Transmission of Cryptococcus neoformans by Organ Transplantation

Short Tandem Repeat Genotyping of Medically Important Fungi: A Comprehensive Review of a Powerful Tool with Extensive Future Potential

Fungal infections pose an increasing threat to public health. New pathogens and changing epidemiology are a pronounced risk for nosocomial outbreaks. To investigate clonal transmission between patients and trace the source, genotyping is required. In the last decades, various typing assays have been developed and applied to different medically important fungal species. While these different typing methods will be briefly discussed, this review will focus on the development and application of short tandem repeat (STR) genotyping. This method relies on the amplification and comparison of highly variable STR markers between isolates. For most common fungal pathogens, STR schemes were developed and compared to other methods, like multilocus sequence typing (MLST), amplified fragment length polymorphism (AFLP) and whole genome sequencing (WGS) single nucleotide polymorphism (SNP) analysis. The pros and cons of STR typing as compared to the other methods are discussed, as well as the requirements for the development of a solid STR typing assay. The resolution of STR typing, in general, is higher than MLST and AFLP, with WGS SNP analysis being the gold standard when it comes to resolution. Although most modern laboratories are capable to perform STR typing, little progress has been made to standardize typing schemes. Allelic ladders, as developed for Aspergillus fumigatus, facilitate the comparison of STR results between laboratories and develop global typing databases. Overall, STR genotyping is an extremely powerful tool, often complimentary to whole genome sequencing. Crucial details for STR assay development, its applications and merit are discussed in this review.

Design of an epitope-based peptide vaccine against Cryptococcus neoformans

Cryptococcus neoformans is the highest-ranked fungal pathogen in the Fungal Priority Pathogens List (FPPL) released by the World Health Organization (WHO). In this study, through in silico simulations, a multi-epitope vaccine against Cryptococcus neoformans was developed using the mannoprotein antigen (MP88) as a vaccine candidate. Following the retrieval of the MP88 protein sequences, these were used to predict antigenic B-cell and T-cell epitopes via the bepipred tool and the artificial neural network, respectively. Conserved B-cell epitopes AYSTPA, AYSTPAS, PASSNCK, and DSAYPP were identified as the most promising B-cell epitopes. While YMAADQFCL, VSYEEWMNY, and FQQRYTGTF were identified as the best candidates for CD8+ T-cell epitopes; and YARLLSLNA, ISYGTAMAV, and INQTSYARL were identified as the most promising CD4+ T-cell epitopes. The vaccine construct was modeled along with adjuvant and peptide linkers and the expasy protparam tool was used to predict the physiochemical properties. According to this, the construct vaccine was predicted to be antigenic, nontoxic, nonallergenic, soluble, stable, hydrophilic, and thermostable. Furthermore, the three-dimensional structure was also used in docking analyses with Toll-like receptor (TLR4). Finally, the cDNA of vaccine was successfully cloned into the E. coli pET-28a (+) expression vector. The results presented here could contribute towards the design of an effective vaccine against Cryptococcus neoformans.

Clinical approach to donor-derived infection in solid organ transplant recipients

Donor-derived infection is an uncommon but potentially devastating complication of solid organ transplantation (SOT). Accurate and timely identification of unexpected infectious disease transmission events has implications not only for the recipient(s) experiencing infection, but also other recipients of organs or tissues from the same donor who may require additional testing or risk mitigation, as well as the broader organ transplant regulatory framework. This narrative review synthesizes data from published reports of symptomatic unexpected donor-derived infections in SOT recipients to provide clinicians with a systematic approach to the evaluation of undifferentiated illnesses that may be of donor origin. Key reasons to consider donor-derived infection include certain microbiologically proven infections in the recipient, especially early after transplant, characteristics of the donor or their management that suggest potential exposure to or infection with specific pathogens prior to organ procurement, and select clinical syndromes that occur in the post-transplant period. Syndromes for which expedited consideration and evaluation of donor-derived infection may be warranted include central nervous system infection, graft or perigraft complications developing in the absence of typical risk factors, and unexplained critical illness/sepsis syndrome in the early post-transplant period. When embarking on an investigation of a suspected donor-derived infection, clinicians should apply knowledge of the entire continuum of the organ procurement and transplant process to ensure unbiased and comprehensive data collection that will facilitate appropriate adjudication of these uncommon but high-consequence events.

Prevalence, treatment, and factors associated with cryptococcal meningitis post introduction of integrase inhibitors antiretroviral based regimens among People Living with HIV in Tanzania

OBJECTIVE

This study aimed to assess the prevalence of Cryptococcal Meningitis (CM), treatment practice, and the associated factors post-introduction of Tenofovir Lamivudine and Dolutegravir (TLD) regimen among People Living with HIV (PLHIV) in Tanzania.

METHODS

This was an analytical cross-sectional study, and the data was collected retrospectively in three public regional referral hospitals (RRHs) in Dar es Salaam, Tanzania. A total of 405 files of the PLHIV admitted in the medical wards on the TLD regimen from January 2019 to December 2022 were reviewed. The collected information includes the patient's demographic characteristics, Cryptococcal status, CD4 level at the time of CM diagnosis, status of using ART, CM treatment approach, and outcome. Data was analyzed using SPSS software version 23.

RESULTS

Out of 405 patients, the majority 267(65.9%) were female, 224(55.3%) were aged between 36-55 years, and 293(72.3%) were married. ART defaulters were found to be 37(9.1%). The prevalence of CM was found to be 48(11.9%), out of which 42(87.5%) received fluconazole alone. ART defaulter and marital status significantly (p-value < 0.05) were associated with those who tested CM positive.

CONCLUSION

The study found the prevalence of CM among PLHIV to be significantly high and the majority were treated with fluconazole alone. ART defaulters and marital status were significantly associated with one being CM positive. Responsible authorities and stakeholders should enforce guideline adherence and PLHIV should be encouraged on medication adherence.

