Chronic Meningitis in Thailand

The challenge of etiologic diagnosis of subacute and chronic meningitis: an analysis of 183 patients

Subacute and chronic meningitis (SCM) presents significant diagnostic challenges, with numerous infectious and non-infectious inflammatory causes. This study examined patients aged 16 and older with SCM admitted to referral centers for neuroinfections and neuroinflammations in Mashhad, Iran, between March 2015 and October 2022. Among 183 episodes, tuberculous meningitis was the most common infectious cause (46.5%), followed by Brucella meningitis (24.6%). The cause of SCM was definitively proven in 40.4%, presumptive in 35.0%, and unknown in 24.6% of cases. In-hospital mortality was 14.4%, and 30.5% of survivors experienced unfavorable outcomes (Glasgow Outcome Scale 2-4). Patients with unknown causes had a significantly higher risk of death compared to those with presumptive or proven diagnoses (risk ratio 4.18). This study emphasizes the diagnostic difficulties of SCM, with one-quarter of cases remaining undiagnosed and over one-third having only a presumptive diagnosis. Improving diagnostic methods could potentially enhance prognosis and reduce mortality.

Global Frequency and Clinical Features of Stroke in Patients With Tuberculous Meningitis: A Systematic Review

IMPORTANCE

Stroke in tuberculous meningitis (TBM) is associated with significant morbidity and mortality.

OBJECTIVE

To determine the country-specific, regional, and overall prevalence of stroke among patients with TBM, including their clinical manifestations, stroke locations, and outcomes.

EVIDENCE REVIEW

This systematic review searched records in MEDLINE by PubMed, Scopus, and EMBASE until July 2020 for relevant articles on the occurrence and characteristics of stroke in TBM. Randomized clinical trials and cohort studies that included a population of patients with TBM were analyzed for clinical manifestations, type of stroke, area of stroke, vascular territory, and outcomes. Studies that did not report the occurrence of stroke, reported as abstract only with no full-texts available, and articles not in English were excluded. The country-specific, regional, and overall frequencies of stroke among patients with TBM were determined; secondary analysis enumerated the summary estimates of the clinical presentations, common locations of stroke, and outcomes. The Murad tool was used to assess methodological quality.

FINDINGS

From 852 articles identified, 71 studies involving 2194 patients with stroke in TBM were included. The sample size for each study ranged from 17 to 806 patients. The frequency of stroke in TBM showed an estimate of 0.30 (95% CI, 0.26-0.33). The most common clinical manifestations were fever and headache. The lateral striate, middle cerebral, and medial striate arteries were typically affected. The basal ganglia, cortex and lobar, and internal capsule were the frequently involved areas of the brain. The pooled proportions of mortality and poor outcomes were 0.22 (95% CI, 0.16-0.29) and 0.51 (95% CI, 0.37-0.66), respectively.

CONCLUSIONS AND RELEVANCE

The results of this systematic review suggest that stroke is considerably frequent among patients with TBM. The reported frequencies of stroke in TBM and its clinical features vary across the studies and populations.

Global morbidity and mortality of central nervous system tuberculosis: a systematic review and meta-analysis

Background

Tuberculosis (TB) is the second most common cause of death due to a single infectious agent worldwide after COVID-19. Up to 15% of the cases are extrapulmonary, and if it is located in the central nervous system (CNS-TB), it presents high morbidity and mortality. Still, the global epidemiology of CNS-TB remains unknown.

Aim

To estimate the global prevalence and incidence of CNS-TB based on the available literature.

Methods

We systematically searched in MEDLINE, Cochrane Central, Scopus, and LILACS databases (April 2020) and included observational studies evaluating the epidemiology of CNS-TB. Two independent researchers selected and assessed the quality of the studies and extracted relevant data. We performed random-effects model meta-analysis of proportions to estimate the pooled prevalence. The protocol of this study was registered in PROSPERO (CRD 42018103946).

