Review

Authors: Eileen K Maziarz, John R Perfect

Cryptococcosis is an invasive mycosis caused by pathogenic encapsulated yeasts in the genus Cryptococcus. Cryptococcus gained prominence as a pathogen capable of widespread disease outbreaks in vulnerable populations. We have gained insight into the pathobiology of Cryptococcus, including the yeast' s capacity to adapt to environmental pressures, exploit new geographic environments, and cause disease in both immunocompromised and apparently immunocompetent hosts. Inexpensive, point-of-care testing makes diagnosis more feasible than ever. The associated worldwide burden and mortality remains unacceptably high. Novel screening strategies and preemptive therapy offer promise at making a sustained and much needed impact on this sugar-coated opportunistic mycosis.

Topics: Antifungal Agents; Cryptococcosis; Cryptococcus; Humans

PubMed: 26897067
DOI: 10.1016/j.idc.2015.10.006

Review

Authors: J Andrew Alspaugh

The human fungal pathogen Cryptococcus neoformans is able to rapidly and effectively adapt to varying conditions, favoring its survival in the environment and in the infected host. Many microbial phenotypes have been specifically correlated with virulence in this opportunistic pathogen, such as capsule production, melanin formation, and the secretion of various proteins. Additionally, cellular features such as the cell wall and morphogenesis play important roles in the interaction of this fungus with host immune recognition and response pathways. Survival in the face of host stress also requires maintaining RNA/DNA integrity. Additionally, aging and senescence of the fungal cells determines resistance to host-derived stresses. New mechanisms regulating the expression of these virulence-associated phenotypes have been recently explored. Importantly, human clinical studies are now confirming the roles of specific microbial factors in human infections.

Topics: Cryptococcosis; Cryptococcus neoformans; Host-Pathogen Interactions; Humans; Virulence; Virulence Factors

PubMed: 25256589
DOI: 10.1016/j.fgb.2014.09.004

Review

Authors: Kali R Iyer, Nicole M Revie, Ci Fu...

Cryptococcus spp., in particular Cryptococcus neoformans and Cryptococcus gattii, have an enormous impact on human health worldwide. The global burden of cryptococcal meningitis is almost a quarter of a million cases and 181,000 deaths annually, with mortality rates of 100% if infections remain untreated. Despite these alarming statistics, treatment options for cryptococcosis remain limited, with only three major classes of drugs approved for clinical use. Exacerbating the public health burden is the fact that the only new class of antifungal drugs developed in decades, the echinocandins, displays negligible antifungal activity against Cryptococcus spp., and the efficacy of the remaining therapeutics is hampered by host toxicity and pathogen resistance. Here, we describe the current arsenal of antifungal agents and the treatment strategies employed to manage cryptococcal disease. We further elaborate on the recent advances in our understanding of the intrinsic and adaptive resistance mechanisms that are utilized by Cryptococcus spp. to evade therapeutic treatments. Finally, we review potential therapeutic strategies, including combination therapy, the targeting of virulence traits, impairing stress response pathways and modulating host immunity, to effectively treat infections caused by Cryptococcus spp. Overall, understanding of the mechanisms that regulate anti-cryptococcal drug resistance, coupled with advances in genomics technologies and high-throughput screening methodologies, will catalyse innovation and accelerate antifungal drug discovery.

Topics: Antifungal Agents; Cell Wall; Cryptococcosis; Cryptococcus; Drug Resistance, Fungal; Echinocandins; Fungal Capsules; Fungal Polysaccharides; Virulence Factors

PubMed: 33558691
DOI: 10.1038/s41579-021-00511-0

Authors: John R Perfect, William E Dismukes, Francoise Dromer...

