Limper, Andrew H.

Introduction. Aspergillus fumigatus phosphoglucomutase ( Af PGM) is a central enzyme in fungal carbohydrate metabolism that catalyses the interconversion of glucose-1-phosphate and glucose-6-phosphate, generating precursors such as uridine diphosphate glucose required for the synthesis of key cell wall polysaccharides. Hypothesis/Gap Statement. Although Af PGM has been implicated in fungal viability and cell wall integrity, further functional and molecular characterization is required to better define its role in cell wall-associated processes and to evaluate its potential as a selective antifungal target. Aim. This study aimed to further characterize the functional contribution of Af PGM to fungal growth, cell wall-related phenotypes, biofilm formation and enzymatic activity. Methodology. A conditional A. fumigatus P alcA ::pgm mutant was used to assess growth, soluble β -glucan levels and biofilm formation. Functional complementation was evaluated by heterologous expression of Afpgm in a Saccharomyces cerevisiae pgm2Δ strain. Enzymatic inhibition was examined using the isothiazolone compound ISFP10. Results. Reduced Af PGM activity was associated with impaired growth, altered cell wall-related phenotypes, decreased soluble β -glucan levels and diminished biofilm biomass. Expression of Afpgm restored growth and sedimentation defects in the yeast pgm2Δ mutant to WT levels, confirming functional conservation. ISFP10 inhibited Af PGM activity and disrupted associated fungal phenotypes. Conclusion. These findings further define the functional role of Af PGM in fungal carbohydrate metabolism and cell wall-associated biology. The selective inhibition of Af PGM relative to human phosphoglucomutase supports its potential as a promising target for the development of novel antifungal therapies.

ABSTRACT Background Solid organ transplant (SOT) recipients are at risk for Pneumocystis jirovecii pneumonia (PCP), yet how their clinical phenotype and outcomes compare with other immunocompromised patients without HIV remains poorly defined. Methods We conducted a multicenter retrospective cohort study of adults with proven or probable PCP from 2017 to 2025, including 95 SOT recipients and 588 non‐SOT, non‐HIV immunocompromised patients. The primary outcome was 90‐day mortality, secondary outcomes included new renal failure requiring dialysis, and 30‐day mortality. Outcomes were analyzed using inverse probability weighting (IPW) with winsorization to adjust for baseline differences. Results In unadjusted analysis, SOT recipients had lower 90‐day mortality (hazard ratio [HR]: 0.62, 95% CI 0.39–0.97, p = 0.037). After IPW with winsorization of extreme weights, SOT status remained associated with lower 90‐day mortality (HR: 0.32, 95% CI 0.13–0.76, p = 0.009), and 30‐day mortality (HR: 0.35, 95% CI: 0.14–0.92, p = 0.034). SOT recipients had higher odds of renal failure requiring dialysis in unadjusted analysis (OR: 3.49, 95% CI 1.94–6.14, p < 0.001), which persisted after IPW adjustment (OR: 1.62, 95% CI: 1.04–2.51, p = 0.032). Conclusions Despite higher rates of renal failure requiring dialysis, SOT recipients with PCP experienced significantly improved short‐ and intermediate‐term survival compared with other non‐HIV immunocompromised patients, underscoring the need for further investigation into transplant‐associated contributors to PCP outcomes.

