He is internationally known for his work on nutritional immunity and the manganese and zinc sequestering innate immune effector calprotectin. His work with Staphylococcus aureus helped establish that the host restricts the availability of these essential metals at sites of infection and that this sequestration inactivates metal-dependent bacterial enzymes. Ongoing work in the Kehl-Fie laboratory is focused on elucidating the adaptations that enable S. aureus, and other successful pathogens, to overcome nutritional immunity and cause disease.