Cryptococcosis in India: the awakening of a giant?

Studying Human Pathogenic Cryptococcus Gattii Lineages by Utilizing Simple Sequence Repeats to Create Diagnostic Markers and Analyzing Diversity

In this study, we compared the occurrence, relative abundance (RA), and density (RD) of simple sequence repeats (SSRs) among the lineages of human pathogenic Cryptococcus gattii using an in-silico approach to gain a deeper understanding of the structure and evolution of their genomes. C. gattii isolate MF34 showed the highest RA and RD of SSRs in both the genomic and transcriptomic sequences, followed by isolate WM276. In both the genomic (50%) and transcriptomic (65%) sequences, trinucleotide SSRs were the most common SSR class. A motif conservation study found that the isolates had stronger conservation (56.1%) of motifs, with isolate IND107 having the most (5.7%) unique motifs. We discovered the presence of SSRs in genes that are directly or indirectly associated with disease using gene enrichment analysis. Isolate-specific unique motifs identified in this study could be utilized as molecular probes for isolate identification. To improve genetic resources among C. gattii isolates, 6499 primers were developed. These genomic resources developed in this study could help with diversity analysis and the development of isolate-specific markers.

1H NMR Using Metabolic Study in Body Fluids for Diagnosis of Cryptococcal Meningitis in Adults

Background

Cryptococcal meningitis is considered to affect HIV patients and those with impaired immune systems. Early identification and treatment are the keys to decreasing morbidity and mortality related to CM. Using 1H NMR spectroscopy, a prospective case-control study will assess the metabolic profile of adults' serum, urine, and CSF.

Methodology

The present multicentric study was conducted at Lucknow. The study included 150 participants, out of which there were 31 cryptococcal meningitis cases, 34 positive meningitis controls, and the rest, 85, were disease controls.

Result

The discriminant function analysis (DFA) of the three biofluids was used to find significant metabolites between the cases and the control group collectively. A group categorization between control group and the cases in serum, urine, and CSF samples was also made possible by the NMR spectral bin-based orthogonal signal correction and principal component analysis score plots of important metabolites produced from DFA. The cases group had a higher proportion of patients with higher CSF protein levels than the positive control group (BM and TM). Acetone was found among urine samples in both control samples, i.e., positive and negative.

Conclusion

This is the first study to explore biomarkers in serum, urine, and CSF in addition to radiological features and clinical symptoms. Hence, a quick, non-invasive prognosis and diagnosis of cryptococcal meningitis in adults can be made using clinical and microbiological investigation, as well as metabolomic analysis of urine samples. This study shows that urine can be used as a biofluid to differentiate between Cryptococcus meningitis in adults. However, when compared to the negative control, our sample size was significantly smaller, necessitating further confirmation on a larger sample size.

Trends of CNS Cryptococcosis during Pre- and Post-HIV era: A 38 years' retrospective cohort analysis from south India

OBJECTIVE

Central nervous system cryptococcosis (CNSc) is an AIDS defining opportunistic infection. This retrospective study aimed to analyze the changing epidemiology of CNSc cases from the period of pre- to post-emergence of HIV epidemic in south India.

METHODS

Confirmed cases of CNSc from 1978 to 2015 were analyzed for demographic and clinical details with special reference to the cases diagnosed in south India during the period 1952-1977. Geographical distribution, affected age groups, clinical aspects, and comorbidities in relation to immune status were analysed RESULTS: The highest number of CNSc cases (n = 125) were recorded in 2006, with 89.6% HIV positivity. The highest HIV-positivity (93.6%) was documented in the years 2002 and 2009. CNSc cases have majorly changed after the introduction and spread of HIV in terms of predisposing factors, comorbidities, severity, affected age groups and treatment. Notably, an overall rise was observed in non-HIV associated CNSc cases from 1997 (8.1%) to 2015 (16.9%).

CONCLUSION

The peak of CNSc had already reached in south India during 2005-2006. However, the number of new infections has slowly decreased in last ten years. Progressive awareness and, early diagnosis of HIV and cryptococcosis, adequate availability of HAART and potential antifungal therapy has played crucial roles in changing epidemiology of the CNSc and its associated mortality.

