Cryptococcus gattii infections in multiple states outside the US Pacific Northwest

Fungal mechanisms of intracellular survival: what can we learn from bacterial pathogens?

Fungal infections represent a major, albeit neglected, public health threat with serious medical and economic burdens globally. With unacceptably high mortality rates, invasive fungal pathogens are responsible for millions of deaths each year, with a steadily increasing incidence primarily in immunocompromised individuals. The poor therapeutic options and rise of antifungal drug resistance pose further challenges in controlling these infections. These fungal pathogens have adapted to survive within mammalian hosts and can establish intracellular niches to promote survival within host immune cells. To do that, they have developed diverse methods to circumvent the innate immune system attack. This includes strategies such as altering their morphology, counteracting macrophage antimicrobial action, and metabolic adaptation. This is reminiscent of how bacterial pathogens have adapted to survive within host cells and cause disease. However, relative to the great deal of information available concerning intracellular bacterial pathogenesis, less is known about the mechanisms fungal pathogens employ. Therefore, here we review our current knowledge and recent advances in our understanding of how fungi can evade and persist within host immune cells. This review will focus on the major fungal pathogens, including Cryptococcus neoformans, Candida albicans, and Aspergillus fumigatus, among others. As we discover and understand the strategies used by these fungi, similarities with their bacterial counterparts are becoming apparent, hence we can use the abundant information from bacteria to guide our studies in fungi. By understanding these strategies, new lines of research will open that can improve the treatments of these devastating fungal diseases.

Genotypic Diversity and Antifungal Susceptibility of Clinical Isolates of Cryptococcus Gattii Species Complex from Argentina

The aim of this study was to determine the genotypic diversity of 22 Cryptococcus gattii species complex clinical isolates from Argentina and to place these genotypes within the diversity of clinical, veterinary and environmental isolates from Latin America. Mating type and antifungal susceptibility of the isolates were also determined. By URA5-RFLP, nine isolates were identified as molecular type VGI, 10 as VGII, one as VGIII and two as VGIV. Multilocus sequence typing (MSLT), following the International Society for Human and Animal Mycology (ISHAM) consensus MLST scheme, was used to determine the genotypic diversity. Our results suggest that, in Argentina, VGI isolates have low genetic diversity, while VGII isolates have high genetic diversity. Both isolates identified as VGIV by URA5-RFLP were genotyped by MLST as belonging to the currently named VGVI clade. From all isolates, eight sequence types (STs) were unique for Argentina, while five STs have been reported already in other countries, being of high interest the genotypes ST20 and ST7 since they belong to the subtypes VGIIa and VGIIb, respectively, which are associated with hypervirulent strains responsible for outbreaks in North America. To note, geographical analysis showed that some genotypes may be associated with some regions in Argentina. Most isolates were MATα, but we are reporting one isolate MATa for the first time in the country. Antifungal susceptibility tests showed that itraconazole, voriconazole and posaconazole had high activity against all isolates, while amphotericin B, fluconazole and 5-fluorocytosine were the least active drugs against all studied isolates.

Host immune responses in the central nervous system during fungal infections

Fungal infections in the central nervous system (CNS) cause high morbidity and mortality. The frequency of CNS mycosis has increased over the last two decades as more individuals go through immunocompromised conditions for various reasons. Nevertheless, options for clinical interventions for CNS mycoses are still limited. Thus, there is an urgent need to understand the host-pathogen interaction mechanisms in CNS mycoses for developing novel treatments. Although the CNS has been regarded as an immune-privileged site, recent studies demonstrate the critical involvement of immune responses elicited by CNS-resident and CNS-infiltrated cells during fungal infections. In this review, we discuss mechanisms of fungal invasion in the CNS, fungal pathogen detection by CNS-resident cells (microglia, astrocytes, oligodendrocytes, neurons), roles of CNS-infiltrated leukocytes, and host immune responses. We consider that understanding host immune responses in the CNS is crucial for endeavors to develop treatments for CNS mycosis.

Comparison of features and outcomes between HIV-negative patients with Cryptococcus gattii meningitis and Cryptococcus neoformans meningitis in South China

OBJECTIVES

To compare the epidemiologic, clinical, laboratory, and imaging features, and outcomes in patients with Cryptococcus gattii meningitis (CGM) and Cryptococcus neoformans meningitis (CNM).

METHODS

We performed a retrospective study of HIV-negative patients with CGM and CNM (2015-2021) distinguished by metagenomic next-generation sequencing in cerebrospinal fluid in South China.

RESULTS

81 patients (17 CGM, 64 CNM) were enrolled (72.8% male, median age 49 years, range 21-77 years), and CGM patients were younger (median, 43 vs 53 years, p = 0.005). Of 17 CGM, VGI and VGII accounted for 70.6% and 29.4%, respectively. CGM patients had less underlying diseases (7/17 [41.2%] vs 48/64 [75%], p=0.018) and focal neurologic deficit (3/17 [17.6%] vs 35/64 [54.7%], p = 0.022), had higher intracranial pressure (15/17 [88.2%] vs 25/64 [39.1%], p=0.002), more meningeal enhancement (14/17 [82.4%] vs 32/64 [50%], p = 0.034), less parenchymal involvement (median, 1 vs 3, p = 0.018), more lung cryptococcomas (6/12 [50%] vs 6/47 [12.8%], p = 0.014), faster CSF fungal clearance (p = 0.004), less complications (median, 1 vs 3, p < 0.001), and more favorable outcomes (16/17 [94.1%] vs 41/64 [64.1%], p =0.035).

