Molecular bacterial load assay, a culture-free biomarker for rapid and accurate quantification of sputum Mycobacterium tuberculosis bacillary load during treatment

A molecular assay to quantify Mycobacterium tuberculosis is described. In vitro, 98% (n = 96) of sputum samples with a known number of bacilli (107 to 102 bacilli) could be enumerated within 0.5 log10. In comparison to culture, the molecular bacterial load (MBL) assay is unaffected by other microorganisms present in the sample, results are obtained more quickly (within 24 h) and are seldom inhibited (0.7% samples), and the MBL assay critically shows the same biphasic decline as observed longitudinally during treatment. As a biomarker of treatment response, the MBL assay responds rapidly, with a mean decline in bacterial load for 111 subjects of 0.99 log10 (95% confidence interval [95% CI], 0.81 to 1.17) after 3 days of chemotherapy. There was a significant association between the rate of bacterial decline during the same 3 days and bacilli ml−1 sputum at day 0 (linear regression, P = 0.0003) and a 3.62 increased odds ratio of relapse for every 1 log10 increase in pretreatment bacterial load (95% CI, 1.53 to 8.59)

Rapid Diagnosis of Smear-Negative Tuberculosis Using Immunology and Microbiology with Induced Sputum in HIV-Infected and Uninfected Individuals

Rationale and Objectives. Blood-based studies have demonstrated the potential of immunological assays to detect tuberculosis. However lung fluid sampling may prove superior as it enables simultaneous microbiological detection of mycobacteria to be performed. Until now this has only been possible using the expensive and invasive technique of broncho-alveolar lavage. We sought to evaluate an immunoassay using non-invasive induced-sputum to diagnose active tuberculosis. Methods and Results. Prospective cohort study of forty-two spontaneous sputum smear-negative or sputum non-producing adults under investigation for tuberculosis. CD4 lymphocytes specific to purified-protein-derivative of Mycobacterium tuberculosis actively synthesising interferon-gamma were measured by flow cytometry and final diagnosis compared to immunoassay using a cut-off of 0.5%. Sixteen subjects (38%) were HIV-infected (median CD4 count [range] = 332 cells/mu l [103748]). Thirty-eight (90%) were BCG-vaccinated. In 27 subjects diagnosed with active tuberculosis, the median [range] percentage of interferon-gamma synthetic CD4+ lymphocytes was 2.77% [0-23.93%] versus 0% [0-2.10%] in 15 negative for active infection (p<0.0001). Sensitivity and specificity of the immunoassay versus final diagnosis of active tuberculosis were 89% (24 of 27) and 80% (12 of 15) respectively. The 3 positive assays in the latter group occurred in subjects diagnosed with quiescent/latent tuberculosis. Assay performance was unaffected by HIV-status, BCG-vaccination or disease site. Combining this approach with traditional microbiological methods increased the diagnostic yield to 93% (25 of 27) alongside acid-fast bacilli smear and 96% (26 of 27) alongside tuberculosis culture. Conclusions. These data demonstrate for the first time that a rapid immunological assay to diagnose active tuberculosis can be performed successfully in combination with microbiological methods on a single induced-sputum sample

A longitudinal examination of the relationship between trauma-related cognitive factors and internalising and externalising psychopathology in physically injured children

Cognitive models of posttraumatic stress disorder (PTSD) highlight maladaptive posttrauma appraisals, trauma memory qualities, and coping strategies, such as rumination or thought suppression, as key processes that maintain PTSD symptoms. Anxiety, depression and externalising symptoms can also present in children in the aftermath of trauma, yet there has been little empirical investigation of the potential relevance of posttrauma cognitive processes for such difficulties. Here, we examined whether: a) acute maladaptive cognitive processes (specifically, maladaptive appraisals, memory qualities, and cognitive coping) were associated with symptoms of PTSD, internalising, and externalising at 1-month posttrauma (T1); and b) changes in these cognitive processes predicted symptom change at a follow-up assessment 6 months later (T2). We recruited 132 6–13 year old children and their parents from emergency departments following the child’s experience of an acute trauma. Children self-reported on their maladaptive appraisals, trauma-memory and cognitive coping strategies, along with symptoms of PTSD, anxiety and depression. Parents also rated children’s internalising and externalising symptoms. We found each cognitive process to be robustly associated with PTSD and non-PTSD internalising symptoms at T1, and change in each predicted change in symptoms to T2. Maladaptive appraisals and cognitive coping were unique predictors of children’s posttrauma internalising. Effects were partially retained even controlling for co-occurring PTSD symptoms. There was less evidence that trauma-specific cognitive processes were associated with externalising symptoms. Findings suggest aspects of cognitive models of PTSD are applicable to broader posttrauma psychopathology, and have implications for how we understand and target children’s posttrauma psychological adjustment

Biomarkers of treatment response in clinical trials of novel antituberculosis agents

Global initiatives have been launched to develop improved tuberculosis chemotherapy. New drugs and potential treatment-shortening regimens require careful assessment in clinical trials, but existing markers of treatment outcome-clinical cure and relapse-require prolonged follow-up of patients. There is, therefore, a need to find alternative biomarkers or surrogate endpoints predictive of response. Effective treatment requires drugs with sterilising activity to produce clinical cure without relapse, and thus a useful biomarker for a drug under trial must predict the likelihood of relapse. We explore the strengths and weaknesses of existing biomarkers, which assess either host response or mycobacterial load. Change in mycobacterial burden is likely to be the best indicator of treatment outcome, but the optimum study techniques remain undefined. Finally, we propose methods to assess candidate markers, and how these candidate markers could be implemented in future clinical trials.</p

Radiological cavitation, sputum mycobacterial load and treatment response in pulmonary tuberculosis

SETTING: Royal Free Hospital, London.OBJECTIVE: To investigate the relationship betweensputum mycobacterial load, assessed by time to positivity(TTP) in liquid culture, radiological cavitation andchange in sputum bacterial load in response to antituberculosis treatment.DESIGN: The study was conducted on 95 patientstreated for sputum culture-positive pulmonary tuberculosis(TB), with pre-treatment TTP and baseline chestX-ray (CXR). Of these, 31 had chest computed tomographyscans assessed for number and volume of cavities.The microbiological treatment response was measuredin 56 patients with serial TTP, and related to baselineradiological cavitation.RESULTS: Cavitation was present in 48% of patients,and was associated with a shorter TTP at baseline (P &lt;0.001). Patients with more cavities and greater total cavitaryvolume had a shorter TTP (P &lt; 0.001 for both).No difference was demonstrated in the rate of change inTTP on treatment (P = 0.36) between patients with andwithout cavities.CONCLUSION: This study confi rms that cavitation isassociated with higher baseline sputum mycobacterialload. The rate of decline in bacterial load in response totreatment is similar in patients with and without radiologicallydemonstrable cavities, suggesting that responseto, and hence duration of, effective treatment may bepredicted by the initial number of organisms present inthe sputum.KEY WORDS: BacT/ALERT® 3D Mycobacteria detectionsystems; time to culture positivity; sputum mycobacterialload; chest X-ray; chest C