HIV-Associated Cryptococcal Meningitis: Bridging the Gap Between Developed and Resource-Limited Settings

An Overview of Diagnostic and Management Strategies for Talaromycosis, an Underrated Disease

Underrated and neglected, talaromycosis is a life-threatening fungal disease endemic to the tropical and subtropical regions of Asia. In China, it has been reported that talaromycosis mortality doubles from 24 to 50% when the diagnosis is delayed, and reaches 100% when the diagnosis is missed. Thus, the accurate diagnosis of talaromycosis is of utmost importance. Herein, in the first part of this article, we provide an extensive review of the diagnostic tools used thus far by physicians in the management of cases of talaromycosis. The challenges encountered and the perspectives which may aid in the discovery of more accurate and reliable diagnostic approaches are also discussed. In the second part of this review, we discuss the drugs used to prevent and treat T. marneffei infection. Alternative therapeutic options and potential drug resistance reported in the contemporary literature are also discussed. We aim to guide researchers towards the discovery of novel approaches to prevent, diagnose, and treat talaromycosis, and therefore improve the prognosis for those afflicted by this important disease.

Etiology of meningitis among adults in three quaternary hospitals in Mozambique, 2016–2017: The role of HIV

Background

Meningitis remains an important cause of morbi-mortality in adults in sub-Saharan Africa. Data on the etiological investigation of meningitis in adults in Mozambique is limited and most studies were conducted in southern Mozambique. Identification of the etiology of meningitis in adults are crucial to guide prevention and treatments strategies. In this study, we determine the burden of fungal and bacterial meningitis among adults at the three largest hospitals in Mozambique.

Method

We performed analysis of data from the routine sentinel surveillance system for meningitis in Mozambique from January 2016 to December 2017. Cerebrospinal fluid (CSF) samples were collected from eligible adults (≥18 years old) who met World Health Organization (WHO) case definition criteria for Meningitis. All samples were tested by cryptococcal antigen (CrAg) lateral flow assay (LFA), culture and triplex real-time polymerase chain reaction (qPCR) assay and all patients were tested for human immunodeficiency virus (HIV) using the national algorithm for HIV testing.

Results

Retrospective analysis of 1501 CSF samples from adults clinically suspected of meningitis revealed that 10.5% (158/1501) were positive for bacterial and fungal meningitis. Of these 158 confirmed cases, the proportion of Cryptococcal meningitis and pneumococcal meningitis was38.6% (95% CI: 31.0% to 46.7%) and 36.7% (95% CI: 29.2% to 44.7%), respectively. The other bacterial agents of meningitis identified include Neisseria meningitidis (8.9%; 14/158), Escherichia coli (6.3%; 10/158), Haemophilus influenzae (5.1%; 8/158) and S. aureus (4.4%; 7/158), which represent (24.7%; 39/158) of the total confirmed cases.

Conclusion

Altogether, our findings show a high burden of Cryptococcal meningitis among adults in Mozambique, especially in people living with HIV, followed by pneumococcal meningitis. Our findings suggest that rollout of CrAg Lateral Flow Assay in the health system in Mozambique for early detection of cryptococcus neoformans is necessary to improve overall patient care.

A global call for talaromycosis to be recognised as a neglected tropical disease

Talaromycosis (penicilliosis) is an invasive mycosis that is endemic in tropical and subtropical Asia. Talaromycosis primarily affects individuals with advanced HIV disease and other immunosuppressive conditions, and the disease disproportionally affects people in low-income and middle-income countries, particularly agricultural workers in rural areas during their most economically productive years. Approximately 17 300 talaromycosis cases and 4900 associated deaths occur annually. Talaromycosis is highly associated with the tropical monsoon season, when flooding and cyclones can exacerbate the poverty-inducing potential of the disease. Talaromycosis can present as localised or disseminated disease, the latter causing cutaneous lesions that are disfiguring and stigmatising. Despite up to a third of diagnosed cases resulting in death, talaromycosis has received little attention and investment from regional and global funders, policy makers, researchers, and industry. Diagnostic and treatment modalities remain extremely insufficient, however control of talaromycosis is feasible with known public health strategies. This Viewpoint is a global call for talaromycosis to be recognised as a neglected tropical disease to alleviate its impact on susceptible populations.

