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.

In vitro activity of olorofim against 507 filamentous fungi including antifungal drug-resistant strains at a tertiary laboratory in Australia: 2020-2023.

BACKGROUND: New antifungal agents are required to mitigate against azole-resistant Aspergillus and drug-resistant non-Aspergillus moulds. The novel orotomide, olorofim (F2G, Manchester, UK), has potent fungicidal activity against Aspergillus including azole-resistant Aspergillus fumigatus, Lomentospora prolificans and Scedosporium spp. Development of olorofim-specific clinical breakpoints/epidemiological cut-off values requires reliable MIC data. OBJECTIVES: Determine the in vitro activity of olorofim compared with standard antifungals against mould pathogens at an Australian hospital. MATERIALS AND METHODS: Olorofim MICs were determined for 507 clinical mould isolates using the CLSI M38-A3 standard. MICs of amphotericin B, anidulafungin, posaconazole, voriconazole and isavuconazole were obtained using Sensititre™ YeastOne YO10 and AUSNMRCI panels (Thermo-Fisher Scientific). RESULTS: A. fumigatus sensu stricto was the commonest species (33.3%) followed by L. prolificans (18.3%), Scedosporium (11.4%) and Fusarium (6%) species. Olorofim modal MICs were ≤0.25 mg/L (MIC90 0.25 mg/L) for all Aspergillus except Aspergillus Section Usti (1 mg/L); MICs for nine azole-resistant/non-wild-type A. fumigatus ranged from 0.008 to 0.125 mg/L. The MIC90 of olorofim for L. prolificans was 0.5 mg/L, 0.25-0.5 mg/L for Scedosporium spp. and 8 mg/L for the F. solani complex but with modal MICs of 0.25 and 0.008 mg/L for F. oxysporum and F. proliferatum complexes, respectively. For Verruconis gallopava (n = 10), the olorofim MIC90 was 0.06 mg/L (voriconazole MIC90 2 mg/L, isavuconazole MICs of 4->8 mg/L). Olorofim had little activity against other dematiaceous moulds including Exophiala species. CONCLUSIONS: Olorofim was highly active against Aspergillus spp. including azole-resistant A. fumigatus, L. prolificans, Scedosporium spp. and some Fusarium species with the new finding of potent activity against V. gallopava.

Histoplasmosis: A systematic review to inform the World Health Organization of a fungal priority pathogens list.

Histoplasmosis, a significant mycosis primarily prevalent in Africa, North and South America, with emerging reports globally, poses notable health challenges, particularly in immunocompromised individuals such as people living with HIV/AIDS and organ transplant recipients. This systematic review, aimed at informing the World Health Organization's Fungal Priority Pathogens List, critically examines literature from 2011 to 2021 using PubMed and Web of Science, focusing on the incidence, mortality, morbidity, antifungal resistance, preventability, and distribution of Histoplasma. We also found a high prevalence (22%-44%) in people living with HIV, with mortality rates ranging from 21% to 53%. Despite limited data, the prevalence of histoplasmosis seems stable, with lower estimates in Europe. Complications such as central nervous system disease, pulmonary issues, and lymphoedema due to granuloma or sclerosis are noted, though their burden remains uncertain. Antifungal susceptibility varies, particularly against fluconazole (MIC: ≥32 mg/l) and caspofungin (MICs: 4-32 mg/l), while resistance to amphotericin B (MIC: 0.125-0.16 mg/l), itraconazole (MICs: 0.004-0.125 mg/l), and voriconazole (MICs: 0.004-0.125 mg/l) remains low. This review identifies critical knowledge gaps, underlining the need for robust, globally representative surveillance systems to better understand and combat this fungal threat.

Fusarium species,Scedosporium species, and Lomentospora prolificans: A systematic review to inform the World Health Organization priority list of fungal pathogens.