CONCLUSIONS

This study demonstrated that species identification helps to guide therapy and predict outcomes.

A Fatal Fungal Infection of Cryptococcus gattii (VGI) Meningitis in Texas

Cryptococcus gattii is an under-recognized cause of meningitis, especially in non-endemic regions. This report details C. gattii disease progression from admission to autopsy in an otherwise healthy 40-year-old male in Texas. It brings awareness to an often unsuspected organism that can cause severe infection requiring early recognition and treatment in immunocompetent individuals.

Ophthalmic manifestations of Cryptococcus gattii species complex: a case series and review of the literature

AIM

To report 4 cases of Cryptococcus gattii (C. gattii) species complex infection with diverse ophthalmic manifestations, and to review the literature to examine pathobiology of disease, classical ophthalmic presentations and outcomes, and treatment modalities for this emerging pathogen.

METHODS

Cases of C. gattii meningoencephalitis with ophthalmic manifestations were identified via chart review at two institutions in Australia and one institution in the mid-west region of the United States and are reported as a case series. Additionally, a MEDLINE literature review was conducted to identify all reported cases of C. gattii with ophthalmic manifestations from 1990-2020. Cases were reviewed and tabulated, together with our series of patients, in this report.

RESULTS

Four cases of C. gattii with ophthalmic manifestations are presented; three from Australia and one from the USA. A literature review identified a total of 331 cases of C. gattii with visual sequelae. The majority of cases occurred in immunocompetent individuals. Blurred vision and diplopia were the most common presenting symptoms, with papilloedema the most common sign, reported in 10%-50% of cases. Visual loss was reported in 10%-53% of cases, as compared to rates of visual loss of 1%-9% in C. neoformans infection. Elevated intracranial pressure, cerebrospinal fluid (CSF) fungal burden, and abnormal neurological exam at presentation correlated with poor visual outcomes. The mainstays of treatment are anti-fungal agents and aggressive management of intracranial hypertension with serial lumbar punctures. CSF diversion procedures should be considered for refractory cases. Acetazolamide and mannitol are associated with high complication rates, and adjuvant corticosteroids have demonstrated higher mortality rates; these treatments should be avoided.

CONCLUSION

Permanent visual loss represents a devastating yet potentially preventable sequelae of C. gattii infection. Intracranial hypertension needs to be recognised early and aggressively managed. Referral to an ophthalmologist/neuro-ophthalmologist in all cases of cryptococcal infection independent of visual symptoms at time of diagnosis is recommended.

Multilocus sequence typing of strains from the Cryptococcus gattii species complex from different continents

BACKGROUND

Cryptococcus neoformans and Cryptococcus gattii species complexes are pathogens causing cryptococcal meningitis, a fungal infection that leads to death unless treated. Worldwide, it is estimated to kill over 180,000 individuals annually.

OBJECTIVES

We aim to investigate the molecular diversity of C. gattii isolates from strains isolated from 1995 to the present day from different continents.

METHOD

In this study, we analysed the molecular diversity by MLST and antifungal susceptibility by using the broth microdilution method according to the CLSI M27-A4 protocol of a total of 26 strains from Cryptococcus gattii species complex from both clinical and environmental sources.

RESULTS

Genotyping showed that most of the strains (17/26; 65.4%) belonged to serotype B and were distributed between three genotypes: VGI (13/17; 76.5%), VGII (3/17; 17.6%) and VGVI (1/17; 5.9%). The serotype C strains (9/26; 34.6%) were distributed between the VGIII (1/9; 11.1%) and VGIV (8/9; 88.9%) genotypes. The 26 strains belonged to 17 different MLST subtypes, and we highlight four new MLST genotypes (ST553, 554, 555 and 556). The two environmental strains were identified as serotype B and genotype VGI, but were of ST 51 and 154. All isolates have wild-type MIC of fluconazole and flucytosine. Regarding amphotericin B, five VGI strains showed MICs to AMB equal to 1 µg/ml, and according to the ECV for these genotypes, they were considered non-wild-type strains.

CONCLUSIONS

The current study reveals the genetic diversity and new sequence types among strains from the C. gattii complex species.

Cryptococcus gattii Meningitis in a Previously Healthy Young Woman: A Case Report

INTRODUCTION

Cryptococcus gattii (C. gatti) is a rare cause of meningitis in the United States. Outbreaks in new geographic distributions in the past few decades raise concern that climate change may be contributing to a broader distribution of this pathogen. We review a case of C. gattii in a 23-year-old woman in Northern California who was diagnosed via lumbar puncture after six weeks of headache, blurred vision, and tinnitus.

CASE REPORT

A 23-year-old previously healthy young woman presented to the emergency department (ED) after multiple visits to primary care, other EDs, and neurologists, for several weeks of headache, nausea, tinnitus, and blurred vision. On examination the patient was found to have a cranial nerve VI palsy (impaired abduction of the left eye) and bilateral papilledema on exam. Lumbar puncture had a significantly elevated opening pressure. Cerebrospinal fluid studies were positive for C. gattii. The patient was treated with serial lumbar punctures, followed by lumbar drain, as well as amphotericin and flucytosine. The patient had improvement in headache and neurologic symptoms and was discharged to another facility that specializes in management of this disease to undergo further treatment with immunomodulators and steroids.

CONCLUSION

Fungal meningitis is uncommon in the US, particularly among immunocompetent patients. Due to climate change, C. gattii may be a new pathogen to consider. This finding raises important questions to the medical community about the way global climate change affects day to day medical care now, and how it may change in the future.

