Arxula adeninivorans causing invasive pulmonary mycosis and fungaemia in cystic fibrosis

Invasive fungal infection caused by Blastobotrys mokoenaii in an immunocompromised patient with acute myeloid leukemia: A case report

Blastobotrys is a genus of rare yeast that is increasingly recognized as a cause of fungal infections in humans. However, there have been no reports of fungal infections in humans caused by Blastobotrys mokoenaii. We describe a case of invasive fungal infection (IFI) caused by B. mokoenaii in an immunocompromised patient with acute myeloid leukemia (AML). A 46-year-old man with relapsed/refractory AML underwent a second allogeneic peripheral blood hematopoietic stem cell transplantation (allo-PBSCT) during remission. The patient had prolonged neutropenia and received systemic steroid therapy for graft-versus-host disease before the second allo-PBSCT. Uncommon yeast was isolated from the blood cultures obtained on day 4. We initially suspected that the uncommon yeast was Trichosporon spp. based on its morphology. However, unlike Trichosporon spp., in vitro antifungal susceptibility tests showed that this yeast isolate was resistant to micafungin, caspofungin, voriconazole, itraconazole, and fluconazole. We performed DNA sequencing and identified it as B. mokoenaii. B. mokoenaii was persistently isolated from blood cultures taken during combination therapy with liposomal amphotericin B and voriconazole. The patient died of multiorgan failure on day 24. B. mokoenaii can cause severe IFI in immunocompromised patients; however, it may not be correctly identified by routine clinical microbiology testing in a hospital laboratory and DNA sequencing is useful for diagnosis.

Stephanoascus ciferrii Complex: The Current State of Infections and Drug Resistance in Humans

In recent years, the incidence of fungal infections in humans has increased dramatically, accompanied by an expansion in the number of species implicated as etiological agents, especially environmental fungi never involved before in human infection. Among fungal pathogens, Candida species are the most common opportunistic fungi that can cause local and systemic infections, especially in immunocompromised individuals. Candida albicans (C. albicans) is the most common causative agent of mucosal and healthcare-associated systemic infections. However, during recent decades, there has been a worrying increase in the number of emerging multi-drug-resistant non-albicans Candida (NAC) species, i.e., C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, C. auris, and C. ciferrii. In particular, Candida ciferrii, also known as Stephanoascus ciferrii or Trichomonascus ciferrii, is a heterothallic ascomycete yeast-like fungus that has received attention in recent decades as a cause of local and systemic fungal diseases. Today, the new definition of the S. ciferrii complex, which consists of S. ciferrii, Candida allociferrii, and Candida mucifera, was proposed after sequencing the 18S rRNA gene. Currently, the S. ciferrii complex is mostly associated with non-severe ear and eye infections, although a few cases of severe candidemia have been reported in immunocompromised individuals. Low susceptibility to currently available antifungal drugs is a rising concern, especially in NAC species. In this regard, a high rate of resistance to azoles and more recently also to echinocandins has emerged in the S. ciferrii complex. This review focuses on epidemiological, biological, and clinical aspects of the S. ciferrii complex, including its pathogenicity and drug resistance.

Fungal Colonization of the Airways of Patients with Cystic Fibrosis: the Role of the Environmental Reservoirs

Filamentous fungi frequently colonize the airways of patients with cystic fibrosis and may cause severe diseases, such as the allergic bronchopulmonary aspergillosis. The most common filamentous fungi capable to chronically colonize the respiratory tract of the patients are Aspergillus fumigatus and Scedosporium species. Defining the treatment strategy may be challenging, the number of available drugs being limited and some of the causative agents being multiresistant microorganisms. The knowledge of the fungal niches in the outdoor and indoor environment is needed for understanding the origin of the contamination of the patients. In light of the abundance of some of the causative molds in compost, agricultural and flower fields, occupational activities related to such environments should be discouraged for patients with cystic fibrosis (CF). In addition, the microbiological monitoring of their indoor environment, including analysis of air and dust on surfaces, is essential to propose preventive measures aiming to reduce the exposure to environmental molds. Nevertheless, some specific niches were also identified in the indoor environment, in relation with humidity which favors the growth of thermotolerant molds. Potted plants were reported as indoor reservoirs for Scedosporium species. Likewise, Exophiala dermatitidis may be spread in the kitchen via dishwashers. However, genotype studies are still required to establish the link between dishwashers and colonization of the airways of CF patients by this black yeast. Moreover, as nothing is known regarding the other filamentous fungi associated with CF, further studies should be conducted to identify other potential specific niches in the habitat.

Clinical Relevance of Fungi in Cystic Fibrosis

In cystic fibrosis, a new era has started with the approval and use of highly effective cystic fibrosis transport regulator (CFTR) modulator therapy. As pulmonary function is increasing and exacerbation rate significantly decreases, the current meaning of fungal pulmonary diseases is questioned. During the past couple of decades, several studies have been conducted regarding fungal colonization and infection of the airways in people with cystic fibrosis. Although Aspergillus fumigatus for filamentous fungi and Candida albicans for yeasts remain by far the most common fungal species in patients with cystic fibrosis, the pattern of fungal species associated with cystic fibrosis has considerably diversified recently. Fungi such as Scedosporium apiospermum or Exophiala dermatitidis are recognized as pathogenic in cystic fibrosis and therefore need attention in clinical settings. In this article, current definitions are stated. Important diagnostic steps are described, and their usefulness discussed. Furthermore, clinical treatment strategies and recommendations are named and evaluated. In cystic fibrosis, fungal entities can be divided into different subgroups. Besides colonization, allergic bronchopulmonary aspergillosis, bronchitis, sensitization, pneumonia, and aspergilloma can occur as a fungal disease entity. For allergic bronchopulmonary aspergillosis, bronchitis, pneumonia, and aspergilloma, clear indications for therapy exist but this is not the case for sensitization or colonization. Different pulmonary fungal disease entities in people with cystic fibrosis will continue to occur also in an era of highly effective CFTR modulator therapy. Whether the percentage will decrease or not will be the task of future evaluations in studies and registry analysis. Using the established definition for different categories of fungal diseases is recommended and should be taken into account if patients are deteriorating without responding to antibiotic treatment. Drug-drug interactions, in particular when using azoles, should be recognized and therapies need to be adjusted accordingly.

