HIV-associated cryptococcal meningitis

Cryptococcal meningitis post autologous stem cell transplantation

Disseminated Cryptococcus disease occurs in patients with defective T-cell immunity. Cryptococcal meningitis following autologous stem cell transplant (SCT) has been described previously in only 1 patient, 4 months post SCT and while off antifungal prophylaxis. We present a unique case of Cryptococcus meningitis pre-engraftment after autologous SCT, while the patient was receiving fluconazole prophylaxis. A 41-year-old man with non-Hodgkin's lymphoma underwent autologous SCT. Post-transplant prophylaxis consisted of fluconazole 400 mg daily, levofloxacin 500 mg daily, and acyclovir 800 mg twice daily. On day 9 post transplant, he developed fever and headache. Peripheral white blood cell count (WBC) was 700/μL. Magnetic resonance imaging of the brain showed lesions consistent with meningoencephalitis. Cerebrospinal fluid (CSF) analysis revealed a WBC of 39 with 77% lymphocytes, protein 63, glucose 38, CSF pressure 20.5 cmH2 O, and a positive cryptococcal antigen. CSF culture confirmed Cryptococcus neoformans. The patient was treated with liposomal amphotericin B 5 mg/kg intravenously daily, and flucytosine 37.5 mg/kg orally every 6 h. He was switched to fluconazole 400 mg daily after 3 weeks of amphotericin therapy, with sterilization of the CSF with negative CSFCryptococcus antigen and negative CSF culture. Review of the literature revealed 9 cases of cryptococcal disease in recipients of SCT. Median time of onset was 64 days post transplant. Only 3 meningitis cases were described; 2 of them after allogeneic SCT. Fungal prophylaxis with fluconazole post autologous SCT is recommended at least through engraftment, and for up to 100 days in high-risk patients. A high index of suspicion is needed to diagnose and treat opportunistic infections, especially in the face of immunosuppression and despite adequate prophylaxis. Infection is usually fatal without treatment, thus prompt diagnosis and therapy might be life saving.

Efficient phagocytosis and laccase activity affect the outcome of HIV-associated cryptococcosis

BACKGROUND

Cryptococcal meningitis (CM) is a leading cause of HIV-associated mortality globally. High fungal burden in cerebrospinal fluid (CSF) at diagnosis and poor fungal clearance during treatment are recognized adverse prognostic markers; however, the underlying pathogenic factors that drive these clinical manifestations are incompletely understood. We profiled a large set of clinical isolates for established cryptococcal virulence traits to evaluate the contribution of C. neoformans phenotypic diversity to clinical presentation and outcome in human cryptococcosis.

METHODS

Sixty-five C. neoformans isolates from clinical trial patients with matched clinical data were assayed in vitro to determine murine macrophage uptake, intracellular proliferation rate (IPR), capsule induction, and laccase activity. Analysis of the correlation between prognostic clinical and host immune parameters and fungal phenotypes was performed using Spearman's r, while the fungal-dependent impact on long-term survival was determined by Cox regression analysis.

RESULTS

High levels of fungal uptake by macrophages in vitro, but not the IPR, were associated with CSF fungal burden (r = 0.38, P = 0.002) and long-term patient survival (hazard ratio [HR] 2.6, 95% CI 1.2-5.5, P = 0.012). High-uptake strains were hypocapsular (r = -0.28, P = 0.05) and exhibited enhanced laccase activity (r = 0.36, P = 0.003). Fungal isolates with greater laccase activity exhibited heightened survival ex vivo in purified CSF (r = 0.49, P < 0.0001) and resistance to clearance following patient antifungal treatment (r = 0.39, P = 0.003).

CONCLUSION

These findings underscore the contribution of cryptococcal-phagocyte interactions and laccase-dependent melanin pathways to human clinical presentation and outcome. Furthermore, characterization of fungal-specific pathways that drive clinical manifestation provide potential targets for the development of therapeutics and the management of CM.

FUNDING

This work was made possible by funding from the Wellcome Trust (WT088148MF), the Medical Research Council (MR/J008176/1), the NIHR Surgical Reconstruction and Microbiology Research Centre and the Lister Institute for Preventive Medicine (to R.C. May), and a Wellcome Trust Intermediate fellowship (089966, to T. Bicanic). The C. neoformans isolates were collected within clinical trials funded by the British Infection Society (fellowship to T. Bicanic), the Wellcome Trust (research training fellowships WT069991, to A.E. Brouwer and WT081794, to J.N. Jarvis), and the Medical Research Council, United Kingdom (76201). The funding sources had no role in the design or conduct of this study, nor in preparation of the manuscript.

Clinically relevant drug-drug interactions between antiretrovirals and antifungals

INTRODUCTION

Complete delineation of the HIV-1 life cycle has resulted in the development of several antiretroviral drugs. Twenty-five therapeutic agents belonging to five different classes are currently available for the treatment of HIV-1 infections. Advent of triple combination antiretroviral therapy has significantly lowered the mortality rate in HIV patients. However, fungal infections still represent major opportunistic diseases in immunocompromised patients worldwide.

AREAS COVERED

Antiretroviral drugs that target enzymes and/or proteins indispensable for viral replication are discussed in this article. Fungal infections, causative organisms, epidemiology and preferred treatment modalities are also outlined. Finally, observed/predicted drug-drug interactions between antiretrovirals and antifungals are summarized along with clinical recommendations.

EXPERT OPINION

Concomitant use of amphotericin B and tenofovir must be closely monitored for renal functioning. Due to relatively weak interactive potential with the CYP450 system, fluconazole is the preferred antifungal drug. High itraconazole doses (> 200 mg/day) are not advised in patients receiving booster protease inhibitor (PI) regimen. Posaconazole is contraindicated in combination with either efavirenz or fosamprenavir. Moreover, voriconazole is contraindicated with high-dose ritonavir-boosted PI. Echinocandins may aid in overcoming the limitations of existing antifungal therapy. An increasing number of documented or predicted drug-drug interactions and therapeutic drug monitoring may aid in the management of HIV-associated opportunistic fungal infections.

