Mucormycosis in lung transplant recipients: A systematic review of the literature and a case series.

BACKGROUND: Mucormycosis is a rare infection in lung transplant recipients (LTR). Our objective was to better define the clinical presentation and optimal management of this frequently lethal infection. METHODS: A systematic review of the literature was performed to identify all published cases of mucormycosis in LTR using PubMed/MEDLINE. These cases were analyzed together with a new case series from our clinic. RESULTS: Literature search yielded 44 articles matching the inclusion criteria, describing 121 cases. Six additional cases were identified from our clinic. Data regarding infection site and outcome were available for a total of 53 patients. The lungs were the most common site of infection (62%), followed by rhinocerebral and disseminated disease. Most cases (78%) developed in the first post-transplant year, with over 40% of them in the first month. Additional risk factors for mucormycosis were identified in over half of the patients. Surgical debridement was uncommon in pulmonary infection (9%). Posaconazole therapy was used in 35% of cases, mostly in combination with amphotericin B. Overall mortality was 32% but varied according to site of infection. CONCLUSION: Mucormycosis in LTRs tends to be an early post-surgical infection, associated with additional risk factors and intensified immunosuppressive states, and most often affects the lungs, where surgical debridement is rarely feasible. Posaconazole as first-line therapy should be further explored.

Role of carbohydrate antigens in antifungal glycoconjugate vaccines and immunotherapy.

The emergence of fungal infection is a growing public health concern that in the latest years is becoming a serious threat to humans, particularly for immunocompromised individuals. Invasive fungal infections (IFIs), which are associated with significant morbidity and mortality, are on the rise due to the availability of only a few old antifungal agents. In addition to this, the growing use of antibiotics makes the population increasingly susceptible to these infections. Since carbohydrates are the main component of the fungal cell wall, the study of fungal glycans as potential targets for the fight against IFIs has aroused much interest in recent decades. In most fungal species the saccharides of the core are made up of chitin and ß-glucans, while the outer layer carbohydrates vary according to the fungal species, such as mannans for Candida albicans, galactomannans for Aspergillus fumigatus hyphae, α-glucans for Aspergillus fumigatus and Cryptococcus neoformans, glucuronoxylomannans (GXM) and galactoxylomannans (GalXM) for Criptococcus neoformans. Being surface antigens, fungal carbohydrates are a logical target for the development of antifungal glycoconjugate vaccines and for immunotherapy with monoclonal antibodies. This review summarizes recent findings on active and passive immunization strategies based on fungal carbohydrates explored preclinically for three of the major fungal pathogens: Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus.

Comparative evaluation of pan-fungal real-time PCR, galactomannan and (1-3)-ß-D-glucan assay for invasive fungal infection in paediatric cancer patients.

Limited specific data and investigations are available for the diagnosis of Invasive Fungal Infection (IFI) in paediatrics cancer patients. Three non-invasive tests; Platelia Aspergillus EIA for galactomannan (GM), ß-D-glucan (BDG) assay and pan-fungal real-time PCR for fungal DNA in blood were evaluated. One hundred twenty-five paediatrics cancer patients at the high risk of IFI were enrolled. Single blood and serum samples were evaluated by all the three methods. Patients were classified into 10 proven, 52 probable and 63 no IFI cases in accordance with EORTC MSG 2008 revised guidelines. The sensitivity, specificity, PPV and NPV of all the three tests in proven, probable and no IFIs cases were analysed singly and in combination. The sensitivity, specificity, PPV and NPV of GM, BDG and pan-fungal real-time PCR were: 87%, 61%, 81%, 69.5% for GM, 88%, 59.5%, 81%, 71.4% for BDG and 89%, 69.2%, 85%, 67.5% for PCR (95% CI). Among different combinations, best combination was found to be GM and PCR with sensitivity, specificity, PPV and NPV of 98.2%, 89.3%, 97.1% and 90% respectively. Single samples must be evaluated by combination of tests.

The Road Ahead: Advancing Antifungal Vaccines and Addressing Fungal Infections in the Post-COVID World.

