The new Xpert Mycobacterium tuberculosis/rifampicin (MTB/Rif) Ultra assay in comparison to Xpert MTB/Rif assay for diagnosis of tuberculosis in children and adolescents

BACKGROUND

Microbiological diagnosis of pediatric tuberculosis (TB) using conventional microbiological techniques has been challenging due to paucibacillary nature of the disease. Molecular methods using cartridge-based tests like Xpert, have immensely improved diagnosis. A novel next-generation cartridge test, Xpert Ultra, incorporates two additional molecular targets and claims to have much lower detection limit. We attempted to compare the two techniques in presumptive pediatric TB patients.

OBJECTIVES

The aim of this study was to compare the diagnostic performance of Xpert MTB/Rif Ultra with Xpert MTB/Rif for the detection of pediatric TB.

STUDY DESIGN

This is an observational comparative analytical study.

METHODS

Children under 15 years of age with presumptive TB were enrolled. Appropriate specimens were obtained (sputum, induced sputum or gastric aspirate for suspected pulmonary TB, cerebrospinal fluid for suspected tubercular meningitis and pleural fluid for suspected tubercular pleural effusion), subjected to smear microscopy, mycobacterial culture, Xpert and Xpert ultra tests and other appropriate diagnostic investigations.

RESULTS

Out of 130 enrolled patients, 70 were diagnosed with TB using a composite reference standard (CRS). The overall sensitivity of Xpert was 64.29% [95% confidence interval (CI) 51.93-75.93%] and that of Xpert Ultra was 80% (95% CI 68.73-88.61%) with 100% overall specificity for both. The sensitivity of Xpert and Xpert Ultra in pulmonary specimens (n = 112) was 66.67% and 79.37% and in extrapulmonary specimens (n = 18) was 42.86% and 85.71%, respectively.

CONCLUSION

Our study found Ultra to be more sensitive than Xpert for the detection of Mycobacterium tuberculosis in children. Our findings support the use of Xpert Ultra as initial rapid molecular diagnostic test in children under evaluation for TB.

Advancing Diagnosis and Treatment in People Living with HIV and Tuberculosis Meningitis

PURPOSE OF REVIEW

Tuberculous meningitis (TBM) is the most severe form of tuberculosis. Inadequate diagnostic testing and treatment regimens adapted from pulmonary tuberculosis without consideration of the unique nature of TBM are among the potential drivers. This review focuses on the progress being made in relation to both diagnosis and treatment of TBM, emphasizing promising future directions.

RECENT FINDINGS

The molecular assay GeneXpert MTB/Rif Ultra has improved sensitivity but has inadequate negative predictive value to "rule-out" TBM. Evaluations of tests focused on the host response and bacterial components are ongoing. Clinical trials are in progress to explore the roles of rifampin, fluoroquinolones, linezolid, and adjunctive aspirin. Though diagnosis has improved, novel modalities are being explored to improve the rapid diagnosis of TBM. Multiple ongoing clinical trials may change current therapies for TBM in the near future.

Transcriptomic and proteomic analyses of Mycobacterium tuberculosis strains isolated from tuberculous meningitis patients

Background

Tuberculous meningitis (TBM) is caused by the dissemination of Mycobacterium tuberculosis (MTB) from the primary site of infection to the central nervous system. However, the bacterial factors associated with the pathogenesis of TBM remain unclear. This study employed transcriptomic and proteomic methods to comprehensively analyze the changes in genes and proteins and their associated pathways in MTB strains isolated from cerebrospinal fluid (CSF) of TBM and sputum of pulmonary TB (PTB) cases.

Methodology

Five MTB strains were subjected to OMICs (transcriptomic and proteomic) analysis. Among five MTB strains, two were isolated from CSF and sputum samples of the same patient with PTB and TBM infections, one from the sputum of a different PTB patient, and a strain obtained from the CSF of another TBM patient. H37Rv was used as a reference strain. The reliability of transcriptomic results was validated by real time polymerase chain reaction with selected genes from 100 MTB isolates (CSF, 50 and sputum, 50).

Results

The transcriptomic study revealed that overlapping differentially expressed genes of MTB strains isolated from TBM patients showed featured enrichment in benzoate degradation, lysine degradation, tryptophan metabolism, fatty acid degradation, ATP binding cassette transporters, microbial metabolism in diverse environments, biosynthesis of antibiotics, and metabolic pathways. Eleven genes were upregulated, and four were downregulated in MTB strains isolated from TBM compared to PTB. From proteomic analysis, we identified three candidate proteins belonging to plasminogen binding proteins (PBP) (enolase, dnaK, and isocitrate lyase 1) that were significantly upregulated in MTB strains isolated from TBM.

Conclusion

Overall, the transcriptomic and proteomic analyses provided an important base for understanding the unique feature of TBM pathogenesis. To the best of our knowledge, this is the first report highlighting the importance of PBPs on TBM pathogenesis.

NMR based CSF metabolomics in tuberculous meningitis: correlation with clinical and MRI findings

We report the potential role of ¹H Nuclear Magnetic Resonance (NMR) based metabolomics in tuberculous meningitis (TBM). We also correlate the significant metabolites with clinical-radiological parameters. Forty-three patients with TBM were included, and their severity of meningitis was graded as stages I to III, and patients with positive Mycobacterium tuberculosis or its nucleic acid was considered as definite TBM. ¹H NMR-based metabolomic study was performed on (CSF) samples, and the significant metabolites compared to healthy controls were identified. Outcome at three months was defined as death, poor and good based on the modified Rankin Scale. These metabolites were compared between definite and probable groups of TBM, and also correlated with MRI findings. About 11 metabolites were found to be significant for distinguishing TBM from the controls. In TBM, lactate, glutamate, alanine, arginine, 2-hydroxyisobutyrate, formate, and cis-aconitate were upregulated, and glucose, fructose, glutamine, and myo-inositol were downregulated compared to the controls. For differentiating TBM from the controls, the AUC of the ROC curve generated using these significant metabolites was 0.99, with a 95% confidence interval from 0.96 to 1, demonstrating that these metabolites were able to classify cases with good sensitivity and specificity. Lactate concentration in CSF correlated with hemoglobin, CSF glucose, and infarction. The outcome did not correlate with metabolomics parameters. NMR-based CSF metabolomics have a potential role in differentiating TBM from the controls.

Diagnostic accuracy of GeneXpert MTB/RIF assay for detection of tubercular pleural effusion

India has been engaged in tuberculosis (TB) control activities for over 50 years and yet TB continues to remain India’s important public health problem. The present study was conducted to compare the performance of GeneXpert MTB/RIF (GXpert) assay with composite reference standard in diagnosing cases of tubercular pleural effusion (TPE) and to evaluate the reliability of rifampicin resistance. A cross-sectional study was performed in a Department of Medicine of a rural teaching tertiary care hospital in central India. In all consecutive patients with pleural effusion on chest radiograph presenting to Department of Medicine, GXpert assay and composite reference standard was performed to evaluate the diagnostic accuracy of GXpert assay for detecting TPE in comparison to composite reference standard. Standard formulae were used to calculate the sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), positive likelihood ratios (LR+) and negative likelihood ratios (LR-). Mc-Nemar’s test was applied to compare variables. All comparisons were two-tailed. We considered the difference to be statistically significant if the P value was less than 0.05. The sensitivity of the GXpert assay in diagnosing TPE was 16.6% among 158 study participants, the specificity was 100% and diagnostic accuracy was 52.5% which was statistically significant (p value < 0.05). It had a PPV of 100% (95%CI: 88.3% - 100%) and a NPV of 47.5% (95%CI: 39.3% - 55.7%). The LR+ and LR-were 23.5 (95%CI: 1.43–38.6) and 0.83 (95%CI: 0.76–0.91) respectively. GXpert assay has a very high specificity in diagnosing TPE but has a low sensitivity. In comparison to composite reference standard Thus its clinical utility is limited when used as a standalone test. A physician’s clinical acumen in combination with routine pleural fluid analysis should be the key factor in the diagnosis of TPE in clinically and radiologically suspected patients, especially in high TB burden countries.

Serum and cerebrospinal fluid host proteins indicate stroke in children with tuberculous meningitis

Introduction

Stroke is a common complication in children with tuberculous meningitis (TBM). Host proteins may give us insight into the mechanisms of stroke in TBM and serve as biomarkers for detection of stroke, however, they have not been widely explored. In this study, we compared the concentrations of cerebrospinal fluid (CSF) and serum proteins between children who had TBM-related stroke and children with TBM without stroke.