Cryptococcal Meningoencephalitis in Phenotypically Normal Patients

Cryptococcosis is an invasive fungal infection found worldwide that causes significant morbidity and mortality among a broad range of hosts. There are approximately 223,000 new cases of cryptococcosis annually throughout the world, and at least 180,000 deaths are attributed to this infection each year. Most of these are due to complications of cryptococcal meningoencephalitis among HIV-infected patients in resource-limited environments. The majority of individuals diagnosed with cryptococcosis have underlying conditions associated with immune dysfunction such as HIV, solid organ transplant, hematologic malignancy, organ failure syndromes, and/or the use of immunosuppressive agents such as glucocorticosteroids and biologic agents. In most clinical series, there is a small proportion of patients with cryptococcosis who are phenotypically normal; that is, they have no clinically obvious predisposition to disease. Cryptococcal meningoencephalitis (CME) presentation and management differ substantially between these normal individuals and their immunocompromised counterparts. In this review, we will focus on CME in the phenotypically normal host and underscore differences in the clinical presentation, management, outcome, and potential risk factors for these patients compared to immunocompromised persons who develop this potential devastating invasive fungal infection.

Cryptococcal Laryngitis: Three Cases Managed With Potassium-Titanyl-Phosphate Laser and Literature Review

OBJECTIVES

To present three case reports of cryptococcal laryngitis managed with potassium-titanyl-phosphate (KTP) laser, where only one case managed with KTP laser has previously been published to date to our knowledge. Further, to systematically review the medical literature and describe the epidemiology, clinical assessment, treatment, and prognosis of laryngeal cryptococcosis.

METHODS

The PubMed, Embase, and OVID MEDLINE databases were searched using the terms "cryptococcal laryngitis" or "cryptococcus" and "larynx or laryngeal."

RESULTS

Thirty-eight cases were identified. The median age was 65 years with a 1 male:1.2 female ratio. Thirty-six cases (95%) presented with hoarseness. Twenty-one cases (55%) were systemically immunosuppressed and 19 (50%) were taking an inhaled corticosteroid. This paper lists the five clinical features (i. white exudate or lesion; ii. exophytic, verrucous or tumor-like mass; iii. diffuse erythema; iv. mucosal irregularity; v. thickened vocal fold) and four pathologic features or tests (i. Grocott Gomori Methenamine stain; ii. Mucicarmine stain; iii. fungal or yeast organisms; iv. fungal culture) that encompass 97% of cases of cryptococcal laryngitis reported in the medical literature. In 34 cases (89%), antifungal therapy was given. Four cases (11%) had excisional biopsy and 11 (29%) received combined surgery and medical therapy. There was uncomplicated resolution in 24 cases (63%).

CONCLUSION

Cryptococcal laryngitis is a rare cause of hoarseness that may be mistaken for malignancy or may be a manifestation of disseminated cryptococcal infection or underlying immunosuppression. Clinicians should be aware of the diagnostic features of cryptococcal laryngitis to facilitate diagnosis and treatment to prevent complicated disease and overly aggressive treatment.

Nanotechnology-Based Strategies to Combat Multidrug-Resistant Candida auris Infections

An emerging multidrug-resistant pathogenic yeast called Candida auris has a high potential to spread quickly among hospitalized patients and immunodeficient patients causing nosocomial outbreaks. It has the potential to cause pandemic outbreaks in about 45 nations with high mortality rates. Additionally, the fungus has become resistant to decontamination techniques and can survive for weeks in a hospital environment. Nanoparticles might be a good substitute to treat illnesses brought on by this newly discovered pathogen. Nanoparticles have become a trend and hot topic in recent years to combat this fatal fungus. This review gives a general insight into the epidemiology of C. auris and infection. It discusses the current conventional therapy and mechanism of resistance development. Furthermore, it focuses on nanoparticles, their different types, and up-to-date trials to evaluate the promising efficacy of nanoparticles with respect to C. auris.

Pulmonary Cryptococcosis

Pulmonary cryptococcosis describes an invasive lung mycosis caused by Cryptococcus neoformans or Cryptococcus gattii complex. It is often a high-consequence disease in both immunocompromised and immunocompetent populations, and may be misdiagnosed as pulmonary malignancy, leading to a delay in therapy. Epidemiology follows that of cryptococcal meningoencephalitis, with C. gattii infection more common in certain geographic regions. Diagnostic tools include histopathology, microscopy and culture, and the detection of cryptococcal polysaccharide antigen or Cryptococcus-derived nucleic acids. All patients with lung cryptococcosis should have a lumbar puncture and cerebral imaging to exclude central nervous system disease. Radiology is key, both as an adjunct to laboratory testing and as the initial means of detection in asymptomatic patients or those with non-specific symptoms. Pulmonary cryptococcomas (single or multiple) may also be associated with disseminated disease and/or cryptococcal meningitis, requiring prolonged treatment regimens. Optimal management for severe disease requires extended induction (amphotericin B and flucytosine) and consolidation therapy (fluconazole) with close clinical monitoring. Susceptibility testing is of value for epidemiology and in regions where relatively high minimum inhibitory concentrations to azoles (particularly fluconazole) have been noted. Novel diagnostic tools and therapeutic agents promise to improve the detection and treatment of cryptococcosis, particularly in low-income settings where the disease burden is high.

Kidney Transplantation From Deceased Donors With Bloodstream Infection: A Multicenter Retrospective Study

BACKGROUND

The use of organs from donors with infection is limited because of the possibility of transmission. We aimed to investigate the transmission after deceased donor transplantation with bloodstream infection (BSI).

METHODS

A retrospective study of patients undergoing kidney or pancreas transplantation at five tertiary centers in Korea from January 2009 and November 2019 was performed. We analyzed the outcomes after transplantation from deceased donors with BSI.

RESULTS

Eighty-six recipients received transplantation from 69 donors with BSI. The most common isolated pathogens from donors were Gram-positive bacteria (72.0%), followed by Gram-negative bacteria (22.7%), and fungi (5.3%). Appropriate antimicrobial agents were used in 47.8% of donors before transplantation. Transmission occurred only in 1 of 83 recipients (1.2%) from bacteremic donors and 1 of 6 recipients (16.7%) from fungemic donors. One-year patient and graft survival was 97.5%and 96.3%, respectively. There was no significant difference in graft and patient survival between patients who received organs from infected donors and noninfected donors.

