The effect of corticosteroids on visual loss in Cryptococcus neoformans var. gattii meningitis

IL-22 and IL-23 regulate the anticryptococcal response during Cryptococcus deuterogattii infection

Cryptococcosis is a neglected fungal disease that causes many deaths annually, is primarily caused by Cryptococcus neoformans and Cryptococcus gattii species. They are environmental fungus that engages lung pneumonia and a severe systemic infection. The rising incidence of affected immunocompetent hosts, particularly by the aggressive Cryptococcus deuterogattii (R265), underscores the urgency to understand factors influencing its dissemination. The immunopathogenesis of R265 infection is incompletely understood. Therefore, we investigate the role of IL-22 and IL-23 cytokines during R265 cryptocococcosis. Our findings highlight the crucial role of IL-22 and IL-23 cytokines in lung barrier homeostasis, preventing excessive lung damage. IL-22 not only prevents neutrophil infiltration and IL-17A production but also facilitates eosinophil lung infiltration. Ultimately, this study contributes vital insights into the selective role of IL-22 and IL-23 cytokines in immune activation and tissue regulation during the aggressive R265 lung and systemic infection.

Infectious optic neuropathy (ION), how to recognise it and manage it

Optic neuropathy can be of infectious or non-infectious/idiopathic aetiology. Many infectious organisms can cause optic neuropathy that can be of varied presentation including papillitis, retrobulbar optic neuritis, neuroretinitis, and optic perineuritis. Detailed history, ocular, systemic/neurologic examination along with appropriate laboratory evaluation can help clinicians to identify the infectious agent causing optic neuropathy. In spite of recent advanced techniques in serological testing and molecular diagnostics like polymerase chain reaction (PCR), the identification of these pathogens is still a diagnostic challenge. It is ideal to have an infectious disease (ID) consultant in the management team, as most of these infections are multisystem involving diseases. Most infectious agents can be effectively treated with specific antibiotics, with or without corticosteroid therapy, but visual recovery is highly variable and depends entirely on early diagnosis of the causative agent. This review article will provide an overview of common pathogens involved in ION and will describe their management paradigms.

Ocular Findings of Cryptococcal Meningitis in Previously Healthy Adults

BACKGROUND

Patients with cryptococcal meningitis (CM) often have ocular manifestations; although data are describing these findings in nonimmunosuppressed, previously healthy individuals are scarce.

METHODS

A retrospective chart review was performed for previously healthy patients with CM who underwent a complete ophthalmological examination within a 5-year period at the National Institutes of Health. Demographics, CSF parameters, findings on initial ophthalmological examination, and MRI abnormalities were analyzed.

RESULTS

Forty-four patients within a median of 12 weeks after CM diagnosis were included in our study; 27 patients (61%) reported abnormal vision on presentation. Seventy-one percent of patients were not shunted at the time of their initial eye examination. The most common ocular abnormalities were visual field defects in 21 (66%), decreased visual acuity in 14 (38%), and papilledema in 8 (26%) patients. Intraocular pressure was within normal range in all patients. Cranial nerve defects were identified in 5 patients and optic neuropathy in 2 patients. Patients who had hydrocephalus or did not receive a ventriculoperitoneal shunt were not noted to have worse ocular abnormalities.

CONCLUSIONS

The most common ocular findings in our cohort of nontransplant, non-HIV cryptococcal meningitis patients were visual field defects, decreased visual acuity, and papilledema. Our results emphasize the need for a comprehensive eye examination in patients with CM who may not always report a change in vision on presentation.

The Impact of Corticosteroids on the Outcome of Fungal Disease: a Systematic Review and Meta-analysis

Purpose of Review

Corticosteroids have a complex relationship with fungal disease - risk for many, benefit for others. This systematic review aims to address the effect of corticosteroids on mortality and visual outcome in different fungal diseases.

Recent Findings

Corticosteroids are a risk factor of aspergillosis for patients who have COVID-19, and they also led to a worse outcome. Similarity, corticosteroids are a risk factor for candidemia and mucormycosis. Some researchers reported that using topical corticosteroid in keratitis was associated with worse visual outcome if fungal keratitis. Some studies showed that corticosteroids are linked to a negative outcome for non-HIV patients with Pneumocystis jirovecii pneumonia (PCP), in contrast to those with HIV and PCP.

Summary

In 59 references, we found that corticosteroid therapy showed a worse clinical outcome in invasive aspergillosis (IA) (HR: 2.50, 95%CI: 1.89-3.31, p < 0.001) and chronic pulmonary aspergillosis (CPA) (HR: 2.74, 95%CI: 1.48-5.06, p = 0.001), PCP without HIV infection (OR: 1.29, 95%CI: 1.09-1.53, p = 0.003), invasive candidiasis and candidaemia (OR: 2.13, 95%CI: 1.85-2.46, p < 0.001), mucormycosis (OR: 4.19, 95%CI: 1.74-10.05, p = 0.001) and early in the course of fungal keratitis (OR: 2.99, 95%CI: 1.14-7.84, p = 0.026). There was equivocal outcome in cryptococcal meningoencephalitis in AIDS and primary coccidioidomycosis, while corticosteroid therapy showed a better outcome in PCP in HIV-infected patients (RR: 0.62, 95%CI: 0.46-0.83, p=0.001) and fungal keratitis patients after keratoplasty surgery (OR: 0.01, 95%CI: 0.00-0.41, p = 0.041) and probably in cryptococcal meningoencephalitis in non-immunocompromised patients. A sub-analysis in invasive aspergillosis and CPA showed that use of more than 2 mg/kg/day of prednisolone equivalents per day is a significant factor in increasing mortality (HR: 2.94, 95%CI: 2.13-4.05, p < 0.001). Corticosteroid therapy during invasive fungal disease was usually associated with a slightly or greatly increased mortality or worse visual outcome (in fungal keratitis), with two disease exceptions. Avoiding the addition of corticosteroids, or minimising dose and duration in those who require them, is likely to improve the outcome of most life- and vision-threatening fungal diseases. This review provides a cornerstone for further research in exploring the accuracy of suitable dose and duration of corticosteroids treatment in fungal diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12281-023-00456-2.