The Repurposing of Acetylsalicylic Acid as a Photosensitiser to Inactivate the Growth of Cryptococcal Cells

Photodynamic treatment (PDT) is often successful when used against aerobic microbes, given their natural susceptibility to oxidative damage. To this end, the current study aimed to explore the photodynamic action of acetylsalicylic acid (ASA; aspirin, which is commonly used to treat non-infectious ailments), when administered to respiring cryptococcal cells. The treatment of cryptococcal cells, i.e., exposure to 0.5 or 1 mM of ASA in the presence of ultraviolet light (UVL) for 10 min, resulted in a significant (p < 0.05) reduction in the growth of tested cells when compared to non-treated (non-Rx) cells, i.e., no ASA and no UVL. The treated cells were also characterised by diseased mitochondria, which is crucial for the survival of respiring cells, as observed by a significant (p < 0.05) loss of mitochondrial membrane potential (ΔΨM) and significant (p < 0.05) accumulation of reactive oxygen species (ROS) when compared to non-Rx cells. Moreover, the photolytic products of acetylsalicylic acid altered the ultrastructural appearance of treated cells as well as limited the expression levels of the capsular-associated gene, CAP64, when compared to non-Rx cells. The results of the study highlight the potential use of ASA as a photosensitiser that is effective for controlling the growth of cryptococcal cells. Potentially, this treatment can also be used as an adjuvant, to complement and support the usage of current anti-microbial agents.

Quality of life and associated factors among HIV positive patients after completion of treatment for Cryptococcal meningitis

Background

Cryptococcal meningitis (CCM) remains one of the leading causes of mortality among HIV infected patients. Due to factors such as the severity of CCM pathology, the quality of life (QOL) of patients post-treatment is likely to be poor. Few studies have reported on QOL of CCM patients post treatment completion. We used data collected among patients in the CryptoDex trial (ISRCTN59144167) to determine QOL and associated factors at week 10 and six months from treatment initiation.

Methodology

CryptoDex was a double-blind placebo-controlled trial of adjunctive dexamethasone in HIV infected adults with CCM, conducted between 2013 and 2015 in six countries in Asia and Africa. QOL was determined using the descriptive and Visual Analog Scales (VAS) of the EuroQol Five-Dimension-Three-Level (EQ-5D-3L) tool. We derived index scores, and described these and the VAS scores at 10 weeks and 6 months; and used linear regression to determine the relationship between various characteristics and VAS scores at both time points. VAS scores were interpreted as very good (81–100), good (51–80), normal (31–50) and bad/very bad (0–30).

Results

Of 451 patients enrolled in the trial, 238 had QOL evaluations at week 10. At baseline, their mean age (SD) was 35.2(8.5) years. The mean index scores (SD) were 0.785(0.2) and 0.619(0.4) among African and Asian patients respectively at week 10, and 0.879(0.2) and 0.731(0.4) among African and Asian patients respectively at month six. The overall mean VAS score (SD) at 10 weeks was 57.2 (29.7), increasing significantly to 72(27.4) at month six (p<0.001). At week 10, higher VAS score was associated with greater weight (p = 0.007) and being African (p<0.001), while lower VAS score was associated with positive yeast culture at day 14 (p = 0.026). At month six, higher VAS score remained associated with African origin (p = 0.006) while lower VAS score was associated with positive yeast culture (p = 0.006). Lower VAS scores were associated with higher number of inpatient days at 10 weeks and 6 months (p = 0.003 and 0.002 respectively).

Conclusion

QOL was good among patients that had completed therapy for CCM, but below perfect. Strategies to improve QOL among CCM survivors are required.

In spite of the remarkable reduction in Cryptococcal meningitis (CCM) related morbidity and mortality with increased use of antiretroviral therapy, incidence remains unacceptably high especially in sub-Saharan Africa and Asia where more than 90% of the cases and deaths occur.

Due to factors such as the severity of CCM pathology, the quality of life (QOL) of patients post-treatment is also likely to be poor. Few studies have reported on QOL of CCM patients post treatment completion. We used data collected among patients in the CryptoDex trial (ISRCTN59144167) to determine self-perceived QOL and associated factors among 238 survivors at week 10 and 203 survivors at six months from treatment initiation. We determined QOL using the descriptive and Visual Analog Scales (VAS) of the EuroQol Five-Dimension-Three-Level (EQ-5D-3L) tool. We found that while self-perceived QOL was only relatively good among this cohort of patients who had survived through treatment for CCM, it continued to improve over the 6 months following diagnosis. Low weight at diagnosis, prolonged hospital admission, positive yeast culture at day 14/treatment completion, and being Asian were associated with lower QOL. QOL is an important outcome that should be considered among HIV infected patients treated for serious infections such as CCM.

