Ernst’s research interests are in the area of infectious diseases and antimicrobial agents. This includes studies pharmacodynamics, pharmacoepidemiology and pharmacogenetics of antibiotics. Pharmacodynamic research has focused on the relationship between drug concentration and antimicrobial killing properties of antifungal and antibacterial agents. This research includes designing dosing regimens that optimize antimicrobial action while minimizing toxicity and the development of resistance. Pharmacoepidemiological studies investigate the relationships between drug utilization and risk factors for infection with resistant organisms and adverse effects of antimicrobial agents. Newer research interests include describing the pharmacogenetic basis for adverse effects of antimicrobial agents.

Ernst’s clinical practice interests are in the area of infectious diseases and appropriate use of antimicrobial agents. Her clinical practice site is the University of Iowa Hospitals & Clinics infectious diseases consult service. While on service she participates in daily medical rounds with the infectious diseases consult service, providing drug information and drug therapy evaluation to physicians, residents, and medical and pharmacy students. She is also a member of the pharmacy and therapeutics committee and the antibiotic advisory subcommittee at UIHC. Her interests include appropriate use of antimicrobial agents, pharmacoepidemiology and antimicrobial resistance.