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Extrapulmonary tuberculosis (EPTB) accounts for a significant proportion of tuberculosis cases worldwide. Nevertheless, the diagnosis is often delayed or even missed due to insidious clinical presentation and poor performance of diagnostic tests. Culture, the classical gold standard for tuberculosis, suffers from increased technical and logistical constraints in EPTB cases. In this review the authors outline current diagnostic options for the main forms of EPTB. The authors also discuss the opportunities and challenges linked in particular to microbiological diagnostics and to the attempts to find a new gold standard test for EPTB. Finally, new biomarkers and tests currently under evaluation are hopefully on the way to introduce significant improvements in EPTB diagnosis, for which clinical suspicion will nevertheless be essential.

Background. Paradoxical neurologic tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a potentially life-threatening condition that occurs within 3 months after starting combination antiretroviral therapy (ART). The reports in the published literature are anecdotal, and the prevalence and outcomes of neurologic TB-IRIS are unknown. Methods. We prospectively assessed patients with suspected TB-IRIS from June 2005 through October 2007 at our hospital in Cape Town, South Africa. We defined paradoxical TB-IRIS and paradoxical neurologic TB-IRIS with use of consensus clinical case definitions. We collected data on tuberculosis diagnosis, ART, details of TB-IRIS diagnosis, other opportunistic infections, corticosteroid use, and outcome. Results. We reviewed 279 patients with suspected TB-IRIS, 54 (19%) of whom had suspected neurologic TB-IRIS, and 225 (81%) of whom had suspected non-neurologic TB-IRIS. Paradoxical TB-IRIS was diagnosed in 190 patients; 23 (12%) of these 190 patients had neurologic TB-IRIS (95% confidence interval, 7%–17%). Eight had meningitis, 7 had tuberculoma, 5 had both tuberculoma and meningitis, and 3 had radiculomyelopathy. Twenty (87%) of the 23 patients with neurologic TB-IRIS required hospital admission (median duration, 12 days; interquartile range, 6–24 days), and 21 (91%) received corticosteroids (median duration, 58 days; interquartile range, 29–86 days). Outcomes 6 months after the initial assessment for neurologic deterioration were as follows: 16 (70%) of the patients were alive (10 of these patients had documented full physical and mental recovery), 3 (13%) were dead, and 4 (17%) were lost to follow-up. Conclusions. Paradoxical neurologic TB-IRIS accounts for 12% of paradoxical TB-IRIS cases. Neurologic TB-IRIS causes considerable short-term morbidity but has reasonable long-term outcomes. Further research is needed to devise optimal diagnostic and management strategies for patients with tuberculosis who experience neurologic deterioration after starting ART.

Background Understanding the pathophysiology of central nervous system tuberculosis (CNS-TB) is hampered by the lack of a good pre-clinical model that mirrors the human CNS-TB infection. We developed a murine CNS-TB model that demonstrates neurobehavioral changes with similar immunopathology with human CNS-TB. Methods We injected two Mycobacterium tuberculosis ( M.tb ) strains, H37Rv and CDC1551, respectively, into two mouse strains, C3HeB/FeJ and Nos2 −/− mice, either into the third ventricle or intravenous. We compared the neurological symptoms, histopathological changes and levels of adhesion molecules, chemokines, and inflammatory cytokines in the brain induced by the infections through different routes in different strains. Results Intra-cerebroventricular infection of Nos2 −/− mice with M.tb led to development of neurological signs and more severe brain granulomas compared to C3HeB/FeJ mice. Compared with CDC1551 M.tb , H37Rv M.tb infection resulted in a higher neurobehavioral score and earlier mortality. Intra-cerebroventricular infection caused necrotic neutrophil-dominated pyogranulomas in the brain relative to intravenous infection which resulted in disseminated granulomas and mycobacteraemia. Histologically, intra-cerebroventricular infection of Nos2 −/− mice with M.tb resembled human CNS-TB brain biopsy specimens. H37Rv intra-cerebroventricular infected mice demonstrated higher brain concentrations of inflammatory cytokines, chemokines and adhesion molecule ICAM-1 than H37Rv intravenous-infected mice. Conclusions Intra-cerebroventricular infection of Nos2 −/− mice with H37Rv creates a murine CNS-TB model that resembled human CNS-TB immunopathology, exhibiting the worst neurobehavioral score with a high and early mortality reflecting disease severity and its associated neurological morbidity. Our murine CNS-TB model serves as a pre-clinical platform to dissect host–pathogen interactions and evaluate therapeutic agents for CNS-TB.