Abstract Candida auris is an emerging fungal pathogen with high rates of multidrug resistance, posing a significant global health threat. Immunosuppressed patients are particularly vulnerable to multidrug-resistant (MDR) C. auris infections. This systematic review and meta-analysis (SR-MA) aimed to assess the global prevalence of MDR-C. auris isolates in humans and their resistance to antifungal drugs, primarily fluconazole (FLZ), voriconazole (VOR), and amphotericin B (AmB). A comprehensive search was conducted in PubMed, Scopus, and ScienceDirect databases on published studies regarding clinical C. auris isolates and the use of antifungal susceptibility testing assay from 17 March 2015 to 1 February 2024. Meta-analysis was conducted using random-effects models to determine the estimated pooled prevalence of MDR-C. auris isolates and their antifungal resistance profiles from immunosuppressed humans. A total of 81 research studies were included in the final analysis, with the overall pooled prevalence of the three most important antifungal drugs; FLZ (92.5% | 95% CI: 89.5–94.7), VOR (49.0% | 95% CI: 37.6–60.4), and AmB (51.0% | 95% CI: 42.3–59.7). According to the subgroup analyses, FLZ-resistant C. auris was the most prevalent isolate observed in the five continents reporting compared to the VOR- and AmB-resistant C. auris having lower pooled prevalence. Further, higher pooled prevalence of MDR-C. auris isolates were observed from males (68.2%, n = 578) compared to females (37.1%, n = 283). Finally, the global pooled prevalence for mortality in immunosuppressed patients with MDR-C. auris from 13 research studies was 41.5% (95% CI: 29.9–54.2). This SR-MA study establishes the variation of MDR-C. auris resistance patterns observed from different continents and the importance to conduct further research studies using potent antifungal drugs. Accordingly, it is imperative to establish stringent surveillance on the increasing prevalence of antifungal resistance particularly in low-income regions with limited research resources to prevent increasing prevalence of MDR-C. auris.

Abstract Pneumocystis jirovecii pneumonia remains a significant cause of mortality and morbidity in immunocompromised populations worldwide. Mortality rates range from 5% to 30% in HIV-positive individuals and 4% to 76% in those without HIV. Recognizing its public health impact, the World Health Organization (WHO) included Pneumocystis jirovecii in its 2022 “Fungal Priority Pathogens” list. In this review, we will summarize published findings over the last 14 years on the immunopathogenic mechanisms underlying Pneumocystis pneumonia–related lung injury and examine the potential for targeting these pathways in adjunctive immune modulation therapy. Notably, recent studies have identified promising immune-based interventions, including PD-1/PD-L1 blockade and IL-7 therapy, which may enhance pathogen clearance while controlling damaging inflammation. Additionally, small molecule inhibitors such as BRD5529 and ALW-II-41-27 have shown potential in reducing lung injury by modulating proinflammatory signaling pathways in Pneumocystis pneumonia.

Pneumocystis jirovecii pneumonia (PCP) is a life-threatening opportunistic infection increasingly recognized among non-HIV immunocompromised patients. In severe cases progressing to acute respiratory distress syndrome, venovenous extracorporeal membrane oxygenation (VV-ECMO) may serve as a rescue therapy. We conducted a retrospective multicenter review of 10 adult patients with proven or probable PCP who received VV-ECMO between 2017 and 2024. Seven of 10 patients survived to discharge, including all three HIV-positive patients and 4 of 7 non-HIV immunocompromised patients. The mean Respiratory ECMO Survival Prediction Score was –1.5, corresponding to a predicted survival of 33–57%. Multiorgan dysfunction was common, including renal failure requiring dialysis in 6 of 10 patients, need for neuromuscular blockade in 8 of 10, and pulmonary vasodilator use in 8 of 10. Despite high acuity and prolonged ECMO support, outcomes were favorable. These findings suggest that VV-ECMO may be a viable salvage therapy for select patients with severe PCP, including those without HIV.