Cryptococcal meningitis: a review for emergency clinicians

INTRODUCTION

Cryptococcal Meningitis (CM) remains a high-risk clinical condition, and many patients require emergency department (ED) management for complications and stabilization.

OBJECTIVE

This narrative review provides an evidence-based summary of the current data for the emergency medicine evaluation and management of CM.

DISCUSSION

This review evaluates the diagnosis, management, and empiric treatment of suspected CM in the ED. CM can easily evade diagnosis with a subacute presentation, and should be considered in any patient with a headache, neurological deficit, or who is immunocompromised. As a definitive diagnosis of CM will not be made in the ED, management of a patient with suspected CM includes prompt diagnostic testing and initiation of empiric treatment. Multiple types of newer Cryptococcal antigen tests provide high sensitivity and specificity both in serum and cerebrospinal fluid (CSF). Patients should be treated empirically for bacterial, fungal, and viral meningitis, specifically with amphotericin B and flucytosine for presumed CM. Additionally, appropriate resuscitation and supportive care, including advanced airway management, management of increased intracranial pressure (ICP), antipyretics, intravenous fluids, and isolation, should be initiated. Antiretroviral therapy (ART) should not be initiated in the ED for those found or known to be HIV-positive for risk of immune reconstitution inflammatory syndrome (IRIS).

CONCLUSIONS

CM remains a rare clinical presentation, but carries significant morbidity and mortality. Physicians must rapidly diagnose these patients while evaluating for other diseases and complications. Early consultation with an infectious disease specialist is imperative, as is initiating symptomatic care.

Disseminated Cryptococcal Disease in A Patient With Chronic Chylothorax and a Pleurovenous Catheter, a Case Report With Autopsy Findings

Cryptococcus species are ubiquitous in the environment with a global distribution. While causing disease predominantly in immunocompromised hosts such as those with advanced HIV, HIV-uninfected patients are increasingly recognized as being affected. The most common forms of infection are cryptococcal pneumonia and meningitis. HIV-uninfected patients and extrapulmonary infections have worse outcomes, likely due to delayed diagnosis and treatment. Cryptococcus infections involving chylothorax or chyloabdomen have rarely been reported in humans. We describe a case of fulminant disseminated cryptococcosis with fungemia, peritonitis, and empyema in a patient with chronic chylothorax treated with an indwelling pleurovenous shunt. Key autopsy findings included cryptococcal organisms identified on calcified lymphadenopathy, pleural adhesions, and pericardium. We discuss the importance of identifying patients with nontraditional risks factors for cryptococcal disease, such as lymphopenia and hypogammaglobulinemia, and the potential implications of pleurovenous catheters in Cryptococcus dissemination.

MSG07: An International Cohort Study Comparing Epidemiology and Outcomes of Patients with Cryptococcus neoformans or Cryptococcus gattii infections

BACKGROUND

Cryptococcosis due to Cryptococcus neoformans and Cryptococcus gattii varies with geographic region, populations affected, disease manifestations and severity of infection, which impact treatment.

METHODS

We developed a retrospective cohort of patients diagnosed with culture-proven cryptococcosis during 1995-2013 from five centers in North America and Australia. We compared underlying diseases, clinical manifestations, treatment and outcomes in patients with C. gattii or C. neoformans infection.

RESULTS

A total of 709 patients (452 C. neoformans; 257 C. gattii) were identified. Mean age was 50.2 years; 61.4% were male; and 52.3% were Caucasian. Time to diagnosis was prolonged in C. gattii patients compared with C. neoformans (mean 52.2 vs 36.0 days; p<0.003) and there was a higher proportion of C. gattii patients without underlying disease (40.5% vs 10.2%; p<0.0001). Overall, 59% had central nervous system (CNS) infection, with lung (42.5%) and blood (24.5%) being common sites. Pulmonary infection was more common in patients with C. gattii than those with C. neoformans (60.7% vs 32.1%; p<0.0001). CNS or blood infections were more common in C. neoformans-infected patients (p≤0.0001 for both). Treatment of CNS disease with induction therapy of amphotericin B and flucytosine occurred in 76.4% of patients. Crude 12-month mortality was higher in patients with C neoformans (28.4% vs 20.2%; Odds Ratio 1.56; 95% CI 1.08, 2.26).

CONCLUSIONS

This study emphasizes differences in species-specific epidemiology and outcomes of patients with cryptococcosis, including underlying diseases, site of infection and mortality. Species identification in patients with cryptococcosis is necessary to discern epidemiologic patterns, guide treatment regimens and predict clinical progression and outcomes.

A case of Cryptococcus gattii infection in South Carolina: A possible challenge to known endemicity

In the United States, C. gattii is considered to be endemic to the Pacific Northwest and although uncommon, additional cases have been documented in other regions including the Southeastern United States. While it has been hypothesized in the past that C. gattii may be endemic to the Southeastern United States, there remains a paucity of evidence. Here, we present a patient with no history of HIV/AIDS and no organ transplant and document the course of his disease and presentation. There were no adverse long-term neurological outcomes in this patient and the combination of steroid use, antifungal agents, and cerebrospinal fluid drainage resulted in his discharge from the hospital after 12 days. This patient’s subacute presentation with vague neurological symptoms highlights the importance of understanding the treatment of rare causes of meningitis.