Clinical characteristics and outcomes in 303 HIV-infected patients with invasive fungal infections: data from the Prospective Antifungal Therapy Alliance registry, a multicenter, observational study

This analysis aimed to characterize the epidemiology, diagnosis, treatment, and outcomes of invasive fungal infections (IFIs) in patients with human immunodeficiency virus (HIV). Data were examined for HIV patients enrolled in the Prospective Antifungal Therapy (PATH) Alliance registry, a multicenter, observational study of patients with IFIs in North America from 2004 to 2008. Patient demographics, clinical characteristics, comorbidities, antifungal therapies, and survival were assessed. In total, 320 fungal isolates were identified from 303 HIV patients with IFIs in the PATH Alliance® registry. These included Cryptococcus (50.0%), Candida (33.1%), Histoplasma (9.1%), and Aspergillus (4.4%). Candida infection occurred mainly as candidemia (86.0%); Cryptococcus as central nervous system infection (76.7%); Histoplasma as disseminated infection (74.1%); and Aspergillus as pulmonary infection (81.8%). The CD4 cell count was ≤200 cells/μL in 91.2% of patients with available data. The majority of patients with Cryptococcus (77.9%), Histoplasma (100.0%), and Aspergillus (71.4%) infections had CD4 cell counts <50 cells/μL compared with 48.9% of patients with Candida infections. Patients with candidiasis were more likely to have other conditions requiring medical services compared with patients with other IFIs. Survival probability was lower in patients with Aspergillus (0.58) and Candida (0.59) infection than in patients with Histoplasma (0.84) and Cryptococcus (0.81) infection. In the highly active antiretroviral therapy era, traditional opportunistic IFIs such as cryptococcosis and histoplasmosis still mainly occur in HIV patients with CD4 counts <50 cells/μL. Fungal infections remain a clinical challenge in HIV patients with severe immunosuppression. Our data also suggest that HIV patients with CD4 cell counts >200 cells/μL and other underlying conditions may be susceptible to invasive candidiasis.

Persistent Cryptococcal Brain Infection despite Prolonged Immunorecovery in an HIV-Positive Patient

Background. HIV-positive people starting combined antiretroviral therapy may develop immune reconstitution to latent or treated opportunistic infections. Immune reconstitution to cerebral Cryptococcus is poorly understood and can be fatal. Case Presentation. A 33-year-old Zimbabwean female presented with cryptococcal meningitis and newly diagnosed HIV with a CD4 count of 51 cells/μL (4%). She was treated with amphotericin and flucytosine. Combined antiretroviral therapy was started four weeks later and she showed early improvement. However, over the ensuing 18 months, her clinical course was marked by periodic worsening with symptoms resembling cryptococcal meningitis despite having achieved CD4 counts ≥400 cells/μL. Although initially treated for relapsing cryptococcal immune reconstitution syndrome, a brain biopsy taken 17 months after initial presentation showed budding Cryptococci. Conclusion. This unusually protracted case highlights the difficulties in differentiating relapsing cryptococcal meningitis from immune reconstitution and raises questions concerning the optimum timing of initiation of combined antiretroviral therapy in such patients.

Defect of CARD9 leads to impaired accumulation of gamma interferon-producing memory phenotype T cells in lungs and increased susceptibility to pulmonary infection with Cryptococcus neoformans

Caspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule signal that is critical for NF-κB activation and is triggered through C-type lectin receptors (CLRs), which are pattern recognition receptors that recognize carbohydrate structures. Previous studies have reported that Cryptococcus neoformans, a fungal pathogen that causes meningoencephalitis in AIDS patients, is recognized through some CLRs, such as mannose receptors or DC-SIGN. However, the role of CARD9 in the host defense against cryptococcal infection remains to be elucidated. In the present study, we analyzed the role of CARD9 in the host defense against pulmonary infection with C. neoformans. CARD9 gene-disrupted (knockout [KO]) mice were highly susceptible to this infection, as shown by the reduced fungal clearance in the infected lungs of CARD9 KO mice, compared to that in wild-type (WT) mice. Gamma interferon (IFN-γ) production was strongly reduced in CARD9 KO mice during the innate-immunity phase of infection. Reduced IFN-γ synthesis was due to impaired accumulation of NK and memory phenotype T cells, which are major sources of IFN-γ innate-immunity-phase production; a reduction in the accumulation of these cells was correlated with reduced CCL4, CCL5, CXCL9, and CXCL10 synthesis. However, differentiation of Th17 cells, but not of Th1 cells, was impaired at the adaptive-immunity phase in CARD9 KO mice compared to WT mice, although there was no significant difference in the infection susceptibility between interleukin 17A (IL-17A) KO and WT mice. These results suggest that CARD9 KO mice are susceptible to C. neoformans infection probably due to the reduced accumulation of IFN-γ-expressing NK and memory phenotype T cells at the early stage of infection.

Opportunistic diseases in HIV-infected patients in Gabon following the administration of highly active antiretroviral therapy: a retrospective study

Opportunistic diseases cause substantial morbidity and mortality to human immunodeficiency virus (HIV)-infected patients. Highly active antiretroviral therapy (HAART) leading to immune reconstitution is the most effective treatment of preventing opportunistic diseases. This retrospective study established an epidemiologic profile of opportunistic diseases 10 years after the introduction of HAART. The HIV antiretroviral therapy-naive patients matching inclusion criteria were included. The primary outcome was the prevalence of opportunistic diseases. From January 1, 2002 to September 30, 2010, 654 opportunistic diseases were identified in 458 patients. Pulmonary tuberculosis, herpes zoster, cerebral toxoplasmosis, oral candidiasis, and severe pneumonia accounted for 22.05%, 15.94%, 14.19%, 14.19%, and 9.39%, respectively. Cryptococcal meningitis and pneumocystosis accounted for 0.44% and 0.21%, respectively. The prevalence of opportunistic diseases in Gabon remains high. New guidelines emphasize the importance of initiating antiretroviral therapy early to reconstitute the immune system, and reduce disease risk, and treat the primary opportunistic infection of pulmonary tuberculosis.

Central nervous system immune reconstitution inflammatory syndrome

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) develops in 9 %-47 % of persons with HIV infection and a CNS opportunistic infection who start antiretroviral therapy and is associated with a mortality rate of 13 %-75 %. These rates vary according to the causative pathogen. Common CNS-IRIS events occur in relation to Cryptococcus, tuberculosis (TB), and JC virus, but several other mycobacteria, fungi, and viruses have been associated with IRIS. IRIS symptoms often mimic the original infection, and diagnosis necessitates consideration of treatment failure, microbial resistance, and an additional neurological infection. These diagnostic challenges often delay IRIS diagnosis and treatment. Corticosteroids have been used to treat CNS-IRIS, with variable responses; the best supportive evidence exists for the treatment of TB-IRIS. Pathogenic mechanisms vary: Cryptococcal IRIS is characterized by a paucity of cerebrospinal inflammation prior to antiretroviral therapy, whereas higher levels of inflammatory markers at baseline predispose to TB meningitis IRIS. This review focuses on advances in the understanding of CNS-IRIS over the past 2 years.