Methods

We collected CSF and serum from 47 children consecutively admitted to the Tygerberg Academic Hospital in Cape Town, South Africa between November 2016, and November 2017, on suspicion of having TBM. A multiplex platform was used to measure the concentrations of 69 host proteins in CSF and serum from all study participants.

Results

After classification of study participants, 23 (48.9%) out of the 47 study participants were diagnosed with TBM, of which 14 (60.9%) demonstrated radiological arterial ischemic infarction. The levels of lipocalin-2, sRAGE, IP-10/ CXCL10, sVCAM-1, MMP-1, and PDGF-AA in CSF samples and the levels of D-dimer, ADAMTS13, SAA, ferritin, MCP-1/ CCL2, GDF-15 and IL-13 in serum samples were statistically different between children who had TBM-related stroke and children with TBM without stroke. After correcting for multiple testing, only the levels of sVCAM-1, MMP-1, sRAGE, and IP-10/ CXCL10 in CSF were statistically different between the two groups. CSF and serum protein biosignatures indicated stroke in children diagnosed with TBM with up to 100% sensitivity and 88.9% specificity.

Conclusion

Serum and CSF proteins may serve as biomarkers for identifying individuals with stroke amongst children diagnosed with TBM at admission and may guide us to understand the biology of stroke in TBM. This was a pilot study, and thus further investigations in larger studies are needed.

Metagenomic next generation sequencing for the diagnosis of tuberculosis meningitis: A systematic review and meta-analysis

Background

Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis and its early diagnosis is very difficult leading to present with severe disability or die. The current study aimed to assess the accuracy of metagenomic next generation sequencing (mNGS) for TBM, and to identify a new test for the early diagnosis of TBM.

Methods

We searched for articles published in Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Data up to June 30, 2020 for studies that assessed the efficacy of mNGS for the diagnosis of TBM. Then, the accuracy between mNGS and a composite reference standard (CRS) in these articles was compared using the meta-analysis approach.

Results

Four independent studies with 342 samples comparing mNGS and a CRS were included in this study. The sensitivity of mNGS for TBM diagnosis ranged from 27% to 84%. The combined sensitivity of mNGS was 61%, and the I² value was 92%. Moreover, the specificity of mNGS for TBM diagnosis ranged from 96% to 100%. The combined specificity of mNGS was 98%, and the I² value was 74%. The heterogeneity between studies in terms of sensitivity and specificity was significant. The area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) of mNGS for TBM was 0.98.

Conclusions

The sensitivity of mNGS for TBM diagnosis was moderate. Furthermore, the specificity was extremely high, and the AUC of the SROC indicated a very good diagnostic efficacy. mNGS could be used as an early diagnostic method for TBM, however, the results should be treated with caution for the heterogeneity between studies was extremely significant.

Systematic review registration

INPLASY202070100.

Molecular diagnosis, genetic diversity and drug sensitivity patterns of Mycobacterium tuberculosis strains isolated from tuberculous meningitis patients at a tertiary care hospital in South India

Tuberculous meningitis (TBM) is the most severe form of Mycobacterium tuberculosis (Mtb) infection in humans and is a public health concern worldwide. We evaluated the performance of GeneXpert MTB/RIF (GeneXpert) for the diagnosis of TBM. In addition, genetic diversity and drug susceptibility profiling of Mtb strains isolated from TBM patients were also investigated. A total of 293 TBM suspected cerebrospinal fluid (CSF) samples were collected and subjected to GeneXpert and Mycobacterial Growth Indicator Tube (MGIT 960) culture, respectively. Sensitivity and specificity of GeneXpert was 72.7% and 98.5%, respectively by using MGIT 960 as a gold standard (GeneXpert (n = 20, 6.8%) vs MGIT 960 (n = 22, 7.5%)). All Mtb positive cultures were subjected to 24-locus Mycobacterial Interspersed Repetitive Unit Variable Number Tandem Repeat (MIRU-VNTR) typing, Line probe assay (LPA) and MGIT 960- Drug Susceptibility Testing (DST). The rpoB gene was amplified and sequenced for selected isolates. Among our TBM patients, East African Indian (EAI) lineage (n = 16, 72.7%) was most predominant followed by Beijing (n = 3, 13.6%), S-family (n = 2, 9.1%) and Delhi/CAS (n = 1, 4.5%). Three Mtb strains were found to be Isoniazid (INH) resistant by MGIT 960; however LPA revealed that two strains were INH resistant and one strain was multi drug resistant (MDR) (Resistant to Isoniazid and Rifampicin (RIF)). We identified rifampicin resistant isolate with the mutation D516F in rifampicin resistance-determining region (RRDR) and observed discordant results between LPA, GeneXpert and MGIT 960. In addition, GeneXpert showing false RIF resistance was identified (no mutation in RRDR). We conclude that GeneXpert is useful for the diagnostic confirmation of TBM; however a GeneXpert negative sample should be subjected to MGIT 960 culture or LPA to rule out TBM. EAI lineage was the most predominant among TBM patients in South India and associated with drug resistance. The discordance between GeneXpert, MGIT 960 and LPA with respect to rifampicin resistance has to be ruled out to avoid TB treatment failure or relapse.

Xpert MTB/RIF and Xpert MTB/RIF Ultra assays for active tuberculosis and rifampicin resistance in children

BACKGROUND

Every year, at least one million children become ill with tuberculosis and around 200,000 children die. Xpert MTB/RIF and Xpert Ultra are World Health Organization (WHO)-recommended rapid molecular tests that simultaneously detect tuberculosis and rifampicin resistance in adults and children with signs and symptoms of tuberculosis, at lower health system levels. To inform updated WHO guidelines on molecular assays, we performed a systematic review on the diagnostic accuracy of these tests in children presumed to have active tuberculosis.

OBJECTIVES

Primary objectives • To determine the diagnostic accuracy of Xpert MTB/RIF and Xpert Ultra for (a) pulmonary tuberculosis in children presumed to have tuberculosis; (b) tuberculous meningitis in children presumed to have tuberculosis; (c) lymph node tuberculosis in children presumed to have tuberculosis; and (d) rifampicin resistance in children presumed to have tuberculosis - For tuberculosis detection, index tests were used as the initial test, replacing standard practice (i.e. smear microscopy or culture) - For detection of rifampicin resistance, index tests replaced culture-based drug susceptibility testing as the initial test Secondary objectives • To compare the accuracy of Xpert MTB/RIF and Xpert Ultra for each of the four target conditions • To investigate potential sources of heterogeneity in accuracy estimates - For tuberculosis detection, we considered age, disease severity, smear-test status, HIV status, clinical setting, specimen type, high tuberculosis burden, and high tuberculosis/HIV burden - For detection of rifampicin resistance, we considered multi-drug-resistant tuberculosis burden • To compare multiple Xpert MTB/RIF or Xpert Ultra results (repeated testing) with the initial Xpert MTB/RIF or Xpert Ultra result SEARCH METHODS: We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, and the International Standard Randomized Controlled Trials Number (ISRCTN) Registry up to 29 April 2019, without language restrictions.

SELECTION CRITERIA

Randomized trials, cross-sectional trials, and cohort studies evaluating Xpert MTB/RIF or Xpert Ultra in HIV-positive and HIV-negative children younger than 15 years. Reference standards comprised culture or a composite reference standard for tuberculosis and drug susceptibility testing or MTBDRplus (molecular assay for detection of Mycobacterium tuberculosis and drug resistance) for rifampicin resistance. We included studies evaluating sputum, gastric aspirate, stool, nasopharyngeal or bronchial lavage specimens (pulmonary tuberculosis), cerebrospinal fluid (tuberculous meningitis), fine needle aspirates, or surgical biopsy tissue (lymph node tuberculosis).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality using the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2). For each target condition, we used the bivariate model to estimate pooled sensitivity and specificity with 95% confidence intervals (CIs). We stratified all analyses by type of reference standard. We assessed certainty of evidence using the GRADE approach.