In vitro synergistic effects of fluoxetine and paroxetine in combination with amphotericin B against Cryptococcus neoformans

Cryptococcus neoformans is a yeast that mainly affects immunocompromised individuals and causes meningoencephalitis depending on the immune status of the host. The present study aimed to validate the efficacy of selective serotonin reuptake inhibitors, fluoxetine hydrochloride (FLH) and paroxetine hydrochloride (PAH), alone and in combination with amphotericin B (AmB) against C. neoformans. Susceptibility tests were conducted using the broth microdilution method and synergistic effects of combining FLH and PAH with AmB were analyzed using the checkerboard assay. Effects of minimum inhibitory concentration (MIC) and synergistic concentration were evaluated in biofilms by quantifying the biomass, measuring the viability by counting the colony-forming units (CFU/mL) and examining the size of the induced capsules. Cryptococcus neoformans was susceptible to FLH and PAH and the synergistic effect of FLH and PAH in combination with AmB reduced the MIC of AmB by up to 8-fold. The isolated substances and combination with AmB were able to reduce biofilm biomass and biofilm viability. In addition, FLH and PAH alone or in combination with AmB significantly decreased the size of the yeast capsules. Collectively, our results indicate the use of FLH and PAH as a promising prototype for the development of anti-cryptococcal drugs.

Cryptococcosis caused by cryptococcus gattii: 2 case reports and literature review

Cryptococcosis caused by Cryptococcus gattii, is a life threatening fungal infection with recently increasing prevalence. C. gattii is a species complex comprising multiple independent species. However, many biological characteristics and clinical features of cryptococcosis due to C. gattii are relatively less well defined. In this paper, we identify two cases of C. gattii infection, and laboratory findings of genotype VGI and VGII in two groups of apparently immunocompetent Chinese individuals respectively. Upon detailed review of all 35 cases of C. gattii infections, it was observed that C. gattii can cause debilitating illness in both immunocompetent and immunocompromised individuals. Cryptococcosis due to C. gattii is a serious systemic fungal infection, with pulmonary central nervous system tropism. Epidemiologically, C. gattii infection is not only restricted in tropical and subtropical regions, but also in other geographical settings.

Phagosomal F-Actin Retention by Cryptococcus gattii Induces Dendritic Cell Immunoparalysis

Cryptococcus yeast species typically display characteristics of opportunistic pathogens, with the exception of C. gattii, which can cause life-threatening respiratory and disseminated brain infections in otherwise healthy people. The pathogenesis of C. gattii is not well understood, but an important characteristic is that C. gattii is capable of evading host cell-mediated immune defenses initiated by DCs. Here, we report that when virulent C. gattii becomes ingested by a DC, the intracellular compartment containing the fungi is covered by a persistent protein cage structure consisting of F-actin. This F-actin cage acts as a barrier to prevent interaction with other intracellular compartments, and as a result, the DC fails to kill the fungi and activate important cell-mediated immune responses. We propose that this unique immune evasion mechanism permits C. gattii to remain unchallenged within host cells, leading to persistent infection.

Cryptococcus gattii is a major cause of life-threatening mycosis in immunocompetent individuals and responsible for the ongoing epidemic outbreak of cryptococcosis in the Pacific Northwest of North America. This deadly fungus is known to evade important host immune responses, including dendritic cell (DC) maturation and concomitant T cell immunity, via immune evasion mechanisms that remain unclear. Here, we demonstrate that primary human DCs phagocytose C. gattii but the maturation of phagosomes to phagolysosomes was blocked as a result of sustained filamentous actin (F-actin) that entrapped and concealed the phagosomes from recognition. Superresolution structured illumination microscopy (SR-SIM) revealed that the persistent phagosomal F-actin formed a cage-like structure that sterically hindered and functionally blocked the fusion of lysosomes. Blocking lysosome fusion was sufficient to inhibit phagosomal acidification and subsequent intracellular fungal killing by DCs. Retention of phagosomal F-actin by C. gattii also caused DC immunoparalysis. Disrupting the retained F-actin cage with cytochalasin D not only restored DC phagosomal maturation but also promoted DC costimulatory maturation and robust T cell activation and proliferation. Collectively, these results reveal a unique mechanism of DC immune evasion that enhances intracellular fungal pathogenicity and may explain suppressed cell-mediated immunity.

False-Negative CSF Cryptococcal Antigen with Cryptococcus gattii Meningoencephalitis in Southeastern United States: A Case Report and Literature Review

A 70-year-old immunocompetent male in South Carolina was admitted secondary to altered mental status and headache without focal neurological deficits. Head CT was negative. Lumbar puncture (LP) revealed normal glucose, elevated protein, and lymphocytosis. Opening pressure was 15 cm of H20. CSF lateral flow assay was negative for cryptococcal antigen; CSF cultures showed no growth. The patient rapidly improved on acyclovir and was diagnosed with presumed viral meningitis, as viral PCR and fungal culture were pending at time of discharge. The patient's condition quickly worsened and the patient returned one day later with right arm weakness and dysarthria. Brain MRI revealed T2/flair signal abnormalities in the left frontal lobe with associated parenchymal enhancement. Repeat LP revealed increasing white blood cell count with a worsening lymphocytosis and decreasing glucose, and opening pressure remained normal. CSF fungal culture from the first admission grew Cryptococcus gattii, and repeated CSF cryptococcal antigen and culture returned positive. The patient was started on IV steroids, induction Amphotericin and Fluconazole, followed by maintenance oral Fluconazole. The patient's clinical course was complicated by a brainstem lacunar infarction, which led to demise. We present this case of Cryptococcus gattii meningoencephalitis to highlight the risk factors, characteristics, and challenges in diagnosis and treatment of an emerging disease in the Southeastern United States.