Recognizing the growing global burden of fungal infections, the World Health Organization established a process to develop a priority list of fungal pathogens (FPPL). In this systematic review, we aimed to evaluate the epidemiology and impact of infections caused by Fusarium spp., Scedosporium spp., and Lomentospora prolificans to inform the first FPPL. PubMed and Web of Sciences databases were searched to identify studies published between January 1, 2011 and February 23, 2021, reporting on mortality, complications and sequelae, antifungal susceptibility, preventability, annual incidence, and trends. Overall, 20, 11, and 9 articles were included for Fusarium spp., Scedosporium spp., and L. prolificans, respectively. Mortality rates were high in those with invasive fusariosis, scedosporiosis, and lomentosporiosis (42.9%-66.7%, 42.4%-46.9%, and 50.0%-71.4%, respectively). Antifungal susceptibility data, based on small isolate numbers, showed high minimum inhibitory concentrations (MIC)/minimum effective concentrations for most currently available antifungal agents. The median/mode MIC for itraconazole and isavuconazole were ≥16 mg/l for all three pathogens. Based on limited data, these fungi are emerging. Invasive fusariosis increased from 0.08 cases/100 000 admissions to 0.22 cases/100 000 admissions over the time periods of 2000-2009 and 2010-2015, respectively, and in lung transplant recipients, Scedosporium spp. and L. prolificans were only detected from 2014 onwards. Global surveillance to better delineate antifungal susceptibility, risk factors, sequelae, and outcomes is required.

Introducing 1,3-beta-d-glucan for screening and diagnosis of invasive fungal diseases in Australian high-risk haematology patients: is there a clinical benefit?

BACKGROUND: Early, accurate diagnosis of invasive fungal disease (IFD) improves clinical outcomes. 1,3-beta-d-glucan (BDG) (Fungitell, Associates of Cape Cod, Inc., Falmouth, MA, USA) detection can improve IFD diagnosis but has been unavailable in Australia. AIMS: To assess performance of serum BDG for IFD diagnosis in a high-risk Australian haematology population. METHODS: We compared the diagnostic value of weekly screening of serum BDG with screening by Aspergillus polymerase chain reaction and Aspergillus galactomannan in 57 at-risk episodes for the diagnosis of IFD (proven, probable, possible IFD). RESULTS: IFD episodes were: proven (n = 4); probable (n = 4); possible (n = 18); and no IFD (n = 31). Using two consecutive BDG results of ≥80 pg/mL to call a result 'positive', the sensitivity, specificity, positive predictive value and negative predictive value was 37.5%, 64.5%, 23.1% and 80.7% respectively. For invasive aspergillosis, test performance increased to 50%, 90.3%, 57.1% and 87.5% respectively if any two of serum BDG/Aspergillus polymerase chain reaction/galactomannan yielded a 'positive' result. In proven/probable IFD, five of eight episodes returned a positive BDG result earlier (mean 6.6 days) than other diagnostic tests. False-negative BDG results occurred in three of eight episodes of proven/probable IFD, and false positive in 10 of 31 patients with no IFD. Erratic patterns of BDG values predicted false positive results (P = 0.03). Using serum BDG results, possible IFD were reassigned to either 'no' or 'probable' IFD in 44% cases. Empiric anti-fungal therapy use may have been optimised by BDG monitoring in 38.5% of courses. CONCLUSIONS: The BDG assay can add diagnostic speed and value but was hampered by low sensitivity and positive predictive value in Australian haematology patients.

Azole-resistant Aspergillus fumigatus is highly prevalent in the environment of Vietnam, with marked variability by land use type.

Azole-resistant environmental Aspergillus fumigatus presents a threat to public health but the extent of this threat in Southeast Asia is poorly described. We conducted environmental surveillance in the Mekong Delta region of Vietnam, collecting air and ground samples across key land-use types, and determined antifungal susceptibilities of Aspergillus section Fumigati (ASF) isolates and azole concentrations in soils. Of 119 ASF isolates, 55% were resistant (or non-wild type) to itraconazole, 65% to posaconazole and 50% to voriconazole. Azole resistance was more frequent in A. fumigatus sensu stricto isolates (95%) than other ASF species (32%). Resistant isolates and agricultural azole residues were overrepresented in samples from cultivated land. cyp51A gene sequence analysis showed 38/56 resistant A. fumigatus sensu stricto isolates carried known resistance mutations, with TR34 /L98H most frequent (34/38).

Consensus guidelines for the diagnosis and management of invasive aspergillosis, 2021.