MAIN RESULTS

For pulmonary tuberculosis, 299 data sets (68,544 participants) were available for analysis; for tuberculous meningitis, 10 data sets (423 participants) were available; for lymph node tuberculosis, 10 data sets (318 participants) were available; and for rifampicin resistance, 14 data sets (326 participants) were available. Thirty-nine studies (80%) took place in countries with high tuberculosis burden. Risk of bias was low except for the reference standard domain, for which risk of bias was unclear because many studies collected only one specimen for culture. Detection of pulmonary tuberculosis For sputum specimens, Xpert MTB/RIF pooled sensitivity (95% CI) and specificity (95% CI) verified by culture were 64.6% (55.3% to 72.9%) (23 studies, 493 participants; moderate-certainty evidence) and 99.0% (98.1% to 99.5%) (23 studies, 6119 participants; moderate-certainty evidence). For other specimen types (nasopharyngeal aspirate, 4 studies; gastric aspirate, 14 studies; stool, 11 studies), Xpert MTB/RIF pooled sensitivity ranged between 45.7% and 73.0%, and pooled specificity ranged between 98.1% and 99.6%. For sputum specimens, Xpert Ultra pooled sensitivity (95% CI) and specificity (95% CI) verified by culture were 72.8% (64.7% to 79.6%) (3 studies, 136 participants; low-certainty evidence) and 97.5% (95.8% to 98.5%) (3 studies, 551 participants; high-certainty evidence). For nasopharyngeal specimens, Xpert Ultra sensitivity (95% CI) and specificity (95% CI) were 45.7% (28.9% to 63.3%) and 97.5% (93.7% to 99.3%) (1 study, 195 participants). For all specimen types, Xpert MTB/RIF and Xpert Ultra sensitivity were lower against a composite reference standard than against culture. Detection of tuberculous meningitis For cerebrospinal fluid, Xpert MTB/RIF pooled sensitivity and specificity, verified by culture, were 54.0% (95% CI 27.8% to 78.2%) (6 studies, 28 participants; very low-certainty evidence) and 93.8% (95% CI 84.5% to 97.6%) (6 studies, 213 participants; low-certainty evidence). Detection of lymph node tuberculosis For lymph node aspirates or biopsies, Xpert MTB/RIF pooled sensitivity and specificity, verified by culture, were 90.4% (95% CI 55.7% to 98.6%) (6 studies, 68 participants; very low-certainty evidence) and 89.8% (95% CI 71.5% to 96.8%) (6 studies, 142 participants; low-certainty evidence). Detection of rifampicin resistance Xpert MTB/RIF pooled sensitivity and specificity were 90.0% (67.6% to 97.5%) (6 studies, 20 participants; low-certainty evidence) and 98.3% (87.7% to 99.8%) (6 studies, 203 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

We found Xpert MTB/RIF sensitivity to vary by specimen type, with gastric aspirate specimens having the highest sensitivity followed by sputum and stool, and nasopharyngeal specimens the lowest; specificity in all specimens was > 98%. Compared with Xpert MTB/RIF, Xpert Ultra sensitivity in sputum was higher and specificity slightly lower. Xpert MTB/RIF was accurate for detection of rifampicin resistance. Xpert MTB/RIF was sensitive for diagnosing lymph node tuberculosis. For children with presumed tuberculous meningitis, treatment decisions should be based on the entirety of clinical information and treatment should not be withheld based solely on an Xpert MTB/RIF result. The small numbers of studies and participants, particularly for Xpert Ultra, limits our confidence in the precision of these estimates.

Reduction of Human DNA Contamination in Clinical Cerebrospinal Fluid Specimens Improves the Sensitivity of Metagenomic Next-Generation Sequencing

Metagenomics next-generation sequencing (mNGS) is increasingly available for the detection of obscure infectious diseases of the central nervous system. However, human DNA contamination from elevated white cells, one of the characteristic cerebrospinal fluid (CSF) features in meningitis patients, greatly reduces the sensitivity of mNGS in the pathogen detection. Currently, effective approaches to selectively reduce host DNA contamination from clinical CSF samples are still lacking. In this study, a total of 20 meningitis patients were enrolled, including 10 definitively diagnosed tuberculous meningitis (TBM) and 10 definite cryptococcal meningitis (CM) cases. To evaluate the effect of reduced human DNA in the sensitivity of mNGS detection, three specimen-processing protocols were performed: (i) To remove human DNA, saponin, a nonionic surfactant, was used to selectively lyse white cells in CSF followed by DNase treatment prior to the extraction of DNA; (ii) to reduce host DNA, CSF was centrifuged to remove human cells, and the supernatant was collected for DNA extraction; and (iii) DNA extraction from the unprocessed specimens was set as the control. We found that saponin processing significantly elevated the NGS unique reads for Cryptococcus (P < 0.01) compared with the control but had no effects for Mycobacterium tuberculosis (P > 0.05). However, detection of centrifuged supernatants improved the NGS unique reads for both TBM and CM compared with controls (P < 0.01). Our results demonstrate that the use of mNGS of centrifuged supernatants from clinical CSF samples in patients with TBM and CM is a simple and effective method to improve the sensitivity of pathogen detection.

Microbiological diagnosis of tuberculous meningitis: Phenotype to genotype

Tuberculous meningitis (TBM) is a commonly encountered central nervous system infection. Characteristic clinical, imaging and cerebrospinal fluid parameters help clinicians to make a prompt presumptive diagnosis that enables them to start empirical anti-tuberculosis treatment. There are several close mimic to TBM, such as partially treated pyogenic meningitis, fungal meningitis, sarcoidosis, meningeal metastases and meningeal lymphomatosis. Microbiological confirmation instils a sense of confidence amongst treating physicians. With conventional phenotypic methods (cerebrospinal fluid microscopy and culture), in more than 50 per cent patients, microbiological confirmation is not achieved. Moreover, these methods take a long time before providing conclusive results. Negative result does not rule out Mycobacterium tuberculosis infection of the brain. Genotypic methods, such as IS 6110 polymerase chain reaction and automated Xpert M. tuberculosis/rifampicin (MTB/RIF) assay system improved the TBM diagnostics, as results are rapidly available. Xpert MTB/RIF assay, in addition, detects rifampicin resistance. Xpert MTB/RIF Ultra is advanced technology which has higher (60-70%) sensitivity and is being considered a game-changer in the diagnostics of TBM. A large number of TBM cases remain unconfirmed. The situation of TBM diagnostics will remain grim, if low-cost technologies are not widely available. Till then, physicians continue to rely on their clinical acumen to start empirical anti-tuberculosis treatment.

Tuberculous meningitis in children: Clinical management & outcome

Although the occurrence of tuberculous meningitis (TBM) in children is relatively rare, but it is associated with higher rates of mortality and severe morbidity. The peak incidence of TBM occurs in younger children who are less than five years of age, and most children present with late-stage disease. Confirmation of diagnosis is often difficult, and other infectious causes such as bacterial, viral and fungal causes must be ruled out. Bacteriological confirmation of diagnosis is ideal but is often difficult because of its paucibacillary nature as well as decreased sensitivity and specificity of diagnostic tests. Early diagnosis and management of the disease, though difficult, is essential to avoid death or neurologic disability. Hence, a high degree of suspicion and a combined battery of tests including clinical, bacteriological and neuroimaging help in diagnosis of TBM. Children diagnosed with TBM should be managed with antituberculosis therapy (ATT) and steroids. There are studies reporting low concentrations of ATT, especially of rifampicin and ethambutol in cerebrospinal fluid (CSF), and very young children are at higher risk of low ATT drug concentrations. Further studies are needed to identify appropriate regimens with adequate dosing of ATT for the management of paediatric TBM to improve treatment outcomes. This review describes the clinical presentation, investigations, management and outcome of TBM in children and also discusses various studies conducted among children with TBM.

Panhypopituitarism- An unusual presenation of tuberculous meningitis

Pituitary gland involvement is a very rare entity of central nervous system tuberculosis. Tubercular meningitis (TBM) is a chronic meningitis on hypothalamic-pituitary axis which causes high morbidity and mortality hence it is the most dreaded form of extra pulmonary tuberculosis. Here we report a case of 24 year old female presenting with three months history of fever and headache along with altered sensorium since four days. There was also complain of secondary amenorrhea and generalised apathy. Neuroimaging revealed subependymal tuberculomas with meningitis and obstructive hydrocephalus. Cerebrospinal fluid (CSF) examination was also suggestive of tubercular meningitis. Endocrinological investigations showed multiple hormonal deficiencies manifesting as pituitary hypothyroidism, hypocortisolism, hypogonadotropic hypogonadism, and hypoprolactinemia. Anti-tuberculosis treatment was started, and it led to significant improvement in the general condition of the patient.