CONCLUSION

Using organs from donors with bacteremia seems to be a safe option with low transmission risk. The overall prognosis of using organs from donors with BSI is favorable.

Donor-derived Cryptococcus gattii sensu stricto infection in two kidney transplant recipients, southeastern United States

Cryptococcus gattii infection is a rare cause of severe pulmonary disease and meningoencephalitis that has only recently been detected in the southeastern United States. We describe an organ transplant-associated outbreak of C. gattii infection involving an HIV-negative immunosuppressed donor in this region who died following new-onset headache and seizure of unknown cause. Retrospective cryptococcal antigen (CrAg) testing of donor serum was positive. Two of the three transplant recipients developed severe C. gattii infection 11 and 12 weeks following transplantation. One recipient died from severe pulmonary infection, identified on autopsy, and the other ill recipient survived following treatment for cryptococcal meningitis. This outbreak underscores the importance of considering cryptococcosis in patients with clinical findings suggestive of subacute meningitis or other central nervous system (CNS) pathology, and the potential benefit of routine pre-transplant donor CrAg screening using lateral flow assay to guide recipient antifungal prophylaxis. The case also adds to emerging evidence that C. gattii is a potential threat in the southeastern United States.

Striking Back against Fungal Infections: The Utilization of Nanosystems for Antifungal Strategies

Fungal infections have become a major health concern, given that invasive infections by Candida, Cryptococcus, and Aspergillus species have led to millions of mortalities. Conventional antifungal drugs including polyenes, echinocandins, azoles, allylamins, and antimetabolites have been used for decades, but their limitations include off-target toxicity, drug-resistance, poor water solubility, low bioavailability, and weak tissue penetration, which cannot be ignored. These drawbacks have led to the emergence of novel antifungal therapies. In this review, we discuss the nanosystems that are currently utilized for drug delivery and the application of antifungal therapies.

Donor-Derived Transmission of Cryptococcus gattii sensu lato in Kidney Transplant Recipients

We describe cases of donor-derived transmission of Cryptococcus deuterogattii in 2 kidney transplant recipients in Brazil and published information on other cases. Prompt reduction of immunosuppression and initiation of antifungal therapy was required to successfully control the fungal infections and preserve engraftment.

Cryptococcosis

Cryptococcosis is an invasive fungal infection of global significance caused by yeasts of the genus Cryptococcus. The prevalence of HIV in certain areas of the world and the expanding population of immunocompromised patients contribute to the ongoing global disease burden. Point-of-care serologic testing has allowed for more rapid diagnosis and implementation of screening programs in resource-limited settings. Management involves therapy aimed at reduction in fungal burden, maintenance of intracranial pressure, and optimization of host immunity. Despite diagnostic and therapeutic advances, cryptococcosis continues to be a disease with unacceptably high incidence and mortality, particularly in resource-limited settings.

Cryptococcus transmission through solid organ transplantation in the United States: A report from the Ad Hoc Disease Transmission Advisory Committee

Cryptococcus species can cause serious life-threatening infection in solid organ transplant recipients by reactivation of prior infection, posttransplant de novo infection, or donor transmission from the transplanted organ. Although previously reported in the literature, the extent of donor-derived cryptococcosis in the United States has not been documented. We analyzed potential donor-derived Cryptococcus transmission events reported to the Organ Procurement and Transplantation Network (OPTN) for investigation by the Ad Hoc Disease Transmission Advisory Committee (DTAC). All reports between 2009 and 2019 in which transmission to recipients was designated proven or probable, or determined to be averted due to implementation of prophylaxis (intervention without disease transmission-"IWDT") were included. During 2009-2019, 58 reports of potential donor-derived cryptococcosis were submitted to DTAC. Among these reports, 12 donors were determined to have resulted in proven or probable transmission to 23/34 (67.6%) recipients. Most of these donors (10/12 [83%]) exhibited central nervous system-related symptoms prior to death and 5/23 (22%) infected recipients died. For 11 different donors, prophylaxis, most often with fluconazole, was administered to 23/35 (65.7%) recipients. Clinicians should maintain awareness of donor-derived cryptococcosis and consider prompt prophylaxis or treatment followed by reporting to OPTN for further investigation.

Dormancy in Cryptococcus neoformans: 60 years of accumulating evidence

Cryptococcus neoformans is an opportunistic yeast that is present worldwide and interacts with various organisms. In humans, it is responsible for cryptococcosis, a deadly invasive fungal infection that represents around 220,000 cases per year worldwide. Starting from the natural history of the disease in humans, there is accumulating evidence on the capacity of this organism to enter dormancy. In response to the harsh host environment, the yeast is able to adapt dramatically and escape the vigilance of the host's immune cells to survive. Indeed, the yeast exposed to the host takes on pleiotropic phenotypes, enabling the generation of populations in heterogeneous states, including dormancy, to eventually survive at low metabolic cost and revive in favorable conditions. The concept of dormancy has been validated in C. neoformans from both epidemiological and genotyping data, and more recently from the biological point of view with the characterization of dormancy through the description of viable but nonculturable cells.

Genotypic diversity and antifungal susceptibility of environmental isolates of Cryptococcus neoformans from the Yangtze River Delta region of East China

Although cryptococcosis is widely recognized as infection by Cryptococcus neoformans sensu lato from environmental sources, information concerning the characteristics of environmental isolates of C. neoformans s. l. and how they are related to clinical isolates is very limited, especially in East China. In this study, 61 environmental isolates of C. neoformans were recovered from pigeon (Columba livia) droppings from the Yangtze River Delta region of East China. These isolates were genotyped using the ISHAM-MLST consensus scheme and their antifungal drug susceptibilities were determined following the CLSI M27-A3 guidelines. The 61 isolates were found belonging to 13 sequence types (STs), including several novel STs such as ST254 and ST194. The dominant ST in this environmental sample was ST31, different from that of clinical strains (ST5) in this region. Azole-resistance, such as fluconazole (FLU)-resistance, was observed among our environmental C. neoformans isolates. The findings of this study expand our understanding of ecological niches, population genetic diversity, and azole-resistance characteristics of the yeast in East China. Our research lays the foundation for further comparative analysis the potential mechanisms for the observed differences between environmental and clinical populations of C. neoformans in China.