Clinicomycological overview of brain abscess in a tertiary care center: A 38 year retrospection: Fungal brain abscess

INTRODUCTION

Brain abscesses (BA) form approximately 8% of intracranial masses in developing and 1-2% in western countries. Fungal BA (FBA) are aggressive and represent a catastrophic manifestation compared to protozoan and bacterial BA. Diagnosis of FBA is rare and usually done postmortem.

OBJECTIVES

The present retrospective study analyses the clinico-mycological aspects of FBA presented to our neurosurgical services over a period of 38 years, from January 1979 to April 2017.

MATERIALS AND METHODS

Patients diagnosed as definitive cases of FBA were included in the study. Clinico- demographic and microbiological data were collected from medical records. BA pus was examined for fungal etiology using standard microbiological procedures.

RESULTS

During the period of 38 years out of total 2,916 brain abscesses, 29 cases of FBA were diagnosed with an overall incidence rate of 0.99% per year. Cladophialophora bantiana (44%) was the most predominant isolate followed by Aspergillus spp and others. Male preponderance was seen with a male:female ratio of 4.8:1. There was no predilection for any age group. Headache, limb weakness and fever were the most common presentations. Amphotericin B was given in 44.8% of cases. Craniotomy with excision (48.2%) was the predominant surgical management. Outcome was fatal in 62% of the cases.

CONCLUSION

Neurotropic C. bantiana is the predominant isolate causing fungal brain abscess. The incidence and trends of fungi causing brain abscess do not show significant change. Young immunocompetent outdoor working males were predominantly susceptible to fungal infection. Advance in the diagnostic modalities show promising in diagnosis of FBA. High index of suspicion with early diagnosis, prompt antifungal therapy and aggressive surgical management is required as FBA are associated with high mortality rate.

An atypical initial presentation of AIDS as cryptococcal lymphadenitis

A patient complained of fever on and off, difficulty in swallowing and cough (with scanty expectoration) since one and a half months and weight loss over 2 months. On examination, pallor was found to be present. Then ultrasonography of abdomen was done and it showed mesenteric and retroperitoneal lymphadenopathy. Sputum for acid-fast Bacilli was examined and found to be negative but despite this, based on the epidemiological data, antitubercular therapy (ATT) was started but after 2 weeks no clinical improvement was found. Then, fine-needle aspiration cytology of lymph node was done and it resulted in the presence of cryptococcal lymphadenitis as the final report. Antifungal therapy was initiated with amphotericin B followed by fluconazole and there was clinical improvement. Ultrasonographical findings also supported it. Though it is a rare case (but not impossible) that cryptococcus is the cause of lymphadenopathy. Thus, in initial presentation of acquired immuno deficiency syndrome it should always be kept in mind that such cases may happen. In India, presuming Mycobacterium tuberculosis as the leading cause exposes the patient to unwanted hepatic and renal toxicity of ATT.

Prevalence, healthcare resource utilization and overall burden of fungal meningitis in the United States

PURPOSE

Previous epidemiological and cost studies of fungal meningitis have largely focused on single pathogens, leading to a poor understanding of the disease in general. We studied the largest and most diverse group of fungal meningitis patients to date, over the longest follow-up period, to examine the broad impact on resource utilization within the United States.

METHODOLOGY

The Truven Health Analytics MarketScan database was used to identify patients with a fungal meningitis diagnosis in the United States between 2000 and 2012. Patients with a primary diagnosis of cryptococcal, Coccidioides, Histoplasma, or Candida meningitis were included in the analysis. Data concerning healthcare resource utilization, prevalence and length of stay were collected for up to 5 years following the original diagnosis.

RESULTS

Cryptococcal meningitis was the most prevalent type of fungal meningitis (70.1 % of cases over the duration of the study), followed by coccidioidomycosis (16.4 %), histoplasmosis (6.0 %) and candidiasis (7.6 %). Cryptococcal meningitis and candidiasis patients accrued the largest average charges ($103 236 and $103 803, respectively) and spent the most time in the hospital on average (70.6 and 79 days). Coccidioidomycosis and histoplasmosis patients also accrued substantial charges and time in the hospital ($82 439, 48.1 days; $78 609, 49.8 days, respectively).