Improving the microbiological diagnosis of tuberculous meningitis: A prospective, international, multicentre comparison of conventional and modified Ziehl-Neelsen stain, GeneXpert, and culture of cerebrospinal fluid

OBJECTIVES

Tuberculous meningitis (TBM) is the severest form of tuberculosis, but current diagnostic tests are insensitive. Recent reports suggest simple modifications to conventional cerebrospinal fluid (CSF) Ziehl-Neelsen (ZN) staining may greatly improve sensitivity. We sought to define the performance of modified and conventional ZN stain for TBM diagnosis.

METHODS

In hospitals in Vietnam, South Africa and Indonesia we conducted a prospective study of modified ZN with or without cytospin, conventional ZN smear, GeneXpert, and culture on CSF in adults with suspected TBM.

RESULTS

A total of 618 individuals were enrolled across 3 sites. Compared with the TBM clinical diagnostic gold standard for research (definite probable or possible TBM), sensitivity of conventional ZN and modified ZN with cytospin were 33.9% and 34.5% respectively (p = 1.0 for the difference between tests), compared with culture 31.8% and Xpert 25.1%. Using culture as a reference, sensitivities of conventional ZN, modified ZN with cytospin, and Xpert were 66.4%, 67.5%, and 72.3%, respectively. Higher CSF volume and lactate, and lower CSF:blood glucose ratio were independently associated with microbiologically confirmed TBM.

CONCLUSIONS

Modified ZN stain does not improve diagnosis of TBM. Currently available tests are insensitive, but testing large CSF volumes improves performance. New diagnostic tests for TBM are urgently required.

Progress on Diagnosis of Tuberculous Meningitis

Central nervous system (CNS) disease caused by Mycobacterium tuberculosis (MTB) is highly devastating. Tuberculous meningitis (TBM) is the most common form of CNS tuberculosis (TB). Rapid, sensitive, and affordable diagnostic tests are not available. Ziehl-Neelsen (ZN) stain has a very low sensitivity in cases of TBM, the sensitivity rates is of about 10-20%.The detection rate can be improved by taking large volume CSF samples (>6 ml) and prolonged slide examination (30 min). Culture of MTB from the CSF is slow and insufficiently sensitive. The sensitivity is different, which varies from 36% to 81.8%. The microscopic observation drug susceptibility (MODS) assay was recommended by the World Health Organization in 2011. The sensitivity is 65%, which is more sensitive and faster than CSF smear. Commercial PCR assays were found to be insensitive at detecting MTB in CSF samples. Many research provided the value of ADA on the TBM diagnosis. Interferon-gamma release assays (IGRAs) are not recommended for diagnosis of active TB disease. Imaging is essential in diagnosis and showing complications of CNS TB. Thwaites criteria and the Lancet consensus scoring system (LCSS) were developed to improve the diagnosis of TBM. Clinicians will continue to make judgment based on clinical examination, inflammatory CSF examinations, imaging studies, and scoring systems.

The SIGLEC14 null allele is associated with Mycobacterium tuberculosis- and BCG-induced clinical and immunologic outcomes

Humans exposed to Mycobacterium tuberculosis (Mtb) have variable susceptibility to tuberculosis (TB) and its outcomes. Siglec-5 and Siglec-14 are members of the sialic-acid binding lectin family that regulate immune responses to pathogens through inhibitory (Siglec-5) and activating (Siglec-14) domains. The SIGLEC14 coding sequence is deleted in a high proportion of individuals, placing a SIGLEC5-like gene under the expression of the SIGLEC14 promoter (the SIGLEC14 null allele) and causing expression of a Siglec-5 like protein in monocytes and macrophages. We hypothesized that the SIGLEC14 null allele was associated with Mtb replication in monocytes, T-cell responses to the BCG vaccine, and clinical susceptibility to TB. The SIGLEC14 null allele was associated with protection from TB meningitis in Vietnamese adults but not with pediatric TB in South Africa. The null allele was associated with increased IL-2 and IL-17 production following ex-vivo BCG stimulation of blood from 10 week-old South African infants vaccinated with BCG at birth. Mtb replication was increased in THP-1 cells overexpressing either Siglec-5 or Siglec-14 relative to controls. To our knowledge, this is the first study to demonstrate an association between SIGLEC expression and clinical TB, Mtb replication, or BCG-specific T-cell cytokines.

Influence of socio-economic inequality measured by the Gini coefficient on meningitis incidence caused by Mycobacterium tuberculosis and Haemophilus influenzae in Colombia, 2008-2011

Bacterial meningitis is an important cause of infectious neurological morbidity and mortality. Its incidence has decreased with the introduction of vaccination programmes against preventable agents. However, low-income and middle-income countries with poor access to health care still have a significant burden of the disease. Thus, the relationship between the Gini coefficient and H. influenzae and M. tuberculosis meningitis incidence in Colombia, during 2008-2011, was assessed. In this ecological study, the Gini coefficient was obtained from the Colombian Department of Statistics, incidence rates were calculated (cases/1,000,000 pop) and linear regressions were performed using the Gini coefficient, to assess the relationship between the latter and the incidence of meningitis. It was observed that when inequality increases in the Colombian departments, the incidence of meningitis also increases, with a significant association in the models (p<0.01) for both M. tuberculosis (r²=0.2382; p<0.001) and H. influenzae (r²=0.2509; p<0.001). This research suggests that high Gini coefficient values influence the incidence of Mycobacterium tuberculosis and Haemophilus influenzae meningitis, showing that social inequality is critical to disease occurrence. Early detection, supervised treatment, vaccination coverage, access to health care are efficient control strategies.

High rate of drug resistance among tuberculous meningitis cases in Shaanxi province, China

The clinical and mycobacterial features of tuberculous meningitis (TBM) cases in China are not well described; especially in western provinces with poor tuberculosis control. We prospectively enrolled patients in whom TBM was considered in Shaanxi Province, northwestern China, over a 2-year period (September 2010 to December 2012). Cerebrospinal fluid specimens were cultured for Mycobacterium tuberculosis; with phenotypic and genotypic drug susceptibility testing (DST), as well as genotyping of all positive cultures. Among 350 patients included in the study, 27 (7.7%) had culture-confirmed TBM; 84 (24.0%) had probable and 239 (68.3%) had possible TBM. DST was performed on 25/27 (92.3%) culture positive specimens; 12/25 (48.0%) had "any resistance" detected and 3 (12.0%) were multi-drug resistant (MDR). Demographic and clinical features of drug resistant and drug susceptible TBM cases were similar. Beijing was the most common genotype (20/25; 80.0%) with 9/20 (45%) of the Beijing strains exhibiting drug resistance; including all 3 MDR strains. All (4/4) isoniazid resistant strains had mutations in the katG gene; 75% (3/4) of strains with phenotypic rifampicin resistance had mutations in the rpoB gene detected by Xpert MTB/RIF®. High rates of drug resistance were found among culture-confirmed TBM cases; most were Beijing strains.

Neurotuberculosis in cattle in southern Brazil

Tuberculosis in cattle is a chronic infectious-contagious disease characterized by the development of nodular lesions (granulomas) in mainly the lungs and regional lymph nodes. It is caused by Mycobacterium tuberculosis complex, an acid-fast bacillus (AFB). Tuberculosis in the central nervous system is a rare condition in cattle. Herein, we describe the clinical and pathological findings of six neurotuberculosis cases in cattle diagnosed in Southern Brazil. The average age of the cattle affected was 12 months, and they varied in breed and sex. The clinical history ranged from 5 to 30 days and was characterized by motor incoordination, opisthotonus, blindness, and progression to recumbency. The cattle were euthanized, and grossly, the leptomeninges at the basilar brain showed marked and diffuse expansion, with nodular yellowish lesions ranging in size. On microscopic examination, there were multifocal granulomas located mainly in the meninges, though sometimes extending to adjacent neuropil or existing as isolated granulomas in neuropil. AFBs were observed in the cytoplasm of epithelioid macrophages and multinucleated giant cells through Ziehl-Neelsen histochemical staining and identified as Mycobacterium sp. through immunohistochemistry.

Diagnosis of tuberculous meningitis: challenges and promises

Tuberculosis (TB) which is caused by Mycobacterium tuberculosis infects primarily the lungs but it also affects other parts of the body. Tuberculous meningitis (TBM) is the most severe form of TB and has the highest mortality and morbidity rate compared to other forms of TB. It is common in young children and HIV-infected patients, but is also seen in adults. Despite anti-tuberculosis treatment, TBM is still a major cause of death and neurological sequelae as treatment given to the patients is often delayed. Early diagnosis is challenging due to the non-specific symptoms of TBM and the low number of tubercle bacilli in cerebrospinal fluid (CSF). Until now, there is no established diagnostic method that can rapidly detect M. tuberculosis in TBM patients with high sensitivity and specificity. The emergence of drug resistant M. tuberculosis strains further complicates the diagnosis and treatment regimen of TBM. This review summarizes challenges of the currently used diagnostic methods and the potential future use of molecular diagnostic methods for TBM.