LAY SUMMARY

Cryptococcosis is widely recognized as infection by Cryptococcus neoformans sensu lato from environmental sources. However, there is currently limited information about the genetic diversity and antifungal susceptibility of environmental C. neoformans s. l. isolates, including how they may differ from clinical samples. In this study, we collected 61 environmental C. neoformans isolates from domestic pigeon droppings from the Yangtze River Delta region of East China. These isolates were genotyped using multi-locus sequencing. We found a high genotypic diversity in this population of C. neoformans, with several novel genotypes and a distribution of genotypes different from that of clinical strains in this region. Azole-resistance, such as fluconazole (FLU)-resistance, was observed among our environmental C. neoformans isolates. The findings of this study expand our understanding of ecological niches, genetic diversity, and azole-resistance characteristics of the yeast in East China. Our research lays the foundation for phylogenomic analysis investigating why and how disparate population structures of C. neoformans isolates formed between environmental and clinical sources in the region.

Transmission of cryptococcosis by liver transplantation: A case report and review of literature

BACKGROUND

Cryptococcosis is a fungal infection caused by the yeast-like encapsulated basidiomycetous fungus of the Cryptococcus neoformans (C. neoformans) species complex. These fungi are ubiquitous in soil and bird droppings, and infection by them is an important global health concern, particularly in immunosuppressed patients, such as organ transplant recipients and those infected by the human immunodeficiency virus. The fungus usually enters the body through the respiratory tract, but extremely rare cases of infection acquired by transplantation of solid organs have been reported.

CASE SUMMARY

We report a case of disseminated cryptococcosis in a liver transplant recipient, diagnosed 2 wk after the procedure. The patient initially presented with fever, hyponatremia and elevated transaminase levels, manifesting intense headache after a few days. Blood cultures were positive for C. neoformans. Liver biopsy showed numerous fungal elements surrounded by gelatinous matrix and sparse granulomatous formations. Magnetic resonance imaging of the brain showed multiple small lesions with low signal in T2, peripheric enhancement and edematous halo, diffuse through the parenchyma but more concentrated in the subcortical regions. Treatment with amphotericin B for 3 wk, followed by maintenance therapy with fluconazole, led to complete resolution of the symptoms. The recipients of both kidneys from the same donor also developed disseminated cryptococcosis, confirming the transplant as the source of infection. The organ donor lived in a rural area, surrounded by tropical rainforest, and had negative blood cultures prior to organ procurement.

CONCLUSION

This case highlights the risk of transmission of fungal diseases, specifically of C. neoformans, through liver graft during liver transplantation.

Pathogen and host genetics underpinning cryptococcal disease

Cryptococcosis is a severe fungal disease causing 220,000 cases of cryptococcal meningitis yearly. The etiological agents of cryptococcosis are taxonomically grouped into at least two species complexes belonging to the genus Cryptococcus. All of these yeasts are environmentally ubiquitous fungi (often found in soil, leaves and decaying wood, tree hollows, and associated with bird feces especially pigeon guano). Infection in a range of animals including humans begins following inhalation of spores or aerosolized yeasts. Recent advances provide fundamental insights into the factors from both the pathogen and its hosts which influence pathogenesis and disease. The complex interactions leading to disease in mammalian hosts have also updated from the availability of better genomic tools and datasets. In this review, we discuss recent genetic research on Cryptococcus, covering the epidemiology, ecology, and evolution of Cryptococcus pathogenic species. We also discuss the insights into the host immune response obtained from the latest genetic modified host models as well as insights from monogenic disorders in humans. Finally we highlight outstanding questions that can be answered in the near future using bioinformatics and genomic tools.

Very early-onset of Cryptococcus neoformans disease following liver transplantation: Report of two cases and a review of the literature

Cryptococcosis is the third most common invasive fungal infection following solid organ transplantation, and mortality is high. Most cases occur late and are due to reactivation of latent infection; however, very early reactivation and donor-derived transmission can occur. Routine screening pre-transplant and antifungal prophylaxis for cryptococcosis post-transplant in solid organ transplantation are not standard practice. We present two cases of very early-onset Cryptococcus neoformans disease following liver transplantation to highlight the need to consider individualized pre-transplant screening and be aware that reactivation of Cryptococcosis neoformans can occur in the immediate post-transplant period.

Cryptococcosis in Patients following Kidney Transplantation: A 9-Year Retrospective Clinical Analysis at a Chinese Tertiary Hospital

Background

Cryptococcosis following kidney transplantation (KT) is rare but is associated with considerably increased risk of mortality. At present, data on the association between cryptococcosis and KT in mainland China remain relatively limited.

Objectives

This study aims to review our experience related to the management of cryptococcosis following KT at a Chinese tertiary hospital.

Methods

All patients with cryptococcosis following KT admitted to our hospital from January 2010 to December 2018 were reviewed.

Results

A total of 37 patients with cryptococcosis were enrolled (males: 62.2%). The mean age of the patients was 49.5 ± 9.38 (20-64) years. The average time to infection following KT was 7.0 ± 5.50 years (5 months to 21 years), and 30 patients (81.1%) had cryptococcosis onset >2 years following transplantation. The most common site of infection was the central nervous system, followed by the pulmonary system and skin. Most patients received fluconazole or voriconazole with or without flucytosine as their initial treatment regimen at our hospital. The 2-week mortality rate was 8.1% (3/37), and five patients (13.5%) died within 6 months of being diagnosed with cryptococcosis. Remarkably, all patients who received high-dose fluconazole (800 mg daily) or voriconazole ± flucytosine survived.