Results

We included 53 studies from 28 countries, representing 12,621 patients with CNS-TB. The prevalence of CNS-TB was 2 per 100,000 inhabitants. According to the clinical setting, the prevalence of CNS-TB represented the 13.91% of all cases of meningitis and 4.55% of all cases of TB. The mortality was calculated by tuberculous meningitis due to the lack of data of other presentation, and it rose up to 42.12% in hospitalized patients. The burden of countries’ TB, Human Development Index (HDI), and the prevalence of HIV were the most important prevalence moderators, especially in patients with TB. No data on incidence were found.

Conclusion

The prevalence and mortality of CNS-TB remain high, and TB meningitis is the most frequent presentation. The highest prevalence was reported in developing countries, and its main moderators were the countries’ HDI and HIV infection. Our study was limited by high heterogeneity, risk of bias, and potential data under registration from developing countries. The integration of CNS-TB early detection and management into national TB programs and population-based studies from developing countries are needed for better global estimation and response.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11052-8.

Infectious ocular motor neuropathies

PURPOSE OF REVIEW

Describe the range of infectious causes of ocular motor neuropathies, from common presentations to unusual manifestations of diseases less frequently seen in the developed world. Provide information on recent developments in diagnostic testing for pathogens that may cause ocular motor neuropathies.

RECENT FINDINGS

Antigen detection in serum or CSF has improved the diagnosis of cryptococcal disease. Cartridge PCR testing for tuberculosis has increased diagnostic accuracy, though tuberculous meningitis remains difficult to diagnose. Rapid, multiplex PCR and unbiased sequencing allow for diagnosis of a wider range of organisms.

SUMMARY

Infectious ocular motor neuropathies can occur anywhere along the length of cranial nerves III, IV, and VI. Characteristic clinical findings and imaging can be used to localize infections. Infectious causes may have characteristic clinical, laboratory, or imaging findings, but must still be carefully separated from inflammatory or neoplastic conditions.

Chronic and Subacute Meningitis: Differentiating Neoplastic From Non-Neoplastic Etiologies

Background and Purpose

Although incidence rates vary, infectious, autoimmune, and neoplastic diseases can all cause chronic and subacute meningitis (CSM). We report a Latin-American, single center, CSM case series, analyzing the main clinical characteristics as well as ancillary diagnostic methods differentiating neoplastic from non-neoplastic etiologies.

Methods

Retrospective review of CSM cases from a single center in Buenos Aires, Argentina.

Results

Seventy patients with CSM diagnosis were identified, 49 with neoplastic and 21 with non-neoplastic meningitis. A history of previous cancer was significantly higher in neoplastic cases, whereas prevalence of autoimmune disease and fever was more common in non-neoplastic meningitis. C-reactive protein values were higher in non-neoplastic CSM, as was pleocytosis in cerebrospinal fluid analysis. The most frequent etiologies were breast and lung cancer for neoplastic meningitis cases; and idiopathic, tuberculous, and fungal infection for non-neoplastic cases.

Conclusions

Chronic and subacute meningitis diagnosis is challenging in daily neurological practice. The results we report contribute information from Latin America regarding etiologies of CSM, which can be identified after a comprehensive evaluation in a majority of cases.

The burden and epidemiology of community-acquired central nervous system infections: a multinational study

Risk assessment of central nervous system (CNS) infection patients is of key importance in predicting likely pathogens. However, data are lacking on the epidemiology globally. We performed a multicenter study to understand the burden of community-acquired CNS (CA-CNS) infections between 2012 and 2014. A total of 2583 patients with CA-CNS infections were included from 37 referral centers in 20 countries. Of these, 477 (18.5%) patients survived with sequelae and 227 (8.8%) died, and 1879 (72.7%) patients were discharged with complete cure. The most frequent infecting pathogens in this study were Streptococcus pneumoniae (n = 206, 8%) and Mycobacterium tuberculosis (n = 152, 5.9%). Varicella zoster virus and Listeria were other common pathogens in the elderly. Although staphylococci and Listeria resulted in frequent infections in immunocompromised patients, cryptococci were leading pathogens in human immunodeficiency virus (HIV)-positive individuals. Among the patients with any proven etiology, 96 (8.9%) patients presented with clinical features of a chronic CNS disease. Neurosyphilis, neurobrucellosis, neuroborreliosis, and CNS tuberculosis had a predilection to present chronic courses. Listeria monocytogenes, Staphylococcus aureus, M. tuberculosis, and S. pneumoniae were the most fatal forms, while sequelae were significantly higher for herpes simplex virus type 1 (p < 0.05 for all). Tackling the high burden of CNS infections globally can only be achieved with effective pneumococcal immunization and strategies to eliminate tuberculosis, and more must be done to improve diagnostic capacity.