What's New in Cryptococcus gattii: From Bench to Bedside and Beyond

Cryptococcus species are a major cause of life-threatening infections in immunocompromised and immunocompetent hosts. While most disease is caused by Cryptococcus neoformans, Cryptococcus gattii, a genotypically and phenotypically distinct species, is responsible for 11-33% of global cases of cryptococcosis. Despite best treatment, C. gattii infections are associated with early mortality rates of 10-25%. The World Health Organization's recently released Fungal Priority Pathogen List classified C. gattii as a medium-priority pathogen due to the lack of effective therapies and robust clinical and epidemiological data. This narrative review summarizes the latest research on the taxonomy, epidemiology, pathogenesis, laboratory testing, and management of C. gattii infections.

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.

Cryptococcus: History, Epidemiology and Immune Evasion

Cryptococcosis is a disease caused by the pathogenic fungi Cryptococcus neoformans and Cryptococcus gattii, both environmental fungi that cause severe pneumonia and may even lead to cryptococcal meningoencephalitis. Although C. neoformans affects more fragile individuals, such as immunocompromised hosts through opportunistic infections, C. gattii causes a serious indiscriminate primary infection in immunocompetent individuals. Typically seen in tropical and subtropical environments, C. gattii has increased its endemic area over recent years, largely due to climatic factors that favor contagion in warmer climates. It is important to point out that not only C. gattii, but the Cryptococcus species complex produces a polysaccharidic capsule with immunomodulatory properties, enabling the pathogenic species of Cryptococccus to subvert the host immune response during the establishment of cryptococcosis, facilitating its dissemination in the infected organism. C. gattii causes a more severe and difficult-to-treat infection, with few antifungals eliciting an effective response during chronic treatment. Much of the immunopathology of this cryptococcosis is still poorly understood, with most studies focusing on cryptococcosis caused by the species C. neoformans. C. gattii became more important in the epidemiological scenario with the outbreaks in the Pacific Northwest of the United States, which resulted in phylogenetic studies of the virulent variant responsible for the severe infection in the region. Since then, the study of cryptococcosis caused by C. gattii has helped researchers understand the immunopathological aspects of different variants of this pathogen.

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.

Consensus guidelines for the diagnosis and management of cryptococcosis and rare yeast infections in the haematology/oncology setting, 2021

Cryptococcosis caused by the Cryptococcus neoformans-Cryptococcus gattii complex is an important opportunistic infection in people with immunodeficiency, including in the haematology/oncology setting. This may manifest clinically as cryptococcal meningitis or pulmonary cryptococcosis, or be detected incidentally by cryptococcal antigenemia, a positive sputum culture or radiological imaging. Non-Candida, non-Cryptococcus spp. rare yeast fungaemia are increasingly common in this population. These consensus guidelines aim to provide clinicians working in the Australian and New Zealand haematology/oncology setting with clear guiding principles and practical recommendations for the management of cryptococcosis, while also highlighting important and emerging rare yeast infections and their recommended management.

Strategies for the diagnosis and management of meningitis in HIV-infected adults in resource limited settings

INTRODUCTION

The incidence of human immunodeficiency virus-1 (HIV-1) associated meningitis has been declining in the post-combination antiretroviral treatment (ART) era, although survival rates remain low for the common causes like tuberculosis and cryptococcal disease. Diagnosis and treatment of meningitis in HIV-1 is complicated by atypical clinical presentations, limited accuracy of diagnostic tests, access to diagnostic tests, and therapeutic agents in low- and middle-income countries (LMIC) and immune reconstitution inflammatory syndrome (IRIS).

AREAS COVERED

We provide an overview of the common etiologies of meningitis in HIV-1-infected adults, suggest a diagnostic approach based on readily available tests, and review specific chemotherapeutic agents, host-directed therapies, supportive care, timing of ART initiation, and considerations in the management of IRIS with a focus on resource-limited settings. They identify key knowledge gaps and suggest areas for future research.

EXPERT OPINION

Evidence-based management of HIV-1-associated meningitis is sparse for common etiologies. More readily available and sensitive diagnostic tests as well as standardized investigation strategies are required in LMIC. There is a lack of availability of recommended drugs in areas of high HIV-1 prevalence and a limited pipeline of novel chemotherapeutic agents. Host-directed therapies have been inadequately studied.

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.

Immune reconstitution inflammatory syndrome following Cryptococcal neoformans infection in an immunocompetent host: A case report and review of the literature

We present a case of Cryptococcus neoformans in an immunocompetent middle-aged woman with a disseminated manifestation of pulmonary cryptoccoma and cryptococcal meningitis resulting in bilateral blindness. The presentation was complicated by delayed diagnosis resulting in optic neuritis and an infected percutaneous lumbar drainage with methicillin resistant staphylococcus aureus (MRSA) and a paradoxical reaction of suspected immune reconstitution inflammatory syndrome (IRIS). We discuss the pathogen, the clinical manifestations and diagnostic approach (through laboratory and radiology findings), differential diagnosis, treatment, and proposed pathogenesis of IRIS and C. neoformans in an immunocompetent patient.

