Defective antifungal immunity in patients with COVID-19

Progress on nonculture based diagnostic tests for invasive mould infection

PURPOSE OF REVIEW

This review describes the current status of diagnosing invasive mould disease and Pneumocystis pneumonia using nonconventional diagnostics methods.

RECENT FINDINGS

There has been significant development in the range of nonculture mycological tests. Lateral flow tests (LFTs) for diagnosing aspergillosis complement galactomannan ELISA testing, and LFTs for other fungal diseases are in development. Rapid and low through-put B-D-Glucan assays increase access to testing and there has been significant progress in the standardization/development of molecular tests. Despite this, no single perfect test exists and combining tests (e.g., antigen and molecular testing) is likely required for the optimal diagnosis of most fungal diseases.

SUMMARY

Based on established clinical performance few mycological tests can be used alone for optimal diagnosis of fungal disease (FD) and combining tests, including classical approaches is the preferred route for confirming and excluding disease. Next-generation sequencing will likely play an increasing role in how we diagnose disease, but optimization, standardization and validation of the entire molecular process is needed and we must consider how host biomarkers can stratify risk. Given the burden of FD in low- and medium-income countries, improved access to novel but more so existing diagnostic testing is critical along with simplification of testing processes.

Corticosteroids for hospitalized patients with severe/critical COVID-19: a retrospective study in Chongqing, China

Corticosteroids have always been recommended for severe cases of COVID-19. However, the efficacy of treatment with corticosteroids for COVID-19 during the SARS-CoV-2 omicron outbreak in China has not been reported. Clinical data from 406 patients hospitalized for severe/critical COVID-19 from December 2022 to January 2023 at six hospitals in Chongqing were retrospectively analyzed. The primary outcome was all-cause mortality at 28 days in the groups with and without corticosteroids treatment after propensity score matching (PSM). Secondary outcomes were to compare in-hospital mortality and length of survival time with corticosteroids and those without corticosteroids. This study included 406 patients with severe or critical COVID-19, divided into the corticosteroids group (231, 56.9%) and non-corticosteroids group (175, 43.1%). After PSM, the use of corticosteroids did not reduce all-cause mortality at 28 days (42.5% vs. 39.1%). Univariate analysis showed that corticosteroids were not associated with improved all-cause mortality at 28 days [hazard ratio (HR), 1.019; 95% confidence interval (CI), 0.639-1.623; p = 0.938]. Multivariate analysis showed similar results (HR, 1.047; 95% CI, 0.633-1.732; p = 0.858). Among non-survivors, the survival time was significantly larger in those who received corticosteroids compared with the non-corticosteroid users [median 13 (IQR 6.5-15.5) vs. 6 (4-11.25), p = 0.007]. The use of systemic corticosteroids in severe/critical COVID-19 may provide certain potential survival benefits but does not improve prognosis.

Association of COVID-19 risk factors with systemic fungal infections in hospitalized patients

Purpose

A new category of systemic co-infections that emerged with the COVID-19 pandemic is known as COVID-19-associated (CA) fungal infections, which include pulmonary aspergillosis (CAPA), candidiasis (CAC), and mucormycosis (CAM). We aimed to study the association between patient characteristics of hospitalized COVID-19 patients, COVID-19 comorbidities, and COVID-19 therapies with secondary non-superficial fungal infections.

Methods

We performed descriptive and regression analyses of data from 4,999 hospitalized COVID-19 patients from the University of Kentucky Healthcare (UKHC) system.

Results

The patients with secondary systemic fungal infections had a 6-fold higher risk of death than those without such infections. Generally, the risk factors for severe COVID-19 (age, obesity, cardiovascular disease, diabetes, and lack of COVID-19 vaccination) were strong predictors of a secondary fungal infection. However, several characteristics had much higher risks, suggesting that a causative link may be at play: ICU admission, mechanical ventilation, length of hospital stay, and steroid use.

Conclusions

In sum, this study found that the known risk factors for severe COVID-19 disease, age, diabetes, cardiovascular disease, obesity, ventilation, and high steroid doses were all predictors of a secondary fungal infection. Steroid therapy may need to be modified to account for a risk or a presence of a fungal infection in vulnerable patients.