Conclusions

Cryptococcosis in kidney transplant recipients is typically a late-occurring infection, with most patients having cryptococcosis onset >2 years following KT at our hospital. The central nervous system, pulmonary system, and skin are the main sites of infection. Voriconazole or high-dose fluconazole can be used as an alternative therapy for post-KT cryptococcosis.

Cryptococcus neoformans Recovered From Olive Trees (Olea europaea) in Turkey Reveal Allopatry With African and South American Lineages

Cryptococcus species are life-threatening human fungal pathogens that cause cryptococcal meningoencephalitis in both immunocompromised and healthy hosts. The natural environmental niches of Cryptococcus include pigeon (Columba livia) guano, soil, and a variety of tree species such as Eucalyptus camaldulensis, Ceratonia siliqua, Platanus orientalis, and Pinus spp. Genetic and genomic studies of extensive sample collections have provided insights into the population distribution and composition of different Cryptococcus species in geographic regions around the world. However, few such studies examined Cryptococcus in Turkey. We sampled 388 Olea europaea (olive) and 132 E. camaldulensis trees from seven locations in coastal and inland areas of the Aegean region of Anatolian Turkey in September 2016 to investigate the distribution and genetic diversity present in the natural Cryptococcus population. We isolated 84 Cryptococcus neoformans strains (83 MATα and 1 MAT a) and 3 Cryptococcus deneoformans strains (all MATα) from 87 (22.4% of surveyed) O. europaea trees; a total of 32 C. neoformans strains were isolated from 32 (24.2%) of the E. camaldulensis trees, all of which were MATα. A statistically significant difference was observed in the frequency of C. neoformans isolation between coastal and inland areas (P < 0.05). Interestingly, the MAT a C. neoformans isolate was fertile in laboratory crosses with VNI and VNB MATα tester strains and produced robust hyphae, basidia, and basidiospores, thus suggesting potential sexual reproduction in the natural population. Sequencing analyses of the URA5 gene identified at least five different genotypes among the isolates. Population genetics and genomic analyses revealed that most of the isolates in Turkey belong to the VNBII lineage of C. neoformans, which is predominantly found in southern Africa; these isolates are part of a distinct minor clade within VNBII that includes several isolates from Zambia and Brazil. Our study provides insights into the geographic distribution of different C. neoformans lineages in the Mediterranean region and highlights the need for wider geographic sampling to gain a better understanding of the natural habitats, migration, epidemiology, and evolution of this important human fungal pathogen.

Intranasal Inoculation of Cryptococcus neoformans in Mice Produces Nasal Infection with Rapid Brain Dissemination

Cryptococcus neoformans is an important fungal pathogen, causing life-threatening pneumonia and meningoencephalitis. Brain dissemination of C. neoformans is thought to be a consequence of an active infection in the lung which then extravasates to other sites. Brain invasion results from dissemination via either transport by free yeast cells in the bloodstream or Trojan horse transport within mononuclear phagocytes. We assessed brain dissemination in three mouse models of infection: intravenous, intratracheal, and intranasal models. All three modes of infection resulted in dissemination of C. neoformans to the brain in less than 3 h. Further, C. neoformans was detected in the entirety of the upper respiratory tract and the ear canals of mice. In recent years, intranasal infection has become a popular mechanism to induce pulmonary infection because it avoids surgery, but our findings show that instillation of C. neoformans produces cryptococcal nasal infection. These findings imply that immunological studies using intranasal infection should assume that the initial sites of infection of infection are brain, lung, and upper respiratory tract, including the nasal airways.IMPORTANCECryptococcus neoformans causes an estimated 181, 000 deaths each year, mostly associated with untreated HIV/AIDS. C. neoformans has a ubiquitous worldwide distribution. Humans become infected from exposure to environmental sources, after which the fungus lays dormant within the human body. Upon AIDS-induced immunosuppression or therapy-induced immunosuppression (required for organ transplant recipients or those suffering from autoimmune disorders), cryptococcal disease reactivates and causes life-threatening meningitis and pneumonia. This study showed that upon contact with the host, C. neoformans can quickly (a few hours) reach the host brain and also colonizes the nose of infected animals. Therefore, this work paves the way to better knowledge of how C. neoformans travels through the host body. Understanding how C. neoformans infects, disseminates, and survives within the host is critically required so that we can prevent infections and the disease caused by this deadly fungus.

Central Nervous System Cryptococcal Infections in Non-HIV Infected Patients

Central nervous system (CNS) cryptococcosis in non-HIV infected patients affects solid organ transplant (SOT) recipients, patients with malignancy, rheumatic disorders, other immunosuppressive conditions and immunocompetent hosts. More recently described risks include the use of newer biologicals and recreational intravenous drug use. Disease is caused by Cryptococcus neoformans and Cryptococcus gattii species complex; C. gattii is endemic in several geographic regions and has caused outbreaks in North America. Major virulence determinants are the polysaccharide capsule, melanin and several ‘invasins’. Cryptococcal plb1, laccase and urease are essential for dissemination from lung to CNS and crossing the blood–brain barrier. Meningo-encephalitis is common but intracerebral infection or hydrocephalus also occur, and are relatively frequent in C. gattii infection. Complications include neurologic deficits, raised intracranial pressure (ICP) and disseminated disease. Diagnosis relies on culture, phenotypic identification methods, and cryptococcal antigen detection. Molecular methods can assist. Preferred induction antifungal therapy is a lipid amphotericin B formulation (amphotericin B deoxycholate may be used in non-transplant patients) plus 5-flucytosine for 2–6 weeks depending on host type followed by consolidation/maintenance therapy with fluconazole for 12 months or longer. Control of raised ICP is essential. Clinicians should be vigilant for immune reconstitution inflammatory syndrome.