Kinetics of T-cell-based assays on cerebrospinal fluid and peripheral blood mononuclear cells in patients with tuberculous meningitis

BACKGROUND/AIMS

The goal of this study was to monitor tuberculosis (TB)-specific T-cell responses in cerebrospinal fluid-mononuclear cells (CSF-MCs) and peripheral blood mononuclear cells (PBMCs) in patients with tuberculous meningitis (TBM) over the course of anti-TB therapy.

METHODS

Adult patients (≥ 16 years) with TBM admitted to Asan Medical Center, Seoul, South Korea, were prospectively enrolled between April 2008 and April 2011. Serial blood or CSF samples were collected over the course of the anti-TB therapy, and analyzed using an enzyme-linked immunosorbent spot (ELISPOT) assay.

RESULTS

Serial ELISPOT assays were performed on PBMCs from 17 patients (seven definite, four probable, and six possible TBM) and CSF-MC from nine patients (all definite TBM). The median number of interferon-gamma (IFN-γ)-producing T-cells steadily increased during the first 6 months after commencement of anti-TB therapy in PBMCs. Serial CSF-MC ELISPOT assays revealed significant variability in immune responses during the first 6 weeks of anti-TB therapy, though early increases in CSF-MC ELISPOT results were associated with treatment failure or paradoxical response.

CONCLUSIONS

Serial analysis of PBMCs by ELISPOT during the course of treatment was ineffective for predicting clinical response. However, increases in TB-specific IFN-γ-producing T-cells in CSF-MC during the early phase of anti-TB therapy may be predictive of clinical failure.

Modeling tuberculous meningitis in zebrafish using Mycobacterium marinum

Tuberculous meningitis (TBM) is one of the most severe extrapulmonary manifestations of tuberculosis, with a high morbidity and mortality. Characteristic pathological features of TBM are Rich foci, i.e. brain- and spinal-cord-specific granulomas formed after hematogenous spread of pulmonary tuberculosis. Little is known about the early pathogenesis of TBM and the role of Rich foci. We have adapted the zebrafish model of Mycobacterium marinum infection (zebrafish-M. marinum model) to study TBM. First, we analyzed whether TBM occurs in adult zebrafish and showed that intraperitoneal infection resulted in granuloma formation in the meninges in 20% of the cases, with occasional brain parenchyma involvement. In zebrafish embryos, bacterial infiltration and clustering of infected phagocytes was observed after infection at three different inoculation sites: parenchyma, hindbrain ventricle and caudal vein. Infection via the bloodstream resulted in the formation of early granulomas in brain tissue in 70% of the cases. In these zebrafish embryos, infiltrates were located in the proximity of blood vessels. Interestingly, no differences were observed when embryos were infected before or after early formation of the blood-brain barrier (BBB), indicating that bacteria are able to cross this barrier with relatively high efficiency. In agreement with this observation, infected zebrafish larvae also showed infiltration of the brain tissue. Upon infection of embryos with an M. marinum ESX-1 mutant, only small clusters and scattered isolated phagocytes with high bacterial loads were present in the brain tissue. In conclusion, our adapted zebrafish-M. marinum infection model for studying granuloma formation in the brain will allow for the detailed analysis of both bacterial and host factors involved in TBM. It will help solve longstanding questions on the role of Rich foci and potentially contribute to the development of better diagnostic tools and therapeutics.

Chronic meningitis in immunocompromised adult Ethiopians visiting Tikur Anbessa Teaching Hospital and Ye'huleshet Clinic from 2003-2004

BACKGROUND

Chronic meningitis is inflammation of the meninges where signs and symptoms develop and last for at least four weeks without alleviation. Little is known about the current etiology and incidence of the disease in adults living in developing countries.

OBJECTIVE

The objective of this study was to elucidate the most common etiologies of chronic meningitis in adult Ethiopian patients and give an aid in the empiric therapy.

METHODOLOGY

A total of 53 adult patients (median age 32 years) having chronic meningitis and who were admitted at Tikur Anbessa Teaching Hospital and Ye'huleshet Clinic, Addis Ababa, Ethiopia were recruited between 2003 and 2004. Of the 53 patients, bacteriological, molecular and immunological investigations were done for 52 of the study participants to detect Cryptococcus neoformans, Mycobacterium tuberculosis, Toxoplasma gondii, Brucella and Neisseria meningitides infections.

RESULTS

Forty eight of the participants were HIV positive and 15% (8/52) of the CSF were positive with Cryptococcal latex antigen detection test; in addition, M. tuberculosis DNA was detected using PCR from CSF ofpatients infew of the patients. Multiple infections were observed in studyparticipants with < 0.1 to 1 CD4 to CD8 ratio.

CONCLUSION

Chronic meningitis mostly occurred in HIV infected patients, where most of the infections were attributed to Cryptococcus neoformans whereas M. tuberculosis appeared secondary.

Stroke in patients with tuberculous meningitis in a low TB endemic country: an increasing medical emergency?

Stroke due to brain vascular disease is a serious complication of tuberculous meningitis (TBM). This study evaluated the frequency, clinical characteristics, risk factors and outcomes of patients with TBM complicated by stroke admitted to the Infectious Disease Clinic, University of Perugia Hospital, Italy from 1971 to 2010. Over four decades, 419 patients were admitted with tuberculosis, of these 30 (7.1%) were diagnosed with TBM: 20 definite, one probable and nine possible. Twenty-six were evaluable for stroke and six (23%) had stroke. The latter six had advanced stages of meningitis, two tested HIV positive, three HIV negative and in one HIV was not performed. Of seven patients without stroke tested for HIV, only one resulted positive. No differences were found regarding CSF cell count, sugar, protein, microscopy or growth of Mycobacterium tuberculosis among patients with or without stroke. The overall survival rate at discharge was 83% in patients with stroke and 95% in those without stroke. It was found that stroke can be frequent among patients with TBM and the presence of HIV infection might be associated with a higher rate of stroke. Further research is needed on these findings, especially in low TB endemic countries.

Cranial nerve palsy as a factor to differentiate tuberculous meningitis from acute bacterial meningitis

Tuberculous meningitis (TBM) and acute bacterial meningitis (ABM) cause substantial mortality and morbidity in both children and adults. Identification of poor prognostic factors at patient's admission could prepare physicians for more aggressive monitoring of patients with meningitis. The objective of this study was to determine the predictive value of neurological features to differentiate ABM and TBM. A retrospective study was conducted between patients affected with ABM or TBM admitted to three teaching hospitals during the last 14 years in Zahedan the central city of Sistan and Balouchestan province (Iran). The neurological features include seizure, level of consciousness, stroke, focal neurologic deficit and cranial nerve palsy at the time of admission. Mean age for patients with TBM and ABM were 41 ± 22.4 and 24 ± 18.5 years respectively. In univariate analysis, all measured variables revealed significant difference between ABM and TBM patients except for seizure episodes. Multivariate logistic regression analysis showed positive predictive effect of cranial nerve palsy (AOR=1.980, CI 95%: 1.161-3.376) on the diagnosis of TBM. In our study cranial nerve palsies was the most important neurological predictor factor to differentiate TBM from ABM.

Tuberculous meningitis: do modern diagnostic tools offer better prognosis prediction?

BACKGROUND

The British Medical Research Council (BMRC) staging has been extensively used to evaluate the disease severity and establish the approximate prognosis of tuberculous meningitis.

AIMS

This study aimed at analyzing the predictive accuracy for mortality and neurological sequelae of a set of clinical features, laboratory tests and imaging.

METHODS

We compared the British Medical Research Council (BMRC) staging with a new scoring proposal to predict the prognosis of patients with Central Nervous System Tuberculosis. Data from Ecuador was collected. A score was built using a Spiegelhalter and Knill-Jones method and compared with BMRC staging with a ROC curve.

RESULTS

A total of 213/310 patients (68.7%) were in BMRC stage II or III. Fifty-seven patients died (18.3%) and 101 (32.5%) survived with sequelae. The associated predictors were consciousness impairment (p = 0.010), motor deficit (p = 0.003), cisternal effacement (p = 0.006) and infarcts (p = 0.015). The new score based on these predictors yielded a larger area under the curve of 0.76 (95% CI: 0.70-0.82), but not significantly different from the BMRC (0.72: 95% CI: 0.65-0.77).