Investigation of risk factors for invasive pulmonary aspergillosis among patients with COVID-19

COVID-19 associated pulmonary aspergillosis (CAPA) had been reported, and raised concern about this secondary infection due to the high mortality. This study aimed to investigate the risk factors for CAPA. The enrolled 114 COVID-19 patients were further divided into CAPA group and non-CAPA group. Demographic characteristics, underlying diseases, laboratory parameters and therapeutic schedule between the two groups were compared to identify the independent risk factors for CAPA by univariate analysis and multivariable logistic regression analysis. Sensitivity and specificity of independent risk factors were confirmed by receiver operating characteristic (ROC) curve analysis. Univariate analysis showed that renal transplant, IL-6 and CRP levels, decreased CD4 + T cell and CD8 + T cell, duration of antibiotics therapy, and prolonged mechanical ventilation were risk factors for development of CAPA. These factors were further analyzed by multivariable logistic regression analysis and the results indicated that elevated IL-6 level, decreased CD4 + T cell and prolonged mechanical ventilation could be recognized as independent risk factors for CAPA in COVID-19 patients. Identification of these risk factors is essential to initiate antifungal therapy as soon as possible to improve outcome of patients with CAPA.

Applications of β-defensins against infectious pathogenic microorganisms

INTRODUCTION

Antimicrobial peptides (AMPs) are polypeptides with potent antimicrobial activity against a broad range of pathogenic microorganisms. Unlike conventional antibiotics, AMPs have rapid bactericidal activity, a low capacity for inducing resistance, and compatibility with the host immune system. A large body of data supports the antimicrobial activities of a large body of data supports the antimicrobial activities of the class of AMPs known as β-defensins. This review provides a comprehensive analysis of the effects of β-defensins against various pathogenic microorganism: bacteria, fungi, viruses, Mycoplasmas and Chlamydiae. The primary mechanisms of β-defensins against pathogenic microorganisms include inhibition of biofilms formations, dissolution of membranes, disruption of cell walls, and inhibition of adhesion and receptor binding. Although further study and structural modifications are needed, β-defensins are promising candidates for antimicrobial therapy.

AREAS COVERED

This review describes the inhibitory effects of β-defensins on various pathogenic microorganisms. Additionally, we focus on elucidating the mechanisms underlying their actions to provide, providing valuable references for the further study of β-defensins.

EXPERT OPINION

The biological activities and modes of action of β-defensins provide powerful resources for clinical microbial infection management. Addressing the salt sensitivity and toxicity of β-defensins may further enhance their potential applications.

Aspergillus fumigatus secretes a protease(s) that displays in silico binding affinity towards the SARS-CoV-2 spike protein and mediates SARS-CoV-2 pseudovirion entry into HEK-293T cells

BACKGROUND

The novel coronavirus disease of 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Data from the COVID-19 clinical control case studies showed that this disease could also manifest in patients with underlying microbial infections such as aspergillosis. The current study aimed to determine if the Aspergillus (A.) fumigatus culture media (i.e., supernatant) possessed protease activity that was sufficient to activate the SARS-CoV-2 spike protein.

METHODS

The supernatant was first analysed for protease activity. Thereafter, it was assessed to determine if it possessed proteolytic activity to cleave a fluorogenic mimetic peptide of the SARS-CoV-2 spike protein that contained the S1/S2 site and a full-length spike protein contained in a SARS-CoV-2 pseudovirion. To complement this, a computer-based tool, HADDOCK, was used to predict if A. fumigatus alkaline protease 1 could bind to the SARS-CoV-2 spike protein.

RESULTS

We show that the supernatant possessed proteolytic activity, and analyses of the molecular docking parameters revealed that A. fumigatus alkaline protease 1 could bind to the spike protein. To confirm the in silico data, it was imperative to provide experimental evidence for enzymatic activity. Here, it was noted that the A. fumigatus supernatant cleaved the mimetic peptide as well as transduced the HEK-293T cells with SARS-CoV-2 pseudovirions.

CONCLUSION

These results suggest that A. fumigatus secretes a protease(s) that activates the SARS-CoV-2 spike protein. Importantly, should these two infectious agents co-occur, there is the potential for A. fumigatus to activate the SARS-CoV-2 spike protein, thus aggravating COVID-19 development.

Prediction of pulmonary aspergillosis in patients with ventilator-associated pneumonia

BACKGROUND

Predictors of ICU-acquired pulmonary aspergillosis (IPA) are not well-established in critically ill patients with ventilator-associated pneumonia (VAP), making IPA commonly misdiagnosed and anti-fungal therapy delayed. We aimed to develop a clinical score for prediction of IPA among patients with VAP.

METHODS

Mechanically ventilated patients who developed VAP in 4 ICUs in Bretagne, Western France, were included. The score was constructed in a learning cohort, based on predictors of IPA in logistic regression model, and validated in a validation cohort.