Geographically structured populations of Cryptococcus neoformans Variety grubii in Asia correlate with HIV status and show a clonal population structure

Cryptococcosis is an important fungal disease in Asia with an estimated 140,000 new infections annually the majority of which occurs in patients suffering from HIV/AIDS. Cryptococcus neoformans variety grubii (serotype A) is the major causative agent of this disease. In the present study, multilocus sequence typing (MLST) using the ISHAM MLST consensus scheme for the C. neoformans/C. gattii species complex was used to analyse nucleotide polymorphisms among 476 isolates of this pathogen obtained from 8 Asian countries. Population genetic analysis showed that the Asian C. neoformans var. grubii population shows limited genetic diversity and demonstrates a largely clonal mode of reproduction when compared with the global MLST dataset. HIV-status, sequence types and geography were found to be confounded. However, a correlation between sequence types and isolates from HIV-negative patients was observed among the Asian isolates. Observations of high gene flow between the Middle Eastern and the Southeastern Asian populations suggest that immigrant workers in the Middle East were originally infected in Southeastern Asia.

A high-throughput screening assay for fungicidal compounds against Cryptococcus neoformans

Cryptococcus neoformans is a pathogenic fungus that causes meningitis worldwide, particularly in human immunodeficiency virus (HIV)-infected individuals. Although amphotericin B is the "gold standard" treatment for cryptococcal meningitis, the toxicity and inconvenience of intravenous injection emphasize a need for development of new anticryptocccal drugs. Recent data from humans and animal studies suggested that a nutrient-deprived host environment may exist in cryptococcal meningitis. Thus, a screening assay for identifying fungicidal compounds under nutrient-deprived conditions may provide an alternative strategy to develop new anticryptococcal drugs for this disease. A high-throughput fungicidal assay was developed using a profluorescent dye, alamarBlue, to detect residual metabolic activity of C. neoformans under nutrient-limiting conditions. Screening the Library of Pharmacologically Active Compounds (LOPAC) with this assay identified a potential chemical scaffold, 10058-F4, that exhibited fungicidal activity in the low micromolar range. These results thus demonstrate the feasibility of this alamarBlue-based assay for high-throughput screening of fungicidal compounds under nutrient-limiting conditions for new anticryptococcal drug development.

A high-throughput screening assay for assessing the viability of Cryptococcus neoformans under nutrient starvation conditions

Cryptococcus neoformans causes an estimated 600,000 AIDS-related deaths annually that occur primarily in resource-limited countries. Fluconazole and amphotericin B are currently available for the treatment of cryptococcal-related infections. However, fluconazole has limited clinical efficacy and amphotericin B requires intravenous infusion and is associated with high renal toxicity. Therefore, there is an unmet need for a new orally administrable anti-cryptococcal drug. We have developed a high-throughput screening assay for the measurement of C. neoformans viability in 1,536-well plate format. The signal-to-basal ratio of the ATP content assay was 21.9 fold with a coefficient of variation and Z' factor of 7.1% and 0.76, respectively. A pilot screen of 1,280 known compounds against the wild-type C. neoformans (strain H99) led to the identification of four active compounds including niclosamide, malonoben, 6-bromoindirubin-3'-oxime, and 5-[(4-ethylphenyl)methylene]-2-thioxo-4-thiazolidinone. These compounds were further tested against nine clinical isolates of C. neoformans, and their fungicidal activities were confirmed. The results demonstrate that this miniaturized C. neoformans assay is advantageous for the high-throughput screening of large compound collections to identify lead compounds for new anti-cryptococcal drug development.

A prospective longitudinal study of the clinical outcomes from cryptococcal meningitis following treatment induction with 800 mg oral fluconazole in Blantyre, Malawi

Introduction

Cryptococcal meningitis is the most common neurological infection in HIV infected patients in Sub Saharan Africa, where gold standard treatment with intravenous amphotericin B and 5 flucytosine is often unavailable or difficult to administer. Fluconazole monotherapy is frequently recommended in national guidelines but is a fungistatic drug compromised by uncertainty over optimal dosing and a paucity of clinical end-point outcome data.

Methods

From July 2010 until March 2011, HIV infected adults with a first episode of cryptococcal meningitis were recruited at Queen Elizabeth Central Hospital, Blantyre, Malawi. Patients were treated with oral fluconazole monotherapy 800 mg daily, as per national guidelines. ART was started at 4 weeks. Outcomes and factors associated with treatment failure were assessed 4, 10 and 52 weeks after fluconazole initiation.

Results

Sixty patients were recruited. 26/60 (43%) died by 4 weeks. 35/60 (58.0%) and 43/56 (77%) died or failed treatment by 10 or 52 weeks respectively. Reduced consciousness (Glasgow Coma Score <14 of 15), moderate/severe neurological disability (modified Rankin Score >3 of 5) and confusion (Abbreviated Mental Test Score <8 of 10) were all common at baseline and associated with death or treatment failure. ART prior to recruitment was not associated with better outcomes.

Conclusions

Mortality and treatment failure from cryptococcal meningitis following initiation of treatment with 800 mg oral fluconazole is unacceptably high. To improve outcomes, there is an urgent need for better therapeutic strategies and point-of-care diagnostics, allowing earlier diagnosis before development of neurological deficit.

Macrophage M1/M2 polarization dynamically adapts to changes in cytokine microenvironments in Cryptococcus neoformans infection

The outcome of cryptococcal pneumonia correlates with local macrophage polarization status, as M1 and M2 polarization marks protective and nonprotective responses, respectively. Overall, pulmonary macrophage polarization status changes over time during a cryptococcal infection. This could have been caused by repolarization of individual macrophages or by a replacement of M2-polarized cells by new M1-polarized cells. To explore the ability of macrophages to change between polarization states, we conducted a series of experiments using in vitro macrophages. Coculture of macrophages with Cryptococcus neoformans resulted in development of a weak M1-like phenotype, with modestly increased inducible nitric oxide synthase (iNOS) but lacking interleukin 6 (IL-6) induction. The C. neoformans-induced M1-like polarization state was plastic, as macrophages stimulated first with C. neoformans and then with gamma interferon (IFN-γ) or IL-4 expressed mRNA polarization patterns similar to those stimulated with cytokines alone. To further evaluate macrophage polarization plasticity, cytokine stimulatory conditions were established which fully polarized macrophages. IFN-γ and IL-4 stimulation differentially induced complete M1 and M2 polarization, defined by differential expression of marker mRNA panels, surface marker expression, and tumor necrosis factor alpha (TNF-α) protein production. Switching IFN-γ- to IL-4-stimulating conditions, and vice versa, resulted in uniform changes in profiles of polarization marker genes consistent with the most recent cytokine environment. Furthermore, the ability of sequentially stimulated macrophages to inhibit C. neoformans reflected the most recent polarizing condition, independent of previous polarization. Collectively, these data indicate that M1/M2 macrophage polarization phenotypes are highly plastic to external signals, and interventions which therapeutically repolarize macrophages could be beneficial for treatment of cryptococcosis.