CONCLUSIONS

This modern score is easy to apply and could be a sound predictor of poor prognosis. However, the availability of modern tests did not improve the ability to predict a bad outcome.

Detection of Mycobacterium tuberculosis GlcB or HspX Antigens or devR DNA impacts the rapid diagnosis of tuberculous meningitis in children

Background

Tuberculous meningitis (TBM) is the most common form of neurotuberculosis and the fifth most common form of extrapulmonary TB. Early diagnosis and prompt treatment are the cornerstones of effective disease management. The accurate diagnosis of TBM poses a challenge due to an extensive differential diagnosis, low bacterial load and paucity of cerebrospinal fluid (CSF) especially in children.

Methodology/Principal Findings

We describe the utility of ELISA and qPCR for the detection of Mycobacterium tuberculosis (M. tb) proteins (GlcB, HspX, MPT51, Ag85B and PstS1) and DNA for the rapid diagnosis of TBM. CSF filtrates (n = 532) derived from children were classified as ‘Definite’ TBM (M. tb culture positive, n = 29), ‘Probable and Possible’ TBM (n = 165) and ‘Not-TBM’ including other cases of meningitis or neurological disorders (n = 338). ROC curves were generated from ELISA and qPCR data of ‘Definite’ TBM and Non-Tuberculous infectious meningitis (NTIM) samples and cut-off values were derived to provide ≥95% specificity. devR qPCR, GlcB, HspX and PstS1 ELISAs showed 100% (88;100) sensitivity and 96–97% specificity in ‘Definite’ TBM samples. The application of these cut-offs to ‘Probable and Possible’ TBM groups yielded excellent sensitivity (98%, 94;99) and specificity (98%, 96;99) for qPCR and for GlcB, HspX and MPT51 antigen ELISAs (sensitivity 92–95% and specificity 93–96%). A test combination of qPCR with GlcB and HspX ELISAs accurately detected all TBM samples at a specificity of ∼90%. Logistic regression analysis indicated that these tests significantly added value to the currently used algorithms for TBM diagnosis.

Conclusions

The detection of M. tb GlcB/HspX antigens/devR DNA in CSF is likely to improve the utility of existing algorithms for TBM diagnosis and also hasten the speed of diagnosis.

Tuberculous meningitis, an unusual presentation in a young lady

A 37-year-old Persian-speaking woman presented with epigastric pain, vomiting and non-specific frontal headache. Examination was unremarkable except for an isolated sixth nerve palsy found a few days after admission. Blood results were normal, as was the chest radiograph and the CT scan of the head. Initial cerebrospinal fluid (CSF) analysis revealed a significantly elevated protein level with reduced glucose, as well as CSF lymphocytosis. Tuberculosis (TB) meningitis was considered and she was commenced on anti-TB treatment before confirmation of the diagnosis. A full contact tracing was performed with regular follow-up with TB nurses. When she was seen in the clinic a month later, her symptoms had subsided completely.

[Tuberculous cranial pachymeningitis presenting with long-standing diffuse brain dysfunction]

We report a 59-year-old immunocompetent man presenting with slowly progressive gait unsteadiness, dysarthria, and clumsiness in writing over 6 months. There were bilateral pyramidal signs, pseudobulbar palsy, and attention deficits. Cerebrospinal fluid examination showed mild mononuclear pleocytosis, and magnetic resonance imaging revealed pachymeningeal pattern of contrast enhancement beneath the calvarium and the posterior cranial fossa. Interferon-gamma release assay in whole blood after stimulation by specific tuberculosis antigens was positive and repeat polymerase chain reaction assay detected Mycobacterium tuberculosis genome in the cerebrospinal fluid. After combination therapy with anti-tuberculous agents and corticosteroids, the patient's pachymeningitis regressed. Tuberculous cranial pachymeningitis may present with chronic diffuse brain dysfunction without headache, fever, or cranial nerve dysfunction.

Meningoencephalitis with Aspergillus and mycobacterium tuberculosis in a renal transplant recipient

OBJECTIVES

We report a case of central nervous system coinfection with 2 types of opportunistic organisms-Aspergillus and Mycobacterium tuberculosis-in a 33-year-old woman who underwent a renal transplant.

MATERIALS AND METHODS

She developed a high-grade fever and right-sided weakness 1 month after the transplant while on mycophenolate mofetil, prednisolone, and cyclosporine.

RESULTS

Brain magnetic resonance imaging revealed multiple mass lesions with peripheral ring enhancement. Colony-stimulating factor polymerase chain reaction was positive for Aspergillus and Mycobacterium tuberculosis.

CONCLUSIONS

Broad-spectrum antibiotics, antituberculous agents, and amphotericin were started. Unfortunately, the woman's condition deteriorated, and she died 2 weeks after admission to the hospital.

Predictors of mortality in tuberculous meningitis: a multivariate analysis of 160 cases

OBJECTIVE

To evaluate predictors of mortality in 160 patients with tuberculous meningitis (TBM).

DESIGN

One hundred and sixty patients with TBM who had been followed for 11 years in a tertiary referral centre hospital were assessed retrospectively. Features considered as predictors of mortality in TBM were studied by multivariate logistic regression to develop a prognostic rule.

RESULTS

Of 160 patients, 84% were in Stages II and III; 27 (17%) died. In univariate analysis, age, stage, altered sensorium, underlying comorbidities, pulmonary tuberculosis, leukocytosis and cerebrospinal fluid (CSF)/blood glucose < 0.30 and rise in CSF protein were associated with an increased risk of death. In multivariable analysis, age (OR 4.64, 95%CI 1.03-24.74, P = 0.046), altered sensorium (OR 8.62, 95%CI 1.25-110.0, P = 0.036), underlying comorbidity (OR 9.75, 95%CI 1.58-59.95, P = 0.014) and leukocytosis (OR 9.74, 95%CI 1.67-56.7, P = 0.011) were shown to be the best predictors of mortality in TBM.

CONCLUSIONS

We observed that TBM patients who died were more likely to be older and have altered mental status on admission, underlying comorbidities and leukocytosis than TBM patients who survived. These factors were the most important predictors of mortality from TBM.

Determination of polymerase chain reaction efficiency for diagnosis of tuberculous meningitis in Chelex-100 extracted DNA samples

SETTING

Polymerase chain reaction (PCR) offers great promise for the rapid, sensitive and specific diagnosis of tuberculous meningitis (TBM). However, the isolation of DNA of high quantity and quality from cerebrospinal fluid (CSF) samples is critical for successful PCR assays.

OBJECTIVE

To develop and use a single-tube method for the isolation of PCR-compatible DNA from Mycobacterium tuberculosis using Chelex-100 chelating resin, which does not require organic solvents or detergents.

DESIGN

The study focused on the standardisation of a suitable Chelex protocol and its evaluation in 32 CSF samples from TBM and non-TBM subjects. A simultaneous comparison was made with the conventional phenol/chloroform extraction method.

RESULT

PCR was found to be more sensitive, more rapid and less technically demanding with the Chelex protocol than the conventional phenol/chloroform extraction method (sensitivity 84.2% vs. 73.6%).

CONCLUSION

The single-tube method and the simplicity of the procedure permits early and reliable diagnosis of TBM and makes it an attractive method for routine laboratory assays.

Specific bacterial genotypes of Mycobacterium tuberculosis cause extensive dissemination and brain infection in an experimental model

Meningeal tuberculosis is a severe type of extrapulmonary disease, which is thought to begin with respiratory infection, followed by hematogenous dissemination and brain infection. Host genetic susceptibility factors and specific mycobacterial substrains could be involved in its development. From an epidemiological study in Colombia, we selected three Mycobacterium tuberculosis clinical strains isolated from the cerebrospinal fluid (CSF) of patients with meningeal tuberculosis, and used them to infect BALB/c mice through the intratracheal route. These strains showed a distinctive spoligotype pattern. The course of infection in terms of strain virulence (mice survival, bacillary loads in lungs), bacilli dissemination and extrapulmonary infection (bacilli loads in blood, brain, liver, kidney and spleen), and immune responses (cytokine expression determined by real time PCR in brain and lung) was studied and compared with that induced by the laboratory strain H37Rv and other five clinical strains isolated from patients with pulmonary TB. All the clinical isolates from meningeal TB patients disseminated extensively through the hematogenous route infecting the brain, producing inflammation in the cerebral parenchyma and meninges, whereas H37Rv and clinical isolates from pulmonary TB patients showed very limited efficiency to infect the brain. Thus, it seems that mycobacterial strains with a distinctive genotype are able to disseminate extensively after the respiratory infection and infect the brain.

