Cryptococcus endocarditis: A case report and review of the literature

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

Cryptococcus neoformans, a global threat to human health

BACKGROUND

Emerging fungal pathogens pose important threats to global public health. The World Health Organization has responded to the rising threat of traditionally neglected fungal infections by developing a Fungal Priority Pathogens List (FPPL). Taking the highest-ranked fungal pathogen in the FPPL, Cryptococcus neoformans, as a paradigm, we review progress made over the past two decades on its global burden, its clinical manifestation and management of cryptococcal infection, and its antifungal resistance. The purpose of this review is to drive research efforts to improve future diagnoses, therapies, and interventions associated with fungal infections.

METHODS

We first reviewed trends in the global burden of HIV-associated cryptococcal infection, mainly based on a series of systematic studies. We next conducted scoping reviews in accordance with the guidelines described in the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for Scoping Reviews using PubMed and ScienceDirect with the keyword Cryptococcus neoformans to identify case reports of cryptococcal infections published since 2000. We then reviewed recent updates on the diagnosis and antifungal treatment of cryptococcal infections. Finally, we summarized knowledge regarding the resistance and tolerance of C. neoformans to approved antifungal drugs.

RESULTS

There has been a general reduction in the estimated global burden of HIV-associated cryptococcal meningitis since 2009, probably due to improvements in highly active antiretroviral therapies. However, cryptococcal meningitis still accounts for 19% of AIDS-related deaths annually. The incidences of CM in Europe and North America and the Latin America region have increased by approximately two-fold since 2009, while other regions showed either reduced or stable numbers of cases. Unfortunately, diagnostic and treatment options for cryptococcal infections are limited, and emerging antifungal resistance exacerbates the public health burden.

CONCLUSION

The rising threat of C. neoformans is compounded by accumulating evidence for its ability to infect immunocompetent individuals and the emergence of antifungal-resistant variants. Emphasis should be placed on further understanding the mechanisms of pathogenicity and of antifungal resistance and tolerance. The development of novel management strategies through the identification of new drug targets and the discovery and optimization of new and existing diagnostics and therapeutics are key to reducing the health burden.

Overwhelming cryptococcosis complicated by cryptococcal endocarditis

Cryptococcal species endocarditis is infrequently described, carries high mortality and nearly always occurs in immunocompromised states or on prosthetic valves. We report the case of a man in his 70s with multiple recent hospitalisations for pneumonia, hypercalcaemia and septic tank exposure who presented with intermittent fevers, progressive weakness,and worsening encephalopathy, manifested as confusion and word-finding difficulties for 3 weeks. Workup revealed cryptococcal species on blood serum gram stain, native aortic valve endocarditis and meningitis. Cerebrospinal fluid analysis demonstrated lymphocytosis, ultimately found to be secondary to chronic lymphocytic leukaemia. Surgical valve replacement was deemed medically contraindicated and antifungal therapy was initiated. Though poorly understood with very few documented cases, management of cryptococcal endocarditis relies on prompt diagnosis, early surgery when indicated, long-term antifungal therapy and treatment of underlying immunocompromising states where possible.

Cryptococcal endocarditis of native valves without immunodeficiency or drug abuse: a case report

Cryptococcal endocarditis has rarely been reported. Most patients with this condition are associated with risk factors, such as structural heart disease/valve replacement, immunodeficiency/immunosuppression or drug abuse. We report a case of cryptococcal endocarditis of the native valves without any risk factors. A 50-year-old Chinese man was admitted to hospital with fever for 1 month without any underlying heart disease, immunodeficiency, or drug use. He was diagnosed as having Cryptococcus neoformans infective endocarditis and was discharged after valve replacement surgery and long-term antifungal therapy.