How Environmental Fungi Cause a Range of Clinical Outcomes in Susceptible Hosts

Environmental fungi are globally ubiquitous and human exposure is near universal. However, relatively few fungal species are capable of infecting humans, and among fungi, few exposure events lead to severe systemic infections. Systemic infections have mortality rates of up to 90%, cost the US healthcare system $7.2 billion annually, and are typically associated with immunocompromised patients. Despite this reputation, exposure to environmental fungi results in a range of outcomes, from asymptomatic latent infections to severe systemic infection. Here we discuss different exposure outcomes for five major fungal pathogens: Aspergillus, Blastomyces, Coccidioides, Cryptococcus, and Histoplasma species. These fungi include a mold, a budding yeast, and thermal dimorphic fungi. All of these species must adapt to dramatically changing environments over the course of disease. These dynamic environments include the human lung, which is the first exposure site for these organisms. Fungi must defend themselves against host immune cells while germinating and growing, which risks further exposing microbe-associated molecular patterns to the host. We discuss immune evasion strategies during early infection, from disruption of host immune cells to major changes in fungal cell morphology.

Cryptococcosis in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of cryptococcosis in the pre- and post-transplant period. The current update now includes a discussion of cryptococcosis, which is the third most common invasive fungal infection in SOT recipients. Infection often occurs a year after transplantation; however, early infections occur and donor-derived infections have been described within 3 months after transplant. There are two main species that cause infection, Cryptococcus neoformans and C gattii. Clinical onset may be insidious, but headaches, fevers, and mental status changes should warrant diagnostic testing. The lateral flow cryptococcal antigen assay is now the preferred test from serum and cerebrospinal fluid due to its rapidity, accuracy, and cost. A lumbar puncture with measurement of opening pressure is recommended for patients with suspected or proven cryptococcosis. Lipid amphotericin B plus 5-flucytosine is used as initial treatment of meningitis, disseminated infection, and moderate-to-severe pulmonary infection, followed by fluconazole as consolidation therapy. Fluconazole is effective for mild-to-moderate pulmonary infection. Immunosuppression reduction as part of management may lead to immune reconstitution syndrome that may resemble active disease.

Disseminated Cryptococcosis After Liver Transplant: A Case Report

Cryptococcosis is an opportunistic infection caused by the Basidiomycota Cryptococcus neoformans (Cryptococcus gattii), which affects immunosuppressed patients and less frequently immunocompetent patients. Solid-organ transplant recipients are a particularly high-risk group, depending on the net state of immunosuppression. In these patients, the infection usually appears after the first year after transplant, although it may occur earlier in liver transplant recipients. In most cases, the infection is secondary to the reactivation of a latent infection, although it may be due to an unidentified pretransplant infection by primary infection. Less frequently, it may be transmitted by the graft. The lung and central nervous system are most frequently involved. Extrapulmonary involvement is seen in 75% of the cases, and disseminated disease occurs in 61%, with mortality ranging from 17% to 50% when the central nervous system is involved. Here, we report a case of disseminated cryptococcosis (lymphadenitis, meningitis, pulmonary nodules, and possibly sacroiliitis) in a patient after liver transplant, with good clinical and microbiological outcomes and without relapse.

Infectious Disease Transmission in Solid Organ Transplantation: Donor Evaluation, Recipient Risk, and Outcomes of Transmission

In 2016, the Transplantation Society of Australia and New Zealand, with the support of the Australian Government Organ and Tissue authority, commissioned a literature review on the topic of infectious disease transmission from deceased donors to recipients of solid organ transplants. The purpose of this review was to synthesize evidence on transmission risks, diagnostic test characteristics, and recipient management to inform best-practice clinical guidelines. The final review, presented as a special supplement in Transplantation Direct, collates case reports of transmission events and other peer-reviewed literature, and summarizes current (as of June 2017) international guidelines on donor screening and recipient management. Of particular interest at the time of writing was how to maximize utilization of donors at increased risk for transmission of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, given the recent developments, including the availability of direct-acting antivirals for hepatitis C virus and improvements in donor screening technologies. The review also covers emerging risks associated with recent epidemics (eg, Zika virus) and the risk of transmission of nonendemic pathogens related to donor travel history or country of origin. Lastly, the implications for recipient consent of expanded utilization of donors at increased risk of blood-borne viral disease transmission are considered.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Design of an epitope-based peptide vaccine againstCryptococcus neoformans.. [DOI: 10.1101/434779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Introduction

This study aimed to design an immunogenic epitope for Cryptococcus neoformans the etiological agent of cryptococcosis using in silico simulations, for epitope prediction, we selected the mannoprotein antigen MP88 which it’s known to induce protective immunity.

Material & method

A total of 39 sequences of MP88 protein with length 378 amino acids were retrieved from the National Center for Biotechnology Information database (NCBI) in the FASTA format were used to predict antigenic B-cell and T cell epitopes via different bioinformatics tools at Immune Epitope Database and Analysis Resource (IEDB). The tertiary structure prediction of MP88 was created in RaptorX, and visualized by UCSF Chimera software.

Result

A Conserved B-cell epitopesAYSTPA, AYSTPAS, PASSNCK, and DSAYPPhave displayed the most promising B cell epitopes. While theYMAADQFCL, VSYEEWMNYandFQQRYTGTFthey represent the best candidates T-cell conserved epitopes, the 9-mer epitopeYMAADQFCLdisplay the greater interact with 9 MHC-I alleles and HLA-A*02:01 alleles have the best interaction with an epitope. TheVSYEEWMNYandFQQRYTGTFthey are non-allergen whileYMAADQFCLwas an allergen. For MHC class II peptide binding prediction, theYARLLSLNA, ISYGTAMAVandINQTSYARLrepresent the most Three highly binding affinity core epitopes. The core epitopeINQTSYARLwas found to interact with 14 MHC-II. The allergenicity prediction revealsISYGTAMAV, INQTSYARLwere non-allergen andYARLLSLNAwas an allergen. Regarding population coverage theYMAADQFCLexhibit, a higher percentage among the world (69.75%) and the average population coverage was93.01%.In MHC-II,ISYGTAMAVepitope reveal a higher percentage (74.39%) and the average population coverage was (81.94%). This successfully designed a peptide vaccine against Cryptococcus neoformans open up a new horizon in Cryptococcus neoformans research; the results require validation by in vitro and in vivo experiments.