Corticosteroids for Posttransplant Immune Reconstitution Syndrome in Cryptococcus gattii Meningoencephalitis: Case Report and Literature Review

Cryptococcus gattii represents an emerging fungal pathogen of immunocompromised and immunocompetent hosts in the United States. To our knowledge, this is the first case of posttransplant immune reconstitution syndrome due to C. gattii meningoencephalitis successfully treated with corticosteroids. We also report successful maintenance phase treatment with isavuconazole, a novel triazole, following fluconazole-induced prolonged QT syndrome.

Improvement of mitochondrial function by Tapinanthus globifer (A.Rich.) Tiegh. Against hepatotoxic agent in isolated rat's liver mitochondria

ETHNOPHARMACOLOGICAL RELEVANCE

Disturbed mitochondrial function and energy crisis serve as key mechanisms for the development of liver injury. Hence, targeting cellular mitochondria in liver diseases might serve as a therapeutic option. Tapinanthus globifer (A.Rich.) Tiegh. has been used in traditional medicine in the management of liver disease. However, there is no scientific evidence supporting such use.

AIM OF THE STUDY

The current investigation was designed to evaluate the protective role of Tapinanthus globifer treatment on the liver mitochondrial function after the induction of hepatotoxicity by the hepatotoxic agent Fe²⁺in vitro.

MATERIALS AND METHODS

In this study, isolated mitochondria from rats' liver was incubated with Fe²⁺ (10 μM) for 1 h in the absence or presence of T. globifer (50, 100 and 200 μg/mL) metanolic extract (MVA). Mitochondrial viability, mitochondrial membrane potential (ΔΨm), mitochondrial swelling (MPTP)., total thiol content, lipid peroxidation (TBARS) and reactive oxygen species (ROS) production were measured. HPLC-DAD was used to identify potential phytochemicals in MVA.

RESULTS

(MVA) was able to improve mitochondrial dysfunction induced by Fe²⁺, by attenuating MTT reduction, increased ΔΨm and mitochondrial swelling. Reduced total thiol and non-protein thiol contents which were associated with increased lipid peroxidation and ROS generation in Fe²⁺-treated mitochondria were significantly improved by MVA co-treatment. HPLC-DAD analysis revealed the presence of gallic acid, catechin, epigallocatechin, caffeic acid, rutin, glycoside flavonoid and quercetin in MVA that can be responsible for its beneficial effect.

CONCLUSION

MVA phyto-compounds enhance mitochondrial redox signaling and possess mitochondrial function improving potential, thereby, providing scientific basis for its use in traditional medicine.

IMMUNE RECONSTITUTION INFLAMMATORY SYNDROME CAUSING PROGRESSIVE OPTIC NERVE EDEMA IN CRYPTOCOCCAL MENINGITIS

PURPOSE

To report an human immunodeficiency virus-positive patient undergoing therapy for cryptococcal meningitis who developed progressive optic disk edema that was steroid responsive.

METHODS

Observational case report.

RESULTS

One month after commencing antifungal treatment for cryptococcal meningitis, the patient developed bilateral, progressive, recurrent optic disk edema with subretinal fluid that coincided with initiation of highly active antiretroviral therapy and recovery of CD4 cell counts. Lumbar puncture revealed normal opening pressure, and cerebrospinal fluid showed no recurrence of cryptococcal infection. There was no evidence of uveitis. The patient rapidly improved with a 5-day course of high-dose intravenous methylprednisolone.

CONCLUSION

Recurrent optic disk edema with loss of vision after treatment of cryptococcal meningitis in the setting of normal intracranial pressure may represent a unique manifestation of immune reconstitution inflammatory syndrome localized to the optic nerve without uveitis. This is consistent with the temporal relationship between starting highly active antiretroviral therapy, CD4 count recovery, and the development of progressive disk edema in the study patient. Isolated optic nerve inflammation as a manifestation of immune reconstitution inflammatory syndrome has not been widely reported.

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.

Do Intracerebral Cytokine Responses Explain the Harmful Effects of Dexamethasone in Human Immunodeficiency Virus-associated Cryptococcal Meningitis?

BACKGROUND

The CryptoDex trial showed that dexamethasone caused poorer clinical outcomes and slowed fungal clearance in human immunodeficiency virus-associated cryptococcal meningitis. We analyzed cerebrospinal fluid (CSF) cytokine concentrations from participants over the first week of treatment to investigate mechanisms of harm and test 2 hypotheses: (1) dexamethasone reduced proinflammatory cytokine concentrations, leading to poorer outcomes and (2) leukotriene A4 hydrolase (LTA4H) genotype influenced the clinical impact of dexamethasone, as observed in tuberculous meningitis.

METHODS

We included participants from Vietnam, Thailand, and Uganda. Using the Luminex system, we measured CSF concentrations of the following: interferon γ, tumor necrosis factor (TNF) α, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant 1, macrophage inflammatory protein 1α, and interleukin 6, 12p70, 8, 4, 10, and 17. We determined the LTA4H genotype based on the promoter region single-nucleotide polymorphism rs17525495. We assessed the impact of dexamethasone on cytokine concentration dynamics and the association between cytokine concentration dynamics and fungal clearance with mixed effect models. We measured the influence of LTA4H genotype on outcomes with Cox regression models.

RESULTS

Dexamethasone increased the rate TNF-α concentration's decline in (-0.13 log2pg/mL/d (95% confidence interval, -.22 to -.06 log2pg/mL/d; P = .03), which was associated with slower fungal clearance (correlation, -0.62; 95% confidence interval, -.83 to -.26). LTA4H genotype had no statistically significant impact on outcome or response to dexamethasone therapy. Better clinical outcomes were associated with higher baseline concentrations of interferon γ.

