Genetic profile of Mycobacterium tuberculosis and treatment outcomes in human pulmonary tuberculosis in Tanzania

Information on the different spoligotype families of Mycobacterium tuberculosis in Tanzania is limited, and where available is restricted to small geographical areas.  This article describes the genetic profile of M. tuberculosis across Tanzania and suggests how spoligotype families might affect drug resistance and treatment outcomes for smear positive pulmonary tuberculosis patients in Tanzania. In this study conducted from 2006 to 2008, the M. tuberculosis isolates were obtained from samples collected under the routine drug resistance surveillance system. The isolates were from specimens collected from 2001 to 2007, and stored at the Central and Reference Tuberculosis Laboratory in Dar es Salaam. A total of 487 isolates from 23 regions in Tanzania were spoligotyped. However, clinical information for 446 isolates was available. Out of the 487 isolates spoligotyped, 195 (40.0%) belonged to the Central Asian (CAS) family, 84 (17.5%) to the Latin American Mediterranean (LAM) family, 49 (10.1%) to the East-African Indian (EAI) family, and 33 (6.8%) to the Beijing family. Other isolates included 1 (0.2%) for H37Rv, 10 (2.1%) for Haarlem, 4 (0.8%) for S family, 58 (11.9%) for T family and 52 (10.7%) for unclassified.  No spoligotype patterns were consistent with M. bovis. As regards to treatment outcomes, the cure rate was 80% with no significant variation between the spoligotype families.  The overall level of MDR-TB was 2.5% (3/121), with no significant difference between the spoligotype families. All Beijing strains (11.8%, 30/254) originated from the Eastern and Southern zones of the country, of which 80% were from Dar es Salaam.  Isolates from the CAS and T families were reported disproportionately from the Eastern-Southern zone, and EAI and LAM families from the Northern-Lake zones but the difference was not statistically significant. Five isolates were identified as Non-tuberculous Mycobacteria. In conclusion, M. tuberculosis isolates from pulmonary tuberculosis cases in Tanzania were classified mostly within the CAS, LAM, and EAI and T families.  Consistently good treatment outcomes were recorded across the spoligotype families.  The proportion of drug resistance strains was low. The findings also suggest variation of spoligotype families with varying geographical localities within the country. 

Mapping of Mycobacterium tuberculosis Complex Genetic Diversity Profiles in Tanzania and Other African Countries

The aim of this study was to assess and characterize Mycobacterium tuberculosis complex (MTBC) genotypic diversity in Tanzania, as well as in neighbouring East and other several African countries. We used spoligotyping to identify a total of 293 M. tuberculosis clinical isolates (one isolate per patient) collected in the Bunda, Dar es Salaam, Ngorongoro and Serengeti areas in Tanzania. The results were compared with results in the SITVIT2 international database of the Pasteur Institute of Guadeloupe. Genotyping and phylogeographical analyses highlighted the predominance of the CAS, T, EAI, and LAM MTBC lineages in Tanzania. The three most frequent Spoligotype International Types (SITs) were: SIT21/CAS1-Kili (n = 76; 25.94%), SIT59/LAM11-ZWE (n = 22; 7.51%), and SIT126/EAI5 tentatively reclassified as EAI3-TZA (n = 18; 6.14%). Furthermore, three SITs were newly created in this study (SIT4056/EAI5 n = 2, SIT4057/T1 n = 1, and SIT4058/EAI5 n = 1). We noted that the East-African-Indian (EAI) lineage was more predominant in Bunda, the Manu lineage was more common among strains isolated in Ngorongoro, and the Central-Asian (CAS) lineage was more predominant in Dar es Salaam (p-value<0.0001). No statistically significant differences were noted when comparing HIV status of patients vs. major lineages (p-value = 0.103). However, when grouping lineages as Principal Genetic Groups (PGG), we noticed that PGG2/3 group (Haarlem, LAM, S, T, and X) was more associated with HIV-positive patients as compared to PGG1 group (Beijing, CAS, EAI, and Manu) (p-value = 0.03). This study provided mapping of MTBC genetic diversity in Tanzania (containing information on isolates from different cities) and neighbouring East African and other several African countries highlighting differences as regards to MTBC genotypic distribution between Tanzania and other African countries. This work also allowed underlining of spoligotyping patterns tentatively grouped within the newly designated EAI3-TZA lineage (remarkable by absence of spacers 2 and 3, and represented by SIT126) which seems to be specific to Tanzania. However, further genotyping information would be needed to confirm this specificity

Implementation of a national anti-tuberculosis drug resistance survey in Tanzania

A drug resistance survey is an essential public health management tool for evaluating and improving the erformance of National Tuberculosis control programmes. The current manuscript describes the implementation of the first national drug resistance survey in Tanzania. Description of the implementation process of a national anti-tuberculosis drug esistance survey in Tanzania, in relation to the study protocol and Standard Operating Procedures. Factors contributing positively to the implementation of the survey were a continuous commitment of the key stakeholders, the existence of a well organized National Tuberculosis Programme, and a detailed design of cluster-specific arrangements for rapid sputum transportation. Factors contributing negatively to the implementation were a long delay between training and actual survey activities, limited monitoring of activities, and an unclear design of the data capture forms leading to difficulties in form-filling. Careful preparation of the survey, timing of planned activities, a strong emphasis on data capture tools and data management, and timely supervision are essential for a proper implementation of a national drug resistance survey