Spatial Quantification of the Population Exposed to Cryptococcus neoformans and Cryptococcus gattii Species Complexes in Europe: Estimating the Immunocompetent and HIV/AIDS Patients Under Risk

Cryptococcus is an important fungal pathogen worldwide, causing serious clinical manifestations that can affect immunocompetent patients and can be particularly severe for immunocompromised patients. The Cryptococcus gattii s.s. (AFLP4/VGI), Cryptococcus tetragattii (AFLP/VGIV), Cryptococcus neoformans, and Cryptococcus deneoformans have been isolated from both clinical and environmental sources in Europe. We aim to quantify the people in Europe and the entire Mediterranean area who are under risk associated with each of the three fungal pathogens in a spatially explicit way, generating a series of maps and population statistics per country. Niche modeling was applied to estimate the potential distribution of each fungal pathogen, then these models were overlapped with a map of population density to estimate risk levels. The potential number of people per risk level and per country was quantified using a map of population count per pixel. Prevalence of HIV per country was also included in the analysis to quantify the HIV-infected population under potential risk. People under risk associated with exposure to C. gattii species (C. gattii s.s. and C. tetragattii) reached 137.65 million, whereas those exposed to C. neoformans and C. deneoformans were 268.58 and 360.78 million people, respectively. More than a half million HIV-infected patients are exposed to each of the two species of the C. neoformans species complex, and more than 200,000 to the C. gattii species complex. The present results can be useful for public health planning by European governments, focusing on the provision of inputs for a "screen-and-treat" approach, availability of medical resources, and continuous monitoring programs in risk zones.

Cryptococcus gattii infection in an immunocompetent host in Greece

We report a case of a 31-year-old otherwise healthy female with pulmonary cryptococcoma along with cryptococcal meningitis due to Cryptococcus gattii molecular type VGI, in Greece. Combined antifungal treatment and surgical excision of pulmonary cryptococcoma yielded a good response.

Lower Mortality Rates from Cryptococcosis in Women and Whites with Human Immunodeficiency Virus in the United States

Cryptococcosis is an opportunistic mycotic infection often found in pigeon droppings and other bird excrement. This serious disease is often fatal and, not unexpectedly, far more common in patients with immune deficiency, including those with human immunodeficiency virus (HIV). It has been hypothesized that women with cryptococcosis and HIV have a more favorable mortality experience than men. In addition, the availability of highly active anti-retroviral therapy (ART) for HIV in the United States (US) has been associated with greater racial disparities in mortality. The US Centers for Disease Control and Prevention Wide-ranging Online Data for Epidemiologic Research (WONDER) database afforded a unique opportunity to explore mortality rates due to cryptococcosis by gender and race in the US among patients with HIV from 1999 to 2016. Mortality rate ratios from cryptococcosis were significantly lower in women and whites with HIV. These descriptive data lead to the formulation of hypotheses requiring testing in analytic studies designed a priori to do so and pose clinical and public health challenges in reducing mortality from cryptococcosis in patients with HIV.

Toward a clinical antifungal peptoid: Investigations into the therapeutic potential of AEC5

Cryptococcus neoformans is a fungal pathogen that causes cryptococcal meningitis in immunocompromised individuals. Existing antifungal treatment plans have high mammalian toxicity and increasing drug resistance, demonstrating the dire need for new, nontoxic therapeutics. Antimicrobial peptoids are one alternative to combat this issue. Our lab has recently identified a tripeptoid, AEC5, with promising efficacy and selectivity against C. neoformans. Here, we report studies into the broad-spectrum efficacy, killing kinetics, mechanism of action, in vivo half-life, and subchronic toxicity of this compound. Most notably, these studies have demonstrated that AEC5 rapidly reduces fungal burden, killing all viable fungi within 3 hours. Additionally, AEC5 has an in vivo half-life of 20+ hours and no observable in vivo toxicity following 28 days of daily injections. This research represents an important step in the characterization of AEC5 as a practical treatment option against C. neoformans infections.

Cryptococcus gattii Complex Infections in HIV-Infected Patients, Southeastern United States

Increased awareness of C. gattii infections in these patients is critical for improving diagnosis, treatment, and outcomes.

Cryptococcus gattii traditionally infects immunocompetent hosts and causes devastating pulmonary or central nervous system disease. However, this infection rarely occurs in patients infected with HIV. We report 3 cases of HIV-associated C. gattii complex infections in the southeastern United States. Detection of C. gattii in HIV-infected patients in this region warrants increased awareness of this threat to ensure appropriate diagnosis and treatment to optimize patient outcomes.

The Frozen Brain State of Cryptococcus gattii: A Globe-Trotting, Tropical, Neurotropic Fungus