Cryptococcosis is a global invasive mycosis associated with significant morbidity and mortality. These guidelines for its management have been built on the previous Infectious Diseases Society of America guidelines from 2000 and include new sections. There is a discussion of the management of cryptococcal meningoencephalitis in 3 risk groups: (1) human immunodeficiency virus (HIV)-infected individuals, (2) organ transplant recipients, and (3) non-HIV-infected and nontransplant hosts. There are specific recommendations for other unique risk populations, such as children, pregnant women, persons in resource-limited environments, and those with Cryptococcus gattii infection. Recommendations for management also include other sites of infection, including strategies for pulmonary cryptococcosis. Emphasis has been placed on potential complications in management of cryptococcal infection, including increased intracranial pressure, immune reconstitution inflammatory syndrome (IRIS), drug resistance, and cryptococcomas. Three key management principles have been articulated: (1) induction therapy for meningoencephalitis using fungicidal regimens, such as a polyene and flucytosine, followed by suppressive regimens using fluconazole; (2) importance of early recognition and treatment of increased intracranial pressure and/or IRIS; and (3) the use of lipid formulations of amphotericin B regimens in patients with renal impairment. Cryptococcosis remains a challenging management issue, with little new drug development or recent definitive studies. However, if the diagnosis is made early, if clinicians adhere to the basic principles of these guidelines, and if the underlying disease is controlled, then cryptococcosis can be managed successfully in the vast majority of patients.

Topics: Antifungal Agents; Case Management; Child; Child, Preschool; Cryptococcosis; Female; Humans; Intracranial Hypertension; Pregnancy; United States

PubMed: 20047480
DOI: 10.1086/649858

Review

Authors: Maria Grazia Pennisi, Katrin Hartmann, Albert Lloret...

OVERVIEW

Cryptococcosis is worldwide the most common systemic fungal disease in cats; it is caused by the Cryptococcus neoformans- Cryptococcus gattii species complex, which includes eight genotypes and some subtypes (strains) with varying geographical distribution, pathogenicity and antimicrobial susceptibility. Cats acquire the infection from a contaminated environment. The prognosis is favourable in most cases, provided a diagnosis is obtained sufficiently early and prolonged treatment is maintained.

INFECTION

Basidiospores are the infectious propagules of Cryptococcus species as they penetrate the respiratory system and induce primary infection. Asymptomatic colonisation of the respiratory tract is more common than clinical disease. Avian guanos, particularly pigeon droppings, offer favourable conditions for the reproduction of C neoformans. Both Cryptococcus species are associated with decaying vegetation.

DISEASE SIGNS

Cryptococcosis caused by C neoformans or C gattii is indistinguishable clinically. The disease can present in nasal, central nervous system (which can derive from the nasal form or occur independently), cutaneous and systemic forms.

DIAGNOSIS

An easy and reliable test for cryptococcosis diagnosis is antigen detection in body fluids. Only isolation and polymerase chain reaction allow identification of the species genotype.

DISEASE MANAGEMENT

Amphotericin B, ketoconazole, fluconazole and itraconazole have all been used to treat cats. Surgical excision of any nodules in the skin, nasal or oral mucosa assists recovery. Continued treatment is recommended until the antigen test is negative.

PREVENTION

Efficient preventive measures have not been demonstrated. Vaccines are not available.

Topics: Animals; Antifungal Agents; Cat Diseases; Cats; Cryptococcosis

PubMed: 23813826
DOI: 10.1177/1098612X13489224

Review

Authors: Robin C May, Neil R H Stone, Darin L Wiesner...

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.

Topics: Antifungal Agents; Cryptococcosis; Cryptococcus; Host-Pathogen Interactions; Humans; Virulence

PubMed: 26685750
DOI: 10.1038/nrmicro.2015.6

Review

Authors: Hiromitsu Noguchi, Tadahiko Matsumoto, Utako Kimura...

Cutaneous cryptococcosis is classified either as primary or secondary based on the route of infection. The disease can also be classified either as localized cutaneous cryptococcosis or cutaneous manifestations of disseminated cryptococcosis. However, from a physician's point of view, whether lesions are localized to the skin or are disseminated/systemic is more important than the route of infection. The Clinical Practice Guidelines for Diagnosis and Treatment of Cryptococcosis, which was established in 2019 by the Japanese Society for Medical Mycology, adopted the latter classification. Localized cutaneous cryptococcosis is defined as a condition in which lesions are confined within a limited part of the skin, not systemically disseminated at the same time, and are associated with neither cryptococcal fungemia nor antigenemia. This type of cutaneous cryptococcosis is uncommon in Japan. Only 65 cases were reported during the 50-year study period from 1968 to August 2018, with the patients divided into two groups: immunocompromised patients (n=44, 68%) and immunocompetent patients (n=21, 32%). None of the patients were infected with the human immunodeficiency virus (HIV). Localized cutaneous cryptococcosis can also occur in non-HIV-infected patients and well-appearing individuals, therefore, it is considered an important infection in routine dermatology practice. Here, we outline the classification, diagnosis, and treatment of cutaneous cryptococcosis and present a summary of cutaneous cryptococcosis cases reported in Japan.

