Environmental Hot Spots and Resistance-Associated Application Practices for Azole-Resistant Aspergillus fumigatus, Denmark, 2020-2023

Azole-resistant Aspergillus fumigatus (ARAf) fungi have been found inconsistently in the environment in Denmark since 2010. During 2018-2020, nationwide surveillance of clinical A. fumigatus fungi reported environmental TR34/L98H or TR46/Y121F/T289A resistance mutations in 3.6% of isolates, prompting environmental sampling for ARAf and azole fungicides and investigation for selection of ARAf in field and microcosmos experiments. ARAf was ubiquitous (20% of 366 samples; 16% TR34/L98H- and 4% TR46/Y121F/T289A-related mechanisms), constituting 4.2% of 4,538 A. fumigatus isolates. The highest proportions were in flower- and compost-related samples but were not correlated with azole-fungicide application concentrations. Genotyping showed clustering of tandem repeat-related ARAf and overlaps with clinical isolates in Denmark. A. fumigatus fungi grew poorly in the field experiment with no postapplication change in ARAf proportions. However, in microcosmos experiments, a sustained complete (tebuconazole) or partial (prothioconazole) inhibition against wild-type A. fumigatus but not ARAf indicated that, under some conditions, azole fungicides may favor growth of ARAf in soil.

Candida auris MIC testing by EUCAST and clinical and laboratory standards institute broth microdilution, and gradient diffusion strips; to be or not to be amphotericin B resistant?

OBJECTIVES

Reported amphotericin B resistance rates for Candida auris vary considerably. This may reflect clinically relevant differences in susceptibility, technical issues with testing, or adoption of a clinical breakpoint that bisects the wild-type population. We compared reference methods and two gradient diffusion strips using a shared C. auris strain collection.

METHODS

Forty C. auris strains from nine U.S. states and ≥3 clades were included. Fourteen MIC data sets were generated using European Committee on Antimicrobial Susceptibility Testing (EUCAST) E.Def 7.4, Clinical and Laboratory Standards Institute (CLSI) M27Ed4, Etest, and MIC gradient test strip (MTS, Liofilchem) MICs. MICs ≤1 mg/L were classified as susceptible.

RESULTS

EUCAST and CLSI amphotericin B MIC testing were robust across the included method variables. The modal MIC was 1 mg/L, distributions unimodal and narrow with similar geometric mean (GM)-MICs (0.745-1.072); however, susceptibility classification varied (0-28% resistance). Gradient diffusion strip testing resulted in wider and bimodal distributions for 8/9 data sets. If adopting, per manufacturer's protocol, double inoculation for the Etest method, the modal MIC increased to 2-4 mg/L and resistance rates to 45-63% versus 25-30% with the single inoculation. The EUCAST, CLSI, Etest, and MTS strip MICs correlated to the optical density of drug-free control EUCAST wells, suggesting that some isolates grew better than others and that this was associated with MIC.

DISCUSSION

The EUCAST and CLSI MIC results were in close agreement, whereas the strip test showed wider and bimodal distributions with reader to reader and centre to centre variation. Our study adds to the concern for commercial MIC testing of amphotericin B against C. auris and suggests the current breakpoint leads to random susceptibility classification.

[Blastocystis--an enigmatic parasite]

Blastocystis can be isolated from roughly 25% of patients suspected of intestinal parasitosis. At least ten subtypes (STs) have been isolated from humans and animals, and recent data demonstrate that the pathogenicity of the parasite is subtype-dependent. For instance, ST1 and ST7 are more prevalent among patients with symptoms than healthy individuals, whereas ST3 predominates among healthy carriers. The article sums up basic aspects of the parasite and gives an introduction to new data and points of criticism of previous studies seeking to unravel the pathogenicity of the parasite.

[Onychomycosis is rare in young children, and treatment is a task for dermatological specialists]

Onychomycosis was diagnosed in a two-year-old girl. The infection was caused by Trichophyton rubrum, which is the most frequent cause of toenail onychomycosis. The diagnosis was confirmed by polymerase chain reaction, microscopy and culture. She was treated with orally given terbinafine and topically given amorolfine with clinical improvement at the following control visit. Onychomycosis is rare in children, but the occurrence seems to be increasing. Medical treatment can be topical, systemic or a combination of these.