CONCLUSION

Our study characterizes the largest longitudinal cohort of fungal meningitis in the United States. Importantly, the health economic impact and long-term morbidity from these infections are quantified and reviewed. The healthcare resource utilization of fungal meningitis patients in the United States is substantial.

Antifungal efficacy of amphotericin B encapsulated fibrin microsphere for treating Cryptococcus neoformans infection in Swiss albino mice

A natural and biocompatible fibrin microsphere is one of the most promising dual delivery vehicle as compared to other traditionally designed delivery modalities. It represents sustained delivery of encapsulated drug and is easily biodegradable in the blood circulation. In the present study, we evaluated the systemic augmentation of the antifungal activity of amphotericin B loaded in fibrin microsphere (AMB-fibrin microsphere) against cryptococcosis in Swiss albino mice. Mice infected with Cryptococcus neoformans were treated with 0.5mg/kg AMB-fibrin microsphere that was given alternately for 7 days. The antifungal potential of AMB-fibrin microsphere was assessed on the basis of reduction of cfu count in the systemic circulation and various vital organs of infected mice. The formulation was found to be highly effective in reducing intracellular pathogen from the experimental animals where fibrin microsphere significantly controlled the release of amphotericin B for longer time duration. The AMB-fibrin microsphere chemotherapy was significantly more effective than free amphotericin B in reducing the fungal burden and showed better survival efficacy (p<0.05). The current study demonstrating the use of novel amphotericin B loaded fibrin microsphere not only imparts protection to the encapsulated amphotericin B but also offers an effective strategy to decrease the drug associated toxicities.

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.

New technology and resources for cryptococcal research

Rapid advances in molecular biology and genome sequencing have enabled the generation of new technology and resources for cryptococcal research. RNAi-mediated specific gene knock down has become routine and more efficient by utilizing modified shRNA plasmids and convergent promoter RNAi constructs. This system was recently applied in a high-throughput screen to identify genes involved in host-pathogen interactions. Gene deletion efficiencies have also been improved by increasing rates of homologous recombination through a number of approaches, including a combination of double-joint PCR with split-marker transformation, the use of dominant selectable markers and the introduction of Cre-Loxp systems into Cryptococcus. Moreover, visualization of cryptococcal proteins has become more facile using fusions with codon-optimized fluorescent tags, such as green or red fluorescent proteins or, mCherry. Using recent genome-wide analytical tools, new transcriptional factors and regulatory proteins have been identified in novel virulence-related signaling pathways by employing microarray analysis, RNA-sequencing and proteomic analysis.

Diagnostic value of latex agglutination in cryptococcal meningitis

Background:

Cryptococcus neoformans is the most common fungal pathogen to infect the central nervous system, and an effective diagnostic method is therefore necessary for the early diagnosis of cryptococcal meningitis.

Aim:

The efficacy of India ink preparation, cerebrospinal fluid (CSF) culture and CSF cryptococcal antigen detection by the latex agglutination test for diagnosis of cryptococcal meningitis are compared to determine the most efficient test.

Materials and Methods:

Two hundred CSF samples from human immunodeficiency virus - positive patients suspected to be suffering from meningitis were screened for Cryptococcus neoformans.

Results:

Latex agglutination for cryptococcal antigen detection was found to be more sensitive compared to India ink staining and CSF culture.

Conclusions:

Antigen detection by latex agglutination proved to be both sensitive and specific method for the diagnosis of cryptococcal meningitis. Rapid, early diagnosis of infection by detection of cryptococcal antigen by latex agglutination may alter the prognosis for these patients.

Disseminated cryptococcosis presenting with generalized lymphadenopathy

Cryptococcosis is a common opportunistic infection among immunocompromised individuals. Some of the commonly affected sites are respiratory and central nervous system. Lymph node is an unusual site of involvement which could mimic tuberculosis, as seen in our case. We report a 32-year-old male immunocompromised patient presenting with generalized lymphadenopathy who was clinically suspected to have tuberculous lymphadenitis. He was diagnosed to have disseminated cryptococcosis on fine needle aspiration cytology and fungal isolation on culture.