Interleukin-17 mediated differences in the pathogenesis of HIV-1-associated tuberculous and cryptococcal meningitis

OBJECTIVE

Mycobacterium tuberculosis and Cryptococcus neoformans are major causes of meningitis in HIV-1-infected patients. Identifying differences in the inflammatory profiles of HIV-1-associated tuberculous meningitis (TBM) and cryptococcal meningitis may inform differences in immunopathogenic mechanisms in these diseases. In this study we compared the clinical and inflammatory features of HIV-1-associated TBM, and cryptococcal meningitis.

METHODS

A prospective study of HIV-1-infected adults who presented with either TBM [antiretroviral therapy (ART)-naive] or cryptococcal meningitis (regardless of ART prescription). Clinical and laboratory findings and concentrations of 40 inflammatory mediators measured in cerebrospinal fluid (CSF, 33 paired with blood) were compared between TBM and cryptococcal meningitis patients regardless of ART prescription and between TBM and cryptococcal meningitis patients not receiving ART.

RESULTS

Clinical and laboratory findings were similar in TBM (n=34) and cryptococcal meningitis (n = 19; ART prescribed: n = 10, no ART prescribed: n = 9). Exceptions included a higher median CD4 cell count [interquartile: 113 (69-199) vs. 25 (8-49) cells/μl, P = 0.0001] and higher HIV-1 median viral load [plasma: 5.46 (4.82-5.89) vs. 4.87 (4.36-5.17) log10copies/ml, P = 0.037; CSF: 6.05 (5.43-6.56) vs. 5.56 (4.52-5.80) log10copies/ml, P = 0.03] in TBM vs. cryptococcal meningitis patients not receiving ART. CSF interleukin (IL)-17A was lower in TBM compared with cryptococcal meningitis [1.00 (0.25-2.35) vs. 9.31 (1.24-23.36) pg/ml, P-adjusted = 0.03].

CONCLUSION

Despite presenting with higher peripheral CD4 cell counts, TBM patients also presented with higher HIV-1 viral loads compared with cryptococcal meningitis patients, suggesting a greater propensity of M. tuberculosis compared with C. neoformans to increase HIV-1 replication in vivo. CSF IL-17A was lower in TBM; its role in the immunopathogenesis of TBM and cryptococcal meningitis deserves further research.

Methods of rapid diagnosis for the etiology of meningitis in adults

Infectious meningitis may be due to bacterial, mycobacterial, fungal or viral agents. Diagnosis of meningitis must take into account numerous items of patient history and symptomatology along with regional epidemiology and basic cerebrospinal fluid testing (protein, etc.) to allow the clinician to stratify the likelihood of etiology possibilities and rationally select additional diagnostic tests. Culture is the mainstay for diagnosis in many cases, but technology is evolving to provide more rapid, reliable diagnosis. The cryptococcal antigen lateral flow assay (Immuno-Mycologics) has revolutionized diagnosis of cryptococcosis and automated nucleic acid amplification assays hold promise for improving diagnosis of bacterial and mycobacterial meningitis. This review will focus on a holistic approach to diagnosis of meningitis as well as recent technological advances.

Cerebral toxoplasmosis mimicking subacute meningitis in HIV-infected patients; a cohort study from Indonesia

BACKGROUND

HIV-associated subacute meningitis is mostly caused by tuberculosis or cryptococcosis, but often no etiology can be established. In the absence of CT or MRI of the brain, toxoplasmosis is generally not considered as part of the differential diagnosis.