[A systematic review on the protective efficacy of BCG against children tuberculosis meningitis and millet tuberculosis]

OBJECTIVE

To Understand the protective efficacy of Bacillus Calmette Guerin (BCG) vacciation against children tuberculosis meningitis and millet tuberculosis, to provide the data to improve immune tactics of BCG.

METHODS

A search CHKD full text database (1979-2007) and CHKD meeting paper database (1999-2008) and WANGFANG database (1982-2007), with BCG, tuberculosis meningitis, millet tuberculosis, then to analyze information from qualified literatures.

RESULTS

28 paper were involved. 25 were correlated with tuberculosis meningitis, 1 correlated with millet tuberculosis, 2 correlated with both. The study about protections of BCG against tuberculosis meningitis showed that BCG has protective action in ecology study. The inoculation of BCG in tuberculosis meningitis cases was 0-69.08%, millet tuberculosis BCG inoculating with 82.76%. Result of Mete analysis showed that it was 81% to the protection tuberculosis meningitis, 95% CI is 57%-91%.

CONCLUSION

BCG vaccine has protective effect for preventing tuberculous meningitis. Due to lack of case-control study, cases in vaccinated and unvaccinated ratio should not an objective description of the effect of BCG vaccination. Protective effect of miliary tuberculosis research literature was less, unable to come to precise conclusions.

rpoB nested PCR and sequencing for the early diagnosis of tuberculous meningitis and rifampicin resistance

SETTING

The prognosis of tuberculous meningitis (TBM) is linked to early diagnosis and prescription of adequate treatment.

OBJECTIVE

To evaluate the efficacy of the rpoB nested polymerase chain reaction (PCR) and sequencing assay to detect and identify Mycobacterium tuberculosis complex (MTC) strains and strains resistant to rifampicin (RMP) in cerebrospinal fluid specimens (CSF) from patients with highly suspected TBM.

DESIGN

Retrospective blinded hospital-based study.

RESULTS

rpoB nested PCR and sequencing assay detected MTC in 31/36 CSF specimens from 16 patients with clinically suspected TBM. All of the control CSF specimens from 25 patients with non-TBM showed negative results. One of the 16 patients had a mutation at codon C526G as compared to the rpoB sequences in GenBank. This corresponds to a diagnostic sensitivity of 86% (95%CI 71-95) and a specificity of 100% (95%CI 86-100).

CONCLUSION

Our results suggest that rpoB nested PCR and sequencing assay can detect MTC and simultaneously determine its RMP susceptibility in CSF from patients with highly suspected TBM.

Aspergillus fumigatus meningitis in immunosuppressed patients; diagnosis, management, prevention and control

Aspergillosis is a fungal disease that may be expressed by a diversity of clinical syndromes being produced by several of more than 170 Aspergillus species. The "Matei Balş" National Institute for Infectious Diseases has a long experience in diagnostic procedures and treatment of the immunosuppressed patients. Irrespective of the place of their residence, most patients with HIV infection and AIDS were investigated in the Institute in the last two decades. The first case of double central nervous infection (Mycobacterium tuberculosis and Aspergillus fumigatus) in a HIV positive patient is discussed.

[A meningitis case of Brucella and tuberculosis co-infection]

Turkey is located at an endemic area for brusellosis and tuberculosis which are both important public health problems. Meningitis caused by Brucella and Mycobacterium spp. may be confused since the clinical and laboratory findings are similar. In this report, a meningitis case with Brucella and tuberculosis co-infection has been presented. A 19-years-old woman was admitted to our clinic with severe headache, fever, vomiting, meningeal irritation symptoms, confusion and diplopia. The patient was initially diagnosed as Brucella meningitis based on her history (stockbreeding, consuming raw milk products, clinical symptoms concordant to brucellosis lasting for 4-5 months), physical examination and laboratory findings of cerebrospinal fluid (CSF). Standard tube agglutination test for brucellosis was positive at 1/80 titer in CSF and at 1/640 titer in serum, whereas no growth of Brucella spp. was detected in CSF and blood cultures. Antibiotic therapy with ceftriaxone, rifampicin and doxycyclin was started, however, there was no clinical improvement and agitation and confusion of the patient continued by the end of second day of treatment. Repeated CSF examination yielded acid-fast bacteria. The patient was then diagnosed as meningitis with double etiology and the therapy was changed to ceftriaxone, streptomycin, morphozinamide, rifampicin and isoniazid for thirty days. Tuberculosis meningitis was confirmed with the growth of Mycobacterium tuberculosis on the 14th day of cultivation (BACTEC, Becton Dickinson, USA) of the CSF sample. On the 30th day of treatment she was discharged on anti-tuberculous treatment with isoniazid and rifampicin for 12 months. The follow-up of the patient on the first and third months of treatment revealed clinical and laboratory improvement. Since this was a rare case of Brucella and tuberculosis co-infection, this report emphasizes that such co-infections should be kept in mind especially in the endemic areas for tuberculosis and brucellosis.

The influence of host and bacterial genotype on the development of disseminated disease with Mycobacterium tuberculosis

The factors that govern the development of tuberculosis disease are incompletely understood. We hypothesized that some strains of Mycobacterium tuberculosis (M. tuberculosis) are more capable of causing disseminated disease than others and may be associated with polymorphisms in host genes responsible for the innate immune response to infection. We compared the host and bacterial genotype in 187 Vietnamese adults with tuberculous meningitis (TBM) and 237 Vietnamese adults with uncomplicated pulmonary tuberculosis. The host genotype of tuberculosis cases was also compared with the genotype of 392 cord blood controls from the same population. Isolates of M. tuberculosis were genotyped by large sequence polymorphisms. The hosts were defined by polymorphisms in genes encoding Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) and Toll-like receptor-2 (TLR-2). We found a significant protective association between the Euro-American lineage of M. tuberculosis and pulmonary rather than meningeal tuberculosis (Odds ratio (OR) for causing TBM 0.395, 95% confidence intervals (C.I.) 0.193–0.806, P = 0.009), suggesting these strains are less capable of extra-pulmonary dissemination than others in the study population. We also found that individuals with the C allele of TLR-2 T597C allele were more likely to have tuberculosis caused by the East-Asian/Beijing genotype (OR = 1.57 [95% C.I. 1.15–2.15]) than other individuals. The study provides evidence that M. tuberculosis genotype influences clinical disease phenotype and demonstrates, for the first time, a significant interaction between host and bacterial genotypes and the development of tuberculosis.

Tuberculosis, caused by the bacterium Mycobacterium tuberculosis, kills over 2 million people each year. It is estimated that approximately one-third of the world population is infected with M. tuberculosis, though the majority will never develop active disease. The most severe form of tuberculosis occurs when the bacterium spreads to the brain to cause meningitis. We examined whether the genetic variation of the person and the bacteria influenced the type of disease a person develops. We have previously shown that certain mutations in genes of the human immune system can predispose adults in Vietnam to developing tuberculous meningitis. In this study we show that some strains of M. tuberculosis commonly found in Europe and America are less likely to cause tuberculous meningitis in Vietnamese adults than strains predominantly found in Asia. We then looked at the interaction between M. tuberculosis strains and mutations in human immune genes and show that a particular mutation, TLR2 T597C, is more commonly found in patients infected with the East-Asian/Beijing strains of M. tuberculosis. This is the first study to look at both the host and pathogen genotypes together in tuberculosis infection, and the findings suggest that the outcome of exposure to M. tuberculosis can depend on both the human genotype and the bacterial genotype.

Drug susceptibility profiling of tuberculous meningitis

Drug-resistant tuberculosis is an increasing problem worldwide. There are few reports of drug susceptibility patterns of Mycobacterium tuberculosis isolated from cases of tuberculous meningitis. A 5-year retrospective study aimed at analysing the drug susceptibility profile of M. tuberculosis isolated from tuberculous meningitis cases was conducted. A total of 366 isolates were analysed. Among these, 301 (82.2%) were sensitive to all the four primary drugs tested, while 65 (17.8%) showed resistance. There were 46 (12.5%) isolates resistant to isoniazid (INH), while 9 (2.4%) demonstrated multidrug resistance. These data suggest that multidrug resistance in tuberculous meningitis is not yet a serious problem. However, a periodic review is required to ascertain the global incidence of drug-resistant tuberculous meningitis.

