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Patrick Cudahy, MD

Current position: Clinical Fellow in Medicine (Infectious Diseases), Yale University


GHES U.S. Fellow 2016-2017

Fellowship Site: Tugela Ferry, South Africa
U.S. Institution: Yale University

Project Title: Biomarkers of early response to multi-drug resistant tuberculosis and composition of multi-drug resistant mycobacterium tuberculosis strains during treatment

Dr. Cudahy is a fellow in Infectious Disease with a research interest in HIV and tuberculosis co-infection at Yale University.

Individuals with HIV who are co-infected with multi drug-resistant tuberculosis (MDR-TB) in South Africa suffer early mortality of more than 50%. Mortality remains high after initiating treatment. Earlier identification of individuals failing to respond to standardized MDR-TB treatment might allow for modification of treatment regimens, avert morbidity and mortality and prevent further spread ofMDR-TB. Biologic markers of disease progression or non-response to therapy could help accomplish these goals but are limited and have not been tested prospectively.

For this project, our first aim was to evaluate trends in inflammatory proteins (CRP, d-dimer and fibrinogen) among individuals co-infected with MDR-TB and HIV to determine whether they could be used as early biomarkers of MDR-TB treatment response. We hypothesized that larger decreases in inflammatory markers during treatment, compared to baseline, were associated with increased culture conversion, and decreased mortality.

The second aim was to obtain sputum samples during the course of treatment to perform whole genome sequencing of M. tuberculosis (Mtb). We sought to understand how diverse mycobacterial populations within a host responded to the selective pressure of treatment and affected treatment outcomes. Previous studies have been limited by the strain typing techniques employed, such as restriction fragment length polymorphism (RFLP) and spoligotyping. These were only able to resolve strains that made up roughly 1-10% of recovered bacilli. By performing whole genome sequencing, we may have been able to increase our sensitivity for detecting mixed strain infections as well as track the selection of mycobacterial populations. We hypothesized that there is an association between within-host strain diversity and persistent culture positivity as well as final outcome of MDR-TB therapy.