Initially reported in tropical regions, Cryptococcus gattii infection is now diagnosed globally. Methods: case report; Literature review. Although initial reports described outbreaks of pulmonary and central nervous system (CNS) disease in tropical regions such as Australia and New Guinea, it is now clear that Cryptococcus gattii is a global, neurotropic pathogen. In contrast with C. neoformans, C. gattii patients are more likely to present with cryptococcomas in the brain and lungs and are often HIV negative. Imaging findings can mimick cancer leading to delays in diagnosis and definitive treatment. Some experts have speculated that the spread of C. gattii is due to climate change, newly recognized genotypes that cause disease in temperate zones (genotype VGII), international travel, and improved awareness among physicians and veterinarians. We emphasize neurocritical and neurosurgical management, because patients with CNS involvement often have high intracranial pressures (ICP). Cryptococcus gattii patients often have elevated ICP without 'red flag' radiographic signs of elevated ICP such as ventriculomegaly, cerebral edema, or effaced basal cisterns. Therefore, diagnosis of high ICP should be suspected based on clinical symptoms such as incapacitating headaches, progressive visual loss and associated papilledema, and then confirmed by measuring the opening pressure with lumbar puncture (LP). Cerebral intraparenchymal deposition of the large cryptococcal polysaccharide capsule and cryptococcal organisms causes poor brain compliance leading to a 'frozen brain state.' Mortality rates and clinical outcomes are significantly improved with early diagnosis, antifungal therapies, steroids, and aggressive management of elevated ICP including cerebrospinal fluid (CSF) diversion by serial LP's, external ventricular drains and CSF shunts. Following institution of antifungal therapy, about 10% of patients can worsen due to immune reconstitution inflammatory syndrome which responds to steroids. We recommend neurocritical and neurosurgical management of C. gattii patients with CNS involvement and elevated ICP. There is often poor correlation between elevated ICP and neuroimaging due to the frozen brain state.

Recovery of Cryptococcus gattii from an Infected Ventriculo-Peritoneal Shunt, Illinois, USA

Cryptococcus gattii is a fungal pathogen endemic in tropical and subtropical regions. Isolated cases and outbreaks have been reported in areas of North America and Europe, expanding the distribution pattern beyond warmer regions. We describe a case of ventriculo-peritoneal shunt infection by C. gattii in an immunocompetent person in Illinois.

Cryptococcus deuterogattii VGIIa Infection Associated with Travel to the Pacific Northwest Outbreak Region in an Anti-Granulocyte-Macrophage Colony-Stimulating Factor Autoantibody-Positive Patient in the United States

Mortality rates associated with C. gattii infections are estimated to be between 13% and 33%, depending on an individual’s predisposition, and C. gattii has caused at least 39 deaths in the PNW region. There have been four other international travel cases reported in patients from Europe and Asia with travel history to the PNW, but this report describes the first North American traveler who acquired C. deuterogattii infection presenting within the United States and the first case of a C. deuterogattii outbreak infection associated with anti-GM-CSF autoantibodies. Early and accurate diagnoses are important for disease prevention and treatment and for control of infectious diseases. Continual reporting of C. deuterogattii infections is necessary to raise awareness of the ongoing outbreak in the PNW and to alert travelers and physicians to the areas of endemicity with potential risks.

The region encompassing the Pacific Northwest (PNW), Vancouver Island, Oregon, and Washington has been the location of an ongoing Cryptococcus gattii outbreak since the 1990s, and there is evidence that the outbreak is expanding along the West Coast into California. Here we report a clinical case of a 69-year-old, HIV-negative man from North Carolina who was diagnosed with a fungal brain mass by magnetic resonance imaging (MRI) and pathology. He had traveled to Seattle and Vancouver 3 years earlier and to Costa Rica 4 months prior to presentation. Phenotypic evidence showed that the fungal mass isolated from the patient’s brain represented C. gattii. In agreement with the phenotypic results, multilocus sequence typing (MLST) provided genotypic evidence that assigned the infecting organism within the C. gattii species complex and to the C. deuterogattii VGIIa clade. Whole-genome sequencing revealed >99.99% identity with the C. deuterogattii reference strain R265, indicating that the infecting strain is derived from the highly clonal outbreak strains in the PNW. We conclude that the patient acquired the C. gattii infection during his travel to the region 3 years prior and that the infection was dormant for an extended period of time before causing disease. The patient tested positive for anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies, supporting earlier reports that implicate these autoantibodies as a risk factor associated with C. gattii infection.

Imaging of Community-acquired Pneumonia

Community-acquired pneumonia refers to an acute infection of the lung in patients who did not meet any of the criteria for health care-acquired pneumonia, and is associated with at least some symptoms of acute infection, accompanied by the presence of an acute infiltrate on a chest radiograph. Chest radiography remains an important component of the evaluation of a patient with a suspicion of pneumonia, and is usually the first examination to be obtained. The diagnosis of community-acquired pneumonia is based on the presence of select clinical features and is supported by imaging of the lung, usually by chest radiography. Infection of the lower respiratory tract typically presents radiologically as one of 3 patterns: (a) focal nonsegmental or lobar pneumonia, (b) multifocal bronchopneumonia or lobular pneumonia, and (c) focal or diffuse "interstitial" pneumonia. High-resolution computed tomography allows a better depiction of the pattern and distribution of pneumonia than the radiograph but is seldom required in the evaluation of patients with suspected or proven bacterial pneumonia. However, high-resolution computed tomography is a useful adjunct to conventional radiography in selected cases.

Case report: A fatal case of cryptococcosis in an immunocompetent patient due to Cryptococcus deuterogattii (AFLP6/VGII)

Introduction

Cryptococcosis in immunocompetent adults is a rare disease in Europe, mostly induced by members of the Cryptococcus gattii species complex. The diagnosis can be challenging due to its rarity, unspecific symptoms and long symptomless latency.