[Gamma interferon testing in blood and cerebrospinal fluid--rapid method for the diagnosis of tuberculous meningitis]

AIM

To evaluate the benefit of this early method of diagnosis of tuberculous meningitis, gamma-interferon levels comparatively in blood and cerebrospinal fluid (CSF).

MATERIAL AND METHOD

We have studied 50 patients with tuberculous meningitis admitted in the Clinic of Infectious Diseases Iaşi between 2006-2007, from the epidemiological, clinical, diagnosis and therapeutical points of view.

RESULTS

Tuberculous meningitis was more frequent in males, with a mean ration of 2.5. The age of patients varied between 2 and 78 years of age, with a mean value of 30.5 years. 35.6% of patients were children. In 32 cases the meningeal infection was secondary, disseminated from a primary site, most frequently from the lungs (68,7%). The bacteriologic confirmation was through culture in 13.3%, with an average of 23.4 days of incubation. In whole blood the sensitivity Quantiferon TB Gold assay (QTF) was 78.57%. In CSF the specificity was higher than in blood (96.1 vs. 88.4%), having a positive prediction value over 90%. Antituberculous therapy prior to QTF testing had a negative impact, 50 to 6 cases having negative QTF results.

CONCLUSION

The performance indicators of TB Gold Quantiferon Test in serum or CSF are high, being more sensitive and rapid than the direct exam of CSF or BK culture.

Validation of a diagnostic algorithm for adult tuberculous meningitis

Tuberculous meningitis (TBM) remains difficult to diagnose. We prospectively evaluated a diagnostic algorithm for TBM in 205 HIV-negative patients with meningitis and a low CSF glucose. Patients were classified as having TBM or bacterial meningitis (BM) by two diagnostic methods: logistic regression method (LRM) and classification and regression tree (CART). We performed analyses of TBM versus BM and TBM versus non-TBM in all patients and in patients with microbiologically confirmed diagnoses. Diagnostic sensitivities for TBM were 99% (LRM) and 87% (CART). For BM, diagnostic sensitivities were 81.5% (LRM) and 86.5% (CART) in the primary analysis and 86.5% (LRM) and 74% (CART) in the secondary analysis. In microbiologically confirmed cases, similar rates were achieved. These figures are superior to microbiological confirmation rates in routine laboratories and support the use of this algorithm in high-prevalence TB settings with limited diagnostic facilities. Validation in an HIV-endemic setting is required.

Diagnosis of tuberculous meningitis: clinical and laboratory parameters

BACKGROUND

Confirming the clinical suspicion of tuberculous meningitis (TBM) has always been problematic. Whilst smear and culture positivity are diagnostic, these tests have low sensitivity. The polymerase chain reaction (PCR) assay has given variable results.

AIM

This study attempted to improve the diagnostic yield by: (a) increasing the cerebrospinal fluid (CSF) volumes; (b) testing the yield from three specimens of CSF assumed to represent lumbar, cervico-thoracic cord, and base of brain CSF samples; (c) undertaking PCR assays using multiple primer sets; and (d) using real-time PCR.

METHOD

Patients suspected of having cranial or spinal meningeal tuberculosis were entered into the study. Three aliquots of CSF were subjected to smear, culture, and conventional and real-time PCR. Three sets of primers - IS6110, MPB64, and PT8/9 - were used. Patients were retrospectively classified into four categories: 'definite TB' (culture positive), 'probable TB' (clinical and other tests suggestive of TB), 'not TB', and 'uncertain diagnosis'.

RESULTS

A total of 68 patients were studied. There were 20 patients classified as definite TB, 24 probable TB, 17 not TB, and seven uncertain diagnosis. Forty-eight of 57 (84.2%) patients tested were HIV seropositive. The IS6110 PCR was positive in 27 patients which included 18/20 culture positive cases, six in the probable TB group, and three in the not TB group. The MPB64 and PT8/9 primers did not increase the yield. Real-time PCR was positive in seven additional patients. Combining the definite and probable TB, the sensitivity of all PCR assays was 70.5% (31/44) and specificity 87.5% (21/24).

CONCLUSION

Targeting multiple sites of the TB genome using conventional PCR did not increase the number of positive cases. Real-time PCR was more sensitive. However, all the current techniques are still too insensitive to confidently exclude the diagnosis on laboratory grounds.

A polymorphism in human TLR2 is associated with increased susceptibility to tuberculous meningitis

Tuberculous meningitis (TBM) results from the haematogenous dissemination of Mycobacterium tuberculosis from the lung to the brain. Dissemination is believed to occur early during infection, before the development of adaptive immunity. Toll-like receptor 2 (TLR2) mediates recognition of M. tuberculosis and initiates the innate immune response to infection. We hypothesized that polymorphisms in the TLR2 gene influence bacterial dissemination and the development of TBM. A case-control study was designed to test the hypothesis. Cases of bacteriologically confirmed pulmonary tuberculosis (TB) (n=183) and TBM (n=175), and cord blood controls (n=389) were enrolled in Vietnam. TLR2 genotype 597CC was associated with susceptibility to TB (odds ratio (OR)=2.22, 95% confidence interval (CI): 1.23-3.99). The association was found with meningeal rather than pulmonary TB (TBM vs control, OR=3.26, 95% CI: 1.72-6.18), and was strongest when miliary TB was found on chest radiography (controls vs TBM with miliary TB, OR=5.28, 95% CI: 2.20-12.65). Furthermore, the association increased with the severity of neurologic symptoms (grade I TBM, OR=1.93, 95% CI: 0.54-6.92; grade II, OR=3.32, 95% CI: 0.84-13.2; and grade III, OR=5.70, 95% CI: 1.81-18.0). These results demonstrate a strong association of TLR2 SNP T597C with the development of TBM and miliary TB and indicate that TLR2 influences the dissemination of M. tuberculosis.

Quantitative nested real-time PCR assay for assessing the clinical course of tuberculous meningitis

Although the "gold standard" for diagnosis of tuberculous meningitis (TBM) is bacterial isolation of Mycobacterium tuberculosis (M. Tb), there are still several complex issues. Recently, in the diagnosis of TBM, the detection of M. Tb DNA in cerebrospinal fluid (CSF) samples using PCR has been widely performed as more rapid, sensitive, and specific diagnostic method. Based on Taq Man(R) PCR, the authors developed a novel technique of internally controlled quantitative nested real-time (QNRT) PCR assay that provided a prominent improvement in detection sensitivity and quantification. Total 43 CSF samples from 8 serial patients with suspected TBM were analyzed. The CSF samples were collected before and during standard anti-tuberculosis treatments (ATT). The QNRT-PCR assay revealed positive results for 24 out of 43 serial CSF samples (55.8%) collected during the treatment course of ATT. Moreover, the bacterial cell (BC) numbers of M. Tb analyzed by the QNRT-PCR assay decreased gradually, correlating with the improvements of the patient's clinical conditions. Since the QNRT-PCR assay provides the ability to calculate a numerical value for the initial BC numbers of M. Tb in CSF samples, this method is an extremely useful and advanced technique for use in assessing the clinical course of TBM.

Molecular analysis of Mycobacterium tuberculosis causing multidrug-resistant tuberculosis meningitis

SETTING

Tertiary referral hospitals in southern Vietnam.

OBJECTIVE

Molecular characterisation of multidrug-resistant (MDR) tuberculous meningitis (TBM).

DESIGN

Mycobacterium tuberculosis isolates from the cerebrospinal fluid (CSF) of 198 Vietnamese adults were compared with 237 isolates from patients with pulmonary tuberculosis (PTB) matched for age, sex and residential district. Isolates resistant to isoniazid or rifampicin (RMP) were sequenced in the rpoB and katG genes, inhA promoter and oxyR-ahpC intergenic regions.

RESULTS

While drug resistance rates were lower in the CSF (2.5% MDR) than pulmonary isolates (5.9% MDR), the difference was not significant. The most commonly mutated codons were 531, 526 and 516 in rpoB and 315 in katG. Four novel triple mutants in rpoB were identified.

CONCLUSION

RMP resistance is a good surrogate marker for MDR-TBM in this setting. However, probes directed against these three codons would have a maximum sensitivity of only 65%. A rapid phenotypic detection test may be more applicable for the diagnosis of MDR-TBM.