RESULTS

Among 1636 mechanically ventilated patients, 215 developed VAP but only 39 developed IPA (4 possible and 35 probable/putative) (18%). Most cases (31/39) were documented through a positive broncho-alveolar sample culture. Independent predictors of IPA were immunodepression (including onco-hematological disorder, immunomodulatory treatment, solid organ transplant, neutropenia < 0.5G/L and high-dose steroids ≥ 1 mg/kg/day of prednisolone equivalent) (p = 0.001; score = 1 point) and lymphocyte count at admission < 0.8 G/L (p = 0.019; score = 1 point). Operational values of the predictive score in the learning/validation cohort were 50%/52% sensitivity and 90%/87% specificity, respectively, for high PiPa score (score = 2) and 94%/91% sensitivity and 44%/46% specificity, respectively, for moderate PiPa score (score = 1). Finally, the AUC for the prediction of IPA was 0.783 in the learning cohort and 0.770 in the validation cohort.

CONCLUSIONS

We evaluated a clinical score with good predictive value which may help to predict IPA in patient with VAP. External validation will be needed to confirm our preliminary findings.

Predictors of disease severity in COVID-19 associated mucormycosis: impact of HbA1C levels, time lag to mucormycosis onset, and radiologic patterns of paranasal sinuses and spaces involvement

BACKGROUND

Identifying early predictors of severe Covid-19 associated mucormycosis (CAM) can help improve management and treatment outcomes.

OBJECTIVES

Primary: To identify clinical and radiological predictors of disease severity in CAM. Secondary: To describe patterns of central nervous system (CNS) involvement in CAM.

METHODS

A total of 71 patients with CAM were included in the study. Based on the anatomical extent of involvement on MRI, patients were divided into three groups: Sinus (paranasal sinuses), Orbit (orbital spread), and CNS (CNS spread). Clinical parameters and radiological patterns of involvement of sinuses and extra sinus spaces were studied between the three groups. Patterns of CNS involvement were also described.

RESULTS

A shorter time lag between COVID-19 infection and CAM, as well as high HbA1C levels, were found to be associated with severe disease. Involvement of the sphenoid, ethmoid and frontal sinuses, T1 hyperintense signal in the sphenoid, as well as bony involvement of the sphenoid sinus, were significantly associated with severe disease. Extra-sinus spread into pre/retroantral space, pterygopalatine fossa, and masticator spaces were also significantly associated with a severe disease course. The most common pattern of CNS spread was cavernous sinus involvement, followed by pachymeningeal spread and cranial nerve involvement.

CONCLUSION

Early identification of the above-described predictors in patients presenting with CAM can help detect those at risk for developing severe disease. A longer duration of amphotericin, combined with a more aggressive surgical approach in selected cases, may lead to better long-term outcomes.

Severe Candida infections in critically ill patients with COVID-19

The frequency of co-infections with bacterial or fungal pathogens has constantly increased among critically ill patients with coronavirus disease 2019 (COVID-19) during the pandemic. Candidemia was the most frequently reported invasive fungal co-infection. The onset of candidemia in COVID-19 patients was often delayed compared to non-COVID-19 patients. Additionally, Candida invasive infections in COVID-19 patients were more often linked to invasive procedures (e.g., invasive mechanical ventilation or renal replacement therapy) during the intensive care stay and the severity of illness rather than more "classic" risk factors present in patients without COVID-19 (e.g., underlying diseases and prior hospitalization). Moreover, apart from the increased incidence of candidemia during the pandemic, a worrying rise in fluconazole-resistant strains was reported, including a rise in the multidrug-resistant Candida auris. Regarding outcomes, the development of invasive Candida co-infection had a negative impact, increasing morbidity and mortality compared to non-co-infected COVID-19 patients. In this narrative review, we present and critically discuss information on the diagnosis and management of invasive fungal infections caused by Candida spp. in critically ill COVID-19 patients.

Invasive Pulmonary Aspergillosis After Sars-CoV-2 Infection as Limitation of Contemporary Transplantology: A Case Report

Invasive fungal infections are uncommon in pediatric heart transplant recipients. Risk and mortality are highest in the first 6 months post-transplant, especially in patients with previous surgery and those requiring mechanical support. There is a possibility that prior SARS-CoV-2 infection may cause a more severe course of pulmonary aspergillosis, especially in immunosuppressed individuals. This report describes a female patient, eight years of age, who was admitted to the pediatric cardiac surgery department with symptoms of end-stage heart failure in urgent need of mechanical circulatory support (MCS). A left ventricular assist device (LVAD) was implanted as a bridge to transplantation. During over a year on the waiting list, LVAD was replaced twice due to the presence of fibrin on the inlet valve. While staying in the ward, the patient underwent SARS-CoV-2 infection. An orthotopic heart transplant was successfully performed after 372 days of MCS with LVAD. One month after transplantation, the girl developed severe pulmonary aspergillosis complicated by sudden cardiac arrest and implantation of venovenous extracorporeal membrane oxygenation (VV ECMO) used for 25 days. Unfortunately, a few days after weaning from VV ECMO, the patient died due to intracerebral bleeding.

