Invasive fungal disease in the immunocompromised host: changing epidemiology, new antifungal therapies, and management challenges.

BACKGROUND: Invasive fungal disease (IFD) causes morbidity and mortality in immunocompromised hosts (ICHs). Based on increasing recognition of the impact of IFD on human disease, a recent WHO priority list identified key areas of need. OBJECTIVES: This review examines changes in the epidemiology of IFD, in particular the emergence of antifungal-resistant pathogens and the current availability of rapid diagnostic tests and antifungal treatment options. SOURCES: Literature between 2000 and January 2024 regarding fungal epidemiology, diagnostic tests, antifungal resistance, emerging fungal pathogens, and novel antifungal agents in both adult and paediatric ICH were reviewed. CONTENT: We describe the changing epidemiology and continued burden and mortality of IFD in ICH. Furthermore, we discuss the emergence of antifungal-resistant organisms driven by new immunosuppressed populations, climate change, and antifungal exposure in the individual and environment. We highlight novel antifungal agents and how they will address current unmet needs. IMPLICATIONS: The changing epidemiology and increased population at risk for IFD, lack of recognition or quantification of risks for IFD with new therapies, current gaps in the availability of rapid diagnostic tests, and the imminent availability of novel antifungals with distinct spectra of activity argue for improved availability of and access to rapid diagnostics, antifungal stewardship programmes, and global access to antifungal agents.

Interplay between host humoral pattern recognition molecules controls undue immune responses against Aspergillus fumigatus.

Pentraxin 3 (PTX3), a long pentraxin and a humoral pattern recognition molecule (PRM), has been demonstrated to be protective against Aspergillus fumigatus, an airborne human fungal pathogen. We explored its mode of interaction with A. fumigatus, and the resulting implications in the host immune response. Here, we demonstrate that PTX3 interacts with A. fumigatus in a morphotype-dependent manner: (a) it recognizes germinating conidia through galactosaminogalactan, a surface exposed cell wall polysaccharide of A. fumigatus, (b) in dormant conidia, surface proteins serve as weak PTX3 ligands, and (c) surfactant protein D (SP-D) and the complement proteins C1q and C3b, the other humoral PRMs, enhance the interaction of PTX3 with dormant conidia. SP-D, C3b or C1q opsonized conidia stimulated human primary immune cells to release pro-inflammatory cytokines and chemokines. However, subsequent binding of PTX3 to SP-D, C1q or C3b opsonized conidia significantly decreased the production of pro-inflammatory cytokines/chemokines. PTX3 opsonized germinating conidia also significantly lowered the production of pro-inflammatory cytokines/chemokines while increasing IL-10 (an anti-inflammatory cytokine) released by immune cells when compared to the unopsonized counterpart. Overall, our study demonstrates that PTX3 recognizes A. fumigatus either directly or by interplaying with other humoral PRMs, thereby restraining detrimental inflammation. Moreover, PTX3 levels were significantly higher in the serum of patients with invasive pulmonary aspergillosis (IPA) and COVID-19-associated pulmonary aspergillosis (CAPA), supporting previous observations in IPA patients, and suggesting that it could be a potential panel-biomarker for these pathological conditions caused by A. fumigatus.

Dual quantitative PCR assays for the rapid detection of Trichophyton indotineae from clinical samples.