METHODOLOGY/PRINCIPAL FINDINGS

We performed cerebrospinal fluid real time PCR and serological testing for Toxoplasma gondii in archived samples from a well-characterized cohort of 64 HIV-infected patients presenting with subacute meningitis in a referral hospital in Indonesia. Neuroradiology was only available for 6 patients. At time of presentation, patients mostly had newly diagnosed and advanced HIV infection (median CD4 count 22 cells/mL), with only 17.2% taking ART, and 9.4% PJP-prophylaxis. CSF PCR for T. Gondii was positive in 21 patients (32.8%). Circulating toxoplasma IgG was present in 77.2% of patients tested, including all in whom the PCR of CSF was positive for T. Gondii. Clinically, in the absence of neuroradiology, toxoplasmosis was difficult to distinguish from tuberculosis or cryptococcal meningitis, although CSF abnormalities were less pronounced. Mortality among patients with a positive CSF T. Gondii PCR was 81%, 2.16-fold higher (95% CI 1.04-4.47) compared to those with a negative PCR.

CONCLUSIONS/SIGNIFICANCE

Toxoplasmosis should be considered in HIV-infected patients with clinically suspected subacute meningitis in settings where neuroradiology is not available.

The evaluation of treatment-resistant epilepsy

An estimated 10% to 40% of children with epilepsy have treatment-resistant epilepsy. Persistent seizures have negative psychosocial, behavioral, cognitive, and financial consequences and are associated with an increased mortality rate. Accurate syndromic and etiologic diagnoses are of vital importance because they may guide medical and/or surgical decision making. Revisitation of the history to confirm the diagnosis of epilepsy and the appropriateness of medication trials to date is vital. Routine imaging should include structural magnetic resonance imaging (MRI) with an established epilepsy protocol. In the setting of a normal previous MRI, repeat imaging may be indicated and may be supplemented with other imaging modalities. The admission for prolonged inpatient video-encephalographic monitoring may lead to a revision of a pre-existing diagnosis. Laboratory evaluations should include genetic, metabolic, and infectious/inflammatory studies when indicated. In this review, we discuss the implication of seizure semiology and syndrome classification when searching for an underlying diagnosis in treatment-resistant epilepsy, and will review both basic and more advanced procedures/studies that may aid diagnosis.

Tuberculous meningitis in patients infected with human immunodeficiency virus

Tuberculosis is the most common opportunistic infection in human immunodeficiency virus (HIV) infected persons. HIV-infected patients have a high incidence of tuberculous meningitis as well. The exact incidence and prevalence of tuberculous meningitis in HIV-infected patients are not known. HIV infection does not significantly alter the clinical manifestations, laboratory, radiographic findings, or the response to therapy. Still, some differences have been noted. For example, the histopathological examination of exudates in HIV-infected patients shows fewer lymphocytes, epithelioid cells, and Langhan's type of giant cells. Larger numbers of acid-fast bacilli may be seen in the cerebral parenchyma and meninges. The chest radiograph is abnormal in up to 46% of patients with tuberculous meningitis. Tuberculous meningitis is likely to present with cerebral infarcts and mass lesions. Cryptococcal meningitis is important in differential diagnosis. The recommended duration of treatment in HIV-infected patients is 9-12 months. The benefit of adjunctive corticosteroids is uncertain. Antiretroviral therapy and antituberculosis treatment should be initiated at the same time, regardless of CD4 cell counts. Tuberculous meningitis may be a manifestation of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome. Some studies have demonstrated a significant impact of HIV co-infection on mortality from tuberculous meningitis. HIV-infected patients with multidrug-resistant tuberculous meningitis have significantly higher mortality. The best way to prevent HIV-associated tuberculous meningitis is to diagnose and isolate infectious cases of tuberculosis promptly and administer appropriate treatment.

The effect of HIV infection on adult meningitis in Indonesia: a prospective cohort study

OBJECTIVE

Indonesia has a concentrated but rapidly growing HIV epidemic. We examined the effect of HIV on causative organisms, clinical features and prognosis of adult meningitis.

DESIGN

A prospective cohort study.

METHODS

All adult patients at a referral hospital who underwent cerebrospinal fluid examination for suspected meningitis were examined for HIV and included in a prospective cohort study. Microbiological testing was done for common bacterial pathogens, mycobacteria and fungi. Patients were followed for at least 6 months, and logistic regression models were used to identify risk factors for mortality.