Topics: Adult; Aged; Aged, 80 and over; Child; Cryptococcosis; Dermatomycoses; Female; Humans; Immunocompetence; Immunocompromised Host; Male; Middle Aged

PubMed: 31787730
DOI: 10.3314/mmj.19.008

Authors: Elaine Cristina Francisco, Auke W de Jong, Ferry Hagen...

Topics: Cryptococcosis; Cryptococcus gattii; Cryptococcus neoformans; Humans

PubMed: 34224075
DOI: 10.1007/s11046-021-00577-7

Authors: Aiken Dao, Hannah Yejin Kim, Katherine Garnham...

Cryptococcosis causes a high burden of disease worldwide. This systematic review summarizes the literature on Cryptococcus neoformans and C. gattii infections to inform the World Health Organization's first Fungal Priority Pathogen List. PubMed and Web of Science were used to identify studies reporting on annual incidence, mortality, morbidity, antifungal resistance, preventability, and distribution/emergence in the past 10 years. Mortality rates due to C. neoformans were 41%-61%. Complications included acute renal impairment, raised intracranial pressure needing shunts, and blindness. There was moderate evidence of reduced susceptibility (MIC range 16-32 mg/l) of C. neoformans to fluconazole, itraconazole, ketoconazole, voriconazole, and amphotericin B. Cryptococcus gattii infections comprised 11%-33% of all cases of invasive cryptococcosis globally. The mortality rates were 10%-23% for central nervous system (CNS) and pulmonary infections, and ∼43% for bloodstream infections. Complications described included neurological sequelae (17%-27% in C. gattii infections) and immune reconstitution inflammatory syndrome. MICs were generally low for amphotericin B (MICs: 0.25-0.5 mg/l), 5-flucytosine (MIC range: 0.5-2 mg/l), itraconazole, posaconazole, and voriconazole (MIC range: 0.06-0.5 mg/l). There is a need for increased surveillance of disease phenotype and outcome, long-term disability, and drug susceptibility to inform robust estimates of disease burden.

Topics: Humans; Cryptococcosis; Antifungal Agents; Cryptococcus gattii; Cryptococcus neoformans; Drug Resistance, Fungal; World Health Organization; Microbial Sensitivity Tests

PubMed: 38935902
DOI: 10.1093/mmy/myae043

Review

Authors: Hisako Kushima, Hiroshi Ishii

Approximately one million new cases of cryptococcosis develop each year worldwide, resulting in approximately 600,000 deaths. Most cases occurred in HIV patients from African countries south of the Sahara Desert. In light of this situation, in 2022, the World Health Organization presented a list of priority fungal pathogens to guide research, development, and public health action, with Cryptococcus neoformans as the most important critical fungus. In contrast, a recent retrospective study in developed countries showed that 90% of cases with cryptococcosis were non-HIV patients, including immunocompetent individuals. Underlying diseases of non-HIV immunocompromised patients include cancer and solid organ transplantation. High serum titers cryptococcal antigens independently predicted the risk of central nervous system involvement. Even if the patient is asymptomatic, high antigen levels are considered a possibility of cryptococcal meningitis, and a spinal fluid examination may be recommended. The absence of a history of contact with pigeons should not be used as a basis for denying cryptococcosis because C. neoformans is often detected in old and dried feces of chickens other than pigeons. Donor-derived cryptococcosis is a unique feature of cryptococcosis in solid organ transplant recipients. Pre-transplant screening tests for cryptococcosis, pre-transplant treatment for the donor, and prophylactic antifungal therapy for the recipient may be useful. Defense against cryptococcal infection is regulated by various mechanisms, including Th1, Th2, and Th17 immune responses. Molecularly targeted medicines that target specific cytokines or surface antigen molecules have been widely used with excellent clinical efficacy for the treatment of various diseases. Since cryptococcosis has been recently reported to develop during the use of certain medicines, such as ibrutinib and eculizumab, clinicians need to be mindful that the number of similar cases may increase in the future.

Topics: Humans; Cryptococcosis; Cryptococcus neoformans; Antifungal Agents; Animals; Immunocompromised Host; Antigens, Fungal

PubMed: 40024791
DOI: 10.3314/mmj.25.001