Strategies to reduce mortality and morbidity due to AIDS-related cryptococcal meningitis in Latin America

Latin America is the region with the third most AIDS-related cryptococcal meningitis infections globally. Highly active antiretroviral therapy (HAART) has reduced the number of infections; however, the number of deaths and the case-fatality rate continues to be unacceptable. In this review, we focus on the burden of AIDS-related cryptococcosis in Latin America and discuss potential strategies to reduce early mortality from Cryptococcus. In this review, we highlight the importance of: (1) earlier HIV diagnosis and HAART initiation with retention-in-care to avoid AIDS; (2) pre-HAART cryptococcal antigen (CRAG) screening with preemptive fluconazole treatment; (3) better diagnostics (e.g. CRAG testing); and (4) optimal treatment with aggressive management of intracranial pressure and induction therapy with antifungal combination. Implementation of these strategies can reduce cryptococcal-related deaths, improve care, and reduce healthcare costs.

The phenotype of the Cryptococcus-specific CD4+ memory T-cell response is associated with disease severity and outcome in HIV-associated cryptococcal meningitis

Background. Correlates of immune protection in patients with human immunodeficiency virus (HIV)–associated cryptococcal meningitis are poorly defined. A clearer understanding of these immune responses is essential to inform rational development of immunotherapies.

Methods. Cryptococcal-specific peripheral CD4⁺ T-cell responses were measured in 44 patients with HIV-associated cryptococcal meningitis at baseline and during follow-up. Responses were assessed following ex vivo cryptococcal mannoprotein stimulation, using 13-color flow-cytometry. The relationships between cryptococcal-specific CD4⁺ T-cell responses, clinical parameters at presentation, and outcome were investigated.

Results. Cryptococcal-specific CD4⁺ T-cell responses were characterized by the production of macrophage inflammatory protein 1α, interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α). Conversely, minimal interleukin 4 and interleukin 17 production was detected. Patients surviving to 2 weeks had significantly different functional CD4⁺ T-cell responses as compared to those who died. Patients with a response predominantly consisting of IFN-γ or TNF-α production had a 2-week mortality of 0% (0/20), compared with 25% (6/24) in those without this response (P = .025). Such patients also had lower fungal burdens (10 400 vs 390 000 colony-forming units/mL; P < .001), higher cerebrospinal fluid lymphocyte counts (122 vs 8 cells/μL; P < .001), and a trend toward faster rates of clearance of infection.

Conclusions. The phenotype of the peripheral CD4⁺ T-cell response to Cryptococcus was associated with disease severity and outcome in HIV-associated cryptococcal meningitis. IFN-γ/TNF-α–predominant responses were associated with survival.

Optimal timing for antiretroviral therapy initiation in patients with HIV infection and concurrent cryptococcal meningitis

BACKGROUND

Currently, initiation of antiretroviral therapy (ART) in most patients with human immunodeficiency virus (HIV) infection is based on the CD4-positive-t-lymphocyte count. However, the point during the course of HIV infection at which ART should be initiated in patients with concurrent cryptococcal meningitis remains unclear. The aim of this systematic review was to summarise the evidence on the optimal timing of ART initiation in patients with cryptococcal meningitis for use in clinical practice and guideline development.

OBJECTIVES

To compare the clinical and immunologic outcomes for early initiation ART (less than four weeks after starting antifungal treatment) versus later initiation of HAART (four weeks or more after starting antifungal treatment) in HIV-positive patients with concurrent cryptococcal meningitis.

SEARCH METHODS

We searched the following databases from January 1980 to February 2011: PubMed, EMBASE, and WHO International Clinical Trials Registry Platform, AEGIS database for conference abstracts, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews. A total of 35 full text articles were identified and supplemented by a bibliographic search. We contacted researchers and relevant organizations and checked reference lists of all included studies.

SELECTION CRITERIA

Randomized controlled trials that compared the effect of ART (consisting of three drug combinations) initiated early or delayed in HIV patients with cryptococcal meningitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, and graded methodological quality. Data extraction and methodological quality were checked by a third author who resolved differences when these arose. Where clinically meaningful, we performed a meta-analysis of dichotomous outcomes using the relative risk (RR) and report the 95% confidence intervals (95% CIs).

MAIN RESULTS

Two eligible randomized controlled trials were included (N = 89). In our pooled analysis, we combined the clinical data for both trials comparing early initiation ART versus delayed initiation of ART. There was no statistically significant difference in mortality (RR=1.40, 95% CI [0.42, 4.68]) in the group with early initiation of ART compared to the group with delayed initiation of ART.

AUTHORS' CONCLUSIONS

This systematic review shows that there is insufficient evidence in support of either early or late initiation of ART. For the moment, because of the high risk of immune reconstitution syndrome in patients with cryptococcal meningitis, we recommend that ART initiation should be delayed until there is evidence of a sustained clinical response to antifungal therapy. However, large studies with appropriate comparison groups, and adequate follow-up are warranted to provide the evidence base for effective decision making.

Unusual galactofuranose modification of a capsule polysaccharide in the pathogenic yeast Cryptococcus neoformans

Galactofuranose (Galf) is the five-membered ring form of galactose. Although it is absent from mammalian glycans, it occurs as a structural and antigenic component of important cell surface molecules in a variety of microbes, ranging from bacteria to parasites and fungi. One such organism is Cryptococcus neoformans, a pathogenic yeast that causes lethal meningoencephalitis in immunocompromised individuals, particularly AIDS patients. C. neoformans is unique among fungal pathogens in bearing a complex polysaccharide capsule, a critical virulence factor reported to include Galf. Notably, how Galf modification contributes to the structure and function of the cryptococcal capsule is not known. We have determined that Galf is β1,2-linked to an unusual tetrasubstituted galactopyranose of the glucuronoxylomannogalactan (GXMGal) capsule polysaccharide. This discovery fills a longstanding gap in our understanding of a major polymer of the cryptococcal capsule. We also engineered a C. neoformans strain that lacks UDP-galactopyranose mutase; this enzyme forms UDP-Galf, the nucleotide sugar donor required for Galf addition. Mutase activity was required for the incorporation of Galf into glucuronoxylomannogalactan but was dispensable for vegetative growth, cell integrity, and virulence in a mouse model.