CONCLUSIONS

Dexamethasone may slow fungal clearance and worsen outcomes by increasing TNF-α concentration's rate of decline.

Rapid Reversal of Complete Binocular Blindness With High-Dose Corticosteroids and Lumbar Drain in a Solid Organ Transplant Recipient With Cryptococcal Meningitis and Immune Reconstitution Syndrome: First Case Study and Literature Review

Blindness is a rare, devastating, usually permanent complication of cryptococcal meningitis (CM). We present the first case of complete vision loss in a solid organ transplant recipient with CM treated with placement of a lumbar drain who had a dramatic visual recovery that started after 3 doses of high-dose steroids.

Cryptococcal Meningitis Masquerading as Normal Pressure Hydrocephalus in an Immune-competent Adult

We report a case of acute cryptococcal meningitis (CM) masquerading as normal pressure hydrocephalus (NPH) in an immune-competent female. An 85-year-old human immunodeficiency virus-negative female presented to the emergency room for altered mental status and difficulty walking. She was increasingly lethargic, with urinary incontinence and gait instability. A previous computed tomography was reported to have ventricular dilatation out of proportion to the degree of cortical atrophy. Magnetic resonance scan of the brain revealed ventricular dilatation and subtle debris layering the occipital horns of the lateral ventricles. A working diagnosis of NPH had been made considering the clinical symptoms and imaging. She became febrile to 103°F. Lumbar puncture was then performed which showed increased protein, decreased glucose, and mononuclear pleocytosis. India ink preparation of the cerebrospinal fluid was positive for Cryptococcus along with a positive cryptococcal antigen test. The patient was started on treatment for CM, but the patient continued to deteriorate further and died on the same day. Blood cultures subsequently grew Cryptococcus neoformans as well.

Corticosteroids for the management of severe intracranial hypertension in meningoencephalitis caused by Cryptococcus gattii: A case report and review

Immune reconstitution inflammatory syndrome in meningitis caused by Cryptococcus gattii in immunocompetent patients after initiation of antifungal therapy appears to be the result of paradoxical antifungal treatment-induced clinical deterioration due to improved local immune responses to cryptococcal organisms. Recent anecdotal reports have suggested a favorable clinical response to corticosteroids in select patients with C. gattii central nervous system (CNS) infections. In this report, we describe a 65-year-old patient with meningoencephalitis caused by C. gattii who developed persistent intracranial hypertension and was successfully managed with antifungal therapy, repeated lumbar puncture and corticosteroids. Our observations suggest a possible benefit of dexamethasone in the management of select cases of C. gattii CNS infection with intracranial hypertension. Further studies are necessary to evaluate the long-term use of steroids in select patients with C. gattii with intracranial hypertension.

Visual pathway abnormalities in tuberculous meningitis

Ophthalmological complications are common and disabling in patients with tuberculous meningitis. We aimed to study the visual pathway abnormalities in patients with tuberculous meningitis. Forty-three patients with tuberculous meningitis were subjected to visual evoked responses (VER) and neuroophthalmologic assessment. Neuroophthalmologic assessment revealed abnormalities in 22 (51.3%) patients. VER were found to be abnormal in 27 (62.8%) patients. The VER abnormalities included prolonged P100 latencies with relatively normal amplitude and significant interocular latency differences. Visual pathways abnormalities are common in patients with tuberculous meningitis and are often subclinical. Pathophysiologic explanations for electrophysiological abnormalities on VER in these patients are incompletely understood and needs further exploration.

Cryptococcal Disease in HIV-Infected Children

Cryptococcus neoformans is an encapsulated fungal pathogen that is remarkable for its tendency to cause meningoencephalitis, especially in patients with AIDS. While disease is less common in children than adults, it remains an important cause of morbidity and mortality among HIV-infected children without access to anti-retroviral therapy. This review highlights recent insights into both the biology and treatment of cryptococcosis with a special emphasis on the pediatric literature.

Adjunctive Dexamethasone in HIV-Associated Cryptococcal Meningitis

BACKGROUND

Cryptococcal meningitis associated with human immunodeficiency virus (HIV) infection causes more than 600,000 deaths each year worldwide. Treatment has changed little in 20 years, and there are no imminent new anticryptococcal agents. The use of adjuvant glucocorticoids reduces mortality among patients with other forms of meningitis in some populations, but their use is untested in patients with cryptococcal meningitis.

METHODS

In this double-blind, randomized, placebo-controlled trial, we recruited adult patients with HIV-associated cryptococcal meningitis in Vietnam, Thailand, Indonesia, Laos, Uganda, and Malawi. All the patients received either dexamethasone or placebo for 6 weeks, along with combination antifungal therapy with amphotericin B and fluconazole.

RESULTS

The trial was stopped for safety reasons after the enrollment of 451 patients. Mortality was 47% in the dexamethasone group and 41% in the placebo group by 10 weeks (hazard ratio in the dexamethasone group, 1.11; 95% confidence interval [CI], 0.84 to 1.47; P=0.45) and 57% and 49%, respectively, by 6 months (hazard ratio, 1.18; 95% CI, 0.91 to 1.53; P=0.20). The percentage of patients with disability at 10 weeks was higher in the dexamethasone group than in the placebo group, with 13% versus 25% having a prespecified good outcome (odds ratio, 0.42; 95% CI, 0.25 to 0.69; P<0.001). Clinical adverse events were more common in the dexamethasone group than in the placebo group (667 vs. 494 events, P=0.01), with more patients in the dexamethasone group having grade 3 or 4 infection (48 vs. 25 patients, P=0.003), renal events (22 vs. 7, P=0.004), and cardiac events (8 vs. 0, P=0.004). Fungal clearance in cerebrospinal fluid was slower in the dexamethasone group. Results were consistent across Asian and African sites.