Determinants of two-year mortality among HIV positive patients with Cryptococcal meningitis initiating standard antifungal treatment with or without adjunctive dexamethasone in Uganda

Globally, early initiation of antiretroviral therapy for HIV led to a reduction in the estimated mortality from cryptococcal meningitis (CCM) from 624,700 in 2009 to 181,100 in 2014. However, CCM remains one of the leading causes of mortality among HIV infected patients especially in sub-Saharan Africa where 75% of the deaths occur. Most of the studies evaluating mortality have reported short-term mortality (at or before 10 weeks of therapy). We determined mortality and associated factors among patients treated for CCM in the CryptoDex trial (ISRCTN59144167) in Uganda, and the effect of dexamethasone adjunctive therapy on mortality at two years. We conducted a retrospective cohort study between May 2017 and July 2017 to determine the long term survival (up to 2 years post-randomization) of all patients who had been enrolled into the CryptoDex trial in Uganda. The CryptoDex trial recruited between April 2013 and February 2015. We estimated mortality rates and determined factors affecting mortality at two years using Cox regression. The study followed up 211 participants, 127 (60.2%) of whom were male. Sixteen participants (7.58%) were diagnosed with HIV at the same admission when CCM was diagnosed. By two years following randomization 127 (60%) participants had died, a mortality rate of 67 deaths per 100 person-years. Mortality was associated with Glasgow coma score (GCS) below 15 (adjusted Hazard ratio (aHR) 1.77, 95% CI: 1.02-2.44), p = 0.040; weight (aHR 0.97, per 1 Kg increase; 95% CI: 0.94-0.99), p = 0.003; and presence of convulsions (aHR 2.31, 95% CI: 1.32-4.04), p = 0.004, while dexamethasone use and fungal burden had no effect. Long-term mortality in CCM patients remains high even among patients receiving recommended therapy. Strategies to improve long-term survival in CCM patients are urgently needed, especially targeting those with reduced GCS, low weight, and convulsions.

Cryptococcal antigenemia and its predictors among HIV infected patients in resource limited settings: a systematic review

Background

Cryptococcosis is an opportunistic fungal infection that primarily affects people with advanced HIV/AIDS and is an important cause of morbidity and mortality around the globe. By far the most common presentation of the disease is cryptococcal meningitis (CM), which leads to an estimated 15–20% of all HIV related deaths worldwide, 75% of which are in sub-Saharan Africa. However, to the best of our knowledge there is quite limited reviewed data on the epidemiology of cryptococcal antigenemia in a large HIV-infected population in resource limited settings.

Methods

Articles published in English irrespective of the time of publication were systematically searched using comprehensive search strings from PubMed/Medline and SCOPUS. In addition, Google Scholar and Google databases were searched manually for grey literature. Two reviewers independently assessed study eligibility, extracted data, and assessed risk of bias. The pooled prevalence of cryptococcal antigenemia was determined with 95% confidence interval (CI).

Results

Among 2941 potential citations, we have included 22 studies with a total of 8338 HIV positive individuals. The studies were reported in ten different countries during the year (2007–2018). Most of the articles reported the mean CD4 count of the participants below 100 cells/μl. The pooled prevalence of cryptococcal antigenemia at different CD4 count and ART status was at 8% (95%CI: 6–10%) (ranged between 1.7 and 33%). Body mass index (BMI) < 18.5 kg/m², CD4 count < 100 cells, patients presenting with headache and male gender were reported by two or more articles as an important predictors of cryptococcal antigenemia.

Conclusions

Implementing a targeted screening of HIV patients with low BMI, CD4 count < 100 cells, having headache and males; and treatment for asymptomatic cryptococcal disease should be considered. Additional data is needed to better define the epidemiology of cryptococcal antigenemia and its predictors in resource limited settings in order to optimize the prevention, diagnosis, and treatment strategies.

