DNA sequencing and analysis (bioinformatics) is an increasingly important tool for understanding biological data, including medical data. In this case study, students will be exposed to DNA sequencing to quickly identify how an outbreak of methicillin-resistant Staphylococcus aureus spreads through a neonatal intensive care unit (NICU). This PowerPoint-driven case is based on an actual outbreak described in the New England Journal of Medicine and students will use the actual DNA sequences from the outbreak that were used by scientists. A handout (Supplemental Materials) provides background and instructions that guide students in how to create and read a phylogenetic tree and use to it identify which organisms are part of the outbreak and which are independent MRSA infections. They will then use this data to assess the containment strategies used at the hospital during the outbreak. Students will learn how DNA sequencing can inform epidemiology to identify outbreak cases, track trajectories of the spreading disease, and quickly put containment measures into place. This case study is especially suited for high school and introductory undergraduate biology classes.