Tuberculosis (TB) of the central nervous system (CNS) is a lethal and incapacitating disease. Several studies have been performed to understand the mechanism of bacterial arrival to CNS, however, it remains unclear. Although the interaction of the host, the pathogen, and the environment trigger the course of the disease, in TB the characteristics of these factors seem to be more relevant in the genesis of the clinical features of each patient. We previously tested three mycobacterial clinical isolates with distinctive genotypes obtained from the cerebrospinal fluid of patients with meningeal TB and showed that these strains disseminated extensively to the brain after intratracheal inoculation and pulmonary infection in BALB/c mice. In this present study, BALB/c mice were infected through the intranasal route. One of these strains reaches the olfactory bulb at the early stage of the infection and infects the brain before the lungs, but the histological study of the nasal mucosa did not show any alteration. This observation suggests that some mycobacteria strains can arrive directly at the brain, apparently toward the olfactory nerve after infecting the nasal mucosa, and guides us to study in more detail during mycobacteria infection the nasal mucosa, the associated connective tissue, and nervous structures of the cribriform plate, which connect the nasal cavity with the olfactory bulb.

IntroductionCentral nervous system (CNS) tuberculomas are a challenging manifestation of extrapulmonary tuberculosis often leading to neurological complications and post-treatment sequelae. The role of adjunctive corticosteroid treatment is not fully understood. Most guidelines on management of tuberculosis do not distinguish between tuberculous meningitis and CNS tuberculomas in terms of corticosteroid therapy.MethodsWe describe five patients with CNS tuberculomas who required intensified dexamethasone treatment for several months, in two cases up to 18 months.ResultsThese patients were initially treated with the standard four-drug tuberculosis regimen and adjuvant dexamethasone. Neurological symptoms improved rapidly. However, multiple attempts to reduce or discontinue corticosteroids according to guideline recommendations led to clinical deterioration with generalized seizures or new CNS lesions. Thus, duration of adjunctive corticosteroid therapy was extended eventually leading to clinical cure and resolution of lesions.ConclusionIn contrast to tuberculous meningitis, the treatment for CNS tuberculomas appears to require a prolonged administration of corticosteroids. These findings need to be verified in controlled clinical studies.

BackgroundCentral nervous system (CNS) tuberculosis is a serious, often fatal disease that disproportionately affects young children. It is thought to develop when Mycobacterium tuberculosis breaches the blood-brain barrier (BBB), which is composed of tightly apposed brain microvascular endothelial cells. However, the mechanism(s) involved in this process are poorly understood Methods To better understand these processes, we developed an in vitro model of M. tuberculosis BBB infection using primary human brain microvascular endothelial cells ResultsM. tuberculosis was found to both invade and traverse the model BBB significantly more than did M. smegmatis (a nonpathogenic mycobacterium). Invasion by M. tuberculosis across the BBB required host-cell actin cytoskeletal rearrangements. By microarray expression profiling, we found 33 M. tuberculosis genes to be highly up-regulated during the early stages of invasion of the BBB by M. tuberculosis; 18 of them belong to a previously described in vivo–expressed genomic island (Rv0960–Rv1001). Defined M. tuberculosis isogenic transposon mutants for the up-regulated genes Rv0980c, Rv0987, Rv0989c and Rv1801 were found to be deficient in their ability to invade the BBB model ConclusionsWe developed an in vitro model of M. tuberculosis BBB infection and identified M. tuberculosis genes that may be involved in CNS invasion