Comparative analysis of the Vitek 2 antifungal susceptibility system and E-test with the CLSI M27-A3 broth microdilution method for susceptibility testing of Indian clinical isolates of Cryptococcus neoformans

The emergence of antifungal resistance among Cryptococcus neoformans isolates is a matter of great concern. The Clinical and Laboratory Standards Institute (CLSI) broth microdilution reference method (BMD) for antifungal susceptibility testing of C. neoformans is tedious and time-consuming. Consequently, there is a greater need for a reproducible in vitro susceptibility testing method for use in clinical microbiology laboratories. By random amplified polymorphic DNA analysis, the 62 Indian clinical isolates were characterized as Cryptococcus neoformans var. grubii. We evaluated the susceptibilities of these isolates for amphotericin B (AMB) and fluconazole (FLC) by two commercial techniques, i.e., Vitek 2 and E-test against the CLSI M27-A3 BMD. The essential agreement (EA) between the Vitek 2 and E-test with the reference procedure for FLC was similar (82.2%). For AMB, EA of 92 and 76% was obtained with E-test and Vitek 2. Excellent categorical agreement (CA) (98.3% and 100% by Vitek 2 and E-test, respectively) was obtained for AMB. The CA for FLC was 81 and 77.4% by Vitek 2 and E-test. We conclude that both E-test and Vitek 2 system have acceptable levels of accuracy for susceptibility testing of both the drugs. Both of them could identify fluconazole-resistant strains. Vitek 2 could be used for testing susceptibility of voriconazole and 5-flucytosine also at the same time.

Low diversity Cryptococcus neoformans variety grubii multilocus sequence types from Thailand are consistent with an ancestral African origin

The global burden of HIV-associated cryptococcal meningitis is estimated at nearly one million cases per year, causing up to a third of all AIDS-related deaths. Molecular epidemiology constitutes the main methodology for understanding the factors underpinning the emergence of this understudied, yet increasingly important, group of pathogenic fungi. Cryptococcus species are notable in the degree that virulence differs amongst lineages, and highly-virulent emerging lineages are changing patterns of human disease both temporally and spatially. Cryptococcus neoformans variety grubii (Cng, serotype A) constitutes the most ubiquitous cause of cryptococcal meningitis worldwide, however patterns of molecular diversity are understudied across some regions experiencing significant burdens of disease. We compared 183 clinical and environmental isolates of Cng from one such region, Thailand, Southeast Asia, against a global MLST database of 77 Cng isolates. Population genetic analyses showed that Thailand isolates from 11 provinces were highly homogenous, consisting of the same genetic background (globally known as VNI) and exhibiting only ten nearly identical sequence types (STs), with three (STs 44, 45 and 46) dominating our sample. This population contains significantly less diversity when compared against the global population of Cng, specifically Africa. Genetic diversity in Cng was significantly subdivided at the continental level with nearly half (47%) of the global STs unique to a genetically diverse and recombining population in Botswana. These patterns of diversity, when combined with evidence from haplotypic networks and coalescent analyses of global populations, are highly suggestive of an expansion of the Cng VNI clade out of Africa, leading to a limited number of genotypes founding the Asian populations. Divergence time testing estimates the time to the most common ancestor between the African and Asian populations to be 6,920 years ago (95% HPD 122.96 - 27,177.76). Further high-density sampling of global Cng STs is now necessary to resolve the temporal sequence underlying the global emergence of this human pathogen.

Cryptococcus peritonitis a rare manifestation in HIV positive host: a case report

Cryptococcus neoformans is an encapsulated yeast found ubiquitously in the environment and causes serious infections in immunocompromised populations. Disseminated disease is uncommon and very rarely manifests as peritonitis. We report a case of cryptococcal peritonitis in a HIV positive patient, who presented with distention of abdomen, vomiting, and dyspnoea, where the diagnosis was made on cytological smears of ascitic fluid. The importance of making a quick diagnosis utilizing cytological smears is emphasized and the cytological features are demonstrated. Disseminated cryptococcosis, particularly with peritonitis, is an uncommon manifestation of C. neoformans infection. A high clinical suspicion and early initiation of therapy is needed to recognize and treat patients effectively.