Preliminary Identification and Typing of Pathogenic and Toxigenic Fusarium Species Using Restriction Digestion of ITS1-5.8S rDNA-ITS2 Region

BACKGROUND

Fusarium species are capable of causing a wide range of crop plants infections as well as uncommon human infections. Many species of the genus produce mycotoxins, which are responsible for acute or chronic diseases in animals and humans. Identification of Fusaria to the species level is necessary for biological, epidemiological, pathological, and toxicological purposes. In this study, we undertook a computer-based analysis of ITS1-5.8SrDNA-ITS2 in 192 GenBank sequences from 36 Fusarium species to achieve data for establishing a molecular method for specie-specific identification.

METHODS

Sequence data and 610 restriction enzymes were analyzed for choosing RFLP profiles, and subsequently designed and validated a PCR-restriction enzyme system for identification and typing of species. DNA extracted from 32 reference strains of 16 species were amplified using ITS1 and ITS4 universal primers followed by sequencing and restriction enzyme digestion of PCR products.

RESULTS

The following 3 restriction enzymes TasI, ItaI and CfoI provide the best discriminatory power. Using ITS1 and ITS4 primers a product of approximately 550bp was observed for all Fusarium strains, as expected regarding the sequence analyses. After RFLP of the PCR products, some species were definitely identified by the method and some strains had different patterns in same species.

CONCLUSION

Our profile has potential not only for identification of species, but also for genotyping of strains. On the other hand, some Fusarium species were 100% identical in their ITS-5.8SrDNA-ITS2 sequences, therefore differentiation of these species is impossible regarding this target alone. ITS-PCR-RFLP method might be useful for preliminary differentiation and typing of most common Fusarium species.

Nomenclature for human and animal fungal pathogens and diseases: a proposal for standardized terminology

Medically important pathogenic fungi invade vertebrate tissue and are considered primary when part of their nature life cycle is associated with an animal host and are usually able to infect immunocompetent hosts. Opportunistic fungal pathogens complete their life cycle in environmental habitats or occur as commensals within or on the vertebrate body, but under certain conditions can thrive upon infecting humans. The extent of host damage in opportunistic infections largely depends on the portal and modality of entry as well as on the host's immune and metabolic status. Diseases caused by primary pathogens and common opportunists, causing the top approximately 80% of fungal diseases [D. W. Denning, Lancet Infect Dis, 24:e428-e438, 2024, https://doi.org/10.1016/S1473-3099(23)00692-8], tend to follow a predictive pattern, while those by occasional opportunists are more variable. For this reason, it is recommended that diseases caused by primary pathogens and the common opportunists are named after the etiologic agent, for example, histoplasmosis and aspergillosis, while this should not be done for occasional opportunists that should be named as [causative fungus] [clinical syndrome], for example, Alternaria alternata cutaneous infection. The addition of a descriptor that identifies the location or clinical type of infection is required, as the general name alone may cover widely different clinical syndromes, for example, "rhinocerebral mucormycosis." A list of major recommended human and animal disease entities (nomenclature) is provided in alignment with their causative agents. Fungal disease names may encompass several genera of etiologic agents, consequently being less susceptible to taxonomic changes of the causative species, for example, mucormycosis covers numerous mucormycetous molds.

Invasive Aspergillosis among Lung Transplant Recipients during Time Periods with Universal and Targeted Antifungal Prophylaxis-A Nationwide Cohort Study

The optimal prevention strategy for invasive aspergillosis (IA) in lung transplant recipients (LTXr) is unknown. In 2016, the Danish guidelines were changed from universal to targeted IA prophylaxis. Previously, we found higher rates of adverse events in the universal prophylaxis period. In a Danish nationwide study including LTXr, for 2010-2019, we compared IA rates in time periods with universal vs. targeted prophylaxis and during person-time with vs. person-time without antifungal prophylaxis. IA hazard rates were analyzed in multivariable Cox models with adjustment for time after LTX. Among 295 LTXr, antifungal prophylaxis was initiated in 183/193 and 6/102 during the universal and targeted period, respectively. During the universal period, 62% discontinued prophylaxis prematurely. The median time on prophylaxis was 37 days (IQR 11-84). IA was diagnosed in 27/193 (14%) vs. 15/102 (15%) LTXr in the universal vs. targeted period, with an adjusted hazard ratio (aHR) of 0.94 (95% CI 0.49-1.82). The aHR of IA during person-time with vs. person-time without antifungal prophylaxis was 0.36 (95% CI 0.12-1.02). No difference in IA was found during periods with universal vs. targeted prophylaxis. Prophylaxis was protective of IA when taken. Targeted prophylaxis may be preferred over universal due to comparable IA rates and lower rates of adverse events.