CONCLUSIONS

Dexamethasone did not reduce mortality among patients with HIV-associated cryptococcal meningitis and was associated with more adverse events and disability than was placebo. (Funded by the United Kingdom Department for International Development and others through the Joint Global Health Trials program; Current Controlled Trials number, ISRCTN59144167.).

Visual loss in HIV-associated cryptococcal meningitis: A case series and review of the mechanisms involved

Permanent visual loss is a devastating yet preventable complication of cryptococcal meningitis. Early and aggressive management of cerebrospinal fluid pressure in conjunction with antifungal therapy is required. Historically, the mechanisms of visual loss in cryptococcal meningitis have included optic neuritis and papilloedema. Hence, the basis of visual loss therapy has been steroid therapy and intracranial pressure lowering without clear guidelines. With the use of high-resolution magnetic resonance imaging of the optic nerve, an additional mechanism has emerged, namely an optic nerve sheath compartment syndrome (ONSCS) caused by severely elevated intracranial pressure and fungal loading in the peri-optic space. An improved understanding of these mechanisms and recognition of the important role played by raised intracranial pressure allows for more targeted treatment measures and better outcomes. In the present case series of 90 HIV co-infected patients with cryptococcal meningitis, we present the clinical and electrophysiological manifestations of Cryptococcus-induced visual loss and review the mechanisms involved.

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.

Management of Cryptococcus gattii meningoencephalitis

Cryptococcosis is a fungal disease caused by Cryptococcus neoformans and Cryptococcus gattii. By inhalation and subsequent pulmonary infection, it may disseminate to the CNS and cause meningitis or meningoencephalitis. Most cases occur in immunosuppressed hosts, including patients with HIV/AIDS, patients receiving immunosuppressing drugs, and solid organ transplant recipients. However, cryptococcosis also occurs in individuals with apparently healthy immune systems. A growing number of cases are caused by C gattii, with infections occurring in both immunosuppressed and immunocompetent individuals. In the majority of documented cases, treatment of C gattii infection of the CNS requires aggressive management of raised intracranial pressure along with standard antifungal therapy. Early cerebrospinal fluid evacuation is often needed through placement of a percutaneous lumbar drain or ventriculostomy. Furthermore, pharmacological immunosuppression with a high dose of dexamethasone is sometimes needed to ameliorate a persistently increased inflammatory response and to reduce intracranial pressure. In this Grand Round, we present the case of an otherwise healthy adolescent female patient, who, despite aggressive management, succumbed to C gattii meningoencephalitis. We also present a review of the existing literature and discuss optimum clinical management of meningoencephalitis caused by C gattii.

Extensive Central Nervous System Cryptococcal Disease Presenting as Immune Reconstitution Syndrome in a Patient with Advanced HIV: Report of a Case and Review of Management Dilemmas and Strategies

One of the complications of the use of antiretroviral therapy (ART), immune reconstitution inflammatory syndrome (IRIS), is particularly problematic in the management of cryptococcal meningitis. We present the case of a 35-year-old male with acquired immune deficiency syndrome diagnosed with extensive central nervous system (CNS) cryptococcal disease, including meningitis and multiple intracranial cysts, diagnosed eight weeks after the initiation of ART. The patient experienced a relapsing and remitting clinical course despite repeated courses of potent antifungal therapy and aggressive management of raised intracranial pressure. This review highlights therapeutic dilemmas and strategies in the management of CNS cryptococcosis complicated with IRIS and highlights gaps in available treatment guidelines.

CryptoDex: a randomised, double-blind, placebo-controlled phase III trial of adjunctive dexamethasone in HIV-infected adults with cryptococcal meningitis: study protocol for a randomised control trial

BACKGROUND

Cryptococcal meningitis (CM) is a severe AIDS-defining illness with 90-day case mortality as high as 70% in sub-Saharan Africa, despite treatment. It is the leading cause of death in HIV patients in Asia and Africa.No major advance has been made in the treatment of CM since the 1970s. The mainstays of induction therapy are amphotericin B and flucytosine, but these are often poorly available where the disease burden is highest. Adjunctive treatments, such as dexamethasone, have had dramatic effects on mortality in other neurologic infections, but are untested in CM. Given the high death rates in patients receiving current optimal treatment, and the lack of new agents on the horizon, adjuvant treatments, which offer the potential to reduce mortality in CM, should be tested.The principal research question posed by this study is as follows: does adding dexamethasone to standard antifungal therapy for CM reduce mortality? Dexamethasone is a cheap, readily available, and practicable intervention.

METHOD

A double-blind placebo-controlled trial with parallel arms in which patients are randomised to receive either dexamethasone or placebo, in addition to local standard of care. The study recruits patients in both Asia and Africa to ensure the relevance of its results to the populations in which the disease burden is highest. The 10-week mortality risk in the control group is expected to be between 30% and 50%, depending on location, and the target hazard ratio of 0.7 corresponds to absolute risk reductions in mortality from 30% to 22%, or from 50% to 38%. Assuming an overall 10-week mortality of at least 30% in our study population, recruitment of 824 patients will be sufficient to observe the expected number of deaths. Allowing for some loss to follow-up, the total sample size for this study is 880 patients. To generate robust evidence across both continents, we aim to recruit roughly similar numbers of patients from each continent. The primary end point is 10-week mortality. Ethical approval has been obtained from Oxford University's Tropical Research Ethics Committee (OxTREC), and as locally mandated at each site.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number: ISRCTN59144167 26-July-2012.

