Invasive Trichosporon infection in solid organ transplant patients: a report of two cases identified using IGS1 ribosomal DNA sequencing and a review of the literature

Rare Yeasts in Latin America: Uncommon Yet Meaningful

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

Orthopedic infections due to Trichosporon species: Case series and literature review

Reports of orthopedic fungal infections caused by Trichosporon species are extremely scarce, thus we aimed to describe a case series and review the cases published in the literature. Patients were retrospectively included if a previous culture of bone, joint, or soft tissues had resulted positive for Trichosporon species along with a clinical diagnosis of an orthopedic infection. Eight patients were included with diverse orthopedic conditions, most of them cases of osteomyelitis. The main isolated species was Trichosporon asahii. All patients were treated with antifungals, mainly voriconazole, and surgical management, resulting in high rates of clinical improvement and low associated mortality.

Comparing the phenotypic, genotypic, and proteomic identification of Trichosporon species: A globally emerging yeast of medical importance

Trichosporon spp. are widely distributed in the nature, comprising species that inhabit different ecological niches and can be found in the water, soil, and body surface of animals and humans. Such microorganisms have been classically associated with superficial infections; however, in the last decades, they have also been related to disseminated infections in immunocompromised patients, behaving as opportunistic agents, which demands rapid and accurate species identification for efficient therapy. Concordance level between the traditional phenotypic method and the molecular technique (gold standard) in the identification of all 59 Trichosporon samples was 59.3%. Identification concordance between MALDI-TOF spectrometry and the molecular technique was 71.2%. No isolate of environmental origin was identifiable by MALDI-TOF mass spectrometry (MS), and 100% of such environmental isolates were discordant for IGS region sequencing and phenotypic characterization. Both comparisons evidenced greatest concordance in the identification of T. asahii. The species T. debeurmannianum, T. dermatis, T. venhuisii and T. insectorum were not properly identified by both MALDI-TOF MS and the phenotypic technique. MALDI-TOF MS, in particular, seems to be appropriate to investigate yeasts of the genus Trichosporon; however, database updates are still necessary, especially for species that are not common in the clinical routine. With the aim of helping understand the aspects involved in early and accurate diagnosis of infections caused by this opportunistic agent, the present study compared the phenotypic, molecular (IGS region) and mass-spectrometry (MALDI-TOF) identification of 59 yeasts of the genus Trichosporon which had clinical and environmental origin and were kept in a mycology collection.

Multidrug-resistant Trichosporon species: underestimated fungal pathogens posing imminent threats in clinical settings

Species of Trichosporon and related genera are widely used in biotechnology and, hence, many species have their genome sequenced. Importantly, yeasts of the genus Trichosporon have been increasingly identified as a cause of life-threatening invasive trichosporonosis (IT) in humans and are associated with an exceptionally high mortality rate. Trichosporon spp. are intrinsically resistant to frontline antifungal agents, which accounts for numerous reports of therapeutic failure when echinocandins are used to treat IT. Moreover, these fungi have low sensitivity to polyenes and azoles and, therefore, are potentially regarded as multidrug-resistant pathogens. However, despite the clinical importance of Trichosporon spp., our understanding of their antifungal resistance mechanisms is quite limited. Furthermore, antifungal susceptibility testing is not standardized, and there is a lack of interpretive epidemiological cut-off values for minimal inhibitory concentrations to distinguish non-wild type Trichosporon isolates. The route of infection remains obscure and detailed clinical and environmental studies are required to determine whether the Trichosporon infections are endogenous or exogenous in nature. Although our knowledge on effective IT treatments is rather limited and future randomized clinical trials are required to identify the best antifungal agent, the current paradigm advocates the use of voriconazole, removal of central venous catheters and recovery from neutropenia.

Microbiology of secondary infections in Buruli ulcer lesions; implications for therapeutic interventions

Background

Buruli ulcer (BU) is a skin disease caused by Mycobacterium ulcerans and is the second most common mycobacterial disease after tuberculosis in Ghana and Côte d’Ivoire. M. ulcerans produces mycolactone, an immunosuppressant macrolide toxin, responsible for the characteristic painless nature of the infection. Secondary infection of ulcers before, during and after treatment has been associated with delayed wound healing and resistance to streptomycin and rifampicin. However, not much is known of the bacteria causing these infections as well as antimicrobial drugs for treating the secondary microorganism. This study sought to identify secondary microbial infections in BU lesions and to determine their levels of antibiotic resistance due to the prolonged antibiotic therapy required for Buruli ulcer.