Point of care testing evaluation of lateral flow immunoassay for diagnosis of cryptococcus meningitis in HIV-positive patients at an urban hospital in Nairobi, Kenya, 2017

Objectives

The objective of this study was to evaluate the performance of lateral flow immunoassay (LFA) against latex agglutination (LA), India ink and culture in point-of-care diagnosis of cryptococcus meningitis (CM). We conducted cross-sectional study among HIV-positive patients with suspected CM at Mbagathi Hospital, Nairobi, April–July 2017.

Results

Of 124 capillary blood and serum and 99 cerebrospinal fluid (CSF) samples, LFA and LA had a concurrence on serum of 94.4%, kappa (0.88), sensitivity (100%) and specificity (91%). LFA and LA on CSF, was 97.9%, kappa (0.96), sensitivity (100%) and specificity (96%). LFA and India ink was 96.9%, kappa (0.94), sensitivity (100%) and specificity (94.1%). On CSF culture, concurrence was 72.7%, kappa (0.43), sensitivity (100%) and specificity (64%) and of LFA on capillary blood, serum and CSF was 100% with kappa (1.00), sensitivity and specificity of 100%.

Factors affecting mortality among HIV positive patients two years after completing recommended therapy for Cryptococcal meningitis in Uganda

BACKGROUND

Cryptococcal meningitis (CCM) remains a leading cause of mortality amongst HIV infected patients in sub-Saharan Africa. When patients receive recommended therapy, mortality at 10 weeks has been reported to vary between 20 to 36%. However, mortality rate and factors affecting mortality after completing recommended therapy are not well known. We investigated mortality rate, and factors affecting mortality at 2 years among CCM patients following completion of recommended CCM therapy in Uganda.

METHODS

A retrospective cohort study was conducted among HIV infected patients that had completed 10 weeks of recommended therapy for CCM (2 weeks of intravenous amphotericin B 1mg/kg and 10 weeks of oral Fluconazole 800mg daily) in the CryptoDex trial (ISRCTN59144167) between 2013 and 2015. Survival analysis applying Cox regression was used to determine the mortality rate and factors affecting mortality at 2 years.

RESULTS

This study followed up 112 participants for 2 years. Mean age (±SD) was 34.9 ± 8, 48 (57.1%) were female and 80 (74.8%) had been on ART for less than 1 year. At 2 years, overall mortality was 30.9% (20 deaths per 100 person-years). Majority of deaths (61.8%) occurred during the first 6 months. In multivariable analysis, mortality was associated with ever being re-admitted since discharge after hospital-based management of CCM (aHR = 13.33, 95% CI: 5.92-30.03), p<0.001; and self-perceived quality of life, with quality of life 50-75% having reduced risk compared to <50% (aHR = 0.21, 95% CI: 0.09-0.5), p<0.001, as well as >75% compared to <50% (HR = 0.29, 95% CI: 0.11-0.81), p = 0.018.

CONCLUSION

There remains a considerable risk of mortality in the first two years after completion of standard therapy for CCM in resource-limited settings with risk highest during the first 6 months. Maintenance of patient follow up during this period may reduce mortality.

Safety and tolerability of intrathecal liposomal amphotericin B (AmBisome) for cryptococcal meningitis: a retrospective study in HIV-infected patients

Background

While mortality of HIV-related cryptococcal meningitis (CM) in developed countries is relatively low, in developing countries over half of patients die within 10 weeks. Current recommended therapies are often not suitable for resource-poor settings, and new shorter regimens are urgently needed. Intrathecal administration of liposomal amphotericin B (lAmB) has shown promising results in animal models. However, the safety and tolerability of intrathecal lAmB in humans are not well known.

Methods

In this retrospective observational study, we report the tolerability and safety of intrathecal lAmB in patients with CM from an HIV cohort study in India.

Results

In all, 18 patients were included in the analysis. Six were female and the median age was 40 years [interquartile range (IQR): 35-45]. The median CD4 count was 42 cells/µl (IQR: 19-127). Compared with a historical control group, the hazard ratio for mortality was 0.59 (95% confidence interval: 0.26-1.29). Two patients complained of transient lumbar pain in single occasion. One patient had a skin reaction to chlorhexidine, which was used as skin disinfectant. After initial improvement, one patient requested to stop lumbar punctures for the last 2 days of treatment.

Conclusion

Intrathecal lAmB was safe and well tolerated in HIV-infected patients with CM.

