Invasive Scedosporium and Lomentospora prolificans Infections in Australia: A Multicenter Retrospective Cohort Study

Scedosporiosis and lomentosporiosis: modern perspectives on these difficult-to-treat rare mold infections

SUMMARYAlthough Scedosporium species and Lomentospora prolificans are uncommon causes of invasive fungal diseases (IFDs), these infections are associated with high mortality and are costly to treat with a limited armamentarium of antifungal drugs. In light of recent advances, including in the area of new antifungals, the present review provides a timely and updated overview of these IFDs, with a focus on the taxonomy, clinical epidemiology, pathogenesis and host immune response, disease manifestations, diagnosis, antifungal susceptibility, and treatment. An expansion of hosts at risk for these difficult-to-treat infections has emerged over the last two decades given the increased use of, and broader population treated with, immunomodulatory and targeted molecular agents as well as wider adoption of antifungal prophylaxis. Clinical presentations differ not only between genera but also across the different Scedosporium species. L. prolificans is intrinsically resistant to most currently available antifungal agents, and the prognosis of immunocompromised patients with lomentosporiosis is poor. Development of, and improved access to, diagnostic modalities for early detection of these rare mold infections is paramount for timely targeted antifungal therapy and surgery if indicated. New antifungal agents (e.g., olorofim, fosmanogepix) with novel mechanisms of action and less cross-resistance to existing classes, availability of formulations for oral administration, and fewer drug-drug interactions are now in late-stage clinical trials, and soon, could extend options to treat scedosporiosis/lomentosporiosis. Much work remains to increase our understanding of these infections, especially in the pediatric setting. Knowledge gaps for future research are highlighted in the review.

A case of Scedosporium prolificans pulmonary infection in a patient with acute myeloid leukemia

An elderly woman with a history of myelodysplastic syndrome complicated by cavitary pneumonia treated with antibiotics and antifungal therapy was admitted with severe sepsis and pulmonary opacities on imaging. Pulmonary infection with Scedosporium prolificans, was diagnosed on bronchopulmonary lavage (BAL). This common environmental fungus is known to cause rare but severe infection in immunocompromised hosts. The patient was diagnosed with progression to acute myeloid leukemia during the hospitalization for which chemotherapy was initiated. Despite broadening antifungal therapy, the patient developed multi-organ system failure and died.

Lung infections due to emerging fungal pathogens

PURPOSE OF REVIEW

This review highlights the epidemiology, pathogenesis and clinical management of pulmonary infections caused by emerging fungal organisms.

RECENT FINDINGS

Emerging fungal infections have arisen as a result of population and environmental changes. An enlarging pool of immunocompromised hosts on triazole antifungal prophylaxis has led to an increased incidence of non- Aspergillus molds, such as Fusarium , Scedosporium and Lomentospora spp. Advances in diagnostic capabilities led to the identification of the Emergomyces genus and non- dermatitidis Blastomyces species, which have a significant disease burden in Africa and the Middle East. Climate change has contributed to changing the distribution of previously confined endemic mycoses, like coccidioidomycosis and talaromycosis. These emerging organisms pose important diagnostic and therapeutic challenges.

SUMMARY

Newly recognized pathogenic fungi and established endemic mycoses with expanding geographic boundaries have become important agents of pulmonary disease. There is a dearth of clinical evidence on the appropriate management of these infections.

A Lateral-Flow Device for the Rapid Detection of Scedosporium Species

Scedosporium species are human pathogenic fungi, responsible for chronic, localised, and life-threatening disseminated infections in both immunocompetent and immunocompromised individuals. The diagnosis of Scedosporium infections currently relies on non-specific CT, lengthy and insensitive culture from invasive biopsy, and the time-consuming histopathology of tissue samples. At present, there are no rapid antigen tests that detect Scedosporium-specific biomarkers. Here, we report the development of a rapid (30 min) and sensitive (pmol/L sensitivity) lateral-flow device (LFD) test, incorporating a Scedosporium-specific IgG1 monoclonal antibody (mAb), HG12, which binds to extracellular polysaccharide (EPS) antigens between ~15 kDa and 250 kDa secreted during the hyphal growth of the pathogens. The test is compatible with human serum and allows for the detection of the Scedosporium species most frequently reported as agents of human disease (Scedosporium apiospermum, Scedosporium aurantiacum, and Scedosporium boydii), with limits of detection (LODs) of the EPS biomarkers in human serum of ~0.81 ng/mL (S. apiospermum), ~0.94 ng/mL (S. aurantiacum), and ~1.95 ng/mL (S. boydii). The Scedosporium-specific LFD (ScedLFD) test therefore provides a potential novel opportunity for the detection of infections caused by different Scedosporium species.

