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

Global guideline for the diagnosis and management of cryptococcosis: an initiative of the ECMM and ISHAM in cooperation with the ASM

Cryptococcosis is a major worldwide disseminated invasive fungal infection. Cryptococcosis, particularly in its most lethal manifestation of cryptococcal meningitis, accounts for substantial mortality and morbidity. The breadth of the clinical cryptococcosis syndromes, the different patient types at-risk and affected, and the vastly disparate resource settings where clinicians practice pose a complex array of challenges. Expert contributors from diverse regions of the world have collated data, reviewed the evidence, and provided insightful guideline recommendations for health practitioners across the globe. This guideline offers updated practical guidance and implementable recommendations on the clinical approaches, screening, diagnosis, management, and follow-up care of a patient with cryptococcosis and serves as a comprehensive synthesis of current evidence on cryptococcosis. This Review seeks to facilitate optimal clinical decision making on cryptococcosis and addresses the myriad of clinical complications by incorporating data from historical and contemporary clinical trials. This guideline is grounded on a set of core management principles, while acknowledging the practical challenges of antifungal access and resource limitations faced by many clinicians and patients. More than 70 societies internationally have endorsed the content, structure, evidence, recommendation, and pragmatic wisdom of this global cryptococcosis guideline to inform clinicians about the past, present, and future of care for a patient with cryptococcosis.

Cryptococcosis in kidney transplant recipients: Current understanding and practices

Cryptococcosis is the third most commonly occurring invasive fungal disease in solid organ transplant recipients (SOT). It is caused by encapsulated yeast, Cryptococcus species, predominantly Cryptococcus neoformans and Cryptococcus gattii. Though kidney transplant recipients are at the lowest risk of cryptococcosis when compared to other solid organ transplant recipients such as lung, liver or heart, still this opportunistic infection causes significant morbidity and mortality in this subset of patients. Mortality rates with cryptococcosis range from 10%-25%, while it can be as high as 50% in SOT recipients with central nervous system involvement. The main aim of diagnosis is to find out if there is any involvement of the central nervous system in disseminated disease or whether there is only localized pulmonary involvement as it has implications for both prognostication and treatment. Detection of cryptococcal antigen (CrAg) in cerebrospinal fluid or plasma is a highly recommended test as it is more sensitive and specific than India ink and fungal cultures. The CrAg lateral flow assay is the single point of care test that can rapidly detect cryptococcal polysaccharide capsule. Treatment of cryptococcosis is challenging in kidney transplant recipients. Apart from the reduction or optimization of immunosuppression, lipid formulations of amphotericin B are preferred as induction antifungal agents. Consolidation and maintenance are done with fluconazole; carefully monitoring its interactions with calcineurin inhibitors. This review further discusses in depth the evolving developments in the epidemiology, pathogenesis, diagnostic assays, and management approach of cryptococcosis in kidney transplant recipients.

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.

Emerging fungal pathogens in solid organ transplantation

PURPOSE OF REVIEW

This review examines recent cases and updated literature on emerging or newly resistant fungal infections in solid organ transplantation.

RECENT FINDINGS

Candida auris, a newly described candida capable of drug resistance and persistence in the environment, is a growing concern with both published cases on donor-derived transmission and a hospital outbreak involving liver transplant recipients. Infections with non-albicans candida species are also increasing in incidence in SOT recipients, leading to increasing antifungal resistance and higher mortality. Aspergillus usti has emerged in immunocompromised patients on antifungal prophylaxis. Cryptococcus species continue to be responsible for a number of infections in SOT recipients. Dimorphic fungi, endemic to geographic areas and responsible for sporadic infections in SOT recipients are noted to have an expanding geographic area. Emergomyces are newly classified groups of five species of dimorphic fungi noted to disseminated disease in immunocompromised patients including SOT recipients.

SUMMARY

Emerging fungal species and the development of resistance in well entrenched fungal pathogens impacts SOT recipients and those caring for them. Knowledge of these trends aids in the successful identification and optimal treatment of these challenging conditions.

Molecular typing, in vitro susceptibility and virulence of Cryptococcus neoformans/Cryptococcus gattii species complex clinical isolates from south-eastern Brazil

BACKGROUND

Cryptococcus neoformans/ Cryptococcus gattii species complex is composed of encapsulated yeast species that are causative agents of cryptococcosis. The characterisation of pathogenic Cryptococcus species provides useful data for epidemiological studies as well as the clinical diagnosis and treatment of patients.

OBJECTIVES

This study aimed to characterise the epidemiology, antifungal susceptibility and virulence of 72 clinical strains isolated from cryptococcosis cases between 2012 and 2017 in a tertiary reference hospital in south-eastern Brazil.

METHODS

Species and molecular types were molecularly assessed by PCR and PCR-restriction fragment length polymorphism (RFLP) of the URA5 gene. Antifungal susceptibility testing was performed according to the CLSI protocols. The virulence was studied in a Galleria mellonella infection model.

RESULTS

The most frequently isolated strain was C. neoformans molecular type VNI (61/72; 84.7%), although C. neoformans molecular type VNII (3/72; 4.2%) was also isolated. Additionally, C. deuterogattii molecular type VGII (8/72; 11.1%) was present, but most frequently from non-HIV-infected patients. Non-wild-type phenotype to the antifungals was observed in 26.4% (19/72) of the C. neoformans and C. deuterogattii clinical isolates, and the latter demonstrated higher MIC to fluconazole and itraconazole than C. neoformans clinical isolates. Finally, the virulence of C. neoformans and C. deuterogattii clinical isolates was diverse in G mellonella larvae and uncorrelated with the virulence factors of melanin and capsule.

CONCLUSIONS

The assessment of the spread of cryptococcal species and molecular types as well as the pattern of corresponding antifungal susceptibility and virulence aids in surveil the emergence of resistant strains, ensuring more accurate management of the cryptococcal infection.