Results

Swabs from fifty-one suspected BU cases were sampled in the Amansie Central District from St. Peters Hospital (Jacobu) and through an active case surveillance. Forty of the samples were M. ulcerans (BU) positive. Secondary bacteria were identified in all sampled lesions (N = 51). The predominant bacteria identified in both BU and Non-BU groups were Staphylococci spp and Bacilli spp. The most diverse secondary bacteria were detected among BU patients who were not yet on antibiotic treatment. Fungal species identified were Candida spp, Penicillium spp and Trichodema spp. Selected secondary bacteria isolates were all susceptible to clarithromycin and amikacin among both BU and Non-BU patients. Majority, however, had high resistance to streptomycin.

Conclusions

Microorganisms other than M. ulcerans colonize and proliferate on BU lesions. Secondary microorganisms of BU wounds were mainly Staphylococcus spp, Bacillus spp and Pseudomonas spp. These secondary microorganisms were less predominant in BU patients under treatment compared to those without treatment. The delay in healing that are experienced by some BU patients could be as a result of these bacteria and fungi colonizing and proliferating in BU lesions. Clarithromycin and amikacin are likely suitable drugs for clearance of secondary infection of Buruli ulcer.

Trichosporon inkin meningitis in Northeast Brazil: first case report and review of the literature

Background

Trichosporon species may colonize the skin, respiratory tract and gastrointestinal tract of human beings. The yeast is recognized as etiological agent of white piedra, a superficial mycosis. Nevertheless, immunocompromised hosts may develop invasive Trichosporonosis. Central nervous system trichosporonosis is a very rare clinical manifestation. In fact, only a few cases have been published in the literature and none of them was caused by Trichosporon inkin.

Case presentation

Here we report the first clinical case of meningoencephalitis due to this species in a female previously healthy patient under corticosteroids and antibiotics therapy for several months. She was submitted to an invasive procedure to remove a left sided acoustic neuroma and further developed a cerebrospinal fistula. After some days of the procedure, she presented a predominantly and intensive occipital holocranial headache, followed by vomiting, hyporexia, weight loss, asthenia, irritability, difficulty to concentrate and rotator vertigo. The patient further developed a cerebrospinal fistula in the occipital region and was submitted to a surgical correction. After several months of clinical interventions, she was diagnosed with CNS Trichosporonosis, after Magnetic Resonance Imaging and positive microbiological cultures obtained within two different occasions (2 weeks apart). Despite the antifungal therapy with Amphotericin B and Voriconazole, the patient did not survive.

Conclusions

Despite CNS Fungal infections are mostly due to Cryptococcus spp., other emergent yeasts, such as T. inkin may be considered as a likely etiological agent. This is the first case report of CNS Trichosporonosis, where species identification was performed with rDNA sequencing.

Trichosporonosis in Pediatric Patients With a Hematologic Disorder

BACKGROUND

Trichosporonosis is an emerging and often fatal opportunistic fungal infection in immunocompromised patients, particularly those with hematologic malignancy, but data in children are lacking.

METHODS

We report here 3 cases of invasive infection caused by Trichosporon asahii in pediatric patients with acute lymphoblastic leukemia at Texas Children's Hospital in Houston, Texas. We also conducted a literature review and identified 16 additional reports of pediatric patients with invasive T asahii infection and an underlying malignant or nonmalignant hematologic disorder.

RESULTS

Of the 19 cases of invasive T asahii infection, the most commonly reported underlying hematologic disorder was acute lymphoblastic leukenia (47%), followed by acute myelogenous leukemia (21%). Most of the patients (94%) had neutropenia, defined as an absolute neutrophil count of <500 cells/mm3. Antifungal prophylaxis information was available in 6 of the 19 cases, and micafungin use was reported in 5 cases. Treatment regimens frequently included voriconazole monotherapy (47%) or the combination of an azole antifungal with amphotericin B (35%). The mortality rate was 58%.

CONCLUSIONS

Recognizing that echinocandins, which are increasingly used for prophylaxis in patients with a hematologic malignancy, are not active against Trichosporon species is of critical importance. The recommended first-line therapy for trichosporonosis is voriconazole, but successful outcome depends largely on the underlying immune status of the host.

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.