In impoverished nations, the COVID-19 pandemic has led to a widespread occurrence of deadly fungal diseases like mucormycosis. The limited availability of effective antifungal treatments and the emergence of drug-resistant fungal strains further exacerbate the situation. Factors such as systemic steroid use, intravenous drug misuse, and overutilization of broad-spectrum antimicrobials contribute to the prevalence of hospital-acquired infections caused by drug-resistant fungi. Fungal infections exploit compromised immune status and employ intricate mechanisms to evade immune surveillance. The immune response involves the innate and adaptive immune systems, leading to phagocytic and complement-mediated elimination of fungi. However, resistance to antifungals poses a challenge, highlighting the importance of antifungal prophylaxis and therapeutic vaccination. Understanding the host-fungal immunological interactions and developing vaccines are vital in combating fungal infections. Further research is needed to address the high mortality and morbidity associated with multidrug-resistant fungal pathogens and to develop innovative treatment drugs and vaccines. This review focuses on the global epidemiological burden of fungal infections, host-fungal immunological interactions, recent advancements in vaccine development and the road ahead.

ICU care through NGS - Based identification of infectious agents: A comparative study.

Background: Sepsis claims 1 in 5 lives annually as per global statistics. Sepsis incidence in recent studies represents at least 35 % of all ICU admissions and has a high mortality rate, especially in the presence of co-existing morbidities. The challenge has been to accurately diagnose the causative organism, considering factors such as possible polymicrobial infections, commensals and environmental contaminants. Legacy techniques such as culture, automated culture systems or even newer species-specific PCR or film array these challenges difficult to overcome. The Bactfast® and Fungifast® assays along with the integrated workflow is based on next generation sequencing and have the ability to demarcate infecting pathogen from contamination and commensal. The unique ability to pinpoint the exact pathogen, considering the commensal and contamination in a variety of samples, with an extremely high sensitivity could lead it to be a tool of diagnostic choice for non-resolving ICU sepsis due to its comprehensive coverage and speed. The aim of this study was to evaluate the use of Bactfast® and Fungifast® as a last mile diagnostic tool in a ICU setting. Method: This study was carried out considering access to four intensive care units (ICU). Legacy testing, mostly done on culture, was conducted at the various integrated microbiology facilities of the hospitals where the ICUs were located, in Chennai, India. NABL accredited laboratory Micro Genomics (India) Pvt Ltd, was established as the central processing facility for next generation sequencing to run the Bactfast® and Fungifast® assay. Co-relation of results for 490 samples was done retrospectively by a multi-disciplinary team of consultants which comprised of microbiologists, and infectious disease physicians. Result: The diagnostic workflow established with the Bactfast® assay provided a sensitivity of 94.1 % and specificity of 86.6 %. Identification of pathogens in Bactfast® was better when compared to the data published in 2017, as reflected by positive co-relation with clinical confirmation. Although the Fungifast® specificity was high, at 99.4 %, only 12 samples were positive on fungal culture out of 490 samples. Therefore, it was concluded a further study for fungi based on multiple technologies with more true positive samples is required to evaluate the test. Conclusion: Bactfast® can identify pathogens in a sample without any bias. Its introduction as diagnostic modality in life threatening ICU sepsis could reduce mortality and morbidity. Although the initial results of Fungifast® are encouraging a further research is required for more information on test sensitivity.

Vaccines against candidiasis: Status, challenges and emerging opportunity.

Candidiasis is a mycosis caused by opportunistic Candida species. The occurrence of fungal infections has considerably increased in the last few years primarily due to an increase in the number of immune-suppressed individuals. Alarming bloodstream infections due to Candida sp. are associated with a higher rate of morbidity and mortality, and are emerged as major healthcare concerns worldwide. Currently, chemotherapy is the sole available option for combating fungal diseases. Moreover, the emergence of resistance to these limited available anti-fungal drugs has further accentuated the concern and highlighted the need for early detection of fungal infections, identification of novel antifungal drug targets, and development of effective therapeutics and prophylactics. Thus, there is an increasing interest in developing safe and potent immune-based therapeutics to tackle fungal diseases. In this context, vaccine design and its development have a priority. Nonetheless, despite significant advances in immune and vaccine biology over time, a viable commercialized vaccine remains awaited against fungal infections. In this minireview, we enumerate various concerted efforts made till date towards the development of anti-Candida vaccines, an option with pan-fugal vaccine, vaccines in the clinical trial, challenges, and future opportunities.