Immune modulation mediated by cryptococcal laccase promotes pulmonary growth and brain dissemination of virulent Cryptococcus neoformans in mice

C. neoformans is a leading cause of fatal mycosis linked to CNS dissemination. Laccase, encoded by the LAC1 gene, is an important virulence factor implicated in brain dissemination yet little is known about the mechanism(s) accounting for this observation. Here, we investigated whether the presence or absence of laccase altered the local immune response in the lungs by comparing infections with the highly virulent strain, H99 (which expresses laccase) and mutant strain of H99 deficient in laccase (lac1Δ) in a mouse model of pulmonary infection. We found that LAC1 gene deletion decreased the pulmonary fungal burden and abolished CNS dissemination at weeks 2 and 3. Furthermore, LAC1 deletion lead to: 1) diminished pulmonary eosinophilia; 2) increased accumulation of CD4+ and CD8+ T cells; 3) increased Th1 and Th17 cytokines yet decreased Th2 cytokines; and 4) lung macrophage shifting of the lung macrophage phenotype from M2- towards M1-type activation. Next, we used adoptively transferred CD4+ T cells isolated from pulmonary lymph nodes of mice infected with either lac1Δ or H99 to evaluate the role of laccase-induced immunomodulation on CNS dissemination. We found that in comparison to PBS treated mice, adoptively transferred CD4+ T cells isolated from lac1Δ-infected mice decreased CNS dissemination, while those isolated from H99-infected mice increased CNS dissemination. Collectively, our findings reveal that immune modulation away from Th1/Th17 responses and towards Th2 responses represents a novel mechanism through which laccase can contribute to cryptococcal virulence. Furthermore, our data support the hypothesis that laccase-induced changes in polarization of CD4+ T cells contribute to CNS dissemination.

Central Nervous System Cryptococcosis among a Cohort of HIV Infected Patients from a University Hospital of North India

BACKGROUND

Cryptococcus neoformans is a ubiquitous encapsulated yeast that causes significant infections which range from asymptomatic pulmonary colonization to the life threatening meningoencephalitis, especially in immunocompromised individuals. Cryptococcal meningitis is one of the AIDS-defining illnesses. Recent data have indicated that, the incidence of the cryptococcal infection is high in developing countries like India. We conducted this study to find out the incidence of cryptococcosis in this area.

MATERIAL AND METHODS

The Cerebrospinal Fluid (CSF) specimens were collected from known HIV positive cases that had a clinical diagnosis of meningitis and they were processed by standard microbiological procedures. The cryptococcal isolates were identified by microscopy, their cultural characteristics, sugar assimilation and by the hydrolysis of urea.

RESULTS

The incidence of cryptococcal meningitis was 12.9%. All the strains were susceptible to amphotericin B, fluconazole, itraconazole and voriconazole.

CONCLUSION

The cryptococcal infection should be suspected in all cases of meningitis, especially among HIV infected persons. An early diagnosis and treatment may alter the prognosis of these patients and hence, an examination of the CSF for cryptococcosis should be considered in all the HIV infected persons who have the symptoms of meningitis.

Epidemiology of central nervous system infection

In cases of central nervous system infection, it is crucial for the neuroradiologist to provide an accurate differential diagnosis of the possible pathogens involved so that treating physicians can be aided in the choice of empiric therapy. This approach requires the radiologist to be aware of local epidemiology and have knowledge of infectious agents that are endemic to their area of practice. This article reviews and discusses the changing epidemiology of pathogens most often observed in meningitis, brain abscess, epidural abscess, postoperative infections, and human immunodeficiency virus infection.

Challenges in diagnosis and management of Cryptococcal immune reconstitution inflammatory syndrome (IRIS) in resource limited settings

In many resource-limited settings, cryptococcal meningitis (CM) contributes up to 20% of all deaths with further complications due to Immune Reconstitution Inflammatory Syndrome (IRIS). We present a case report on a patient who developed CM-IRIS and then subsequent CM-relapse with a fluconazole-resistant organism and then later CM-IRIS once again, manifesting as cystic cryptococcomas, hydrocephalus, and sterile CSF. In this case we, demonstrate that CM-IRIS and persistent low level cryptococcal infection are not mutually exclusive phenomena. The management of IRIS with corticosteroids may increase the risk of culture positive CM-relapse which may further increase the risk of recurrent IRIS and resulting complications including death. We also highlight the role of imaging and fluconazole resistance testing in patients with recurrent meningitis and the importance of CSF cultures in guiding treatment decisions.

Adjunctive interferon-γ immunotherapy for the treatment of HIV-associated cryptococcal meningitis: a randomized controlled trial

BACKGROUND

Interferon-gamma (IFNγ) is of key importance in the immune response to Cryptococcus neoformans. Mortality related to cryptococcal meningitis remains high, and novel treatment strategies are needed. We performed a randomized controlled trial to determine whether addition of IFNγ to standard therapy increased the rate of clearance of cryptococcal infection in HIV-associated cryptococcal meningitis.

METHODS

Patients were randomized to amphotericin B 1 mg/kg per day and 5FC 100 mg/kg per day for 2 weeks (standard therapy), standard therapy and IFNγ1b 100 μg days 1 and 3 (IFNγ two doses), or standard therapy and IFNγ1b 100 μg days 1, 3, 5, 8, 10 and 12 (IFNγ six doses). Primary outcome was rate of clearance of cryptococcus from the cerebrospinal fluid (CSF) (early fungicidal activity, EFA) calculated from serial quantitative cultures, previously shown to be independently associated with survival.

RESULTS

Rate of fungal clearance was significantly faster in IFNγ containing groups than with standard treatment. Mean EFA [log colony forming unit (CFU)/ml per day] was -0.49 with standard treatment, -0.64 with IFNγ two doses, and -0.64 with IFNγ six doses. Difference in EFA was -0.15 [confidence interval (95% CI) -0.02 to -0.27, P=0.02] between standard treatment and IFNγ two doses, and -0.15 (95% CI -0.05 to -0.26, P=0.006) between standard treatment and IFNγ six doses. Mortality was 16% (14/88) at 2 weeks and 31% (27/87) at 10 weeks, with no significant difference between groups. All treatments were well tolerated.

CONCLUSION

Addition of short-course IFNγ to standard treatment significantly increased the rate of clearance of cryptococcal infection from the CSF, and was not associated with any increase in adverse events. Two doses of IFNγ are as effective as six doses.

Different presentations and outcomes between HIV-infected and HIV-uninfected patients with Cryptococcal meningitis

BACKGROUND AND PURPOSE

Cryptococcus species are the most common causative agents of fungal meningitis. Different populations may show different clinical manifestations and outcomes. In this retrospective study, we investigated these differences in patients with and without HIV infection.

METHODS

From 1995 to 2009, we collected data from HIV-infected or HIV-uninfected patients aged 18 years or over who had cryptococcal meningitis (CM) in a medical center in Taiwan. We reviewed and analyzed their demographic data, clinical manifestations, therapeutic strategies and outcomes.