Detection of Cryptococcus by conventional, serological and molecular methods

The rising incidence of cryptococcosis in India is posing a serious threat. Due to lack of sensitive methods for diagnosis, high morbidity and mortality are associated with the disease. Early diagnosis is essential to prevent serious complications. Therefore, we attempted to find highly sensitive and specific detection methods. A comparative evaluation of the detection of cryptococcosis was done by conventional (direct microscopy and culture) and rapid diagnostic [latex agglutination test (LAT), enzyme immunoassay (EIA) and PCR] methods. The study was done on 359 samples from 52 positive patients and 30 negative controls in an Indian set-up. Evaluation was done for cerebrospinal fluid (CSF), serum and urine separately. The diagnostic value of the tests was assessed in pre-treatment samples, and follow-up tests were also done on samples obtained after initiation of treatment. PCR had the highest sensitivity, followed by EIA and LAT, both before and after treatment. The positive detection by LAT, EIA and PCR was the longest in CSF (>90 days), followed by serum (∼65 days) then urine (∼45 days) after initiation of treatment. Our results indicated that the sensitivity and specificity of PCR and EIA were comparable in urine, CSF and serum for diagnosis of cryptococcosis.

Cryptococcus gattii: Emergence in Western North America: Exploitation of a Novel Ecological Niche

The relatively uncommon fungal pathogen Cryptococcus gattii recently emerged as a significant cause of cryptococcal disease in human and animals in the Pacific Northwest of North America. Although genetic studies indicated its possible presence in the Pacific Northwest for more than 30 years, C. gattii as an etiological agent was largely unknown in this region prior to 1999. The recent emergence may have been encouraged by changing conditions of climate or land use and/or host susceptibility, and predictive ecological niche modeling indicates a potentially wider spread. C. gattii can survive wide climatic variations and colonize the environment in tropical, subtropical, temperate, and dry climates. Long-term climate changes, such as the significantly elevated global temperature in the last 100 years, influence patterns of disease among plants and animals and create niche microclimates habitable by emerging pathogens. C. gattii may have exploited such a hitherto unrecognized but clement environment in the Pacific Northwest to provide a wider exposure and risk of infection to human and animal populations.

Prevalence and clinical presentation of Cryptococcal meningitis among HIV seropositive patients

A total of 573 HIV seropositive and clinically suspected cases of Cryptococcal meningitis were included in the study, from January 2006 to January 2007. CSF samples were processed by negative staining with 10% Nigrosin, cultured on Sabouraud's dextrose agar, biochemical tests, such as urease test and brownish growth in Niger seed agar. The prevalence of Cryptococcal meningitis was found to be 2.79%. The most common signs and symptoms were: fever (100%), headache (100%), altered sensorium (100%), and neck stiffness (90%). All the patients responded to intravenous Amphotericin B treatment.

Three galactose inducible promoters for use in C. neoformans var. grubii

Cryptococcus neoformans is the causative agent of cryptococcal meningoencephalitis, most frequently occurring in immunocompromised individuals. There are three varieties of C. neoformans, var. grubii, var. neoformans, and var. gatti. Worldwide var. grubii is the most prevalent clinical isolate. However, few tools for the study of essential genes in var. grubii exist. Here we describe three endogenous inducible promoters for use in the study of this important opportunistic pathogen. We identified eight potential homologs of S. cerevisiae galactose genes in var. grubii. We found that GAL1, GAL7, and UGE2 were regulated by glucose and galactose and can be used successfully during mating. Our analysis indicated these promoters should prove to be excellent tools for analysis of genes in var. grubii.

Cryptococcus gattii: an emerging cause of pulmonary nodules

BACKGROUND

Since the fall of 1999, a new endemic focus of Cryptococcus gattii serotype B infection has emerged on Vancouver Island (Victoria, British Columbia), with infections occurring in both animals and humans. In the human cases, symptoms have manifested as pulmonary nodules, meningitis or both. This organism has added a new nonmalignant cause of pulmonary nodules to the literature, resulting in a change in the management of these nodules by health care professionals.

METHODS

A search of the number of cases recorded and treated in hospitals of the Vancouver Island Health Authority, along with a review of the literature regarding this emerging organism, was undertaken. The pathology, epidemiology and clinical course of this previously uncommon fungus was determined, and representative cases were chosen for illustration.