Solving the mystery: Hyalinized cyst wall containing organism-like structures in a lung transplant donor

A 59-year-old man with non-ischemic cardiomyopathy underwent orthotopic heart transplantation. The donor, a 31-year-old male declared brain dead after a gunshot wound to the head, was considered high risk due to history of incarceration, illicit drug use, and sex with a HIV-positive partner. At organ procurement, the heart, kidneys, pancreas, and liver looked grossly normal. A small right lower lobe nodule was noticed, and lung biopsy was performed. Bronchoscopy showed purulent secretions in the right lower lobe. Images from pathology are presented. Lung biopsy confirmed the presence of hyalinized cyst wall containing organism-like structures. A combination of culture, microscopic morphology, and gene sequencing was used to identify the causative organism. The patient and all other organ recipients received appropriate antifungal prophylaxis and remain asymptomatic 6 months post-transplant.

Intensive Care of Pulmonary Complications Following Liver Transplantation

Chronic liver disease has been associated with pulmonary dysfunction both before and after liver transplantation. Post-liver transplantation pulmonary complications can affect both morbidity and mortality often necessitating intensive care during the immediate postoperative period. The major pulmonary complications include pneumonia, pleural effusions, pulmonary edema, and atelectasis. Poor clinical outcomes have been known to be associated with age, severity of liver dysfunction, and preexisting lung disease as well as perioperative events related to fluid balance, particularly transfusion and fluid volumes. Delineating each and every one of these pulmonary complications and their associated risk factors becomes paramount in guiding specific therapeutic strategies.

Cryptococcal disease in the solid organ transplant setting: review of clinical aspects with a discussion of asymptomatic cryptococcal antigenemia

PURPOSE OF REVIEW

Cryptococcal infections are an important cause of morbidity and mortality in solid organ transplant patients. Here, we review the microbiology, epidemiology, clinical course, treatment, and outcomes of Cryptococcus in solid organ transplant recipients.

RECENT FINDINGS

We identify the unique findings in solid organ transplant patients when compared to other immunocompromised patients such as those with HIV. We also describe our experience and outcomes with regard to solid organ transplant patients who do not have positive fungal cultures, but cryptococcal antigen positivity and concern for cryptococcal disease.

SUMMARY

Our review will highlight the importance of these new diagnostic techniques in those with Cryptococcus and solid organ transplant, which will be the subject of new research.

Nutritional Requirements and Their Importance for Virulence of Pathogenic Cryptococcus Species

Cryptococcus sp. are basidiomycete yeasts which can be found widely, free-living in the environment. Interactions with natural predators, such as amoebae in the soil, are thought to have promoted the development of adaptations enabling the organism to survive inside human macrophages. Infection with Cryptococcus in humans occurs following inhalation of desiccated yeast cells or spore particles and may result in fatal meningoencephalitis. Human disease is caused almost exclusively by the Cryptococcus neoformans species complex, which predominantly infects immunocompromised patients, and the Cryptococcus gattii species complex, which is capable of infecting immunocompetent individuals. The nutritional requirements of Cryptococcus are critical for its virulence in animals. Cryptococcus has evolved a broad range of nutrient acquisition strategies, many if not most of which also appear to contribute to its virulence, enabling infection of animal hosts. In this review, we summarise the current understanding of nutritional requirements and acquisition in Cryptococcus and offer perspectives to its evolution as a significant pathogen of humans.

Successful multiple organ donation after donor brain death due to Actinomyces israelii meningitis

The increasing gap between availability of solid organs for transplantation and the demand has led to the inclusion of donor organs that, according to current guidelines, may be discarded, some of them because of the possibility for transmission of infection to the recipients. We present the first report, to the best of our knowledge, of a case of a brain-dead donor with a localized and treated Actinomyces israelii central nervous system infection who, after a thorough evaluation, provided organs for successful transplant procedures in four recipients. There was no evidence of transmission of infection within a 6-month follow-up. Relative contraindications must be individualized in order to expand the number of real organ donors, emphasizing caution in rare causes for brain death in which patients should be thoroughly evaluated for possible donation.

Progressive cutaneous Cryptococcosis complicated with meningitis in a myasthenia gravis patient on long-term immunosuppressive therapy - a case report

BACKGROUND

Cryptococcosis is an opportunistic infection caused by the encapsulated yeast Cryptococcus neoformans and most remarkably manifests in HIV-infected individuals, especially in the settings of very low CD4 count. Development of cryptococcosis in HIV-uninfected individuals is exceedingly rare and usually signifies a marked immunodeficiency. Cryptococcosis in association with myasthenia gravis or thymoma has been previously documented in only very few cases in the literature.

CASE PRESENTATION

We reported a complicated case of severe cutaneous cryptococcosis in a 39-year-old Vietnamese male patient with myasthenia gravis on long-term immunosuppressive therapy. The patient presented with a five month history of recurrent and progressive skin lesions that later on progressed into cryptococcal meningitis.

CONCLUSION

Through this case, we aimed to emphasize the importance of including cutaneous cryptococcosis in the differential diagnosis of cutaneous lesions in patients on chronic immunosuppressive therapy. The cutaneous manifestations of cryptococcosis can be the first clue for a disseminated disease, which makes early recognition crucial and life-saving.

Guidelines for the assessment and acceptance of potential brain-dead organ donors

Organ transplantation is the only alternative for many patients with terminal diseases. The increasing disproportion between the high demand for organ transplants and the low rate of transplants actually performed is worrisome. Some of the causes of this disproportion are errors in the identification of potential organ donors and in the determination of contraindications by the attending staff. Therefore, the aim of the present document is to provide guidelines for intensive care multi-professional staffs for the recognition, assessment and acceptance of potential organ donors.