Background Tuberculosis (TB) affects one third of the global population, and TB of the central nervous system (CNS-TB) is the most severe form of tuberculosis which often associates with high mortality. The pro-inflammatory cytokine tumour necrosis factor (TNF) plays a critical role in the initial and long-term host immune protection against Mycobacterium tuberculosis ( M. tuberculosis ) which involves the activation of innate immune cells and structure maintenance of granulomas. However, the contribution of TNF, in particular neuron-derived TNF, in the control of cerebral M. tuberculosis infection and its protective immune responses in the CNS were not clear. Methods We generated neuron-specific TNF-deficient (NsTNF −/− ) mice and compared outcomes of disease against TNF f/f control and global TNF −/− mice. Mycobacterial burden in brains, lungs and spleens were compared, and cerebral pathology and cellular contributions analysed by microscopy and flow cytometry after M. tuberculosis infection. Activation of innate immune cells was measured by flow cytometry and cell function assessed by cytokine and chemokine quantification using enzyme-linked immunosorbent assay (ELISA). Results Intracerebral M. tuberculosis infection of TNF −/− mice rendered animals highly susceptible, accompanied by uncontrolled bacilli replication and eventual mortality. In contrast, NsTNF −/− mice were resistant to infection and presented with a phenotype similar to that in TNF f/f control mice. Impaired immunity in TNF −/− mice was associated with altered cytokine and chemokine synthesis in the brain and characterised by a reduced number of activated innate immune cells. Brain pathology reflected enhanced inflammation dominated by neutrophil influx. Conclusion Our data show that neuron-derived TNF has a limited role in immune responses, but overall TNF production is necessary for protective immunity against CNS-TB.

Background Central nervous system disease is the most serious form of tuberculosis, and is associated with high mortality and severe neurological sequelae. Though recent clinical reports suggest an association of distinct Mycobacterium tuberculosis strains with central nervous system disease, the microbial virulence factors required have not been described previously. Results We screened 398 unique M. tuberculosis mutants in guinea pigs to identify genes required for central nervous system tuberculosis. We found M. tuberculosis pknD ( Rv0931c ) to be required for central nervous system disease. These findings were central nervous system tissue-specific and were not observed in lung tissues. We demonstrated that pknD is required for invasion of brain endothelia (primary components of the blood-brain barrier protecting the central nervous system), but not macrophages, lung epithelia, or other endothelia. M. tuberculosis pknD encodes a \"eukaryotic-like\" serine-threonine protein kinase, with a predicted intracellular kinase and an extracellular (sensor) domain. Using confocal microscopy and flow cytometry we demonstrated that the M. tuberculosis PknD sensor is sufficient to trigger invasion of brain endothelia, a process which was neutralized by specific antiserum. Conclusions Our findings demonstrate a novel in vivo role for M. tuberculosis pknD and represent an important mechanism for bacterial invasion and virulence in central nervous system tuberculosis, a devastating and understudied disease primarily affecting young children.

Background Central nervous system tuberculosis (CNS-TB) may be fatal even with treatment. Neutrophils are the key mediators of TB immunopathology, and raised CSF matrix metalloproteinase-9 (MMP-9) which correlates to neutrophil count in CNS-TB is associated with neurological deficit and death. The mechanisms by which neutrophils drive TB-associated CNS matrix destruction are not clearly defined. Methods Human brain biopsies with histologically proven CNS-TB were stained for neutrophils, neutrophil elastase, and MMP-9. Neutrophil MMP-9 secretion and gene expression were analyzed using Luminex and real-time PCR. Type IV collagen degradation was evaluated using confocal microscopy and quantitative fluorescent assays. Intracellular signaling pathways were investigated by immunoblotting and chemical inhibitors. Results MMP-9-expressing neutrophils were present in tuberculous granulomas in CNS-TB and neutrophil-derived MMP-9 secretion was upregulated by Mycobacterium tuberculosis ( M.tb ). Concurrent direct stimulation by M.tb and activation via monocyte-dependent networks had an additive effect on neutrophil MMP-9 secretion. Destruction of type IV collagen, a key component of the blood-brain barrier, was inhibited by neutralizing neutrophil MMP-9. Monocyte-neutrophil networks driving MMP-9 secretion in TB were regulated by MAP-kinase and Akt-PI 3 kinase pathways and the transcription factor NF-kB. TNFα neutralization suppressed MMP-9 secretion to baseline while dexamethasone did not. Conclusions Multiple signaling paths regulate neutrophil-derived MMP-9 secretion, which is increased in CNS-TB. These paths may be better targets for host-directed therapies than steroids currently used in CNS-TB.

Pregabalin, widely used in the treatment of several pain disorders, is usually well tolerated. Uncommonly, the drug may induce cardiac side effects, rarely prolongation of the PR interval. The latter has never been described in patients with healthy heart or normal rel function. We characterize a unique case of a young man with extrapulmory tuberculosis and no detectable or known cardiac or kidney diseases, treated with pregabalin to control the severe pain due to the involvement of the spil cord by the tuberculosis, showing an atrioventricular (AV) block due to pregabalin administration. The reported case emphasizes the need of monitoring PR interval during treatment with pregabalin, even in patients without background of cardiac or rel diseases.