohaense Taj-Aldeen, Meis & Boekhout sp. nov

Trichosporon species have been reported as emerging pathogens and usually occur in severely immunocompromised patients. In the present work, 27 clinical isolates of Trichosporon species were recovered from 27 patients. The patients were not immunocompromised, except for one with acute myeloid leukemia. Sequence analysis revealed the isolation of Trichosporon dohaense Taj-Aldeen, Meis & Boekhout sp. nov., with CBS 10761(T) as the holotype strain, belonging to the Ovoides clade. In the D1-D2 large-subunit rRNA gene analysis, T. dohaense is a sister species to T. coremiiforme, and in the internal transcribed spacer analysis, the species is basal to the other species of this clade. Molecular identification of the strains yielded 17 T. asahii, 3 T. inkin, 2 T. japonicum, 2 T. faecale, and 3 T. dohaense isolates. The former four species exhibited low MICs for five antifungal azoles but showed high MICs for amphotericin B. T. dohaense demonstrated the lowest amphotericin B MIC (1 mg/liter). For the majority of T. asahii isolates, amphotericin B MICs were high (MIC at which 90% of isolates were inhibited [MIC(90)], > or = 16 mg/liter), and except for fluconazole (MIC(90), 8 mg/liter), the azole MICs were low: MIC(90)s were 0.5 mg/liter for itraconazole, 0.25 mg/liter for voriconazole, 0.25 mg/liter for posaconazole, and 0.125 mg/liter for isavuconazole. The echinocandins, caspofungin and anidulafungin, demonstrated no activity against Trichosporon species.

Endocrine and metabolic manifestations of invasive fungal infections and systemic antifungal treatment

Systemic fungal infections are increasingly reported in immunocompromised patients with hematological malignancies, recipients of bone marrow and solid organ allografts, and patients with AIDS. Mycoses may infiltrate endocrine organs and adversely affect their function or produce metabolic complications, such as hypopituitarism, hyperthyroidism or hypothyroidism, pancreatitis, hypoadrenalism, hypogonadism, hypernatremia or hyponatremia, and hypercalcemia. Antifungal agents used for prophylaxis and/or treatment of mycoses also have adverse endocrine and metabolic effects, including hypoadrenalism, hypogonadism, hypoglycemia, dyslipidemia, hypernatremia, hypocalcemia, hyperphosphatemia, hyperkalemia or hypokalemia, and hypomagnesemia. Herein, we review how mycoses and conventional systemic antifungal treatment can affect the endocrine system and cause metabolic abnormalities. If clinicians are equipped with better knowledge of the endocrine and metabolic complications of fungal infections and antifungal therapy, they can more readily recognize them and favorably affect outcome.

Disseminated Trichosporon inkin and Histoplasma capsulatum in a patient with newly diagnosed AIDS

Histoplasma capsulatum and Trichosporon inkin may cause disseminated disease in immunocompromised patients. Disseminated T inkin, the causative agent of white piedra, is rare and difficult to diagnose. We report the case of a 28 year-old man with newly diagnosed HIV infection who developed asymptomatic lesions on his trunk and extremities. Histology demonstrated perivascular and intravascular budding yeasts. Blood cultures revealed fungal organisms that were difficult to culture. Specimens were positive for H capsulatum (confirmed by DNA probe) and T inkin. Compared with disseminated histoplasmosis, disseminated Trichosporon is relatively uncommon. Physicians should be aware of this agent in immunocompromised hosts.

Supplemental utility of nested PCR for the pathological diagnosis of disseminated trichosporonosis

Disseminated trichosporonosis is known to be a severe opportunistic mycosis and has a high mortality rate. In autopsy cases, it is often difficult to diagnose as trichosporonosis because the causative Trichosporon species are pathologically similar to other fungi, especially the Candida species. Immunohistochemical analysis is essential for the differential diagnosis, but an antibody to Trichosporon is not available commercially. In the present study, we investigated the supplemental utility of nested polymerase chain reaction (PCR) for the pathological diagnosis of trichosporonosis from formalin-fixed and paraffin-embedded tissues. Total DNA was purified from 30 major organs in three autopsy cases, and Trichosporon DNA was specifically amplified by nested PCR using three sets of primers. Of 22 organs in which Grocott's stain was positive for fungal infection, 170- and 259-bp PCR products were detected in 20 (91%) and 12 (55%) organs, respectively. In short-term fixation (about 1 day), these bands were highly detected in ten (100%) and nine (90%) organs, whereas the detection efficiency tended to decrease after long-term fixation and decalcification. No PCR product of 412 bp was detected in any organs. These findings suggest that nested PCR from short-term-fixed tissues is useful for supportive pathological diagnosis of disseminated trichosporonosis.