Trichophyton indotineae is an emerging species of the Trichophyton mentagrophytes complex (TMC), responsible for an epidemic of widespread hairless skin infections that is frequently (50-70%) resistant to terbinafine. In order to initiate appropriate treatment as quickly as possible without waiting for culture positivity (10-15 days) and molecular identification from the strain, we developed a dual quantitative PCR (qPCR) for the direct detection of T. indotineae in clinical samples. We first designed a T. indotineae-specific qPCR assay (TI-qPCR) targeting a single specific polymorphism in the internal transcribed spacer region. Although none of the 94 non-dermatophyte and 7 dermatophyte species were amplified, this TI-qPCR allowed amplification of other TMC species at a lower yield. With equal amounts (0.1 ng) of DNA per reaction, the mean quantitative cycle (Cq) values for T. indotineae and non-indotineae TMC were 27.9 (±0.1) and 38.9 (±0.3), respectively. Therefore, we normalized this assay against a previously validated pan-dermatophyte qPCR assay (PD-qPCR) and relied on the ΔCq [(TI-qPCR) - (PD-qPCR)] to identify T. indotineae versus other TMC species. Dual assay was validated using 86 clinical samples of culture-confirmed T. indotinea and 19 non-indotineae TMC cases. The mean ΔCq for non-indotineae TMC was 9.6 ± 2.7, whereas the ΔCq for T. indotinea was -1.46 ± 2.1 (P < .001). Setting the ΔCq at 4.5 as a cutoff value resulted in 100% specificity for the detection of T. indotineae. This dual qPCR assay quickly detects T. indotineae from skin scrapings, aiding in early diagnosis and treatment for patients with suspected infection.

Identifying the emerging species Trichophyton indotineae is long and requires to wait for culture positivity. We developed a dual qPCR strategy to detect T. indotineae directly from clinical sample with a 100% sensitivity.

Risk factors and outcome associated with fungal infections in patients with severe burn injury: 10-year retrospective IFI-BURN study.

BACKGROUND: In burn patients, skin barrier disruption and immune dysfunctions increase susceptibility to invasive fungal diseases (IFDs) like invasive candidiasis (IC) and invasive mold infections (IMI). We provide an in-depth analysis of IFD-related factors and outcomes in a 10-year cohort of severe burn patients. METHOD: Retrospective cohort study including adult patients admitted to the Burn Intensive Care Unit (BICU) between April 2014 and May 2023 with Total Burn Surface Area (TBSA) ≥15%. Patients were classified as proven IFD according to EORTC/MSGERC criteria applicable for IC. Putative IMIs were defined with: ≥2 positive cultures from a skin biopsy/bronchoalveolar lavage OR ≥2 positive blood specific-qPCRs OR a combination of both. RESULTS: Among 1381 patients admitted, 276 consecutive patients with TBSA ≥15% were included. Eighty-seven (31.5%; IC n=30; IMI n=43; both n=14) patients fulfilled the criteria for probable/putative IFD. At Day 30 after the burn injury, the estimated cumulative incidence pr/pu IFD was 26.4% (95%CI 21.4-31.8%). Factors independently associated with IFDs were TBSA, severity scores and indoor burn injury (i.e., from confined space fire). Overall mortality was 15.3% and 36.8% in the no IFD, pr/pu IFD groups respectively (p<0.0001). IFD was independently associated with a risk of death (HR: 1.94 for pr/pu IFD; 95%CI, 1.12-3.36; p=0.019). DISCUSSION: This study describes 21st-century characteristics of IFDs in sever burn patients confirming known risk factors with thresholds and identifying the indoor injury as an independent factor associated to IFDs. This suggests a link to contamination caused by fire damage, which is highly susceptible to aerosolizing spores.

Deep cutaneous mycoses in kidney transplant recipients: Diagnostic and therapeutic challenges.