Invasive aspergillosis (IA) in haematology/oncology patients presents as primary infection or breakthrough infection, which can become refractory to antifungal treatment and has a high associated mortality. Other emerging patient risk groups include patients in the intensive care setting with severe respiratory viral infections, including COVID-19. These guidelines present key diagnostic and treatment recommendations in light of advances in knowledge since the previous guidelines in 2014. Culture and histological-based methods remain central to the diagnosis of IA. There is increasing evidence for the utility of non-culture methods employing fungal biomarkers in pre-emptive screening for infection, as well as for IA diagnosis when used in combination. Although azole resistance appears to be uncommon in Australia, susceptibility testing of clinical Aspergillus fumigatus complex isolates is recommended. Voriconazole remains the preferred first-line antifungal agent for treating primary IA, including for extrapulmonary disease. Recommendations for paediatric treatment broadly follow those for adults. For breakthrough and refractory IA, a change in class of antifungal agent is strongly recommended, and agents under clinical trial may need to be considered. Newer immunological-based imaging modalities warrant further study, while surveillance for IA and antifungal resistance remain essential to informing the relevance of current treatment recommendations.

Diagnosis, management and prevention of Candida auris in hospitals: position statement of the Australasian Society for Infectious Diseases.

Candida auris is an emerging drug-resistant yeast responsible for hospital outbreaks. This statement reviews the evidence regarding diagnosis, treatment and prevention of this organism and provides consensus recommendations for clinicians and microbiologists in Australia and New Zealand. C. auris has been isolated in over 30 countries (including Australia). Bloodstream infections are the most frequently reported infections. Infections have crude mortality of 30-60%. Acquisition is generally healthcare-associated and risks include underlying chronic disease, immunocompromise and presence of indwelling medical devices. C. auris may be misidentified by conventional phenotypic methods. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry or sequencing of the internal transcribed spacer regions and/or the D1/D2 regions of the 28S ribosomal DNA are therefore required for definitive laboratory identification. Antifungal drug resistance, particularly to fluconazole, is common, with variable resistance to amphotericin B and echinocandins. Echinocandins are currently recommended as first-line therapy for infection in adults and children ≥2 months of age. For neonates and infants <2 months of age, amphotericin B deoxycholate is recommended. Healthcare facilities with C. auris should implement a multimodal control response. Colonised or infected patients should be isolated in single rooms with Standard and Contact Precautions. Close contacts, patients transferred from facilities with endemic C. auris or admitted following stay in overseas healthcare institutions should be pre-emptively isolated and screened for colonisation. Composite swabs of the axilla and groin should be collected. Routine screening of healthcare workers and the environment is not recommended. Detergents and sporicidal disinfectants should be used for environmental decontamination.

Surveillance for azole resistance in clinical and environmental isolates of Aspergillus fumigatus in Australia and cyp51A homology modelling of azole-resistant isolates.

Background: The prevalence of azole resistance in Aspergillus fumigatus is uncertain in Australia. Azole exposure may select for resistance. We investigated the frequency of azole resistance in a large number of clinical and environmental isolates. Methods: A. fumigatus isolates [148 human, 21 animal and 185 environmental strains from air (n = 6) and azole-exposed (n = 64) or azole-naive (n = 115) environments] were screened for azole resistance using the VIPcheck™ system. MICs were determined using the Sensititre™ YeastOne YO10 assay. Sequencing of the Aspergillus cyp51A gene and promoter region was performed for azole-resistant isolates, and cyp51A homology protein modelling undertaken. Results: Non-WT MICs/MICs at the epidemiological cut-off value of one or more azoles were observed for 3/148 (2%) human isolates but not amongst animal, or environmental, isolates. All three isolates grew on at least one azole-supplemented well based on VIPcheck™ screening. For isolates 9 and 32, the itraconazole and posaconazole MICs were 1 mg/L (voriconazole MICs 0.12 mg/L); isolate 129 had itraconazole, posaconazole and voriconazole MICs of >16, 1 and 8 mg/L, respectively. Soil isolates from azole-exposed and azole-naive environments had similar geometric mean MICs of itraconazole, posaconazole and voriconazole (P > 0.05). A G54R mutation was identified in the isolates exhibiting itraconazole and posaconazole resistance, and the TR34/L98H mutation in the pan-azole-resistant isolate. cyp51A modelling predicted that the G54R mutation would prevent binding of itraconazole and posaconazole to the haem complex. Conclusions: Azole resistance is uncommon in Australian clinical and environmental A. fumigatus isolates; further surveillance is indicated.

PCR-based tests for the early diagnosis of sepsis. Where do we stand?