RESULTS

Among the 72 patients with CM, 19 HIV-infected patients were predominantly younger males, and all of them had AIDS status when CM was diagnosed. In contrast, the 53 HIV-uninfected patients were mostly older males with underlying diseases. The time from initial symptoms to diagnosis was shorter in HIV-infected patients (median 10 vs. 18 days, p = 0.048). The HIV-infected patients presented with less pleocytosis (p = 0.003) and lower protein levels in the cerebrospinal fluid (CSF), but a higher proportion had positive results for cryptococci in the CSF (90% vs. 60%, p = 0.02) and blood (53% vs. 21%, p = 0.009) cultures. Surgical drains and repeated lumbar punctures for the management of increased intracranial pressure were performed in 47% of the HIV-infected patients and 38% of the HIV-uninfected patients. A lower mortality rate was observed in the HIV-infected patients (p = 0.038). On multivariate analysis, initial CD4 count ≤20/mm(3) was an indicator of death or relapse in HIV-infected patients. In the HIV-uninfected group, the initial high cryptococcal antigen titer in the CSF (≥1:512) and hydrocephalus were related to unsatisfactory outcomes.

CONCLUSION

In addition to well-known differences, we found a lower mortality in HIV-infected patients than in HIV-uninfected patients. Cryptococci and inflammation in the central nervous system may play important roles in the pathogenesis of CM. Low intensity of inflammation and effective surgical CSF drains for increased intracranial pressure and cryptococci removal may contribute to lower mortality in HIV-infected patients.

Role of quantitative CSF microscopy to predict culture status and outcome in HIV-associated cryptococcal meningitis in a Brazilian cohort

This retrospective study aimed to evaluate the clinical, laboratory, and quantitative cerebrospinal fluid (CSF) cryptococcal cell counts for associations with in-hospital outcomes of HIV-infected patients with cryptococcal meningitis. Ninety-eight HIV-infected adult patients with CSF culture-proven cryptococcal meningitis were admitted between January 2006 and June 2008 at a referral center in Sao Paulo, Brazil. Cryptococcal meningitis was the first AIDS-defining illness in 69%, of whom 97% (95/98) had known prior HIV infection. The median CD4+ T-cell count was 39 cells/μL (interquartile range 17-87 cells/μL). Prior antiretroviral therapy was reported in 50%. Failure to sterilize the CSF by 7-14 days was associated with baseline fungal burden of ≥ 10 yeasts/μL by quantitative CSF microscopy (odds ratio [OR] = 15.3, 95% confidence interval [CI] 4.1-56.7; P < 0.001) and positive blood cultures (OR = 11.5, 95% CI 1.2-109; P = 0.034). At 7-14 days, ≥ 10 yeasts/μL CSF was associated with positive CSF cultures in 98% versus 36% with <10 yeasts/μL CSF (P < 0.001). In-hospital mortality was 30% and was associated with symptoms duration for >14 days, altered mental status (P < 0.001), CSF white blood cell counts <5 cells/μL (P = 0.027), intracranial hypertension (P = 0.011), viral loads >50,000 copies/mL (P = 0.036), ≥ 10 yeasts/μL CSF at 7-14 days (P = 0.038), and intracranial pressure >50 cmH(2)0 at 7-14 days (P = 0.007). In conclusion, most patients were aware of their HIV status. Fungal burden of ≥ 10 yeasts/μL by quantitative CSF microscopy predicted current CSF culture status and may be useful to customize the induction therapy. High uncontrolled intracranial pressure was associated with mortality.

Integrating cryptococcal antigen screening and pre-emptive treatment into routine HIV care

Cryptococcal meningitis is a leading cause of death in AIDS patients in sub-Saharan Africa. Cryptococcal antigen (CRAG) can be detected weeks before onset of symptoms, and those who are asymptomatic but CRAG positive have a high risk of subsequent cryptococcal meningitis and mortality. A new CRAG point of care immunochromatographic test is available that is remarkably easy to administer without laboratory infrastructure or expertise and has excellent sensitivity and specificity. We review the benefits of targeted CRAG screening, developments in CRAG diagnostics, and evidence regarding treatment options that can be implemented into routine HIV care in areas of high cryptococcal burden. Based on published CRAG+ prevalence rates of 2%-12%, the cost to save one life is between $20 to $140 in sub-Saharan Africa. We provide recommendations for implementation, pre-emptive treatment, and identify the gaps in our current knowledge.

The Impact of HIV Coinfection on Cerebral Malaria Pathogenesis

HIV infection is widespread throughout the world and is especially prevalent in sub-Saharan Africa and Asia. Similarly, Plasmodium falciparum, the most common cause of severe malaria, affects large areas of sub-Saharan Africa, the Indian subcontinent, and Southeast Asia. Although initial studies suggested that HIV and malaria had independent impact upon patient outcomes, recent studies have indicated a more significant interaction. Clinical studies have shown that people infected with HIV have more frequent and severe episodes of malaria, and parameters of HIV disease progression worsen in individuals during acute malaria episodes. However, the effect of HIV on development of cerebral malaria, a manifestation of P. falciparum infection that is frequently fatal, has not been characterized. We review clinical and basic science studies pertaining to HIV and malaria coinfection and cerebral malaria in particular in order to highlight the likely role HIV plays in exacerbating cerebral malaria pathogenesis.

Cryptococcus infection in a non-HIV patient: a case report

Cryptococcal infections are fungal infections most commonly seen in immunocompromised patients. Chronic high-dose steroid may precipitate such an immunocompromised state and thus create susceptibility to fungal infections. Cryptococcus neoformans is a saprophyte usually found in soil contaminated with pigeon droppings. Suspicion to diagnose begins with clinical symptoms that can be non-specific such as fevers, cough, and headaches. We present a case of steroid-induced cryptococcal infection in a non-HIV-infected person.

Clinical, epidemiological and outcome features of patients with cryptococcosis in Uberaba, Minas Gerais, Brazil

Nearly one million of cryptococcosis cases occur yearly around the world, involving mainly HIV-infected patients who are not receiving antiretroviral therapy (ART) or present poor adherence. This study aims to evaluate epidemiological, clinical and outcome aspects of patients with cryptococcosis from 1998-2010. Patients were prospectively recruited, and their medical and laboratory records were reviewed. A total of 131 cases were included, and of these, 119 (90.83%) had AIDS, 4 received a renal transplant, 2 presented systemic lupus erythematosus and 6 (4.6%) were apparently immunocompetent. Ninety-one (69.46%) were men, and the median age was 38.7 years. Cryptococcal meningitis (CM) was diagnosed in 103 (78.62%), whereas 28 (21.38%) had cryptococcal infection in other sites. Of patients with CM, 94 (91.26%) had AIDS being cryptococcosis the first defining illness in 61 (64.9%), while 37 (60.65%) of them presented simultaneously both diagnosis. Headache, altered mental status, papilledema and seizures at admission were significatively associated with a poor outcome. Of 163 different isolates, 155 (95.09%) were Cryptococcus neoformans and eight (4.88%) Cryptococcus gattii. Antifungal therapy was warranted in 8 (87.4%) patients with CM, but 46 (51.1%) died during the first days or weeks. Of 28 patients without CM, 21 (75%) received treatment, but 6 (28.6%) died. The poor outcome among this case series was similar to that reported from other developing countries, but it is paradoxal in Brazil where the ART is at free disposal in the public health services. Despite, at least 60-70% of patients present advanced immunosuppression when they receive the AIDS diagnosis.