Deep cutaneous mycoses (DCMs) are rare infections that extend throughout the dermis and subcutis, often occurring after inoculation with pathogenic fungi. Trends toward a growing incidence have been observed that may be partially related to an increasing population of solid organ transplant patients. The aim of this study is to describe the diagnostics and the outcomes of DCM among kidney transplant recipients so as to optimize their management. We performed a retrospective review of cases of DCM occurring among kidney transplant recipients in our institution over 12 years. Twenty cases were included. Lesions were only located on the limbs and presented mainly as single (10/20, 50%) nodular lesions (15/20, 75%), with a mean size of 3 cm. Direct mycological examination was positive for 17 patients (17/20, 85%) and the cultures were consistently positive. Thirteen different fungal species were observed, including phaehyphomycetes (n = 8), hyalohyphomycetes (n = 3), dermatophytes (n = 1), and mucorale (n = 1). The (1-3) beta-D-glucan antigen (BDG) was also consistently detected in the serum (20/20, 100%). Systematic imaging did not reveal any distant infectious lesions, but locoregional extension was present in 11 patients (11/14, 79%). Nineteen patients received antifungal treatment (19/20, 95%) for a median duration of 3 months, with surgery for 10 (10/20, 50%). There is a great diversity of fungal species responsible for DCMs in kidney transplant recipients. The mycological documentation is necessary to adapt the antifungal treatment according to the sensitivity of the species. Serum BDG positivity is a potentially reliable and useful tool for diagnosis and follow-up.

Bronchial aspirate obtained during bronchoscopy yields increased fungal load compared to bronchoalveolar lavage fluid in patients at risk of invasive aspergillosis and Pneumocystis pneumonia.

Bronchoalveolar lavage fluid (BALF) is a standard respiratory sample for diagnosing invasive fungal diseases like Pneumocystis pneumonia (PCP) and invasive pulmonary aspergillosis (IPA). However, procedural variations exist across medical centers and wards. This study aimed to compare the diagnostic potential of BALF and bronchial aspirate (BA) obtained during bronchoscopy in 173 patients suspected of fungal infections. A prospective observational study was conducted from April 2020 to November 2021. BALF and BA were collected during bronchoscopy and subjected to direct examination, fungal culture, Aspergillus fumigatus qPCR (AfqPCR), and Pneumocystis jirovecii qPCR (PjqPCR). Galactomannan detection was performed on BALF. Patients were classified based on established European Organization for Research and Treatment of Cancer (EORTC) criteria. Out of 173 patients, 75 tested positive for at least one test in BA or BALF. For Aspergillus, proportion of positive AfqPCR (14.5% vs. 9.2%; P < 0.0001) and fungal loads (Cq of 31.3 vs. 32.8; P = 0.0018) were significantly higher in BA compared to BALF. For Pneumocystis, fungal loads by PjqPCR was also higher in BA compared to BALF (Cq of 34.2 vs. 35.7; P = 0.003). BA only detected A. fumigatus and P. jirovecii in 12 (42.9%) and 8 (19.5%) patients, respectively. BA obtained during a BAL procedure can be a suitable sample type for increased detection of P. jirovecii and A. fumigatus by qPCR. The use of BA in diagnostic algorithms requires further investigation in prospective studies.

Bronchoalveolar lavage fluid (BALF) vs. bronchial aspirate (BA) for fungal diagnosis in 173 patients suspected of invasive fungal infection: BA showed higher fungal loads than in BALF by qPCR for the detection of Aspergillus fumigatus and Pneumocystis jirovecii.

Sexually Transmitted Trichophyton mentagrophytes Genotype VII Infection among Men Who Have Sex with Men.

Transmission of dermatophytes, especially Trichophyton mentagrophytes genotype VII, during sexual intercourse has been recently reported. We report 13 such cases in France. All patients were male; 12 were men who have sex with men. Our findings suggest sexual transmission of this pathogen within a specific population, men who have sex with men.

Humoral Immunity Against Aspergillus fumigatus.

Aspergillus fumigatus is one the most ubiquitous airborne opportunistic human fungal pathogens. Understanding its interaction with host immune system, composed of cellular and humoral arm, is essential to explain the pathobiology of aspergillosis disease spectrum. While cellular immunity has been well studied, humoral immunity has been poorly acknowledge, although it plays a crucial role in bridging the fungus and immune cells. In this review, we have summarized available data on major players of humoral immunity against A. fumigatus and discussed how they may help to identify at-risk individuals, be used as diagnostic tools or promote alternative therapeutic strategies. Remaining challenges are highlighted and leads are given to guide future research to better grasp the complexity of humoral immune interaction with A. fumigatus.