Disruption of thalamic functional connectivity is a neural correlate of dexmedetomidine-induced unconsciousness

Understanding the neural basis of consciousness is fundamental to neuroscience research. Disruptions in cortico-cortical connectivity have been suggested as a primary mechanism of unconsciousness. By using a novel combination of positron emission tomography and functional magnetic resonance imaging, we studied anesthesia-induced unconsciousness and recovery using the α2-agonist dexmedetomidine. During unconsciousness, cerebral metabolic rate of glucose and cerebral blood flow were preferentially decreased in the thalamus, the Default Mode Network (DMN), and the bilateral Frontoparietal Networks (FPNs). Cortico-cortical functional connectivity within the DMN and FPNs was preserved. However, DMN thalamo-cortical functional connectivity was disrupted. Recovery from this state was associated with sustained reduction in cerebral blood flow and restored DMN thalamo-cortical functional connectivity. We report that loss of thalamo-cortical functional connectivity is sufficient to produce unconsciousness. DOI: http://dx.doi.org/10.7554/eLife.04499.00

Molecular Epidemiology of HIV-Associated Tuberculosis in Dar es Salaam, Tanzania: Strain Predominance, Clustering, and Polyclonal Disease.

Molecular typing of Mycobacterium tuberculosis can be used to elucidate the epidemiology of tuberculosis, including the rates of clustering, the frequency of polyclonal disease, and the distribution of genotypic families. We performed IS6110 typing and spoligotyping on M. tuberculosis strains isolated from HIV-infected subjects at baseline or during follow-up in the DarDar Trial in Tanzania and on selected community isolates. Clustering occurred in 203 (74%) of 275 subjects: 124 (80%) of 155 HIV-infected subjects with baseline isolates, 56 (69%) of 81 HIV-infected subjects with endpoint isolates, and 23 (59%) of 39 community controls. Overall, 113 (41%) subjects had an isolate representing the East Indian "GD" family. The rate of clustering was similar among vaccine and placebo recipients and among subjects with or without cellular immune responses to mycobacterial antigens. Polyclonal disease was detected in 6 (43%) of 14 patients with multiple specimens typed. Most cases of HIV-associated tuberculosis among subjects from this study in Dar es Salaam resulted from recently acquired infection. Polyclonal infection was detected and isolates representing the East Indian GD strain family were the most common

Increased in vivo glial activation in patients with amyotrophic lateral sclerosis: Assessed with [11C]-PBR28

Evidence from human post mortem, in vivo and animal model studies implicates the neuroimmune system and activated microglia in the pathology of amyotrophic lateral sclerosis. The study aim was to further evaluate in vivo neuroinflammation in individuals with amyotrophic lateral sclerosis using [11C]-PBR28 positron emission tomography. Ten patients with amyotrophic lateral sclerosis (seven males, three females, 38–68 years) and ten age- and [11C]-PBR28 binding affinity-matched healthy volunteers (six males, four females, 33–65 years) completed a positron emission tomography scan. Standardized uptake values were calculated from 60 to 90 min post-injection and normalized to whole brain mean. Voxel-wise analysis showed increased binding in the motor cortices and corticospinal tracts in patients with amyotrophic lateral sclerosis compared to healthy controls (pFWE < 0.05). Region of interest analysis revealed increased [11C]-PBR28 binding in the precentral gyrus in patients (normalized standardized uptake value = 1.15) compared to controls (1.03, p < 0.05). In patients those values were positively correlated with upper motor neuron burden scores (r = 0.69, p < 0.05), and negatively correlated with the amyotrophic lateral sclerosis functional rating scale (r = –0.66, p < 0.05). Increased in vivo glial activation in motor cortices, that correlates with phenotype, complements previous histopathological reports. Further studies will determine the role of [11C]-PBR28 as a marker of treatments that target neuroinflammation

Simultaneous fMRI–PET of the opioidergic pain system in human brain

MRI and PET provide complementary information for studying brain function. While the potential use of simultaneous MRI/PET for clinical diagnostic and disease staging has been demonstrated recently; the biological relevance of concurrent functional MRI-PET brain imaging to dissect neurochemically distinct components of the blood oxygenation level dependent (BOLD) fMRI signal has not yet been shown. We obtained sixteen fMRI-PET data sets from eight healthy volunteers. Each subject participated in randomized order in a pain scan and a control (nonpainful pressure) scan on the same day. Dynamic PET data were acquired with an opioid radioligand, [(11)C]Diprenorphine, to detect endogenous opioid releases in response to pain. BOLD fMRI data were collected at the same time to capture hemodynamic responses. In this simultaneous human fMRI-PET imaging study, we show co-localized responses in thalamus and striatum related to pain processing, while modality specific brain networks were also found. Co-localized fMRI and PET signal changes in the thalamus were positively correlated suggesting pain-induced changes in opioid neurotransmission contribute a significant component of the fMRI signal change in this region. Simultaneous fMRI-PET provides unique opportunities allowing us to relate specific neurochemical events to functional hemodynamic activation and to investigate the impacts of neurotransmission on neurovascular coupling of the human brain in vivo