Marjory A. Bravard

Clinical Evaluation of Tuberculosis Viability Microscopy for Assessing Treatment Response

Tuberculosis viability microscopy predicted, within 1 hour, quantitative culture results that became available weeks later. Viability microscopy provides promising results for informing decisions concerning drug susceptibility testing, treatment changes, and infection control measures in resource-constrained settings where most tuberculosis occurs.

Cough detection algorithm for monitoring patient recovery from pulmonary tuberculosis

In regions of the world where tuberculosis (TB) poses the greatest disease burden, the lack of access to skilled laboratories is a significant problem. A lab-free method for assessing patient recovery during treatment would be of great benefit, particularly for identifying patients who may have drug-resistant tuberculosis. We hypothesize that cough analysis may provide such a test. In this paper we describe algorithm development in support of a pilot study of TB patient coughing. We describe several approaches to event detection and classification, and show preliminary data which suggest that cough count decreases after the start of treatment in drug-responsive patients. Our eventual goal is development of a low-cost ambulatory cough analysis system that will help identify patients with drug-resistant tuberculosis.

Indirect recognition of MHC class I allopeptides accelerates lung allograft rejection in miniature swine.

The role of indirect allorecognition in graft rejection is examined in two experiments using a swine lung transplantation model. First, two swine received class I mismatched grafts without immunosuppression; another two recipients were treated postoperatively with cyclosporine (CsA). These swine exhibited acute and chronic rejection, respectively. All four recipients developed T‐cell reactivity to donor‐derived class I major histocompatibility complex (MHC) peptides. Second, six swine were immunized with synthetic donor‐derived class I allopeptides prior to transplantation. Control groups consisted of nonimmunized recipients (n = 6) and recipients immunized with an irrelevant peptide (n = 3). These recipients all received a 12‐day course of post‐operative CsA. Swine immunized with allopeptides exhibited accelerated graft rejection, as compared to both control groups (p < 0.01 and p = 0.03, respectively). Within the experimental group, the dominant histologic finding was acute rejection (AR). Obliterative bronchiolitis (OB) was seen in the graft with the longest survival. Both control groups showed a lesser degree of AR, with four out of six nonimmunized swine ultimately developing OB. These studies suggest that indirect allorecognition is operative during lung allograft rejection, and that pre‐transplant sensitization to donor‐derived MHC allopeptides can accelerate graft rejection.

Validation of an Automated Cough Detection Algorithm for Tracking Recovery of Pulmonary Tuberculosis Patients

Background A laboratory-free test for assessing recovery from pulmonary tuberculosis (TB) would be extremely beneficial in regions of the world where laboratory facilities are lacking. Our hypothesis is that analysis of cough sound recordings may provide such a test. In the current paper, we present validation of a cough analysis tool. Methodology/Principal Findings Cough data was collected from a cohort of TB patients in Lima, Peru and 25.5 hours of recordings were manually annotated by clinical staff. Analysis software was developed and validated by comparison to manual scoring. Because many patients cough in bursts, coughing was characterized in terms of cough epochs. Our software correctly detects 75.5% of cough episodes with a specificity of 99.6% (comparable to past results using the same definition) and a median false positive rate of 4 false positives/hour, due to the noisy, real-world nature of our dataset. We then manually review detected coughs to eliminate false positives, in effect using the algorithm as a pre-screening tool that reduces reviewing time to roughly 5% of the recording length. This cough analysis approach provides a foundation to support larger-scale studies of coughing rates over time for TB patients undergoing treatment.

Dynamics of Cough Frequency in Adults Undergoing Treatment for Pulmonary Tuberculosis.

Summary This is the first research to evaluate cough frequency continuously over 24-hour periods and to characterize associations with mycobacterial load and treatment. This study provides novel information on the circadian cycle of cough frequency and risk factors for increased cough frequency.

Protocol for studying cough frequency in people with pulmonary tuberculosis

Introduction Cough is a key symptom of tuberculosis (TB) as well as the main cause of transmission. However, a recent literature review found that cough frequency (number of coughs per hour) in patients with TB has only been studied once, in 1969. The main aim of this study is to describe cough frequency patterns before and after the start of TB treatment and to determine baseline factors that affect cough frequency in these patients. Secondarily, we will evaluate the correlation between cough frequency and TB microbiological resolution. Methods This study will select participants with culture confirmed TB from 2 tertiary hospitals in Lima, Peru. We estimated that a sample size of 107 patients was sufficient to detect clinically significant changes in cough frequency. Participants will initially be evaluated through questionnaires, radiology, microscopic observation drug susceptibility broth TB-culture, auramine smear microscopy and cough recordings. This cohort will be followed for the initial 60 days of anti-TB treatment, and throughout the study several microbiological samples as well as 24 h recordings will be collected. We will describe the variability of cough episodes and determine its association with baseline laboratory parameters of pulmonary TB. In addition, we will analyse the reduction of cough frequency in predicting TB cure, adjusted for potential confounders. Ethics and dissemination Ethical approval has been obtained from the ethics committees at each participating hospital in Lima, Peru, Asociación Benéfica PRISMA in Lima, Peru, the Universidad Peruana Cayetano Heredia in Lima, Peru and Johns Hopkins University in Baltimore, USA. We aim to publish and disseminate our findings in peer-reviewed journals. We also expect to create and maintain an online repository for TB cough sounds as well as the statistical analysis employed.