Reliability of a terbinafine agar containing method for the screening of dermatophyte resistance.

The increase in terbinafine resistance worldwide due to Trichophyton indotineae underlies the need for surveillance networks, deploying easy to perform methods to correctly identify resistant isolates and thereby reduce their spread. In the present study, we evaluated the performances of the terbinafine containing agar method (TCAM). Different technical parameters, such as culture medium (RPMI agar [RPMIA] or Sabouraud dextrose agar [SDA]) and inoculum size, were evaluated. Our study showed that terbinafine susceptibility determined using the TCAM was reliable and independent of the inoculum or medium used. We then performed a multicenter, blinded study. 5 isolates of T. indotineae and 15 of genotype I or II of T. interdigitale, including 5 terbinafine-resistant isolates (4 T. indotineae and 1 T. interdigitale), were sent to eight clinical microbiology laboratories. Each laboratory analyzed the 20 isolates' terbinafine susceptibility by the TCAM using both culture media. TCAM allowed all participants to correctly determine the terbinafine susceptibility of analyzed isolates without prior training. All participants agreed that the dermatophyte tested, regardless of species or genotype, grew better on SDA than on RPMIA medium but accumulated fungal growth after 14 days eventually minimized the effect of this difference. In conclusion, TCAM is a reliable, easy to perform screening method for assessing terbinafine resistance. However, despite good performances, TCAM is a qualitative method and minimal inhibitory concentrations must be determined by the European Committee for Antimicrobial Susceptibility Testing standardized method to follow the evolution of terbinafine resistance levels.

The increase in terbinafine resistance worldwide due to Trichophyton indotineae underlies the need for surveillance networks. The terbinafine containing agar method is a reliable and easy-to-use tool in clinical microbiology laboratories. It can be used to rapidly screening resistant isolates, thereby reducing their spread.

MALDI-TOF Mass Spectrometry Online Identification of Trichophyton indotineae Using the MSI-2 Application.

Trichophyton indotineae is an emerging pathogen which recently spread from India to Europe and that is more prone than other species of the Trichophyton mentagrophytes complex to show resistance to terbinafine, resulting in the necessity of rapid identification. Here, we improved the online MSI-2 MALDI-TOF identification tool in order to identify T. indotineae. By multiplying the culture conditions (2 culture media and 6 stages of growth) prior to protein extractions for both test isolates and reference strains, we added 142 references corresponding to 12 strains inside the T. mentagrophytes complex in the online MSI-2 database, of which 3 are T. indotineae strains. The resulting database was tested with 1566 spectra of 67 isolates from the T. mentagrophytes complex, including 16 T. indotineae isolates. Using the newly improved MSI-2 database, we increased the identification rate of T. indotineae from 5% to 96%, with a sensitivity of 99.6%. We also identified specific peaks (6834/6845 daltons and 10,634/10,680 daltons) allowing for the distinction of T. indotineae from the other species of the complex. Our improved version of the MSI-2 application allows for the identification of T. indotineae. This will improve the epidemiological knowledge of the spread of this species throughout the world and will help to improve patient care.

First Patient-to-Patient Intrahospital Transmission of Clade I Candida auris in France Revealed after a Two-Month Incubation Period.