Case presentation

A 49-year-old woman with a three weeks history of headache was admitted to the hospital due to discrete ataxia and impaired vision. Cranial magnetic resonance imaging (MRI) showed a contrast-enhancing mass in the cerebellum. Further investigations detected a slight leukocytosis and a single subpleural nodule in the right inferior lung lobe. The cerebral lesion was surgically removed, and a direct frozen section only showed an unspecific inflammation. In the course of her admission she developed non-treatable cerebral edema and died ten days after surgical intervention. Histopathological examination of the surgical specimen and postmortem evaluation of the lung and the cerebrum demonstrated fungal elements. Molecular identification of the fungal elements in formalin-fixed paraffin-embedded tissue lead to the diagnosis of cryptococcosis induced by C. gattii sensu lato. Molecular genetic analysis identified the involved cryptococcal species as genotype AFLP6/VGII, recently described as Cryptococcus deuterogattii, which is known to be endemic to the west-coast of Canada and the USA. Additional heteroanamnestic information revealed that she had spent her holidays on Vancouver Island, Canada, two years before disease onset, indicating that infection during this stay seems to be plausible.

Conclusion

Cryptococcosis due to C. deuterogattii is a rarely encountered fungal disease in Europe, not particularly associated with immunodeficiency, and infection is likely to be contracted in endemic areas. Due to its rarity, long symptomless latency, unspecific symptoms and misleading radiological features the diagnosis can be challenging. Physicians need to be aware of this differential diagnosis in immunocompetent patients, as early adequate therapy can be lifesaving.

Whole-Genome Analysis of Cryptococcus gattii, Southeastern United States

Cryptococcus gattii is a recognized pathogenic fungus along the Pacific coast of the United States from California to Washington. Here we report that C. gattii may also be endemic to the southeastern United States and has probably been present there longer than in the Pacific Northwest.

Cryptococcus gattii Infection Presenting as an Aggressive Lung Mass

Cryptococcus gattii is an endemic fungus predominantly isolated in the tropical and subtropical regions, causing predominantly pulmonary disease with a predilection for the central nervous system. Herein, we report a case of rapidly progressing C. gattii pneumonia in an immune-deficient but virologically suppressed host with underlying human immunodeficiency viral (HIV) infection, exhibiting various fungal morphologies from bronchoalveolar lavage (BAL) cytological specimens. A 51-year-old Chinese male with known HIV disease was admitted to the Singapore General Hospital for evaluation of functional decline, febrile episodes, and a left hilar mass on chest radiograph. Computed tomography (CT) showed consolidation in the apical segment of the left lower lobe. He underwent bronchoscopy and BAL. Positron emission tomography-computed tomography done 10 days after the initial CT showed approximate doubling of the pulmonary lesion. Cytological examination of the fluid revealed yeasts of varying sizes. Subsequent fungal culture from BAL fluid grew C. gattii 10 days later.

Modulation of Zinc Homeostasis in Acanthamoeba castellanii as a Possible Antifungal Strategy against Cryptococcus gattii

Cryptococcus gattii is a basidiomycetous yeast that can be found in the environment and is one of the agents of cryptococcosis, a life-threatening disease. During its life cycle, cryptococcal cells take hold inside environmental predators such as amoebae. Despite their evolutionary distance, macrophages and amoebae share conserved similar steps of phagocytosis and microbial killing. To evaluate whether amoebae also share other antifungal strategies developed by macrophages, we investigated nutritional immunity against cryptococcal cells. We focused on zinc homeostasis modulation in Acanthamoeba castellanii infected with C. gattii. The intracellular proliferation rate (IPR) in amoebae was determined using C. gattii R265 and mutants for the ZIP1 gene, which displays defects of growth in zinc-limiting conditions. We detected a reduced IPR in cells lacking the ZIP1 gene compared to wild-type strains, suggesting that amoebae produce a low zinc environment to engulfed cells. Furthermore, flow cytometry analysis employing the zinc probe Zinpyr-1 confirmed the reduced concentration of zinc in cryptococcal-infected amoebae. qRT-PCR analysis of zinc transporter-coding genes suggests that zinc export by members of the ZnT family would be involved in the reduced intracellular zinc concentration. These results indicate that amoebae may use nutritional immunity to reduce fungal cell proliferation by reducing zinc availability for the pathogen.

Emerging Fungal Infections in the Pacific Northwest: The Unrecognized Burden and Geographic Range of Cryptococcus gattii and Coccidioides immitis

Both Cryptococcus gattii and Coccidioides can cause debilitating diseases if not identified early. It is imperative that clinicians recognize these diseases and begin treatment quickly when necessary. In order to have these two mycoses in their differential diagnosis, clinicians, microbiologists, and public health officials must be aware of the expanding geographic boundary in the case of Coccidioides immitis and the new emergence in the case of C. gattii. Accordingly, there is now mandatory reporting for cases of C. gattii and C. immitis in both Washington and Oregon, and the Centers for Disease Control and Prevention keeps a repository of available isolates. Through the One Health initiative, clinicians, veterinarians, and public health officials are collaborating to better understand the emergence and expanding geographic range of these extremely important fungal diseases.

Name Changes for Fungi of Medical Importance, 2012 to 2015

This article lists proposed new or revised species names and classification changes associated with fungi of medical importance for the years 2012 through 2015. While many of the revised names listed have been widely adopted without further discussion, some may take longer to achieve more general usage.

Climatic Influences on Cryptococcus gattii [corrected] Populations, Vancouver Island, Canada, 2002-2004

Vancouver Island, Canada, reports the world's highest incidence of Cryptococcus gattii infection among humans and animals. To identify key biophysical factors modulating environmental concentrations, we evaluated monthly concentrations of C. gatti in air, soil, and trees over a 3-year period. The 2 study datasets were repeatedly measured plots and newly sampled plots. We used hierarchical generalized linear and mixed effect models to determine associations. Climate systematically influenced C. gattii concentrations in all environmental media tested; in soil and on trees, concentrations decreased when temperatures were warmer. Wind may be a key process that transferred C. gattii from soil into air and onto trees. C. gattii results for tree and air samples were more likely to be positive during periods of higher solar radiation. These results improve the understanding of the places and periods with the greatest C. gattii colonization. Refined risk projections may help susceptible persons avoid activities that disturb the topsoil during relatively cool summer days.