Cryptococcosis diagnosis and treatment: What do we know now

Cryptococcosis has evolved into a major invasive fungal disease over the last century. Its primary epidemiology has been focused on three major outbreaks of disease that reflects both changing environmental exposures and growth of host risk factors. The molecular understandings of yeast pathobiology have been bolstered by identification of the yeast's dynamic genomic structures and functions. It is during these new insights into epidemiology and pathobiology that we have also improved our diagnosis of this infection with a new point-of-care, simple, cheap test which utilizes a lateral flow assay for antigen detection. With methods for effective identification of Cryptococcus in the host, the principles for management of this deadly infection include both use of old drugs and new insights into treatment strategies to improve outcome. In this review there are a series of recent insights, opinions, and facts which attempt to summarize our present knowledge base for this deadly fungal central nervous system infection with a particular emphasis on its diagnosis and management.

Bilateral optic neuropathy associated with cryptococcal meningitis in an immunocompetent patient

Cryptococcal meningitis is associated with significant morbidity and is rare among immunocompetent patients. Clinical presentation as well as the course of disease is usually indolent which may delay the diagnosis. We present the case of a 52-year-old woman admitted with headaches, vomiting and fatigue for 3 weeks. She was diagnosed with cryptococcal meningitis and treated with antifungal therapy. She was referred for ophthalmological examination presenting with decreased vision in the left eye (OS; count fingers), left relative afferent pupillary defect and bilateral sixth nerve palsy. Funduscopy revealed florid bilateral papilloedema. Cranial MRI showed indirect signs of intracranial hypertension as well as multiple parenchymal lesions and optic nerve sheath enhancement after contrast administration. A ventriculoperitoneal shunt was placed. In spite of the control of intracranial pressure there was a decrease in vision in the right eye (OD) and deterioration of visual fields. Intravenous methylprednisolone was used to reverse optic neuropathy and to prevent OD visual loss.

Cryptococcal meningitis: epidemiology and therapeutic options

Cryptococcal meningitis causes morbidity and mortality worldwide. The burden of disease is greatest in middle- and low-income countries with a high incidence of human immunodeficiency virus (HIV) infection. Patients taking immunosuppressive drugs and some immunocompetent hosts are also at risk. Treatment of cryptococcal meningitis consists of three phases: induction, consolidation, and maintenance. Effective induction therapy requires potent fungicidal drugs (amphotericin B and flucytosine), which are often unavailable in low-resource, high-endemicity settings. As a consequence, mortality is unacceptably high. Wider access to effective treatment is urgently required to improve outcomes. For human immunodeficiency virus-infected patients, judicious management of asymptomatic cryptococcal antigenemia and appropriately timed introduction of antiretroviral therapy are important.

Cryptococcus gattii infections in multiple states outside the US Pacific Northwest

Clonal VGII subtypes (outbreak strains) of Cryptococcus gattii have caused an outbreak in the US Pacific Northwest since 2004. Outbreak-associated infections occur equally in male and female patients (median age 56 years) and usually cause pulmonary disease in persons with underlying medical conditions. Since 2009, a total of 25 C. gattii infections, 23 (92%) caused by non-outbreak strain C. gattii, have been reported from 8 non-Pacific Northwest states. Sixteen (64%) patients were previously healthy, and 21 (84%) were male; median age was 43 years (range 15-83 years). Ten patients who provided information reported no past-year travel to areas where C. gattii is known to be endemic. Nineteen (76%) patients had central nervous system infections; 6 (24%) died. C. gattii infection in persons without exposure to known disease-endemic areas suggests possible endemicity in the United States outside the outbreak-affected region; these infections appear to differ in clinical and demographic characteristics from outbreak-associated C. gattii. Clinicians outside the outbreak-affected areas should be aware of locally acquired C. gattii infection and its varied signs and symptoms.

Early clinical and subclinical visual evoked potential and Humphrey's visual field defects in cryptococcal meningitis

Cryptococcal induced visual loss is a devastating complication in survivors of cryptococcal meningitis (CM). Early detection is paramount in prevention and treatment. Subclinical optic nerve dysfunction in CM has not hitherto been investigated by electrophysiological means. We undertook a prospective study on 90 HIV sero-positive patients with culture confirmed CM. Seventy-four patients underwent visual evoked potential (VEP) testing and 47 patients underwent Humphrey's visual field (HVF) testing. Decreased best corrected visual acuity (BCVA) was detected in 46.5% of patients. VEP was abnormal in 51/74 (68.9%) right eyes and 50/74 (67.6%) left eyes. VEP P100 latency was the main abnormality with mean latency values of 118.9 (±16.5) ms and 119.8 (±15.7) ms for the right and left eyes respectively, mildly prolonged when compared to our laboratory references of 104 (±10) ms (p<0.001). Subclinical VEP abnormality was detected in 56.5% of normal eyes and constituted mostly latency abnormality. VEP amplitude was also significantly reduced in this cohort but minimally so in the visually unimpaired. HVF was abnormal in 36/47 (76.6%) right eyes and 32/45 (71.1%) left eyes. The predominant field defect was peripheral constriction with an enlarged blind spot suggesting the greater impact by raised intracranial pressure over that of optic neuritis. Whether this was due to papilloedema or a compartment syndrome is open to further investigation. Subclinical HVF abnormalities were minimal and therefore a poor screening test for early optic nerve dysfunction. However, early optic nerve dysfunction can be detected by testing of VEP P100 latency, which may precede the onset of visual loss in CM.