Pulmonary infection secondary to Blastobotrys raffinosifermentans in a cystic fibrosis patient: Review of the literature

BACKGROUND

The genus Blastobotrys consists of at least 20 species. Disease in humans has been reported with B adeninivorans, B raffinosifermentans, B proliferans and B serpentis, mostly in immunocompromised patients and those with cystic fibrosis.

OBJECTIVE

We report a lung infection secondary to B raffinosifermentans in a cystic fibrosis patient successfully treated with isavuconazole and review the literature of invasive infections caused this genus. We also evaluated clinical isolates in our laboratory for species identification and antifungal susceptibility.

METHODS

Phylogenetic analysis was performed on a collection of 22 Blastobotrys isolates in our reference laboratory, and antifungal susceptibility patterns were determined for nine clinically available antifungals against 19 of these isolates.

RESULTS

By phylogenetic analysis, 21 of the 22 isolates in our collection were identified as B raffinosifermentans and only 1 as B adeninivorans. Most were cultured from the respiratory tract, although others were recovered from other sources, including CSF and blood. Isavuconazole, caspofungin and micafungin demonstrated the most potent in vitro activity, followed by amphotericin B. In contrast, fluconazole demonstrated poor activity. The patient in this case responded to isavuconazole treatment for breakthrough infection due to B raffinosifermentans that was cultured from pleural fluid while on posaconazole prophylaxis post-bilateral lung transplantation for cystic fibrosis.

CONCLUSIONS

Blastobotrys species are rare causes of infections in humans and primarily occur in immunocompromised hosts. In our collection, the majority of isolates were identified as B raffinosifermentans. To our knowledge, this is the first report of successful treatment of such an infection with isavuconazole.

Evaluation of a New Culture Protocol for Enhancing Fungal Detection Rates in Respiratory Samples of Cystic Fibrosis Patients

Cystic fibrosis (CF) can be complicated by fungal infection of the respiratory tract. Fungal detection rates in CF sputa are highly dependent on the culture protocol and incubation conditions and thus may lead to an underestimation of the true prevalence of fungal colonization. We conducted a prospective study to evaluate the additional value of mucolytic pre-treatment, increased inoculum (100 µL), additional fungal culture media (Sabouraud agar; SAB, Medium B+, Scedosporium selective agar; SceSel+ and Dichloran-Glycerol agar; DG18) and longer incubation time (3 weeks) compared with our current protocol. Using the new protocol, we prospectively analyzed 216 expectorated sputum samples from adult and pediatric CF patients (n = 77) and compared the culture yield to a three year retrospective cohort that used direct 10 µL loop inoculation on SAB with 5 days incubation (867 sputum samples/103 patients). Detection rates for molds increased from 42% to 76% (p < 0.0001). Twenty-six percent of cultures were polymicrobial in the prospective cohort as opposed to 4.7% in the retrospective cohort (p < 0.0001). Colonization rate with A. fumigatus increased from 36% to 57%. SAB and DG18 showed the highest detection rates for all molds (SAB 58.6%; DG18 56.9%) and DG18 had the best performance for molds other than A. fumigatus. The larger sample volume and longer incubation also contributed to the increased recovery of molds. The introduction of a modified fungal culture protocol leads to a major increase in detection rate and the diversity of molds, which influences fungal epidemiology and may have implications for treatment decisions.

Fungus-Specific CD4 T Cells as Specific Sensors for Identification of Pulmonary Fungal Infections

Patients with cystic fibrosis (CF) suffer from chronic lung infections, caused by bacterial, viral or fungal pathogens, which determine morbidity and mortality. The contribution of individual pathogens to chronic disease and acute lung exacerbations is often difficult to determine due to the complex composition of the lung microbiome in CF. In particular, the relevance of fungal pathogens in CF airways remains poorly understood due to limitations of current diagnostics to identify the presence of fungal pathogens and to resolve the individual host-pathogen interaction status. T-lymphocytes play an essential role in host defense against pathogens, but also in inappropriate immune reactions such as allergies. They have the capacity to specifically recognize and discriminate the different pathogens and orchestrate a diverse array of effector functions. Thus, the analysis of the fungus-specific T cell status of an individual can in principle provide detailed information about the identity of the fungal pathogen(s) encountered and the actual fungus-host interaction status. This may allow to classify patients, according to appropriate (protective) or inappropriate (pathology-associated) immune reactions against individual fungal pathogens. However, T cell-based diagnostics are currently not part of the clinical routine. The identification and characterization of fungus-specific T cells in health and disease for diagnostic purposes are associated with significant challenges. Recent technological developments in the field of fungus-specific T helper cell detection provide new insights in the host T cell-fungus interaction. In this review, we will discuss basic principles and the potential of T cell-based diagnostics, as well as the perspectives and further needs for use of T cells for improved clinical diagnostics of fungal diseases.