Prediction of unfavorable outcomes in cryptococcal meningitis: results of the multicenter Infectious Diseases International Research Initiative (ID-IRI) cryptococcal meningitis study

Cryptococcal meningitis (CM) is mostly seen in immunocompromised patients, particularly human immunodeficiency virus (HIV)-positive patients, but CM may also occur in apparently immunocompetent individuals. Outcome analyses have been performed in such patients but, due to the high prevalence of HIV infection worldwide, CM patients today may be admitted to hospitals with unknown HIV status, particularly in underdeveloped countries. The objective of this multicenter study was to analyze all types of CM cases in an aggregate cohort to disclose unfavorable outcomes. We retrospectively reviewed the hospitalized CM patients from 2000 to 2015 in 26 medical centers from 11 countries. Demographics, clinical, microbiological, radiological, therapeutic data, and outcomes were included. Death, neurological sequelae, or relapse were unfavorable outcomes. Seventy (43.8%) out of 160 study cases were identified as unfavorable and 104 (65%) were HIV infected. On multivariate analysis, the higher Glasgow Coma Scale (GCS) scores (p = 0.021), cerebrospinal fluid (CSF) leukocyte counts > 20 (p = 0.038), and higher CSF glucose levels (p = 0.048) were associated with favorable outcomes. On the other hand, malignancy (p = 0.026) was associated with poor outcomes. Although all CM patients require prompt and rational fungal management, those with significant risks for poor outcomes need to be closely monitored.

HIV-Associated Cryptococcal Disease in Resource-Limited Settings: A Case for "Prevention Is Better Than Cure"?

Cryptococcal disease remains a significant source of global morbidity and mortality for people living with HIV, especially in resource-limited settings. The recently updated estimate of cryptococcal disease revealed a global incidence of 223,100 cases annually with 73% of these cases being diagnosed in sub-Saharan Africa. Furthermore, 75% of the estimated 181,100 deaths associated with cryptococcal disease occur in sub-Saharan Africa. Point-of-care diagnostic assays have revolutionised the diagnosis of this deadly opportunistic infection. The theory of asymptomatic cryptococcal antigenaemia as a forerunner to symptomatic meningitis and death has been conclusively proven. Thus, cryptococcal antigenaemia screening coupled with pre-emptive antifungal therapy has been demonstrated as a cost-effective strategy with survival benefits and has been incorporated into HIV national guidelines in several countries. However, this is yet to be implemented in a number of other high HIV burden countries. Flucytosine-based combination therapy during the induction phase is associated with improved survival, faster cerebrospinal fluid sterilisation and fewer relapses. Flucytosine, however, is unavailable in many parts of the world. Studies are ongoing on the efficacy of shorter regimens of amphotericin B. Early diagnosis, proactive antifungal therapy with concurrent management of raised intracranial pressure creates the potential to markedly reduce mortality associated with this disease.

A novel bZIP protein, Gsb1, is required for oxidative stress response, mating, and virulence in the human pathogen Cryptococcus neoformans

The human pathogen Cryptococcus neoformans, which causes life-threatening meningoencephalitis in immunocompromised individuals, normally faces diverse stresses in the human host. Here, we report that a novel, basic, leucine-zipper (bZIP) protein, designated Gsb1 (general stress-related bZIP protein 1), is required for its normal growth and diverse stress responses. C. neoformans gsb1Δ mutants grew slowly even under non-stressed conditions and showed increased sensitivity to high or low temperatures. The hypersensitivity of gsb1Δ to oxidative and nitrosative stresses was reversed by addition of a ROS scavenger. RNA-Seq analysis during normal growth revealed increased expression of a number of genes involved in mitochondrial respiration and cell cycle, but decreased expression of several genes involved in the mating-pheromone-responsive MAPK signaling pathway. Accordingly, gsb1Δ showed defective mating and abnormal cell-cycle progression. Reflecting these pleiotropic phenotypes, gsb1Δ exhibited attenuated virulence in a murine model of cryptococcosis. Moreover, RNA-Seq analysis under oxidative stress revealed that several genes involved in ROS defense, cell-wall remodeling, and protein glycosylation were highly induced in the wild-type strain but not in gsb1Δ. Gsb1 localized exclusively in the nucleus in response to oxidative stress. In conclusion, Gsb1 is a key transcription factor modulating growth, stress responses, differentiation, and virulence in C. neoformans.