An official American Thoracic Society statement: Treatment of fungal infections in adult pulmonary and critical care patients

With increasing numbers of immune-compromised patients with malignancy, hematologic disease, and HIV, as well as those receiving immunosupressive drug regimens for the management of organ transplantation or autoimmune inflammatory conditions, the incidence of fungal infections has dramatically increased over recent years. Definitive diagnosis of pulmonary fungal infections has also been substantially assisted by the development of newer diagnostic methods and techniques, including the use of antigen detection, polymerase chain reaction, serologies, computed tomography and positron emission tomography scans, bronchoscopy, mediastinoscopy, and video-assisted thorascopic biopsy. At the same time, the introduction of new treatment modalities has significantly broadened options available to physicians who treat these conditions. While traditionally antifungal therapy was limited to the use of amphotericin B, flucytosine, and a handful of clinically available azole agents, current pharmacologic treatment options include potent new azole compounds with extended antifungal activity, lipid forms of amphotericin B, and newer antifungal drugs, including the echinocandins. In view of the changing treatment of pulmonary fungal infections, the American Thoracic Society convened a working group of experts in fungal infections to develop a concise clinical statement of current therapeutic options for those fungal infections of particular relevance to pulmonary and critical care practice. This document focuses on three primary areas of concern: the endemic mycoses, including histoplasmosis, sporotrichosis, blastomycosis, and coccidioidomycosis; fungal infections of special concern for immune-compromised and critically ill patients, including cryptococcosis, aspergillosis, candidiasis, and Pneumocystis pneumonia; and rare and emerging fungal infections.

A prospective descriptive study of cryptococcal meningitis in HIV uninfected patients in Vietnam - high prevalence of Cryptococcus neoformans var grubii in the absence of underlying disease

Background

Most cases of cryptococcal meningitis occur in patients with HIV infection: the course and outcome of disease in the apparently immunocompetent is much more poorly understood. We describe a cohort of HIV uninfected Vietnamese patients with cryptococcal meningitis in whom underlying disease is uncommon, and relate presenting features of patients and the characteristics of the infecting species to outcome.

Methods

A prospective descriptive study of HIV negative patients with cryptococcal meningitis based at the Hospital for Tropical Diseases, Ho Chi Minh City. All patients had comprehensive clinical assessment at baseline, were cared for by a dedicated study team, and were followed up for 2 years. Clinical presentation was compared by infecting isolate and outcome.

Results

57 patients were studied. Cryptococcus neoformans var grubii molecular type VN1 caused 70% of infections; C. gattii accounted for the rest. Most patients did not have underlying disease (81%), and the rate of underlying disease did not differ by infecting species. 11 patients died while in-patients (19.3%). Independent predictors of death were age ≥ 60 years and a history of convulsions (odds ratios and 95% confidence intervals 8.7 (1 - 76), and 16.1 (1.6 - 161) respectively). Residual visual impairment was common, affecting 25 of 46 survivors (54.3%). Infecting species did not influence clinical phenotype or outcome. The minimum inhibitory concentrations of flucytosine and amphotericin B were significantly higher for C. neoformans var grubii compared with C. gattii (p < 0.001 and p = 0.01 respectively).

Conclusion

In HIV uninfected individuals in Vietnam, cryptococcal meningitis occurs predominantly in people with no clear predisposing factor and is most commonly due to C. neoformans var grubii. The rates of mortality and visual loss are high and independent of infecting species. There are detectable differences in susceptibility to commonly used antifungal drugs between species, but the clinical significance of this is not clear.

Cryptococcosis: an emerging respiratory mycosis

Cryptococcosis occurs in immunocompromised and, in special cases, immunocompetent individuals. There have been a number of important advances in the field, but, despite current treatment, patients continue to die of the infection. This article reviews cryptococcosis epidemiology, clinical features, and management. Current knowledge is incomplete, however, so this article also discusses some of the gaps in the present understanding of cryptococcosis. The hope is that current research striving to understand the mechanisms of host evasion of Cryptococcus will result in improved treatment regimens that decrease both the mortality and morbidity of cryptococcosis.

Treatment of acute cryptococcal meningitis in HIV infected adults, with an emphasis on resource-limited settings

BACKGROUND

Despite the advent and increasingly wide availability of antiretroviral therapy, cryptococcal meningitis (CM) remains a significant cause of mortality and morbidity amongst individuals with HIV infection in resource-limited settings. The ideal management of CM remains unclear. The aim of this review is to assess the evidence for deciding on which antifungal regimen to use as well as other modalities of management to utilise especially resource poor settings in order to achieve the best possible outcome and enable an individual with CM to survive their acute illness and benefit from antiretroviral therapy.

OBJECTIVES

To determine the most effective initial and consolidation treatment strategy for CM in HIV infected adults.

SEARCH STRATEGY

The Cochrane HIV/AIDS group search strategy was used. Key words in the search included, meningitis, cryptococcus neoformans, treatment, trial, human immunodeficiency virus, acquired immunodeficiency syndrome, antifungal agents, amphotericin, flucytosine, fluconazole, azole, lumbar puncture, cerebrospinal fluid (CSF) pressure and acetazolamide.

SELECTION CRITERIA

Randomised of HIV-infected adults with a first episode of CM diagnosed on CSF examination, by India ink staining, CSF culture or cryptococcal antigen testing.

DATA COLLECTION AND ANALYSIS

Data were extracted using standardised forms and analysed using Rev Man 4.2.7 software.