RESULTS

More than 130 cases were recorded in the six-year period from late 1999 to mid-July 2006. The number of cases increased steadily over this period, but appears to be levelling off. Representative cases with medical imaging, along with photos of the pathology, are included. Recommendations for diagnosis, treatment and follow-up are outlined.

CONCLUSIONS

The emergence of cryptococcal lung and central nervous system lesions on Vancouver Island have made it important to include travel to or residence of the island as part of the history in patients with pulmonary nodules. A registry of patients from Vancouver Island has been established, and it may be of value to include nonisland patients who are found to be infected with this organism.

Therapeutic efficacy of a conjugate vaccine containing a peptide mimotope of cryptococcal capsular polysaccharide glucuronoxylomannan

Vaccination with P13, a peptide mimotope of the cryptococcal capsular polysaccharide glucuronoxylomannan (GXM), has been shown to confer protection against a subsequent lethal Cryptococcus neoformans challenge. In this study, we sought to investigate whether P13-based vaccines could be effective in an already-established infection. To address this question, we developed a systemic chronic cryptococcal infection model. We vaccinated chronically infected mice with P13-protein conjugates and monitored their survival. Compared to the controls, the conjugates prolonged the survival of chronically infected mice. The degree of protection was a function of the mouse strain (BALB/c or C57BL/6), the carrier protein (tetanus toxoid or diphtheria toxoid), and the route of infection (intraperitoneal or intravenous). Serum GXM levels were correlated with the day of death, but the correlation was driven by the carrier protein and mouse strain. The passive transfer of heat-treated sera from P13 conjugate-vaccinated mice conferred protection to naïve BALB/c mice, indicating that antibody immunity could contribute to protection. The measurement of peripheral blood cytokine (gamma interferon [IFN-gamma], interleukin-10 [IL-10], and IL-6) gene expression showed that P13 conjugate-vaccinated BALB/c and C57BL/6 mice mounted a strong Th2 (IL-10)-like response relative to the Th1 (IFN-gamma)-like response, with the degree depending on the mouse strain and carrier protein. Taken together, our data suggest that a vaccine could hold promise in the setting of chronic cryptococcosis, and that vaccine efficacy could depend on immunomodulation and augmentation of the natural immune response of the host.

Antibody responses to Cryptococcus neoformans in Indian patients with cryptococcosis

An important element of the host response to cryptococcosis is humoral immunity. Specific antibody responses in patients with cryptococcosis however, have not been extensively studied. We analyzed the antibody responses of 22 Indian patients with cryptococcosis, including both HIV+ and HIV- individuals. Sera from 10 Indian patients with AIDS and without cryptococcosis were studied as controls. Antibody responses to cryptococcal proteins were detected by immunoblot, while antibodies to glucuronoxylomannan (GXM), the main component of the cryptococcal capsular polysaccharide were measured by ELISA. Our results indicate that cryptococcosis elicits antibodies to a specific pattern of cytoplasmic proteins. Further, we find that antibody responses to both cytoplasmic proteins and GXM are less robust in HIV+ patients when compared with HIV- patients.

Towards a vaccine for Cryptococcus neoformans: principles and caveats

In the Damage-response framework of microbial pathogenesis, infectious diseases are one outcome of a host-microorganism interaction in a susceptible host. In cryptococcal disease, damage to the host is caused by Cryptococcus neoformans virulence determinants, the nature of the host response, or both. Further, the disease may be acute or reactivated from a latent state. Hence, a vaccine for C. neoformans would need to prevent disease resulting from either acute or reactivated infection. The evidence to support the development of a vaccine for C. neoformans that induces antibody-mediated immunity is discussed herein.

Feasibility and prospects for a vaccine to prevent cryptococcosis

Cryptococcosis is a relatively common fungal disease caused by Cryptococcus neoformans that has high morbidity and mortality. Numerous studies have established the feasibility of enhancing host immunity to C neoformans in naive immunocompetent animal models by vaccination. Several antigens have been identified that appear to be suitable vaccine candidates. Induced immune responses can mediate protection through both humoral and cellular immunity. Hence, a vaccine against cryptococcosis in humans is probably feasible but there are significant obstacles to vaccine development that range from uncertainties about the pathogenesis of infection to economic considerations.