Sputum microscopy with fluorescein diacetate predicts tuberculosis infectiousness

Summary Fluorescein diacetate microscopy was used to assess Mycobacterium tuberculosis metabolic activity in pretreatment sputa. Lower results predicted greater infectiousness in transmitting tuberculosis to household contacts. Fluorescein diacetate microscopy–negative bacteria may be better adapted to airborne tuberculosis transmission and consequently more contagious.

Operational tolerance to class I disparate lungs can be induced despite pretransplant immunization with class I allopeptides

Background. Using a class I-disparate swine lung transplant model, we examined whether an intensive course of tacrolimus could induce operational tolerance and whether preoperative allopeptide immunization would prevent the development of tolerance. Methods. Left lung grafts were performed using class I-disparate (class II-matched) donors. Recipients were treated with 12 days of postoperative tacrolimus. Three recipients were immunized prior to transplantation with class I allopeptides. Three other recipients were not immunized. Results. The nonimmunized recipients maintained their grafts long term (>497, >451, and >432 days), without developing chronic rejection. The immunized swine also maintained their grafts long term (>417, >402, >401 days), despite developing a variety of in vitro and in vivo responses to the immunizing peptides, as well as having strong mixed lymphocyte reactions to donor cells prior to transplantation. Conclusions. Using only a brief course of tacrolimus, we have been able to induce a state of operational tolerance in a class I-disparate preclinical lung transplant model. Moreover, preoperative alloimmunization did not block tolerance induction or induce chronic rejection. These data show that it is possible to create a state of operational tolerance to lung allografts even in the presence of donor-sensitized cells.

Cough Frequency During Treatment Associated With Baseline Cavitary Volume and Proximity to the Airway in Pulmonary TB

Background: Cough frequency, and its duration, is a biomarker that can be used in low‐resource settings without the need of laboratory culture and has been associated with transmission and treatment response. Radiologic characteristics associated with increased cough frequency may be important in understanding transmission. The relationship between cough frequency and cavitary lung disease has not been studied. Methods: We analyzed data in 41 adults who were HIV negative and had culture‐confirmed, drug‐susceptible pulmonary TB throughout treatment. Cough recordings were based on the Cayetano Cough Monitor, and sputum samples were evaluated using microscopic observation drug susceptibility broth culture; among culture‐positive samples, bacillary burden was assessed by means of time to positivity. CT scans were analyzed by a US‐board‐certified radiologist and a computer‐automated algorithm. The algorithm evaluated cavity volume and cavitary proximity to the airway. CT scans were obtained within 1 month of treatment initiation. We compared small cavities (≤ 7 mL) and large cavities (> 7 mL) and cavities located closer to (≤ 10 mm) and farther from (> 10 mm) the airway to cough frequency and cough cessation until treatment day 60. Results: Cough frequency during treatment was twofold higher in participants with large cavity volumes (rate ratio [RR], 1.98; P = .01) and cavities located closer to the airway (RR, 2.44; P = .001). Comparably, cough ceased three times faster in participants with smaller cavities (adjusted hazard ratio [HR], 2.89; P = .06) and those farther from the airway (adjusted HR, 3.61;, P = .02). Similar results were found for bacillary burden and culture conversion during treatment. Conclusions: Cough frequency during treatment is greater and lasts longer in patients with larger cavities, especially those closer to the airway.

Exhaled nitric oxide is not a biomarker for pulmonary tuberculosis

Abstract. To reduce transmission of tuberculosis (TB) in resource-limited countries where TB remains a major cause of mortality, novel diagnostic tools are urgently needed. We evaluated the fractional concentration of exhaled nitric oxide (FeNO) as an easily measured, noninvasive potential biomarker for diagnosis and monitoring of treatment response in participants with pulmonary TB including multidrug resistant–TB in Lima, Peru. In a longitudinal study however, we found no differences in baseline median FeNO levels between 38 TB participants and 93 age-matched controls (13 parts per billion [ppb] [interquartile range (IQR) = 8–26] versus 15 ppb [IQR = 12–24]), and there was no change over 60 days of treatment (15 ppb [IQR = 10–19] at day 60). Taking this and previous evidence together, we conclude FeNO is not of value in either the diagnosis of pulmonary TB or as a marker of treatment response.