PURPOSE OF REVIEW: Bloodstream infections are a major cause of hospital and ICU admission with high morbidity and mortality; however, early and targeted antimicrobial therapy reduces mortality in high-risk patients. This article focuses on the diagnosis of bloodstream infections by PCR-based approaches at an early stage to enable prompt treatment and prevent organ dysfunction. RECENT FINDINGS: PCR systems offering highly multiplexed targeting of bacterial and/or fungal pathogens (in whole blood) offer the best opportunity for clinical impact, as informed decisions can be made within 4-8 h of the blood draw. Although more rapid, these systems are typically associated with lower sensitivity and specificity than postculture detection methods which rely on microbial growth. Additionally, unlike postculture methods, detection directly from blood is not prone to misleading results because of concurrent (or previous) therapy, which limit clinical relevance. SUMMARY: Rapid and accurate identification of the cause of sepsis is essential in improving patient outcomes. Early identification of these pathogens by nucleic acid detection assays directly from blood samples remains key to achieving this, particularly if taken at the time of presentation. Selection of the most suitable PCR system is typically influenced by local epidemiology and by the resources of the testing laboratory.

Performance of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Aspergillus, Scedosporium, and Fusarium spp. in the Australian Clinical Setting.

We developed an Australian database for the identification of Aspergillus, Scedosporium, and Fusarium species (n = 28) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In a challenge against 117 isolates, species identification significantly improved when the in-house-built database was combined with the Bruker Filamentous Fungi Library compared with that for the Bruker library alone (Aspergillus, 93% versus 69%; Fusarium, 84% versus 42%; and Scedosporium, 94% versus 18%, respectively).

Molecular Diagnostics for Invasive Fungal Diseases: Current and Future Approaches.

Invasive fungal diseases (IFDs) comprise a growing healthcare burden, especially given the expanding population of immunocompromised hosts. Early diagnosis of IFDs is required to optimise therapy with antifungals, especially in the setting of rising rates of antifungal resistance. Molecular techniques including nucleic acid amplification tests and whole genome sequencing have potential to offer utility in overcoming limitations with traditional phenotypic testing. However, standardisation of methodology and interpretations of these assays is an ongoing undertaking. The utility of targeted Aspergillus detection has been well-defined, with progress in investigations into the role of targeted assays for Candida, Pneumocystis, Cryptococcus, the Mucorales and endemic mycoses. Likewise, whilst broad-range polymerase chain reaction assays have been in use for some time, pathology stewardship and optimising diagnostic yield is a continuing exercise. As costs decrease, there is also now increased access and experience with whole genome sequencing, including metagenomic sequencing, which offers unparalleled resolution especially in the investigations of potential outbreaks. However, their role in routine diagnostic use remains uncommon and standardisation of techniques and workflow are required for wider implementation.

Update on methods used for mycological testing: wide diversity and opportunities for improvement persist.

Past analysis of laboratory methods used for mycology specimens revealed significant variation in practices, many of which fell short of recommended procedures. In 2016 these findings led to a set of recommendations for laboratories to consider modification of their methods where appropriate, to analyse current laboratory methods used by participants in the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Mycology module, and to compare these to the 2016 recommendations. Seven test items, with 105-107 participants each, were analysed. Several laboratories (7-12%) did not handle specimens as recommended in an appropriate biological safety cabinet. Direct microscopy was not performed on tissue specimens 23-25% of the time. The most used staining method was potassium hydroxide with an optical brightener for fluorescent microscopy (49%) followed by Gram stain (33%). While 17-25% of laboratories used three or more media, use of four or more was uncommon (<3%). Between 9-13% of participants used only a single non-inhibitory medium for cultures. Urine specimens were incubated longer than recommended with 57% of laboratories incubating for >7days and 24% >21 days. Duration of incubation was shorter than recommended for several specimen types with 36% of skin specimens and 37-48% of tissue specimens being kept ≤21 days. For cultures kept >7 days, 13% were inspected daily but for those incubating >14 days only 3%. The methods of several laboratories remain outside recommended practice. An updated set of recommendations are made.

Panfungal PCR on formalin-fixed, paraffin-embedded tissue: to proceed or not proceed?