RESULTS

Among 185 patients who mostly presented with subacute meningitis, 60% were male and the median age was 30 years. HIV infection was present in 25% of the patients; almost two-thirds were newly confirmed, and all presented with severe immunosuppression (median CD4 cell count 13/microl, range 2-98). One-third of HIV-infected patients had cryptococcal meningitis whereas two-thirds suffered from tuberculosis. After 1 month, 41% of patients had died. HIV infection was strongly associated with 1-month mortality (adjusted odds ratio 12.15; 95% confidence interval 3.04-15.72) and death during extended follow-up (hazard ratio 2.48; 95% confidence interval 1.97-5.74).

CONCLUSION

Although HIV is still uncommon in the general population in Indonesia, its prevalence among adult meningitis cases already seems high. Mycobacterium tuberculosis and Cryptococcus neoformans are the main causes of meningitis in this setting, and mortality is very high, especially in HIV-infected patients. Our data suggest that adult meningitis cases in Indonesia should be screened routinely for HIV infection. Further studies are needed to address the high mortality.

IgM(+) memory B cell expression predicts HIV-associated cryptococcosis status

BACKGROUND

The role of B cells in resistance to Cryptococcus neoformans disease (i.e., cryptococcosis) is unknown. Given evidence that IgM(+) memory B cells are required for immunity to other encapsulated pathogens, we hypothesized that these cells might contribute to resistance to cryptococcosis.

METHODS

We compared levels of IgM expression on memory B cells in 29 HIV-infected individuals who had a history of cryptococcosis (the HIV+CN+ group) with levels in 30 human immunodeficiency virus (HIV)-infected subjects who had no history of cryptococcosis (the HIV+CN- group) and 20 HIV-uninfected subjects who had no history of cryptococcosis (the HIV- group) (cohort 1). We also determined levels of IgM expression on memory B cells in banked samples obtained before cryptococcosis onset from 31 participants in the Multicenter AIDS Cohort Study, of whom 8 had HIV infection and subsequently developed cryptococcosis (the HIV+CN+ group), 8 had HIV infection and did not develop cryptococcosis (the HIV+CN- group), and 15 did not have HIV infection and did not develop cryptococcosis (the HIV- group) (cohort 2).

RESULTS

In cohort 1, the percentage of memory B cells that expressed IgM was lower among HIV+CN+ subjects, compared with HIV+CN- subjects (P < .01) and HIV- subjects (P < .05); expression of IgM on 50% of memory B cells was a significant predictor of C. neoformans disease status (odds ratio, 5.5; P = .03). In cohort 2, the percentage of memory B cells that expressed IgM was lower in HIV+CN+ subjects than in HIV+CN- subjects (P = .02) and HIV- subjects (P < .01); an IgM(+) memory B cell percentage of 38.5% was a significant predictor of future development of cryptococcosis (odds ratio, 14; P = .02).

CONCLUSIONS

These findings suggest that HIV-infected persons in whom the percentage of memory B cells that express IgM is decreased might be at greater risk for the development of cryptococcosis.

Efflux-mediated antifungal drug resistance

Fungi cause serious infections in the immunocompromised and debilitated, and the incidence of invasive mycoses has increased significantly over the last 3 decades. Slow diagnosis and the relatively few classes of antifungal drugs result in high attributable mortality for systemic fungal infections. Azole antifungals are commonly used for fungal infections, but azole resistance can be a problem for some patient groups. High-level, clinically significant azole resistance usually involves overexpression of plasma membrane efflux pumps belonging to the ATP-binding cassette (ABC) or the major facilitator superfamily class of transporters. The heterologous expression of efflux pumps in model systems, such Saccharomyces cerevisiae, has enabled the functional analysis of efflux pumps from a variety of fungi. Phylogenetic analysis of the ABC pleiotropic drug resistance family has provided a new view of the evolution of this important class of efflux pumps. There are several ways in which the clinical significance of efflux-mediated antifungal drug resistance can be mitigated. Alternative antifungal drugs, such as the echinocandins, that are not efflux pump substrates provide one option. Potential therapeutic approaches that could overcome azole resistance include targeting efflux pump transcriptional regulators and fungal stress response pathways, blockade of energy supply, and direct inhibition of efflux pumps.

Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS

OBJECTIVE

Cryptococcal meningitis is one of the most important HIV-related opportunistic infections, especially in the developing world. In order to help develop global strategies and priorities for prevention and treatment, it is important to estimate the burden of cryptococcal meningitis.

DESIGN

Global burden of disease estimation using published studies.

METHODS

We used the median incidence rate of available studies in a geographic region to estimate the region-specific cryptococcal meningitis incidence; this was multiplied by the 2007 United Nations Programme on HIV/AIDS HIV population estimate for each region to estimate cryptococcal meningitis cases. To estimate deaths, we assumed a 9% 3-month case-fatality rate among high-income regions, a 55% rate among low-income and middle-income regions, and a 70% rate in sub-Saharan Africa, based on studies published in these areas and expert opinion.

RESULTS

Published incidence ranged from 0.04 to 12% per year among persons with HIV. Sub-Saharan Africa had the highest yearly burden estimate (median incidence 3.2%, 720 000 cases; range, 144 000-1.3 million). Median incidence was lowest in Western and Central Europe and Oceania (</=0.1% each). Globally, approximately 957 900 cases (range, 371 700-1 544 000) of cryptococcal meningitis occur each year, resulting in 624 700 deaths (range, 125 000-1 124 900) by 3 months after infection.

CONCLUSION

This study, the first attempt to estimate the global burden of cryptococcal meningitis, finds the number of cases and deaths to be very high, with most occurring in sub-Saharan Africa. Further work is needed to better define the scope of the problem and track the epidemiology of this infection, in order to prioritize prevention, diagnosis, and treatment strategies.

Chronic meningitis

Chronic meningitis is an inflammation of the meninges with subacute onset and persisting cerebrospinal fluid (CSF) abnormalities lasting for at least one month. Several non-infectious and infectious etiologies are known to be causative. The wide range of different etiologies renders the approach to patients with this syndrome particularly difficult. There is no standardized diagnostic procedure, thus, taking an in depth history combined with a complete physical examination is mandatory in every patient.This review aims to present the current knowledge on etiology, neurological course of disease, diagnostic and therapeutic management steps of patients presenting with clinical signs and symptoms of chronic meningitis and meningoencephalitis. Still, the etiology of one third of patients remains unclear, reflecting the diagnostic challenge of this syndrome for each physician or neurologist, respectively. However, most patients with idiopathic chronic meningitis have a relatively good outcome.

Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating

The ubiquitous environmental human pathogen Cryptococcus neoformans is traditionally considered a haploid fungus with a bipolar mating system. In nature, the α mating type is overwhelmingly predominant over a. How genetic diversity is generated and maintained by this heterothallic fungus in a largely unisexual α population is unclear. Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions generating both diploid intermediates and haploid recombinant progeny. Same-sex mating (α-α) also occurs in nature as evidenced by the existence of natural diploid αADα hybrids that arose by fusion between two α cells of different serotypes (A and D). How significantly this novel sexual style contributes to genetic diversity of the Cryptococcus population was unknown. In this study, ∼500 natural C. neoformans isolates were tested for ploidy and close to 8% were found to be diploid by fluorescence flow cytometry analysis. The majority of these diploids were serotype A isolates with two copies of the α MAT locus allele. Among those, several are intra-varietal allodiploid hybrids produced by fusion of two genetically distinct α cells through same-sex mating. The majority, however, are autodiploids that harbor two seemingly identical copies of the genome and arose via either endoreplication or clonal mating. The diploids identified were isolated from different geographic locations and varied genotypically and phenotypically, indicating independent non-clonal origins. The present study demonstrates that unisexual mating produces diploid isolates of C. neoformans in nature, giving rise to populations of hybrids and mixed ploidy. Our findings underscore the importance of same-sex mating in shaping the current population structure of this important human pathogenic fungus, with implications for mechanisms of selfing and inbreeding in other microbial pathogens.