Molecular epidemiology of clinical Cryptococcus neoformans strains from India

Little is known about the molecular epidemiology of the human pathogenic fungus Cryptococcus neoformans in India, a country now in the midst of an epidemic of AIDS-related cryptococcosis. We studied 57 clinical isolates from several regions in India, of which 51 were C. neoformans var. grubii, 1 was C. neoformans var. neoformans, and 5 were C. neoformans var. gattii. This strain set included 18 additional sequential isolates from 14 patients. Strains were characterized phenotypically by measuring the polysaccharide capsule and by determining the MICs of standard antifungals. Molecular typing was performed by a PCR-based method using the minisatellite-specific core sequence (M13), by electrophoretic karyotyping, by restriction fragment length polymorphisms with the C. neoformans transposon 1 (TCN-1), and by URA5 DNA sequence analysis. Overall, Indian isolates were less heterogeneous than isolates from other regions and included a subset that clustered into one group based on URA5 DNA sequence analysis. In summary, our results demonstrate (i) differences in genetic diversity of C. neoformans isolates from India compared to isolates from other regions in the world; (ii) that DNA typing with the TCN-1 probe can adequately distinguish C. neoformans var. grubii strains; (iii) that TCN-1 sequences are absent in many C. neoformans var. gattii strains, supporting previous studies indicating that these strains have a limited geographical dispersal; and (iv) that human cryptococcal infection can be associated with microevolution of the infecting strain and by simultaneous coinfection with two distinct C. neoformans strains.

Dual infections with pigmented and albino strains of Cryptococcus neoformans in patients with or without human immunodeficiency virus infection in India

Cryptococcus neoformans is an encapsulated yeast-like fungus of worldwide distribution. Melanin production is an important virulence factor of C. neoformans. We report the identification of distinct cryptococcal isolates with either pigmented or white colony phenotypes on L-dihydroxyphenylalanine agar plates in three patients who presented with meningitis to the All India Institute of Medical Sciences in India. Two of the patients were also infected with human immunodeficiency virus. Biochemical studies, India ink analysis, immunofluorescence with antibodies specific to capsular antigen, and serotyping confirmed that the melanotic and albino strains were C. neoformans serotypes A and D, respectively. Genotyping with M13 and [GACA]4 primers revealed that all the C. neoformans isolates were genetically different. The CNLAC1 gene associated with melanin production was identified in all the strains by PCR. Standard MIC testing revealed that the strains had similar susceptibilities to amphotericin B, but time-kill assays with the antifungal showed reduced susceptibility in melanin-producing strains. Infection studies with A/Jcr mice showed that the melanin-lacking yeast were less virulent than melanin-producing isolates. These findings indicate that these patients had dual infections with pigmented and albino strains of C. neoformans that were phenotypically and biologically different. Continued surveillance of primary isolates from patients with cryptococcosis by analyzing phenotypic differences and by molecular methods may reveal that mixed infections occur more commonly than is currently realized.

Cryptococcus neoformans-reactive and total immunoglobulin profiles of human immunodeficiency virus-infected and uninfected Ugandans

We determined total and Cryptococcus neoformans glucuronoxylomannan (GXM)-reactive antibody repertoires of human immunodeficiency virus (HIV)-infected and HIV-uninfected Ugandans in a retrospective, case-control study of participants in a randomized controlled trial of pneumococcal vaccination. The study included 192 adults: 48 who subsequently developed cryptococcal meningitis (CM); (HIV+ CM+); 2 individuals who matched them in CD4+ T-cell level, stage of HIV disease, and age but did not develop CM (HIV+ CM-); and 48 HIV-uninfected individuals. Total serum immunoglobulin concentrations and titers of immunoglobulin M (IgM), IgG, and IgA to GXM, pneumococcal polysaccharides, and antibodies expressing certain V(H)3 idiotypes were determined with banked sera obtained before the development of cryptococcosis for HIV+ CM+ subjects. The results showed that HIV-infected subjects had significantly lower levels of IgM to GXM but higher levels of total immunoglobulin and IgG and IgA to GXM than those of HIV-uninfected subjects. HIV-infected subjects with a history of pneumonia had higher levels, and those with a history of herpes zoster had lower levels of GXM-binding antibodies than subjects with no history of either disease. Minimal to no cross-reactivity was demonstrated between antibodies to GXM and polysaccharides in a pneumococcal vaccine. No significant differences between the antibody repertoires of HIV+ CM+ and HIV+ CM- subjects were identified, but among subjects without a history of pneumonia, there was a trend towards lower V(H)3-positive antibody levels among HIV+ CM+ than among HIV+ CM- subjects. Our findings demonstrate an association between previous infectious diseases and differences in the total and GXM-reactive antibody repertoires of HIV-infected subjects and suggest the question of whether certain microbes modulate subsequent antibody responses to GXM deserves further study.