MAIN RESULTS

Six studies are included in the review. Five of the studies compared antifungal treatments and one study addressed lowering intracranial pressure. This study was stopped early due to excess adverse effects. The results of the other five studies as summarised as follows.Mayanja-Kizza 1998 compared fluconazole to fluconazole with 5 flucytosine. The dose of fluconazole used 200mg initially is lower than the recommended initial dose of 400mg. No survival advantage was found with the use of 5 flucytosine in addition to fluconazole.Two studies Brouwer 2004 and van der Horst 1997 compared Amphotericin (AmB) to AmB with 5 flucytosine. Both drugs were given at currently recommended doses for 2 weeks. No survival difference was found at 14 days or at 10 weeks (only recorded in Brouwer 2004). There were significantly more patients with sterile CSF cultures at 14 days in the group that received AmB with flucytosine.Brouwer 2004 compared AmB given alone to AmB given with flucytosine and fluconazole alone or in combination. This was a small study and no differences in mortality were noted between the groups.Bicanic 2008 compared high to standard dose AmB both with flucytosine. There was no difference in mortality between the two groups or adverse events.Leenders 1997 compared standard AmB to liposomal AmB. There was no difference in death rates between the two groups. But there were significantly fewer side effects in the group treated with liposomal AmB.

AUTHORS' CONCLUSIONS

The main aim of this review was to determine the best treatment for cryptococcal meningitis in resource-limited settings. In these settings usually only AmB and fluconazole are available. No studies suitable for inclusion in the review were found that compared these two drugs. Therefore we are unable to recommend either treatment as superior to the other. The recommended treatment for CM is a combination of AmB and flucytosine. The optimal dosing of AmB remains unclear. Liposomal AmB is associated with less adverse events than AmB and may be useful in selected patients where resources allow.Future research into the management of cryptococcal meningitis in resource-limited settings should focus on the most effective use of medications that are available in these settings.Flucytosine in combination with AmB leads to faster and increased sterilisation of CSF compared to using AmB alone. As Flucytosine is often not available in developing countries, policy makers and national departments of heath should consider procuring this drug for HIV treatment programmes.

Immune dysfunction in HIV-seronegative, Cryptococcus gattii meningitis

The pathophysiology of meningitis caused by Cryptococcus gattii in apparently immunocompetent individuals remains unclear. We measured multiple cytokines in CSF from a HIV-seronegative, apparently immunocompetent, Thai patient with C. gattii meningitis, over the first 2 weeks of antifungal therapy. Levels of proinflammatory IFN-gamma, TNF-alpha, and IL-6 were very low compared to patients with HIV-related Cryptococcus neoformans meningitis and of IL-10 very high. While patients with C. gattii meningitis may be a heterogeneous group, these data suggest in this case a maladapted immune response to cryptococcal exposure had allowed progression to clinical cryptococcal disease.

Prospective use of RFLP analysis on amplified Cryptococcus neoformans URA5 gene sequences for rapid identification of varieties and serotypes in clinical samples

Clinical isolates of Cryptococcus neoformans, whole blood, cerebrospinal fluid, bronchoalveolar lavage fluid from patients with positive cryptococcal antigen latex-agglutination test, and spiked clinical material from healthy individuals, were tested by polymerase chain reaction (PCR) with primers amplifying C. neoformans URA5 gene sequences. To test compatibility of different DNA extraction protocols with the PCR-restriction fragment length polymorphism (RFLP) assay, a commercial DNA extraction kit (XTRAX; Gull Laboratories, UT, USA) was used alongside with the hexadecyltrimethylammonium bromide (CTAB) method on spiked biological fluids. Both methods extracted DNA from spiked clinical samples containing C. neoformans (8 +/- 2 cells ml(-1)) and generated amplification products suitable for restriction enzyme analysis. Alu I digestion differentiated the two varieties of C. neoformans. Three distinct RFLP patterns were obtained upon restriction with MspI corresponding to serotypes A, AD and B, C and D. URA5 PCR followed by RFLP analysis, coupled with a sensitive in-house or commercially available DNA extraction method from clinical samples, could be successfully incorporated into rapid routine diagnostic strategies. It could also provide an expeditious tool for epidemiology-based population genetics studies.

Cryptococcal meningitis in the immunocompromised host: intracranial hypertension and other complications

Cryptococcosis as a complication of the immunocompromised host has dramatically increased in frequency since the start of the AIDS epidemic. This trend has heightened awareness of the complications of cryptococcal meningitis; of these, intracranial hypertension is common, severe, and life-threatening, as exemplified by three cases in our institutions presented here in detail. An aggressive approach to management of this complication has not been the standard of care, but neurosurgical interventional studies combined with physiologic observations suggest early intervention may reduce the devastating morbidity and mortality.

Visual loss in immunocompetent patients with Cryptococcus neoformans var. gattii meningitis

In Papua New Guinea cryptococcal meningitis occurs predominantly in immunocompetent patients in whom Cryptococcus neoformans var, gattii is implicated in 95% of cases. Ocular complications are common. We have reviewed ophthalmic findings in 82 immunocompetent patients and have attempted to identify those features of the disease that predict an unfavourable visual outcome. Visual loss occurred in 52.6% of survivors and was associated with optic atrophy following optic disc swelling in 60.9%. Progression of disc swelling to optic atrophy was predicted by the presence of an abducens palsy (P = 0.049) and cerebrospinal fluid (CSF) cryptococcal antigen titres > 1:1024 (P = 0.036). Raised intracranial pressure (defined as opening CSF pressure > or = 300 mm on admission) was not associated with visual loss. Vision deteriorated in 17.3% of patients despite anticryptococcal therapy and in 3.7% it followed curative therapy. The high rate of visual loss in immunocompetent patients with C. neoformans var. gattii infection contrasts with others' experience of immunosuppressed patients with C. neoformans var. neoformans infection, in whom visual loss was rare. This difference may reflect immune mediated optic nerve dysfunction in C. neoformans var. gattii meningitis caused by either compression due to arachnoid adhesions or oedema and inflammatory cell-mediated damage.