Although sex typically involves partners of opposite mating type (sexuality), it can also occur with just one mating type and even single individuals (parthenogenesis, homothallism). However, from a population perspective, sexual reproduction occurs by either outcrossing or inbreeding regardless of the partners' sexuality. Here the impact of sex was studied for Cryptococcus neoformans, a pathogen that causes fungal meningitis. While sex in the laboratory is known to occur via opposite-sex-mating, the population is largely unisexual (α) in nature. Recently, an unusual α-α unisexual mating process involving only mating type α was discovered in the lab, but the impact of unisexual mating in nature was unknown. The global survey of this typically haploid organism reveals ∼8% diploids in the population produced by unisexual α-α mating. Some diploids result from fusion of two genetically distinct parents while other diploids arise via sibling mating or genome duplication. Although hybrid fitness is well-documented, how sex between identical isolates benefits the population is a conundrum. The diploid state may confer growth advantages or serve as a capacitor for evolution, allowing mutations to arise that would be deleterious on their own in the haploid, and then releasing these in novel combinations by meiosis and sporulation.

Central nervous system infections in the systemic vasculitides

PURPOSE OF REVIEW

Central nervous system infections are not uncommon in systemic vasculitides. Being vigilant of central nervous system infections as an alternative consideration, instead of systemic vasculitides per se, could prove to be lifesaving in certain circumstances.

RECENT FINDINGS

Common pathogens, such as tuberculosis, Cryptococcus, and Listeria, still occur commonly as the major causes of central nervous system infection in systemic vasculitides. However, rare pathogens could be responsible among those immunocompromised hosts, and they should not be overlooked. The manifestation of central nervous system infection tends to be atypical among systemic vasculitides patients. History, physical, and cerebrospinal fluid analyses are still time-honored approaches to establishing the correct diagnosis. Newer techniques such as interferon-gamma release assay for tuberculosis, cerebrospinal fluid cytokine, or chemokine profiling need further validation and careful interpretation among such a special patient population. Immune disturbance, mainly due to immunosuppressive therapy, and polymorphism of the innate immune pathway (for example, Toll-like receptor) could be susceptibility factors for certain central nervous system infections. The biologic agents (for example, anti-tumor necrosis factor alpha, and B-cell depletion therapy) represent novel methods for treating systemic vasculitides, but they raise a critical issue owing to their increased likelihood for being associated with opportunistic infections.

SUMMARY

Despite the recent progress in this special field, the mortality of central nervous system infection in systemic vasculitides is still high, and the prognostic factors are still largely undetermined.

Impact of mating type, serotype, and ploidy on the virulence of Cryptococcus neoformans

Hybridization with polyploidization is a significant biological force driving evolution. The effect of combining two distinct genomes in one organism on the virulence potential of pathogenic fungi is not clear. Cryptococcus neoformans, the most common cause of fungal infection of the central nervous system, has a bipolar mating system with a and alpha mating types and occurs as A (haploid), D (haploid), and AD hybrid (mostly diploid) serotypes. Diploid AD hybrids are derived either from a-alpha mating or from unisexual mating between haploid cells. The precise contributions of increased ploidy, the effect of hybridization between serotypes A and D, and the combination of mating types to the virulence potential of AD hybrids have remained elusive. By using in vitro and in vivo characterization of laboratory-constructed isogenic diploids and AD hybrids with all possible mating type combinations in defined genetic backgrounds, we found that higher ploidy has a minor negative effect on virulence in a murine inhalation model of cryptococcosis. The presence of both mating types a and alpha in AD hybrids did not affect the virulence potential, irrespective of the serotype origin. Interestingly, AD hybrids with only one mating type behaved differently, with the virulence of alphaADalpha strains similar to that of other hybrids, while aADa hybrids displayed significantly lower virulence due to negative epistatic interactions between the Aa and Da alleles of the mating type locus. This study provides insights into the impact of ploidy, mating type, and serotype on virulence and the impact of hybridization on the fitness and virulence of a eukaryotic microbial pathogen.

