David N. Fredricks, MD

The human body hosts a collection of complex microbial ecosystems where microbes frequently outnumber human cells, and hundreds to thousands of bacterial species are represented. The Fredricks laboratory, based at the Fred Hutchinson Cancer Research Center, studies the human indigenous microbiota to determine how changes in microbial communities impact human health. The Fredricks lab uses tools in molecular biology such as broad range 16S rRNA gene PCR to describe microbial diversity in human body sites with a focus on the vaginal microbiota and the common condition bacterial vaginosis (BV). BV is a poorly understood condition associated with preterm birth, pelvic inflammatory disease, HIV acquisition, and other STDs.

The Fredricks lab has identified several fastidious bacterial species that are useful markers of BV and are associated with adverse health outcomes. We are using novel cultivation methods to propagate some of these bacteria in the lab, and study how indigenous microbes interact with each other and the human host. There are many research projects available for fellows that will develop laboratory research skills in molecular biology, microbiology, immunology, and cell biology.  Alternatively, there are opportunities to focus on clinical epidemiology by studying microbial ecology in different human hosts. We have ongoing research collaborations with Jeanne Marrazzo, Grace John Stewart, and Scott McClelland in this area.

The Fredricks laboratory also develops molecular diagnostic tests for the detection and identification of bacterial and fungal pathogens in immunocompromised hosts. Patients with cancer are prone to a variety of infections as a result of cytotoxic therapies, defective mucosal barriers, and use of immunosuppressive drugs. The diagnosis of many such infections remains challenging due to the poor sensitivity and specificity of conventional diagnostic tests. We use quantitative PCR assays targeting ribosomal RNA genes to detect bacterial and fungal pathogens in blood, bronchoalveolar lavage fluid, and other tissues obtained from patients with cancer. Syndromes of interest include fever with neutropenia, fungal pneumonia, and unexplained pneumonia.  Both laboratory and clinical research opportunities are available for fellows interested in this patient population. In addition, we are studying the impact of the human microbiome on transplant outcomes.