Tuberculosis is an enormous global public health problem and the second leading cause of death due to an infectious disease. The global emergence of multidrug-resistant (MDR) TB is a significant barrier to effective TB control. Response rates to second-line anti-TB drugs (SLDs) used to treat MDR-TB are much lower than those for treatment of drug susceptible TB. Recent reports highlight the substantial risk of development of additional drug resistance during SLD treatment. Critical knowledge gaps exist regarding the mechanisms of amplified drug resistance during treatment of MDR-TB. Our preliminary data suggests that the TB cavity may be the site of further drug resistant development. With this background, we have hypothesized that pulmonary cavities in patients with MDR-TB facilitate the development and amplification of drug resistance as a result of sub-therapeutic intra-cavitary SLD concentrations. An enhanced understanding of SLD pharmacokinetics including tissue penetration properties and mechanisms of drug resistance will help guide improved MDR-TB treatment and prevention strategies.
The Specific AIMs of this proposal include: 1) To determine the pharmacokinetics of key SLDs (levofloxacin and capreomycin) in plasma, pulmonary tissue, and cavitary lung among patients undergoing treatment for MDR-TB. Utilizing a unique patient cohort of MDR-TB patients undergoing adjunctive surgery in the Republic of Georgia and an innovative microdialysis method we will assess SLD concentrations among various compartments including pulmonary cavities, the site of the highest concentration of M. tuberculosis (MTB). 2) To investigate phenotypic and genotypic drug resistance profiles of MTB isolates recovered from sputum, lung, and cavitary lung tissue. We propose to perform whole genome sequencing and bioinformatics analysis comparing paired MTB isolates from different sites in the same patients (cavity, more normal lung tissue, sputum) to determine if cavities are sites of drug resistance development and amplification and to study population dynamics of MTB within the cavitary environment. 3) To determine the relationship between SLD tissue levels and the development of additional drug resistance mutations in MTB isolates from resected cavitary lung. We will use the pharmacokinetic and genomic sequencing data derived from AIMS 1 and 2 along with pharmacokinetic modeling to assess if low drug concentrations are associated with increasing drug resistance. The proposed investigations will provide novel data on mechanisms of amplified drug resistance and will challenge the way we currently dose SLDs and treat MDR-TB patients with cavitary disease. Candidate My long-term goal is to become an independent clinical and translational investigator and global leader in tuberculosis (TB) focusing on the mechanisms, transmission, and virulence of drug-resistant TB. A K23 award would be critical to my career development and provide protected time for research and research training. A Training Plan has been developed that links a training goal to each of the specific aims of the research proposal. During this K23 award period, I will build expertise in clinical research, pharmacokinetics study design and modeling, performing microdialysis, bacterial genomics including DNA sequencing, and performing bioinformatics analysis. My career development plan combines formal didactics, laboratory training, and hands on mentoring with relevant research experiences that address global TB priorities. A multi-disciplinary team of recognized leaders in clinical TB research, genomics, and pharmacokinetics will provide professional and scientific mentorship during the award period. The K23 award will allow for the investigation and accumulation of additional data that can subsequently serve as the basis for a subsequent R01 application focused on translational research involving investigation of the pulmonary cavity. Environment The substantial intellectual and physical resources of Emory University and established collaborations with partners in the country of Georgia at the National Center for Tuberculosis and Lung Disease (NCTBLD) provide a unique opportunity to carry out this translational research. The Georgian NCTBLD also has a long history of productive collaborations with Emory University including numerous ongoing funded research projects (including the site of a NIH Fogarty grant). Emory University is a research-intensive university with over half a billion dollars in research funding each year. The Emory Division of Infectious Diseases has 59 full time faculty members including leaders in clinical TB, pharmacokinetics and bacterial genomics research. The Emory Rollins School of Public Health, Emory Global Health Institute, and the Atlanta Clinical and Translational Science Institute (ACTSI, the NIH-funded CTSA) provide further excellent resources for career enhancement, development and research training. The proposal will also benefit from collaboration with the University of Florida Infectious Diseases Pharmacokinetics Laboratory (IDPL). The IDPL is a national reference laboratory for anti-mycobacterial drug concentrations and has extensive expertise in performing microdialysis.
The global emergence of multidrug-resistant tuberculosis (MDR-TB) is an enormous public health threat and major barrier to effective TB control. Poor response to treatment with second-line anti-TB drugs and high rates of amplification of drug resistance among patients undergoing treatment for MDR-TB are issues that need to be addressed to effectively combat the global TB epidemic. The proposed research seeks to provide vital information about the pharmacokinetics of second-line anti-TB drugs and the association of poor drug tissue penetration and the tuberculosis cavity in development and amplification of drug resistance.
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