Cryptococcal meningitis in two apparently immunocompetent Maltese patients

Two cases of cryptococcal meningitis occurring in immunocompetent men are described. The first case involves a farmer in whom cryptococcal meningitis was rapidly diagnosed using direct microscopy, latex antigen tests and culture of cerebrospinal fluid (CSF). In the second case, initial mycological tests on CSF (direct microscopy and culture) were repetitively negative and latex antigen tests gave unconvincing results. The patient was started on triple antituberculosis therapy, on which he improved immediately; therapy was continued for 1 year with the patient remaining well. However, within 1 week of stopping therapy, he had to be readmitted with neurological signs and symptoms. Culture of CSF this time yielded Cryptococcus neoformans and the antigen test was consistently positive. These are the first reported cases of cryptococcal meningitis in immunocompetent patients in Malta.

Immunogenicity and efficacy of Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan peptide mimotope-protein conjugates in human immunoglobulin transgenic mice

Peptide mimotopes of capsular polysaccharides have been proposed as antigens for vaccines against encapsulated pathogens. In this study, we determined the antibody response to and efficacy of P13, a peptide mimetic of the Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM), in mice that produce human antibodies. P13 was conjugated to tetanus toxoid (TT) or diphtheria toxoid (DT) and administered subcutaneously in Alhydrogel with or without CpG to mice transgenic for human immunoglobulin loci (XenoMouse mice) and expressing either immunoglobulin G2 (IgG2) (G2 mice) or IgG4 (G4 mice). Mice were vaccinated and revaccinated two or three times. The serum antibody responses of the mice to GXM and P13 and antibody idiotype expression were analyzed by an enzyme-linked immunosorbent assay. The results showed that both P13-TT and P13-DT were antigenic, inducing a mimetic response to P13 in both G2 and G4 mice, and immunogenic, inducing a mimotope response including VH3 (idiotype)-positive antibodies to GXM in G2 but not G4 mice. CpG led to higher titers of IgG to P13 and GXM in P13-TT-vaccinated G2 mice. C. neoformans challenge of P13-protein conjugate-vaccinated and control G2 mice induced anamnestic IgG- and VH3-positive responses to GXM and was associated with a significantly decreased risk of death and a prolongation of survival in P13-DT-vaccinated mice compared to phosphate-buffered saline-treated or protein carrier-vaccinated mice. These findings reveal that P13 elicited a human antibody response with VH3 expression in human immunoglobulin transgenic mice that has been observed for human antibodies to GXM and support the concept that peptide mimotope-based vaccines may hold promise for the treatment of C. neoformans infections.

Serotype distribution ofCryptococcusneoformansin patients in a tertiary care center in India1

The prevalence of specific serotypes of Cryptococcus neoformans in a given area bears on regional epidemiological patterns, the expected spectrum of clinical disease, and predicted response to therapy. In this retrospective study we analyzed the serotypes of 45 degrees C neoformans isolates from 36 North Indian patients with varied clinical presentations. The majority of the isolates were serotype A (87%), and surprisingly, a significant number were serotype B (five isolates, 11%), which caused infection in patients both positive and negative for HIV. One unusual isolate was not typable with factor sera. Study of serotype distribution in patients showed serotypes A and B to be present, respectively, in 92% and 8% of 36 patients. In one apparently immunocompetent patient two serotypes, A and B, were isolated simultaneously from two different sites, lung and scalp abscess. This is the first reported case in which an individual was infected with two serotypes at the same time. In one HIV-infected child serotype A was isolated from blood. Our results suggest that the distribution of serotypes in Indian clinical isolates is different than that found in other regions.