Two Cases of Proximal Subungual Onychomycosis Caused by Trichophyton rubrum in HIV-negative Patients During Treatment with TNF-α Inhibitors Combined with Methotrexate

Proximal subungual onychomycosis (PSO) is a rare subtype of onychomycosis with a clinical presentation characterized by proximal leukonychia in the lunular area of the nail. PSO is associated with immunosuppression and regarded a sign of Human Immunodeficiency Virus (HIV) infection when caused by Trichophyton (T.) rubrum. We present two cases of PSO caused by T. rubrum developed during treatment with TNF-α inhibitors combined with methotrexate (MTX).

The Impact of the Fungal Priority Pathogens List on Medical Mycology: A Northern European Perspective

Fungal diseases represent a considerable global health concern, affecting >1 billion people annually. In response to this growing challenge, the World Health Organization introduced the pivotal fungal priority pathogens list (FPPL) in late 2022. The FPPL highlights the challenges in estimating the global burden of fungal diseases and antifungal resistance (AFR), as well as limited surveillance capabilities and lack of routine AFR testing. Furthermore, training programs should incorporate sufficient information on fungal diseases, necessitating global advocacy to educate health care professionals and scientists. Established international guidelines and the FPPL are vital in strengthening local guidance on tackling fungal diseases. Future iterations of the FPPL have the potential to refine the list further, addressing its limitations and advancing our collective ability to combat fungal diseases effectively. Napp Pharmaceuticals Limited (Mundipharma UK) organized a workshop with key experts from Northern Europe to discuss the impact of the FPPL on regional clinical practice.

Associations between invasive aspergillosis and cytomegalovirus in lung transplant recipients: a nationwide cohort study

Cytomegalovirus (CMV) and invasive aspergillosis (IA) cause morbidity among lung transplant recipients (LTXr). Early diagnosis and treatment could improve outcomes. We examined rates of CMV after IA and vice versa to assess whether screening for one infection is warranted after detecting the other. All Danish LTXr, 2010-2019, were followed for IA and CMV for 2 years after transplantation. IA was defined using ISHLT criteria. Adjusted incidence rate ratios (aIRR) were estimated by Poisson regression adjusted for time after transplantation. We included 295 LTXr, among whom CMV and IA were diagnosed in 128 (43%) and 48 (16%). The risk of CMV was high the first 3 months after IA, IR 98/100 person-years of follow-up (95% CI 47-206). The risk of IA was significantly increased in the first 3 months after CMV, aIRR 2.91 (95% CI 1.32-6.44). Numbers needed to screen to diagnose one case of CMV after IA, and one case of IA after CMV was approximately seven and eight, respectively. Systematic screening for CMV following diagnosis of IA, and vice versa, may improve timeliness of diagnosis and outcomes for LTXr.

[Tinea capitis in children is an overlooked disease]

In this review, we discuss tinea capitis, which is a disease most prevalent in children and caused by dermatophytes infecting the hair and scalp. The clinical presentation varies from scaling and alopecia to inflammatory lesions with pain and pruritus. Treatment includes systemic and topical antifungal agents. Due to the aetiological shift in pathogens from zoophilic dermatophytes to anthropophilic dermatophytes, spread of the infection may occur more easily. Therefore, early disease detection and treatment of asymptomatic carriers is important to avoid epidemics.

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

Development and preliminary validation of a modified EUCAST yeast broth microdilution MIC method with Tween 20-supplemented medium for rezafungin

BACKGROUND

Rezafungin is a novel, once-weekly echinocandin. EUCAST rezafungin MIC testing has been associated with a good separation of WT and target gene mutant isolates in single-centre studies, but an unacceptable inter-laboratory MIC variation has prevented EUCAST breakpoint setting. This has been attributed to non-specific binding to surfaces across microtitre plates, pipettes, reservoirs, etc. used, as previously encountered for some antibiotics.