Candida auris is a recently described emerging pathogen in hospital settings. Five genetic clades have been delineated, with each clade being isolated from specific geographic regions. We here describe the first transmission between 2 patients (P0 and P1) of a clade I C. auris strain imported into our burn intensive care unit from the Middle East. The strains have been investigated with whole-genome sequencing, which validated the high similarity of the genomes between isolates from P0 and P1. We repeatedly screened the two patients and contact patients (i.e., other patients present in the same hospital ward at the time of the first positive sample from P0 or P1; n = 49; 268 tests) with fungal culture and a C. auris-specific quantitative PCR assay to assess transmission patterns. We observed that P1 developed C. auris colonization between 41 and 61 days after potential exposure to P0 contamination, despite three negative screening tests as recommended by our national authorities. This study illustrates that transmission of C. auris between patients can lead to long-term incubation times before the detection of colonization. The recommended screening strategy may not be optimal and should be improved in the light of our findings. IMPORTANCE While large outbreaks of C. auris in hospital settings have been described, few clear cases of direct transmission have been documented. We here investigated the transmission of C. auris clade I between two patients with a 41- to 61-day delay between exposure and the development of colonization. This may lead to changes in the recommendations concerning treatment of C. auris cases, as an incubation period of this length is one of the first to be reported.

Detection of circulating DNA for the diagnosis of invasive fusariosis: retrospective analysis of 15 proven cases.

Fusarium spp. are plant pathogens and opportunistic pathogens in severely immunocompromised (hematological malignancy, neutropenia, solid organ transplantation, etc.) and severely burned patients. Invasive fusariosis often disseminates and mortality remains high partly due to delayed diagnosis in the absence of a positive culture. The aim of our study is to design a quantitative PCR (qPCR) assay and evaluate the detection of Fusarium spp. DNA for early diagnosis of invasive infection. A qPCR assay was designed and optimized to identify all Fusarium species complex and secondarily evaluated on patient samples. A total of 81 blood samples from 15 patients diagnosed with proven invasive fusariosis from 9 centers in France were retrospectively tested. Circulating DNA was detected in 14 patients out of 15 (sensitivity of 93% [95% Confidence Interval (CI95), 70.1-99.7]). Detection was possible up to 18 days (median 6 days) before the diagnosis was confirmed by positive blood culture or biopsy. By comparison serum galactomannan and ß-D-glucan were positive in 7.1 and 58.3% of patients respectively. qPCR was negative for all patients with other invasive fungal diseases (IFD) tested (n = 12) and IFD-free control patients (n = 40). No cross-reactions were detected using DNA extracted from 81 other opportunistic fungi. We developed and validated a pan-Fusarium qPCR assay in serum/plasma with high sensitivity, specificity, and reproducibility that could facilitate early diagnosis and treatment monitoring of invasive fusariosis. LAY ABSTRACT: Fusariosis ranks third among invasive mould infections. It is frequently diagnosed late due to the lack of specific tools. We designed and evaluated a new qPCR assay with high sensitivity and specificity allowing detection of Fusarium DNA in serum samples up to 18 days before conventional diagnosis.

Role and perception of clinical microbiology and infectious diseases trainees during the COVID-19 crisis.

Aim: To evaluate the role and perceptions of trainees during the COVID-19 pandemic. Method: An online survey was designed to provide an insight into the significance of the COVID-19 pandemic on working conditions of infectious diseases and clinical microbiology trainees. Results: The main roles of trainees included management of patients hospitalized for COVID-19 (55%), research (53%) and diagnostic procedures (43%). The majority (82%) of trainees felt useful in managing the crisis. However, more than two-thirds felt more stressed and more tired compared with other rotations. Only 39% of the participants had access to psychological support. Conclusion: Due to the significant impact of the pandemic on infectious diseases and clinical microbiology trainees, further research should focus on their health and welfare in the post-pandemic period.

Surfactant protein D inhibits growth, alters cell surface polysaccharide exposure and immune activation potential of Aspergillus fumigatus.