Integrated therapy for HIV and cryptococcosis

Cryptococcosis has been one of the most common opportunistic infections and causes of mortality among HIV-infected patients, especially in resource-limited countries. Cryptococcal meningitis is the most common form of cryptococcosis. Laboratory diagnosis of cryptococcosis includes direct microscopic examination, isolation of Cryptococcus from a clinical specimen, and detection of cryptococcal antigen. Without appropriate treatment, cryptococcosis is fatal. Early diagnosis and treatment is the key to treatment success. Treatment of cryptococcosis consists of three main aspects: antifungal therapy, intracranial pressure management for cryptococcal meningitis, and restoration of immune function with antiretroviral therapy (ART). Optimal integration of these three aspects is crucial to achieving successful treatment and reducing the mortality. Antifungal therapy consists of three phases: induction, consolidation, and maintenance. A combination of two drugs, i.e. amphotericin B plus flucytosine or fluconazole, is preferred in the induction phase. Fluconazole monotherapy is recommended during consolidation and maintenance phases. In cryptococcal meningitis, intracranial pressure rises along with CSF fungal burden and is associated with morbidity and mortality. Aggressive control of intracranial pressure should be done. Management options include therapeutic lumbar puncture, lumbar drain insertion, ventriculostomy, or ventriculoperitoneal shunt. Medical treatment such as corticosteroids, mannitol, and acetazolamide are ineffective and should not be used. ART has proven to have a great impact on survival rates among HIV-infected patients with cryptococcosis. The time to start ART in HIV-infected patients with cryptococcosis has to be deferred until 5 weeks after the start of antifungal therapy. In general, any effective ART regimen is acceptable. Potential drug interactions between antiretroviral agents and amphotericin B, flucytosine, and fluconazole are minimal. Of most potential clinical relevance is the concomitant use of fluconazole and nevirapine. Concomitant use of these two drugs should be cautious, and patients should be monitored closely for nevirapine-associated adverse events, including hepatotoxicity. Overlapping toxicities of antifungal and antiretroviral drugs and immune reconstitution inflammatory syndrome are not uncommon. Early recognition and appropriate management of these consequences can reinforce the successful integrated therapy in HIV-infected patients with cryptococcosis.

Cryptococcal osteomyelitis of the skull in a liver transplant patient

Cryptococcus neoformans is an opportunistic fungal pathogen and an important cause of morbidity and mortality in immunocompromised patients. We report a case of osteomyelitis caused by C. neoformans in a liver transplant recipient who presented with a headache and scalp lump after sustaining mild head trauma. There was no evidence of central nervous system involvement or dissemination. This is the first known case report of isolated cryptococcal osteomyelitis in a liver transplant recipient.

Colliding Epidemics and the Rise of Cryptococcosis

Discovered more than 100 years ago as a human pathogen, the Cryptococcus neoformans–Cryptococcus gattii (C. neoformans–C. gattii) complex has seen a large global resurgence in its association with clinical disease in the last 30 years. First isolated in fermenting peach juice, and identified as a human pathogen in 1894 in a patient with bone lesions, this environmental pathogen has now found niches in soil, trees, birds, and domestic pets. Cryptococcosis is well recognized as an opportunistic infection and was first noted to be associated with reticuloendothelial cancers in the 1950s. Since then, advances in transplant immunology, medical science and surgical techniques have led to increasing numbers of solid organ transplantations (SOT) and hematological stem cell transplantations being performed, and the use of biological immunotherapeutics in increasingly high-risk and older individuals, have contributed to the further rise in cryptococcosis. Globally, however, the major driver for revivification of cryptococcosis is undoubtedly the HIV epidemic, particularly in Sub-Saharan Africa where access to care and antiretroviral therapy remains limited and advanced immunodeficiency, poverty and malnutrition remains the norm. As a zoonotic disease, environmental outbreaks of both human and animal cryptococcosis have been reported, possibly driven by climate change. This is best exemplified by the resurgence of C. gattii infection in Vancouver Island, Canada, and the Pacific Northwest of the United States since 1999. Here we describe how the colliding epidemics of HIV, transplantation and immunologics, climate change and migration have contributed to the rise of cryptococcosis.

Cryptococcus: from environmental saprophyte to global pathogen

Cryptococcosis is a globally distributed invasive fungal infection that is caused by species within the genus Cryptococcus which presents substantial therapeutic challenges. Although natural human-to-human transmission has never been observed, recent work has identified multiple virulence mechanisms that enable cryptococci to infect, disseminate within and ultimately kill their human host. In this Review, we describe these recent discoveries that illustrate the intricacy of host-pathogen interactions and reveal new details about the host immune responses that either help to protect against disease or increase host susceptibility. In addition, we discuss how this improved understanding of both the host and the pathogen informs potential new avenues for therapeutic development.

[Cryptococcus where they are not expected: Five case reports of extra-cerebral and extra-pulmonary cryptococcosis]

Cryptococcosis is a serious infection, possibly lethal, of worldwide distribution. It mainly affects immunosuppressed patients resulting with pulmonary and/or meningeal involvements or disseminated infections. Due to the rarity of visceral and osseous infections, and to the absence of specific clinical symptoms, this diagnosis is often deferred. Resulting of diagnostic errors, samples are often directed to the department of pathology and more rarely to the department of mycology. Histopathological examination appears crucial, highlighting encapsulated yeasts with alcian blue staining. Once the diagnosis is performed, an appropriate antifungal therapy must be quickly introduced because these infections are associated with a high mortality rate. The aim of our work was to report five extra-cerebral and extra-pulmonary cryptococcosis cases, to describe their histopathological features, to evoke diagnostic techniques and to discuss the differential diagnoses.

Cryptococcus: Shedding New Light on an Inveterate Yeast

Cryptococcus has emerged as a significant pathogen in immunocompromised patients. While the diagnostic testing and the antifungal treatment of cryptococcal infections have become firmly established in clinical practice, new developments and areas of ambiguity merit further consideration. These include the potential for donor transmission of Cryptococcus; cirrhosis-associated cryptococcosis, particularly during transplant candidacy; the utility of serum cryptococcal antigen testing of asymptomatic individuals in high-prevalence, poor-resource areas; pathogenesis and treatment of the immune reconstitution syndrome, specifically in relation to antiretroviral therapy and immunosuppressive medications; and new challenges posed by the emerging species of Cryptococcus gatti. In this article, we summarize the literature pertaining to these topics, focusing on recent progress.