Pneumocystis pneumonia (PCP) is a serious fungal infection affecting immunocompromised hosts. Decompensated cirrhosis leads to cirrhosis-associated immune dysfunction (CAID), a form of impaired cellular immunity that may predispose patients to opportunistic infections such as PCP. We conducted a retrospective review of 727 patients with proven or probable PCP from 2017 to 2025. Of these, 33 had decompensated cirrhosis. These patients were stratified into two groups: Cirrhosis Only (n = 16) and Cirrhosis with Additional Immunocompromising Conditions (n = 17). Among the patients with cirrhosis, the overall mortality was 48%, with the 90-day mortality reaching 57.6% (95% CI: 39.2–74.5%). Compared with those without cirrhosis, the patients with cirrhosis had a higher risk of mortality (OR: 4.08, 95% CI: 2.01–8.30, p < 0.001), increased intensive care unit (ICU) admission (87% vs. 42%, p < 0.001), and greater need for renal replacement therapy (54.6% vs. 7.5%, p < 0.001). These findings suggest that decompensated cirrhosis alone may represent a sufficient and underrecognized risk factor for PCP, with a high associated mortality. Given the preventable nature of this infection, future studies are needed to assess the incidence, define the risk, and investigate the role of prophylaxis in this vulnerable population.

Abstract Background Pneumocystis jirovecii pneumonia (PCP) is increasingly seen in patients who are non-HIV immunocompromised hosts, yet modern risk factors and outcomes are poorly recognized and defined. Methods A retrospective review was conducted of adult patients who met criteria for proven or probable PCP from 2017 to 2024 across a large academic multicenter health system. The primary outcome was mortality among cohorts, defined by etiology of immunosuppression through univariate and age-adjusted logistic regression. Secondary analyses included trends in annual diagnoses and testing patterns. Results A total of 701 patients met criteria for inclusion, representing one of the largest clinically characterized cohorts of PCP to date. The median age was 65 years (IQR, 54–73) and 62% were male. The most common risk groups were hematologic malignancy (32.2%), solid tumor cancers receiving chemotherapy (22.4%), and autoimmune disease with immunosuppression (17.7%). Annual PCP diagnoses increased at a rate of 15.8% (95% CI, 8.9%–23.2%) in parallel with increased testing. Only 5.4% of patients were receiving prophylaxis at the time of diagnosis. Overall mortality was 20% (95% CI, 17%–23%) and highest in cirrhosis (adjusted odds ratio, 6.24; 95% CI, 2.84–13.69; P &lt; .001). Conclusions PCP in the current era affects a broad range of patients who are immunocompromised, with high associated mortality and low rates of prophylaxis. Patients with solid tumors and those with cirrhosis are at particularly high risk of mortality. These findings highlight the need to reassess and redefine PCP prophylaxis guidelines in specific populations and our understanding of who is at risk.

Abstract INTRODUCTION Candida auris has emerged as a global pathogenic yeast that disproportionately affects patients in healthcare settings. Infection ranges from localized skin infections to severe bloodstream infections. Multidrug resistance, hardiness on environmental surfaces, and the ability to persist as a colonizer in both sick and healthy patients enables it to spread rapidly in healthcare settings leading to significant morbidity and mortality. Multidrug resistance has led to limited effective therapies and necessitates the need for novel therapeutic options. Here we evaluate the efficacy of ISFP10, an antifungal compound with a novel mechanism of action, against C. auris. ISFP10 inhibits fungal phosphoglucomutase (PGM), an enzyme required for production of substrates for fungal cell wall synthesis (Figure 1). METHODSMIC Testing The compound ISFP10 was submitted to the National Institute of Allergy and Infectious Diseases Therapeutic Development Services for half-maximal and maximal inhibitory concentration (IC50/IC100) testing. C. auris isolates were tested using typical drug-dilution methods. Saccharomyces cerevisiae – C. auris PGM Growth Curve Testing This proof of mechanism assay was instituted to isolate PGM in Saccharomyces for growth curve testing. The Candida auris PGM was cloned into pYES2.1 downstream of an inducible galactose promoter. This plasmid was transformed into S. cerevisiae. C. auris PGM plasmid-containing S. cerevisiae was incubated for 24 hours in 2% glucose minimal media. Using absorbance readings, the inoculum was normalized to 5x105 cells/mL in galactose-containing media. The inoculum was plated onto a 96-well plate in a drug-dilution scheme with ISFP10 at concentrations ranging from 200uM to 6.25uM along with DMSO control wells. Plates were incubated at 30° C for 72 hours in a spectrophotometer with absorbance readings every hour. Growth curves were plotted using GraphPad Prism software. RESULTS The half-maximal inhibitory concentrations (IC50) and maximal inhibitory concentrations (IC100) were consistently low across the three C. auris isolates. The IC50 ranged from 0.5 µg/mL to 1.0 µg/mL, while the IC100 was 1.0 µg/mL for each of the three isolates (Table 1). Growth curves demonstrated concentration-dependent inhibition of C. auris PGM plasmid-containing S. cerevisiae. Figure 2 shows full inhibition of fungal growth at 25µM with dose-dependent delayed growth at lower concentrations. CONCLUSIONS ISFP10 shows promise for inhibiting C. auris PGM in a dose-dependent pattern. It's high in vitro activity and novel mechanism of action necessitates further investigation as a potential therapeutic for C. auris.