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.

Fluconazole Susceptibility in Cryptococcus gattii Is Dependent on the ABC Transporter Pdr11

Cryptococcus gattii isolates from the Pacific Northwest have exhibited higher fluconazole MICs than isolates from other sites. The mechanism of fluconazole resistance in C. gattii is unknown. We sought to determine the role of the efflux pumps Mdr1 and Pdr11 in fluconazole susceptibility. Using biolistic transformation of the parent isolate, we created a strain lacking Mdr1 (mdr1Δ) and another strain lacking Pdr11 (pdr11Δ). Phenotypic virulence factors were assessed by standard methods (capsule size, melanin production, growth at 30 and 37 °C). Survival was assessed in an intranasal murine model of cryptococcosis. Antifungal MICs were determined by the M27-A3 methodology. No differences in key virulence phenotypic components were identified. Fluconazole susceptibility was unchanged in the Mdr1 knockout or reconstituted isolates. However, fluconazole MICs decreased from 32 μg/ml for the wild-type isolate to <0.03 μg/ml for the pdr11Δ strain and reverted to 32 μg/ml for the reconstituted strain. In murine models, no difference in virulence was observed between wild-type, knockout, or reconstituted isolates. We conclude that Pdr11 plays an essential role in fluconazole susceptibility in C. gattii. Genomic and expression differences between resistant and susceptible C. gattii clinical isolates should be assessed further in order to identify other potential mechanisms of resistance.

Cryptococcus gattii genotype VGIIb infection in Japan

This report describes a case of Cryptococcus gattii VGIIb infection of the pulmonary and central nervous systems in an immunocompetent Japanese man with a travel history, and it hypothesizes the place where he was infected with C. gattii using the genotype information.

How Cryptococcus interacts with the blood-brain barrier

Cryptococcus demonstrates predilection for invasion of the brain, but the mechanism by which Cryptococcus crosses the blood-brain barrier (BBB) to cause brain invasion is largely unknown. In order for Cryptococcus to cross the BBB, there must be a way to either cross human brain microvascular endothelial cells, which are the main constitute of the BBB, or go in between tight junctions. Recent evidence of human brain microvascular endothelial cell responses to transcellular brain invasions includes membrane rearrangements, intracellular signaling pathways and cytoskeletal activations. Several Cryptococcal genes related to the traversal of BBB have been identified, including CPS1, ITR1a, ITR3c, PLB1, MPR1, FNX1 and RUB1. In addition, Cryptococcus neoformans-derived microvesicles may contribute to cryptococcal brain invasion. Paracellularly, Cryptococcus may traverse across BBB using either routes utilizing plasmin, ammonia or macrophages in a Trojan horse mechanism.

Cryptococcus gattii infections

Understanding of the taxonomy and phylogeny of Cryptococcus gattii has been advanced by modern molecular techniques. C. gattii probably diverged from Cryptococcus neoformans between 16 million and 160 million years ago, depending on the dating methods applied, and maintains diversity by recombining in nature. South America is the likely source of the virulent C. gattii VGII molecular types that have emerged in North America. C. gattii shares major virulence determinants with C. neoformans, although genomic and transcriptomic studies revealed that despite similar genomes, the VGIIa and VGIIb subtypes employ very different transcriptional circuits and manifest differences in virulence phenotypes. Preliminary evidence suggests that C. gattii VGII causes severe lung disease and death without dissemination, whereas C. neoformans disseminates readily to the central nervous system (CNS) and causes death from meningoencephalitis. Overall, currently available data indicate that the C. gattii VGI, VGII, and VGIII molecular types more commonly affect nonimmunocompromised hosts, in contrast to VGIV. New, rapid, cheap diagnostic tests and imaging modalities are assisting early diagnosis and enabling better outcomes of cerebral cryptococcosis. Complications of CNS infection include increased intracranial pressure, severe neurological sequelae, and development of immune reconstitution syndrome, although the mortality rate is low. C. gattii VGII isolates may exhibit higher fluconazole MICs than other genotypes. Optimal therapeutic regimens are yet to be determined; in most cases, initial therapy with amphotericin B and 5-flucytosine is recommended.

Current trends in the prevalence of Cryptococcus gattii in the United States and Canada

The incidence of Cryptococcus gattii infections in both Canada and the United States (US) is provided in this literature review beyond the British Columbia (BC) outbreak (1999-2013). Based on a search of the literature, case reports of C. gattii human infections including the prevalent molecular genotypes causing these infections in both Canada and the US have been documented since the C. gattii outbreak in BC. The literature reveals that: i) although C. gattii infections continue to be reported in both countries, the preliminary overall number of confirmed C. gattii infections may be decreasing in both Canada and the US (~23 cases each in 2012 versus ~17 and 20 cases, respectively in 2013); ii) C. gattii genotype distribution is region-dependent; iii) C. gattii is more frequently isolated from infections in the immunocompromised host (including acquired immune deficiency syndrome [AIDS] infection) than previously expected; iv) although pulmonary disease is higher than in C. neoformans infections, central nervous system disease is also reported among patients infected with C. gattii.