Performance of panfungal PCR-DNA sequencing assays for diagnosis of invasive fungal disease on formalin-fixed, paraffin-embedded tissue (FFPE) is influenced by many variables. Interpretation of a positive result can be challenging due to the need to differentiate colonisers and contaminants from clinically significant pathogens. We conducted a retrospective audit on FFPE tissue specimens that underwent panfungal PCR from January 2021 to August 2022. Panfungal PCR results from samples where fungal elements were visualised on histopathology were compared with results from samples where no fungal elements were visualised. The cost per clinically significant positive sample in each group was calculated. Of the 248 FFPE tissues sampled, 18.1% (45/248) had fungal forms seen on histopathology. Panfungal PCR was positive in 22/45 samples (48.9%), with 16 (35.6%) results deemed clinically significant. For the remaining 203 specimens, panfungal PCR was positive in 19 (9.4%) samples with only six (3.0%) clinically significant. The average cost per clinically significant result was AUD 258.13 in the histopathology positive group and AUD 3,105.22 in the histopathology negative group. Our data suggest panfungal PCR has limited clinical utility in FFPE tissue when no fungal elements are seen. Restricting the assay to only those samples that are positive on histopathological examination aids interpretation of PCR positive results and conserves laboratory resources.

Outbreaks of Fungal Infections in Hospitals: Epidemiology, Detection, and Management.

Nosocomial clusters of fungal infections, whilst uncommon, cannot be predicted and are associated with significant morbidity and mortality. Here, we review reports of nosocomial outbreaks of invasive fungal disease to glean insight into their epidemiology, risks for infection, methods employed in outbreak detection including genomic testing to confirm the outbreak, and approaches to clinical and infection control management. Both yeasts and filamentous fungi cause outbreaks, with each having general and specific risks. The early detection and confirmation of the outbreak are essential for diagnosis, treatment of affected patients, and termination of the outbreak. Environmental sampling, including the air in mould outbreaks, for the pathogen may be indicated. The genetic analysis of epidemiologically linked isolates is strongly recommended through a sufficiently discriminatory approach such as whole genome sequencing or a method that is acceptably discriminatory for that pathogen. An analysis of both linked isolates and epidemiologically unrelated strains is required to enable genetic similarity comparisons. The management of the outbreak encompasses input from a multi-disciplinary team with epidemiological investigation and infection control measures, including screening for additional cases, patient cohorting, and strict hygiene and cleaning procedures. Automated methods for fungal infection surveillance would greatly aid earlier outbreak detection and should be a focus of research.

Epidemiology, Modern Diagnostics, and the Management of Mucorales Infections.

Mucormycosis is an uncommon, yet deadly invasive fungal infection caused by the Mucorales moulds. These pathogens are a WHO-assigned high-priority pathogen group, as mucormycosis incidence is increasing, and there is unacceptably high mortality with current antifungal therapies. Current diagnostic methods have inadequate sensitivity and specificity and may have issues with accessibility or turnaround time. Patients with diabetes mellitus and immune compromise are predisposed to infection with these environmental fungi, but COVID-19 has established itself as a new risk factor. Mucorales also cause healthcare-associated outbreaks, and clusters associated with natural disasters have also been identified. Robust epidemiological surveillance into burden of disease, at-risk populations, and emerging pathogens is required. Emerging serological and molecular techniques may offer a faster route to diagnosis, while newly developed antifungal agents show promise in preliminary studies. Equitable access to these emerging diagnostic techniques and antifungal therapies will be key in identifying and treating mucormycosis, as delayed initiation of therapy is associated with higher mortality.

Phaeohyphomycosis in Kidney Transplant Recipients: Highlighting the Importance of Early Recognition and Surgical Debridement.

Fungal infections are a recognized complication of immunosuppression in solid organ transplant recipients. Phaeohyphomycoses are fungal infections caused by a diverse group of dematiaceous fungi. Methods: We share the learning points from 2 Australian cases of phaeohyphomycosis secondary to Phaeacreomonium species (spp). A literature review was performed using Medline, Embase, and Google Scholar to identify this condition among kidney transplant recipients. Results: With the 2 cases reported in this article, a total of 17 cases were identified in the literature. Phaeacremonium spp is ubiquitous in humid and temperate flora, including Australia. Minor trauma is likely the source of inoculation in most cases and diagnosis is often delayed. Presently, no guidelines for management exist given the rarity of this condition. Most known cases have been treated with surgical debulking combined with long-course antifungal therapy. Conclusion: This paper describes 2 Australian cases of phaeohyphomycosis in kidney transplant recipients. A high index of suspicion, especially in the immunosuppressed, is essential for timely diagnosis in kidney transplant recipients. There are several diagnostic and therapeutic challenges that remain with this condition.