Trends in the Epidemiology of Pneumocystis Pneumonia in Immunocompromised Patients without HIV Infection

The increasing morbidity and mortality of life-threatening Pneumocystis pneumonia (PCP) in immunocompromised people poses a global concern, prompting the World Health Organization to list it as one of the 19 priority invasive fungal diseases, calling for increased research and public health action. In response to this initiative, we provide this review on the epidemiology of PCP in non-HIV patients with various immunodeficient conditions, including the use of immunosuppressive agents, cancer therapies, solid organ and stem cell transplantation, autoimmune and inflammatory diseases, inherited or primary immunodeficiencies, and COVID-19. Special attention is given to the molecular epidemiology of PCP outbreaks in solid organ transplant recipients; the risk of PCP associated with the increasing use of immunodepleting monoclonal antibodies and a wide range of genetic defects causing primary immunodeficiency; the trend of concurrent infection of PCP in COVID-19; the prevalence of colonization; and the rising evidence supporting de novo infection rather than reactivation of latent infection in the pathogenesis of PCP. Additionally, we provide a concise discussion of the varying effects of different immunodeficient conditions on distinct components of the immune system. The objective of this review is to increase awareness and knowledge of PCP in non-HIV patients, thereby improving the early identification and treatment of patients susceptible to PCP.

Unveiling the Culprit: Candida-Induced Spondylodiscitis Following SARS-CoV-2 Infection

We present a case of a 57-year-old male patient with a history of prolonged intensive care unit (ICU) stay for coronavirus disease 2019 (COVID-19) who developed fungal spondylodiscitis, a rare complication. The patient initially presented complaining of respiratory symptoms and was subsequently treated with tocilizumab, remdesivir, enoxaparin, and dexamethasone. Following ICU discharge, he experienced recurrent infections, including extended-spectrum beta-lactamase Klebsiella urinary tract infection. Two months later, he developed back pain; magnetic resonance imaging (MRI) revealed inflammatory spondylodiscitis. Despite empirical antibiotic therapy, his condition did not improve, and a bone biopsy confirmed Candida albicans infection. Antifungal treatment with fluconazole and anidulafungin resulted in a significant clinical improvement. The patient achieved complete recovery after six months of therapy. This case highlights the rare occurrence of fungal spondylodiscitis in COVID-19 patients with a history of ICU stay and emphasizes the importance of early recognition and appropriate management to mitigate potential complications.

Oral Candidiasis in Adult and Pediatric Patients with COVID-19

Oral Candidiasis (OC) is an opportunistic fungal infection of the oral cavity, frequently reported under local and systemic predisposing circumstances. While the recurrence of OC HIV-infected subjects has been well described and reported, the association between oral candidiasis and the SARS-CoV-2 infection is a recent finding that still is worthy of further study. The present paper focuses on this novel association, reporting the incidence and prevalence of OC occurring during and after COVID-19 and the possible etiopathogenic mechanisms underlying the onset of OC in COVID-19 subjects. The work found that the immune inflammatory hypo reactions and immunosuppression found in children and adults with COVID-19 could favor the proliferation colonization of Candida species and the following infection. At the same time, poor oral hygiene and iatrogenic causes seem to be the main risk factors.

Lower Concentrations of Amphotericin B Combined with Ent-Hardwickiic Acid Are Effective against Candida Strains

Life-threatening Candida infections have increased with the COVID-19 pandemic, and the already limited arsenal of antifungal drugs has become even more restricted due to its side effects associated with complications after SARS-CoV-2 infection. Drug combination strategies have the potential to reduce the risk of side effects without loss of therapeutic efficacy. The aim of this study was to evaluate the combination of ent-hardwickiic acid with low concentrations of amphotericin B against Candida strains. The minimum inhibitory concentration (MIC) values were determined for amphotericin B and ent-hardwickiic acid as isolated compounds and for 77 combinations of amphotericin B and ent-hardwickiic acid concentrations that were assessed by using the checkerboard microdilution method. Time–kill assays were performed in order to assess the fungistatic or fungicidal nature of the different combinations. The strategy of combining both compounds markedly reduced the MIC values from 16 µg/mL to 1 µg/mL of amphotericin B and from 12.5 µg/mL to 6.25 µg/mL of ent-hardwickiic acid, from isolated to combined, against C. albicans resistant to azoles. The combination of 1 µg/mL of amphotericin B with 6.25 µg/mL of ent-hardwickiic acid killed all the cells of the same strain within four hours of incubation.