Immunoproteomic and Immunopeptidomic Analyses of Histoplasma capsulatum Reveal Promiscuous and Conserved Epitopes Among Fungi With Vaccine Potential.

As there are more than 6 million human deaths due to mycoses each year, there is an urgent need to develop fungal vaccines. Moreover, given the similarities among pathogenic fungi, it may be possible to create a multi-fungi vaccine. In this study, we combined immunoproteomic and immunopeptidomic methods, for which we have adapted a technique based on co-immunoprecipitation (Co-IP) that made it possible to map Histoplasma capsulatum epitopes for the first time in a natural context using murine dendritic cells (DCs) and macrophages (Mφ). Although polysaccharide epitopes exist, this research focused on mapping protein epitopes as these are more immunogenic. We used different algorithms to screen proteins and peptides identified by two-dimensional electrophoresis (2-D) and Co-IP. Seventeen proteins were revealed by 2-D gels, and 45 and 24 peptides from distinct proteins were presented by DCs and Mφ, respectively. We then determined which epitopes were restricted to MHC-I and II from humans and mice and showed high promiscuity, but lacked identity with human proteins. The 4 most promising peptides were synthesized, and the peptides with and without incorporation into glucan particles induced CD4+ and CD8+ T cell proliferation and produced a Th1 and Th17 response marked by the secretion of high levels of IFN-γ, IL-17 and IL-2. These epitopes were from heat shock protein 60, enolase, and the ATP-dependent molecular chaperone HSC82, and they each have a high degree of identity with proteins expressed by other medically important pathogenic fungi. Thus, the epitopes described in this study have the potential for use in the development of vaccines that could result in cross-protection among fungal species.

Sterol 14α-Demethylase Ligand-Binding Pocket-Mediated Acquired and Intrinsic Azole Resistance in Fungal Pathogens.

The fungal cytochrome P450 enzyme sterol 14α-demethylase (SDM) is a key enzyme in the ergosterol biosynthesis pathway. The binding of azoles to the active site of SDM results in a depletion of ergosterol, the accumulation of toxic intermediates and growth inhibition. The prevalence of azole-resistant strains and fungi is increasing in both agriculture and medicine. This can lead to major yield loss during food production and therapeutic failure in medical settings. Diverse mechanisms are responsible for azole resistance. They include amino acid (AA) substitutions in SDM and overexpression of SDM and/or efflux pumps. This review considers AA affecting the ligand-binding pocket of SDMs with a primary focus on substitutions that affect interactions between the active site and the substrate and inhibitory ligands. Some of these interactions are particularly important for the binding of short-tailed azoles (e.g., voriconazole). We highlight the occurrence throughout the fungal kingdom of some key AA substitutions. Elucidation of the role of these AAs and their substitutions may assist drug design in overcoming some common forms of innate and acquired azole resistance.

Heat-Killed Yeast as a Pan-Fungal Vaccine.

Fungal infections continue to rise worldwide. Antifungal therapy has long been a mainstay for the treatment of these infections, but often can fail for a number of reasons. These include acquired or innate drug resistance of the causative agent, poor drug penetration into the affected tissues, lack of cidal activity of the drug and drug toxicities that limit therapy. In some instances, such as coccidioidal meningitis, therapy is life-long. In addition, few new antifungal drugs are under development. In light of this information a preventative vaccine is highly desirable. Although numerous investigators have worked toward the development of fungal vaccines, none have become commercially available for use in humans. In the course of our studies, we have discovered that heat-killed yeast (HKY) of Saccharomyces cerevisiae can be used as a vaccine and have shown that it has efficacy in the prevention and reduction of five different fungal infections when used experimentally in mice, which raises the possibility of a pan-fungal vaccine preparation. In our studies we grow S. cerevisiae in broth and heat-kill the organism at 70 ° C for 3 h. The number of dead yeast cells is adjusted and mice are vaccinated subcutaneously beginning 3-7 weeks prior to infection. After infection, efficacy is assessed on the basis of survival and residual burden of the fungus in the target organs. Alternatively, efficacy can be assessed solely on fungal burden at a predetermined time postinfection. Although itself it is unlikely to be moved toward commercialization, HKY can be used a positive control vaccine for studies on specific molecular entities as vaccines, and as a guidepost for the key elements of potential, more purified, pan-fungal vaccine preparations.