Short course amphotericin B with high dose fluconazole for HIV-associated cryptococcal meningitis

OBJECTIVE

To define more rapidly effective initial antifungal regimens sustainable in resource-constrained settings.

METHODS

Cohort study in SW Uganda: Thirty HIV-seropositive, antiretroviral therapy-naïve, patients with first episode cryptococcal meningitis were treated with high dose fluconazole (1200 mg/d for 2 weeks, then 800 mg/d until ART started) plus amphotericin B (AmB, 1 mg/kg/d), with routine normal saline and potassium supplementation, for the initial 5 days. Outcome measures were early fungicidal activity (EFA), determined by serial quantitative CSF cultures, safety, and mortality.

RESULTS

EFA was -0.30 ± 0.11 log CFU/day calculated over the first 2 weeks of treatment, with no reduction in the rate of clearance between days 5 and 14. There was no grade IV hypokalemia or elevated creatinine, and no grade III or IV anemia or elevation of ALT. AmB or high dose fluconazole were not stopped early in any patient. Mortality was 23% at 2, and 28% at 10 weeks.

CONCLUSIONS

Short course AmB was associated with rapid clearance of infection and was well-tolerated, suggesting it could be used safely in many centres currently relying on fluconazole monotherapy. Phase III trials are needed in African centres to compare short course with the standard 2-week course of AmB.

Cryptococcus gattii: where do we go from here?

Infections caused by the emerging pathogen Cryptococcus gattii are increasing in frequency in North America. During the past decade, interest in the pathogen has continued to grow, not only in North America but also in other areas of the world where infections have recently been documented. This review synthesizes existing data and raises issues that remain to be addressed.

Cryptococcus neoformans suppresses the activation of bone marrow-derived dendritic cells stimulated with its own DNA, but not with DNA from other fungi

DNA from Cryptococcus neoformans activates bone marrow-derived dendritic cells (BM-DCs) in a TLR9-dependent manner. In this study, we examined the effect of the culture supernatants of C. neoformans on the activation of BM-DCs caused by its own DNA. C. neoformans supernatants suppressed IL-12p40, IL-6 production and CD40 expression by BM-DCs stimulated with its own DNA, but not with CpG-ODN and DNA from Candida albicans, Saccharomyces cerevisiae or Escherichia coli. In a confocal microscopic analysis, C. neoformans DNA was colocalized with LAMP-1, a late endosomal marker, and TLR9. The culture supernatants did not show any apparent suppression of these responses. In a luciferase reporter assay, C. neoformans supernatants inhibited NFκB activation caused by its own DNA. These inhibitory activities were attenuated by treatment with heat or trypsin. These results indicate that C. neoformans secrete certain proteinous molecules that suppress the activation of BM-DCs caused by its own DNA.

N-termini of fungal CSL transcription factors are disordered, enriched in regulatory motifs and inhibit DNA binding in fission yeast

BACKGROUND

CSL (CBF1/RBP-Jκ/Suppressor of Hairless/LAG-1) transcription factors are the effector components of the Notch receptor signalling pathway, which is critical for metazoan development. The metazoan CSL proteins (class M) can also function in a Notch-independent manner. Recently, two novel classes of CSL proteins, designated F1 and F2, have been identified in fungi. The role of the fungal CSL proteins is unclear, because the Notch pathway is not present in fungi. In fission yeast, the Cbf11 and Cbf12 CSL paralogs play antagonistic roles in cell adhesion and the coordination of cell and nuclear division. Unusually long N-terminal extensions are typical for fungal and invertebrate CSL family members. In this study, we investigate the functional significance of these extended N-termini of CSL proteins.

METHODOLOGY/PRINCIPAL FINDINGS

We identify 15 novel CSL family members from 7 fungal species and conduct bioinformatic analyses of a combined dataset containing 34 fungal and 11 metazoan CSL protein sequences. We show that the long, non-conserved N-terminal tails of fungal CSL proteins are likely disordered and enriched in phosphorylation sites and PEST motifs. In a case study of Cbf12 (class F2), we provide experimental evidence that the protein is proteolytically processed and that the N-terminus inhibits the Cbf12-dependent DNA binding activity in an electrophoretic mobility shift assay.

CONCLUSIONS/SIGNIFICANCE

This study provides insight into the characteristics of the long N-terminal tails of fungal CSL proteins that may be crucial for controlling DNA-binding and CSL function. We propose that the regulation of DNA binding by Cbf12 via its N-terminal region represents an important means by which fission yeast strikes a balance between the class F1 and class F2 paralog activities. This mode of regulation might be shared with other CSL-positive fungi, some of which are relevant to human disease and biotechnology.

Cryptococcus neoformans isolation from swallow (Hirundo rustica) excreta in Iran

Cryptococcus neoformans is an encapsulated yeast that can cause cryptococcosis, a life-threatening infection that mainly occurs in immunocompromised patients. The major environmental sources of C. neoformans have been shown to be soil contaminated with avian droppings. In the present study, we evaluated the isolation of C. neoformans from swallow (Hirundo rustica) excreta in two northern cities of Iran. Ninety-seven swallow droppings were evaluated and 498 yeast-like colonies were isolated and identified as Rhodotorula spp. (62.8%), Candida spp. (28.5%)and C. neoformans (8.7%). Cryptococcus neoformans was isolated from 5/97 (5.2%) of collected samples. Min-Max colony forming units (CFU) per one gram for the positive samples were 3-10 C. neoformans colonies. The total mean CFU per one gram for the positive samples was 4.8. The results of this study demonstrate that excreta of swallow may harbor different species of potentially pathogenic yeasts, mainly C. neoformans, and may be capable of disseminating these fungi in the environment.

Optimum time to start antiretroviral therapy during HIV-associated opportunistic infections

PURPOSE OF REVIEW

We review recently published literature concerning the optimum time to start antiretroviral therapy (ART) in patients with HIV-associated opportunistic infections.

RECENT FINDINGS

In addition to data from observational studies, results from six randomized controlled clinical trials were available by July 2010. The collective findings of these trials were that patients with CD4 cell counts less than 200 cells/μl who start ART within the first 2 weeks of treatment for opportunistic infections including Pneumocystis jirovecii pneumonia, serious bacterial infections or pulmonary tuberculosis have lower mortality when compared to patients starting ART at later time-points. Moreover, patients with pulmonary tuberculosis and CD4 counts of 200-500 cells/μl who started ART during tuberculosis (TB) treatment had improved survival compared to those who deferred ART until after the end of treatment. In contrast, in two separate studies, immediate ART conferred no survival benefit in patients with TB meningitis and was associated with substantially higher mortality risk in patients with cryptococcal meningitis.