The epidemiology of invasive fungal infections in transplant recipients

Transplant patients, including solid-organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients, are exposed to various types of complications, particularly rejection. To prevent these outcomes, transplant recipients commonly receive long-term immunosuppressive regimens that in turn make them more susceptible to a wide array of infectious diseases, notably those caused by opportunistic pathogens. Among these, invasive fungal infections (IFIs) remain a major cause of mortality and morbidity in both SOT and HSCT recipients. Despite the continuing improvement in early diagnostics and treatments of IFIs, the management of these infections in transplant patients is still complicated. Here, we provide an overview concerning the most recent trends in the epidemiology of IFIs in SOT and HSCT recipients by describing the prominent yeast and mold species involved, the timing of post-transplant IFIs and the risk factors associated with their occurrence in these particularly weak populations. We also give special emphasis into basic research advances in the field that recently suggested a role of the global and long-term prophylactic regimen in orchestrating various biological disturbances in the organism and conditioning the emergence of the most adapted fungal strains to the particular physiological profiles of transplant patients.

A case of Lomentospora prolificans endophthalmitis treated with the novel antifungal agent Olorofim

PURPOSE

To report a case of endogenous Lomentospora prolificans endophthalmitis treated with the novel antifungal agent Olorofim.

CASE REPORT

A 57-year-old man developed disseminated Lomentospora prolificans with right endophthalmitis on the background of immunosuppression following lung transplantation for interstitial lung disease. He was treated with early vitrectomy, intravitreal voriconazole, and systemic Olorofim, voriconazole and terbinafine. His symptoms improved and remained stable in the right eye. Eight weeks later the patient represented with Lomentopora prolificans endophthalmitis in the left eye when systemic voriconazole and terbinafine treatment were withdrawn. Despite aggressive treatment he ultimately succumbed due to vascular complications of extensive disseminated disease.

CONCLUSION

We report a rare case of disseminated Lomentosporosis with panophthalmitis in an immunocompromised host with prolonged survival on systemic Olorofim, voriconazole and terbinafine in conjunction with pars plana vitrectomy and intravitreal voriconazole. Early suspicion of an opportunistic fungal infection is critical, as managing disseminated disease is often unsuccessful. Despite presumed inherent resistance, intravitreal and systemic voriconazole appeared to limit disease progression in the right eye. The potential synergistic effects of combined antifungal therapy with orotomides warrant further investigation.

Altered gut mycobiome in patients with end-stage renal disease and its correlations with serum and fecal metabolomes

BACKGROUND

The relationship between the gut mycobiome and end-stage renal disease (ESRD) remains largely unexplored.

METHODS

In this study, we compared the gut fungal populations of 223 ESRD patients and 69 healthy controls (HCs) based on shotgun metagenomic sequencing data, and analyzed their associations with host serum and fecal metabolites.

RESULTS

Our findings revealed that ESRD patients had a higher diversity in the gut mycobiome compared to HCs. Dysbiosis of the gut mycobiome in ESRD patients was characterized by a decrease of Saccharomyces cerevisiae and an increase in various opportunistic pathogens, such as Aspergillus fumigatus, Cladophialophora immunda, Exophiala spinifera, Hortaea werneckii, Trichophyton rubrum, and others. Through multi-omics analysis, we observed a substantial contribution of the gut mycobiome to host serum and fecal metabolomes. The opportunistic pathogens enriched in ESRD patients were frequently and positively correlated with the levels of creatinine, homocysteine, and phenylacetylglycine in the serum. The populations of Saccharomyces, including the HC-enriched Saccharomyces cerevisiae, were frequently and negatively correlated with the levels of various toxic metabolites in the feces.

CONCLUSIONS

Our results provided a comprehensive understanding of the associations between the gut mycobiome and the development of ESRD, which had important implications for guiding future therapeutic studies in this field.

