Welcome to the Laboratory of Andrew Y. Koh, M.D. in the Departments of Pediatrics (Hematology/Oncology and Infectious Diseases) and Microbiology at the University of Texas Southwestern Medical Center.

The major goal of our lab is to understand the molecular mechanisms by which bacteria and fungi that reside in the gastrointestinal tract transform into invasive and deadly pathogens once the host’s immune system has been suppressed.  Within the body of a healthy adult, microbial cells (bacteria, fungi, viruses) are estimated to outnumber human cells by a factor of 10 to 1.  Remarkably, humans are usually able to coexist with our microbial partners without ill effects.  When the host’s immune system is suppressed (e.g. surgery, chemotherapy for cancer treatment), microbes are able to translocate into extraintestinal tissues and cause severe, often fatal, infections.

Very little is known about what changes in the host’s immune system (cellular, humoral, mucosal) trigger virulence changes in bacteria and fungi.  Even less is known about how bacteria and fungi interact with each other and the hosts’ mucosal immune system.  To study these questions, we use a combination of techniques in molecular biology, immunology, and microbiology.   Our long-term goal is to find methods for reachieving immune and microbiological homeostasis in order to prevent bacterial and fungal infections in immunocompromised patients


Koh Lab