We have recently created a technique that allows us to identify which nutrient-iron sources are preferred by bacteria during infection. This technique is based on utilizing nutrient samples that are exclusively labeled with minor stable isotopes of iron, and tracking these samples with sensitive mass spectrometry techniques as they move through the metabolic pathways of the cell. Stable isotope tracking has revealed that S. aureus preferentially imports heme-iron over other iron sources. In addition, stable isotope tracking identified a second system responsible for heme acquisition in S. aureus which we call the heme transport system (hts). Inactivation of the hts system revealed a requirement for heme acquisition in staphylococcal pathogenesis. The creation of a stable isotope tracking technique allows us to answer previously unanswerable questions about bacterial nutrient acquisition during infection.

Our long term goals are to define the nutrient acquisition capabilities of Gram positive pathogens in the hopes of identifying novel antimicrobial targets against organisms that are quickly becoming resistant to all existing therapies.