SUMMARY

Initiation of ART during the first 2 weeks of treatment for serious opportunistic infections has been shown to be associated with improved survival with the exception of patients with tuberculous meningitis and cryptococcal meningitis. Further clinical trials are ongoing.

Cryptococcal meningitis in patients with or without human immunodeficiency virus: experience in a tertiary hospital

PURPOSE

Cryptococcal meningitis is a relatively common opportunistic infection in human immunodeficiency virus (HIV) patients and it can frequently occur in immunocompetent hosts without any apparent underlying disease. Nevertheless, little is known about cyptococcal meningitis in the Korean population. The purpose of this study was to evaluate the clinical features and initial laboratory findings of cryptococcal meningitis in patients with and without HIV at a tertiary care teaching hospital.

MATERIALS AND METHODS

We performed a retrospective study at a tertiary care teaching hospital from January 2001 to December 2009. Eleven HIV positive patients and nine HIV negative patients were included.

RESULTS

The most common symptoms were headache and fever in cryptococcal meningitis, and diabetic mellitus, end stage renal disease and liver cirrhosis were the main associated conditions in patients without HIV. Patients with HIV showed lower peripheral CD4+ cell counts (median: 9, range: 1-107) and a higher burden of cryptococcus than patients without HIV. There were no statistically significant differences in serum CRP level and other cerebrospinal fluid parameters between patients with HIV and without HIV. The in-hospital mortality was 10%, and recurrence of cyptococcal meningitis was observed in 3 patients with HIV and this occurred within 5 months of the first episode.

CONCLUSION

Cryptococcal meningitis is fatal without treatment, therefore, rapid recognition of symptoms such as fever and headache and diagnosis is required to decrease the mortality. Recurrence of meningitis after treatment should carefully be followed up, especially in advanced HIV patients.

Pathogenesis and prevention of immune reconstitution disease during antiretroviral therapy

The risks of unmasking and paradoxical forms of immune reconstitution disease in HIV-infected patients starting antiretroviral therapy (ART) are fuelled by a combination of the late presentation of patients with advanced immunodeficiency, the associated high rates of opportunistic infections (OIs) and the need for rapid initiation of ART to minimize overall mortality risk. We review the risk factors and our current knowledge of the immunopathogenesis of immune reconstitution disease, leading to a discussion of strategies for prevention. Initiation of ART at higher CD4 counts, use of OI-preventive therapies prior to ART eligibility, intensified screening for OIs prior to ART initiation and optimum therapy for OIs are all needed. In addition, use of a range of pharmacological agents with immunosuppressive and immunomodulatory activity is being explored.

Cryptococcal Meningitis in an HIV-Positive Pregnant Woman

Cryptococcal meningitis is uncommon in pregnant HIV-infected women. The clinical care of an HIV-1 positive pregnant woman with cryptococcal meningitis whose pathology has been previously reported is reviewed to highlight the treatment of the disease and some of the challenges associated with antifungal therapy during pregnancy, including the teratogenicity of antifungal agents, their variable pharmacokinetics in pregnancy, the lack of well-defined treatment duration for such infections, and host factors including compliance. This patient's disease relapsed due to nonadherence after an initial course of intravenous amphotericin. Subsequently, she was successfully treated, with a favorable fetal outcome, with another 2 weeks of amphotericin B, followed by consolidation and maintenance with fluconazole and antiretroviral treatment. This case highlights and reviews the complexities of the management of cryptococcal meningitis in HIV-infected pregnant women.

Mechanisms of cryptococcal virulence and persistence

Cryptococcus neoformans is an environmental yeast that is a leading cause of fatal mycosis in AIDS patients and a major cause of meningoencephalitis and CNS-related mortality around the globe. Although C. neoformans infection is mostly a manifestation of immune deficiency, up to 25% of cases reported in the USA occur in patients without recognizable immune defects, indicating that C. neoformans can develop mechanisms that allow it to evade immune defenses and persist in noncompromised hosts. This article discusses mechanisms and routes of infection and the most important elements of host response as well as the mechanisms that promote cryptococcal survival within the host. Metabolic adaptation to physiological host conditions and the mechanisms limiting immune recognition, interfering with phagocytosis and extending intracellular survival of C. neoformans are highlighted. We describe the mechanisms by which C. neoformans can alter adaptive host responses, especially cell-mediated immunity, which is required for clearance of this microbe. We also review cryptococcal strategies of survival in the CNS and briefly discuss adaptations developing in response to medical treatment.

An update on Cryptococcus among HIV-infected patients

Cryptococcus remains an important opportunistic infection in HIV patients despite considerable declines in prevalence during the highly active antiretroviral therapy era. This is particularly apparent in sub-Saharan Africa, where Cryptococcus continues to cause significant mortality and morbidity. This review discusses the microbiology, epidemiology, pathogenesis and clinical presentation of cryptococcal infections in HIV patients. Additionally, a detailed approach to the management of cryptococcosis is provided.

Paucity of initial cerebrospinal fluid inflammation in cryptococcal meningitis is associated with subsequent immune reconstitution inflammatory syndrome

BACKGROUND

Cryptococcal meningitis (CM)-related immune reconstitution inflammatory syndrome (IRIS) complicates antiretroviral therapy (ART) in 20%-40% of ART-naive persons with AIDS and prior CM. Pathogenesis is unknown.

METHODS

We compared initial cerebrospinal fluid (CSF) cultures, inflammatory markers, and cytokine profiles in ART-naive patients with AIDS who did or did not subsequently develop IRIS after starting ART. We also compared results obtained at IRIS events or CM relapse.

RESULTS

Of 85 subjects with CM, 33 (39%) developed CM-related IRIS and 5 (6%) developed culture-positive CM relapse. At CM diagnosis, subjects subsequently developing IRIS had less inflammation, with decreased CSF leukocytes, protein, interferon-gamma, interleukin-6, interleukin-8, and tumor necrosis factor-alpha, compared with subjects not developing IRIS (P<.05, for each). Initial CSF white blood cell counts < or =25 cells/microL and protein levels < or =50 mg/dL were associated with development of IRIS (odds ratio, 7.2 [95% confidence interval, 2.7-18.7]; P<.001). Compared with baseline levels, we identified CSF elevations of interferon-gamma, tumor necrosis factor-alpha, granulocyte colony-stimulating factor, vascular-endothelial growth factor, and eotaxin (CCL11) (P<.05, for each) at the time of IRIS but minimal inflammatory changes in those with CM relapse.

CONCLUSIONS

Patients who subsequently develop CM-related IRIS exhibit less initial CSF inflammation at the time of CM diagnosis, compared with those who do not develop IRIS. The inflammatory CSF cytokine profiles observed at time of IRIS can distinguish IRIS from CM relapse.