Detection of Scedosporium spp.: Colonizer or pathogen? A retrospective analysis of clinical significance and management in a large tertiary center

Infections with Scedosporium spp. are emerging in the past two decades and are associated with a high mortality rate. Microbiological detection can be associated with either colonization or infection. Evolution from colonization into infection is difficult to predict and clinical management upon microbiological detection is complex. Microbiological samples from 2015 to 2021 were retrospectively analyzed in a single tertiary care center. Classification into colonization or infection was performed upon first microbiological detection. Clinical evolution was observed until July 2023. Further diagnostic procedures after initial detection were analyzed. Among 38 patients with microbiological detection of Scedosporium spp., 10 were diagnosed with an infection at the initial detection and two progressed from colonization to infection during the observation time. The main sites of infection were lung (5/12; 41.6%) followed by ocular sites (4/12; 33.3%). Imaging, bronchoscopy or biopsies upon detection were performed in a minority of patients. Overall mortality rate was similar in both groups initially classified as colonization or infection [30.7% and 33.3%, respectively (P = 1.0)]. In all patients where surgical debridement of site of infection was performed (5/12; 42%); no death was observed. Although death occurred more often in the group without eradication (3/4; 75%) compared with the group with successful eradication (1/8; 12.5%), statistical significance could not be reached (P = 0.053). As therapeutic management directly impacts patients' outcome, a multidisciplinary approach upon microbiological detection of Scedosporium spp. should be encouraged. Data from larger cohorts are warranted in order to analyze contributing factors favoring the evolution from colonization into infection.

Costs associated with invasive Scedosporium and Lomentospora prolificans infections: a case-control study

BACKGROUND

Little is known about the short- and long-term healthcare costs of invasive Scedosporium/Lomentospora prolificans infections, particularly in patient groups without haematological malignancy. This study investigated excess index hospitalization costs and cumulative costs of these infections. The predictors of excess cost and length of stay (LOS) of index hospitalization were determined. These estimates serve as valuable inputs for cost-effectiveness models of novel antifungal agents.

METHODS

A retrospective case-control study was conducted at six Australian hospitals. Cases of proven/probable invasive Scedosporium/L. prolificans infections between 2011 and 2021 (n = 34) were matched with controls (n = 66) by predefined criteria. Cost data were retrieved from activity-based costing systems and analysis was performed from the Australian public hospital perspective. All costs were presented in 2022 Australian dollars (AUD). Median regression analysis was used to adjust excess costs of index hospitalization whereas cumulative costs up to 1.5 years follow-up were estimated using interval-partitioned survival probabilities.

RESULTS

Invasive Scedosporium/L. prolificans infections were independently associated with an adjusted median excess cost of AUD36 422 (P = 0.003) and LOS of 16.27 days (P < 0.001) during index hospitalization. Inpatient stay was the major cost driver (42.7%), followed by pharmacy cost, of which antifungal agents comprised 23.8% of the total cost. Allogeneic haematopoietic stem cell transplant increased the excess cost (P = 0.013) and prolonged LOS (P < 0.001) whereas inpatient death within ≤28 days reduced both cost (P = 0.001) and LOS (P < 0.001). The median cumulative cost increased substantially to AUD203 292 over 1.5 years in cases with Scedosporium/L. prolificans infections.

CONCLUSIONS

The economic burden associated with invasive Scedosporium/L. prolificans infections is substantial.

Scedosporium species and Lomentospora prolificans fungaemia is uniformly fatal in patients with haematological malignancy

Scedosporium and Lomentospora species are environmental moulds that are virulent in immunocompromised hosts and rarely cause bloodstream infection (BSI). Patients with Scedosporium and Lomentospora species BSI were identified by the state public laboratory service in Queensland, Australia, over a 20-year period. Twenty-two incident episodes occurred among 21 residents; one patient had a second episode 321 days following the first. Of these, 18 were Lomentospora prolificans, three were Scedosporium apiospermum complex and one was a nonspeciated Scedosporium species. Seventeen (81%) patients died during their index admission, and all-cause mortality at 30, 90 and 365 days was 73%, 82% and 91% respectively. All 20 patients with haematological malignancy died within 365 days of follow-up with a median time to death of 9 days (interquartile range, 6-20 days) following diagnoses of BSI.