OBJECTIVES

To investigate use of a surfactant to mitigate non-specific binding of rezafungin in EUCAST E.Def 7.3 MIC testing.

METHODS

Surfactants including Tween 20 (T20), Tween 80 (T80) and Triton X-100 (TX100) were evaluated for stand-alone or synergistic antifungal activity via checkerboard assays in combination with rezafungin. Subsequent T20 studies defined an optimized assay concentration, validated in up to four microtitre plate types for WT and fks mutant Candida strains (seven species total) and the six-strain EUCAST Candida quality control (QC) panel. Lastly, T20 inter-manufacturer variability, thermostability and best handling practices were investigated.

RESULTS

T20 and T80 performed equivalently, with characteristics slightly preferable to TX100. Due to existing use in EUCAST mould susceptibility testing, T20 was pursued. An optimized concentration of 0.002% T20 normalized rezafungin MIC values across plate types for all Candida spp. evaluated, maintained differentiation of WT versus fks mutants and generated robust QC ranges. Additionally, T20 performance was consistent across manufacturers and temperatures. T20 can be reliably transferred utilizing a syringe, wide-orifice pipette tip and/or by mass.

CONCLUSIONS

Supplementation of RPMI (Roswell Park Memorial Institute) 1640 medium with 0.002% T20 generated a highly reproducible EUCAST yeast MIC methodology for rezafungin.

[The first two cases of Candida auris in Denmark]

This is a case report of the first two cases of Candida auris in Denmark. Patient 1 was known to be colonized with C. auris when transferred from a foreign hospital to a Danish hospital. The patient was isolated during the entire hospitalization and the room was thoroughly cleaned after discharge. Patient 2 who had no travel history spent five hours in the room of Patient 1 after disinfection. One month later, C. auris was found in the blood of Patient 2. Transmission from Patient 1 to Patient 2 must be suspected.

Correction: Astvad et al. Increasing Terbinafine Resistance in Danish Trichophyton Isolates 2019–2020. J. Fungi 2022, 8, 150

In paragraph four of the discussion in the original article [...]

[Diagnosing and treating of onychomycosis]

Onychomycosis is a frequent disorder, which accounts for approximately 50% of nail changes. Many patients are treated for onychomycosis without a mycological verification being done. The patients may be in risk of being treated for a non-existent fungal infection with lack of effect and potential adverse events. This review highlights the importance of choosing the correct sampling and diagnostic methods, as genus and/or species identification is essential when choosing the optimal treatment strategies.

Twenty Years in EUCAST Anti-Fungal Susceptibility Testing: Progress & Remaining Challenges

Since its inception in 2002, the EUCAST Antifungal Susceptibility Testing Subcommittee (AFST) has developed and refined susceptibility testing methods for yeast, moulds and dermatophytes, and established epidemiological cut-off values and breakpoints for antifungals. For yeast, three challenges have been addressed. Interpretation of trailing growth in fluconazole susceptibility testing, which has been proven without impact on efficacy if below the 50% endpoint. Variability in rezafungin MIC testing due to laboratory conditions, which has been solved by the addition of Tween 20 to the growth medium in E.Def 7.4. And third, interpretation of MICs for rare yeast with no breakpoints, where recommendations have been established for MIC-based clinical advice. For moulds, refinements include the validation of spectrophotometer reading for A. fumigatus to facilitate objective MIC determination, and for dermatophytes the establishment of a microdilution method with automated reading and a selective medium to minimise the risk of contaminations. Recent initiatives involve development and validation of agar-based screening assays for detection of potential azole and echinocandin resistance in A. fumigatus and Aspergillus species, respectively, and of terbinafine resistance in Trichophyton species. Moreover, the development of a EUCAST guidance document for molecular resistance testing represents an advancement, particularly for identifying target gene alterations associated with resistance. In summary, EUCAST AFST continues to play a pivotal role in standardizing AFST and facilitating accurate interpretation of susceptibility data for clinical decision-making. Adoption of EUCAST breakpoints for commercial test methods, however, requires thorough validation to ensure concordance with EUCAST reference testing species-specific MIC distributions.