ABSTRACT Background and Objective Previously, the novel small molecule ISFP10 has been shown to inhibit fungal phosphoglucomutase (PGM) activity in Aspergillus fumigatus and Pneumocystis spp. With 50-fold selectivity over the human PGM molecule due to the presence of a unique yet conserved cysteine residue present in a number pathogenic fungal PGMs, use of this compound may provide a novel broad-spectrum approach to treating fungal infections. Accordingly, we sought to determine the tolerability in test animals receiving this compound, as well as the potential antifungal activity of ISFP10 on cultures of the common fungal pathogens Candida albicans and Candida glabrata . Methods C57BL6 mice received once daily intraperitoneal (IP) injections of 100 mL of vehicle control (DMSO) or ISFP10 at a concentration of 10 mg/kg. Body weights were recorded daily for 7 days of treatment. On the final day, mice were weighed and euthanized. Postmortem blood collection was conducted via cardiac puncture and distributed to EDTA and lithium heparin tubes for complete blood count (CBC) and comprehensive blood chemistry panels, respectively. Liver, kidney, and lung tissue were also harvested and placed in 10% formalin for H&E staining and blinded histopathologic scoring. Lung samples were further analyzed for proinflammatory cytokines using enzyme-linked immunosorbent assays (ELISA) and quantitative PCR (qPCR). Furthermore, ISPF10 was tested for antifungal activity via 8-hour growth curve analysis in a concentration-dependent fashion against Candida albicans and Candida glabrata . Results There was no significant difference in the daily or final body weights of the mice receiving 10 mg/kg of ISFP10 compared to those of the vehicle control group. Extracellular matrix (ECM) transcripts for IL-6 and TNFα were statistically similar via qPCR. ELISA results of proinflammatory cytokines for IL-6 was not significant whereas TNFα levels in lung tissue from the ISFP10 treatment group were significantly reduced, indicating a potential anti-inflammatory effect of ISFP10 at this dosage. Overall, blood chemistry and CBC analysis revealed no overall significant differences between the two groups, except for increased neutrophil counts and decreased potassium levels in samples collected from ISFP10 treated animals compared to the vehicle control group. These laboratory abnormalities were not of clinical significance to the test animals. Blinded histopathological examination revealed no abnormalities or evidence of critical organ toxicity from all groups. Inhibition of C. albicans and C. glabrata culture growth by ISFP10 was concentration-dependent in YPD liquid media containing the ISFP10 compared to vehicle control. Conclusions Our preliminary testing of ISFP10 revealed no inherent safety or toxicology concerns within the observed parameters. These data further support significant culture suppressive activity against C. albicans and C. glabrata . Taken together, these observations of ISFP10 further indicate that targeting PGM might be a novel and viable therapeutic strategy for serious fungal infections. Key points An inhibitor specific to fungal PGM enzymes, termed ISFP10, was generally well tolerated when administered via intraperitoneal (IP) injection in mice. ISFP10 displays antifungal activity in a concentration-dependent manner against C. albicans and C. glabrata .