Presentation and outcome of tuberculous meningitis in adults in the province of Castellon, Spain: a retrospective study

The aim of this study was to describe the epidemiological and clinical features of tuberculous meningitis in the province of Castellon, Spain. Retrospective analysis was done of all cases attended during the last 15 years. The following groups of variables were assessed: sociodemographic data, medical antecedents, clinical presentation, imaging study results, analyses, cerebrospinal fluid microbiology, treatment, and outcome. Twenty-nine cases were included. Median of age of patients was 34 years, and 17 (59%) were males. HIV infection was present in 15 cases (52%), fever, the most common symptom, occurred in 27 (93%), nuchal rigidity was noted in only 16 (55%), and syndrome of inappropriate ADH secretion (SIADH) occurred in 13 cases (45%). Chest radiograph was abnormal in 15 cases (52%). Anaemia was found in 22 subjects (76%), hypoalbuminaemia in 18 (62%) and hyponatraemia in 15 (52%). Macroscopic aspect of cerebrospinal fluid was normal in 17 cases (65%). Acid-fast stain was positive in only one case (4%). Two patients presented resistance to anti-tuberculous medications. Twelve patients (41%) died and eight (28%) presented sequelae. An association was found between death as outcome and presence of SIADH and lower level of serum cholesterol. Tuberculous meningitis is a rare and frequently difficult to recognize disease, which results in significant morbidity and mortality. We found an association of mortality with SIADH and lower level of serum cholesterol.

Time course of cerebral hemodynamics in cryptococcal meningitis in HIV-negative adults

To evaluate the cerebral hemodynamics in cryptococcal meningitis (CM) patients using non-invasive studies. Serial trans-cranial color-coded sonography (TCCS) and magnetic resonance angiography (MRA) studies were performed to measure the cerebral vasculopathy of 12 HIV-negative CM patients. With TCCS, 8 of the 22 middle cerebral arteries (MCAs) showed stenotic velocities, whereas the time-mean velocity (V(mean)) of the 20 anterior cerebral arteries (ACAs), 22 posterior cerebral arteries (PCAs), and 12 basilar arteries (BAs) did not. In total, five patients had stenotic velocities, three of whom had bilateral M1 stenosis (<50%), whilst two had unilateral M1 stenosis (<50%). The V(mean) of MCA increased from day 1 to day 35 and substantially decreased thereafter. The mean Pulsatility Index (PI) in the studied vessels was higher during the study period. A mismatch of the findings between TCCS and MRA studies were also demonstrated. There was a high incidence and a longer time-period of disturbed cerebral hemodynamics during the clinical course of CM. However, because of the limited case numbers for this study, further large-scale studies are needed to delineate the clinical characteristics and therapeutic influence of cerebrovascular insults in HIV-negative CM patients.

Cryptococcosis-a review of 13 autopsy cases from a 54-year period in a large hospital

From 1952 to 2005, 13 cases of cryptococcosis confirmed by postmortem examination were diagnosed in autopsy material from the University Hospital in Hradec Králové, the Czech Republic. Histologically, Cryptococcus was found in multiple organs (brain and spinal cord, lungs, lymph nodes, spleen, bone marrow, liver, kidneys and adrenal glands). The lungs and CNS were the organs most often involved. Only in two cases was the diagnosis of cryptococcal infection established during the patient's lifetime, in both presenting clinically as meningitis, with positive result of CSF cultivation. Data and issues of diagnostics and treatment of cryptococcosis are discussed.

The biology of the Cryptococcus neoformans species complex

Cryptococcus neoformans is a major cause of fungal meningoencephalitis in immunocompromised patients. Despite recent advances in the genetics and molecular biology of C. neoformans, and improved techniques for molecular epidemiology, aspects of the ecology, population structure, and mode of reproduction of this environmental pathogen remain to be established. Application of recent insights into the life cycle of C. neoformans and its different ways of engaging in sexual reproduction under laboratory conditions has just begun to affect research on the ecology and epidemiology of this human pathogenic fungus. The melding of these disparate disciplines should yield rich dividends in our understanding of the evolution of microbial pathogens, providing insights relevant to diagnosis, treatment, and prevention.