Humoral immunity plays a defensive role against invading microbes. However, it has been largely overlooked with respect to Aspergillus fumigatus, an airborne fungal pathogen. Previously, we have demonstrated that surfactant protein D (SP-D), a major humoral component in human lung-alveoli, recognizes A. fumigatus conidial surface exposed melanin pigment. Through binding to melanin, SP-D opsonizes conidia, facilitates conidial phagocytosis, and induces the expression of protective pro-inflammatory cytokines in the phagocytic cells. In addition to melanin, SP-D also interacts with galactomannan (GM) and galactosaminogalactan (GAG), the cell wall polysaccharides exposed on germinating conidial surfaces. Therefore, we aimed at unravelling the biological significance of SP-D during the germination process. Here, we demonstrate that SP-D exerts direct fungistatic activity by restricting A. fumigatus hyphal growth. Conidial germination in the presence of SP-D significantly increased the exposure of cell wall polysaccharides chitin, α-1,3-glucan and GAG, and decreased ß-1,3-glucan exposure on hyphae, but that of GM was unaltered. Hyphae grown in presence of SP-D showed positive immunolabelling for SP-D. Additionally, SP-D treated hyphae induced lower levels of pro-inflammatory cytokine, but increased IL-10 (anti-inflammatory cytokine) and IL-8 (a chemokine) secretion by human peripheral blood mononuclear cells (PBMCs), compared to control hyphae. Moreover, germ tube surface modifications due to SP-D treatment resulted in an increased hyphal susceptibility to voriconazole, an antifungal drug. It appears that SP-D exerts its anti-A. fumigatus functions via a range of mechanisms including hyphal growth-restriction, hyphal surface modification, masking of hyphal surface polysaccharides and thus altering hyphal immunostimulatory properties.

Coronavirus Disease 2019-Associated Mucormycosis in France: A Rare but Deadly Complication.

We studied COVID-19 associated mucormycosis based on 17 cases reported nationwide and assessed the differences with India. They differed by frequencies of diabetes mellitus (47% in France versus up to 95% in India), hematological malignancies (35% versus 1%), anatomical sites (12% versus >80% rhino-orbito-cerebral) and prognosis (88% mortality versus <50%).

Combination of Mycological Criteria: a Better Surrogate to Identify COVID-19-Associated Pulmonary Aspergillosis Patients and Evaluate Prognosis?

Diagnosis of coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) remains unclear especially in nonimmunocompromised patients. The aim of this study was to evaluate seven mycological criteria and their combination in a large homogenous cohort of patients. All successive patients (n = 176) hospitalized for COVID-19 requiring mechanical ventilation and who clinically worsened despite appropriate standard of care were included over a 1-year period. Direct examination, culture, Aspergillus quantitative PCR (Af-qPCR), and galactomannan testing were performed on all respiratory samples (n = 350). Serum galactomannan, ß-d-glucan, and plasma Af-qPCR were also assessed. The criteria were analyzed alone or in combination in relation to mortality rate. Mortality was significantly different in patients with 0, ≤2, and ≥3 positive criteria (log rank test, P = 0.04) with death rate of 43.1, 58.1, and 76.4%, respectively. Direct examination, plasma qPCR, and serum galactomannan were associated with a 100% mortality rate. Bronchoalveolar lavage (BAL) galactomannan and positive respiratory sample culture were often found as isolated markers (28.1 and 34.1%) and poorly repeatable when a second sample was obtained. Aspergillus DNA was detected in 13.1% of samples (46 of 350) with significantly lower quantitative cycle (Cq) when associated with at least one other criterion (30.2 versus 35.8) (P < 0.001). A combination of markers and/or blood biomarkers and/or direct respiratory sample examination seems more likely to identify patients with CAPA. Af-qPCR may help identifying false-positive results of BAL galactomannan testing and culture on respiratory samples while quantifying fungal burden accurately.

Emergence of Difficult-to-Treat Tinea Corporis Caused by Trichophyton mentagrophytes Complex Isolates, Paris, France.

We describe 7 cases of extensive tinea corporis since 2018 in a hospital in Paris, France, after failure to cure with terbinafine. Molecular analysis indicated Trichophyton mentagrophytes internal transcribed spacer type VIII (T. indotineae). This strain, which has mutations in the squalene epoxidase gene, is spreading on the Indian subcontinent.