In November 2012, 18-year-old Meredith Littlejohn was a high school senior eagerly awaiting college acceptance letters, prom, and graduation when she was diagnosed with acute myeloid leukemia, a type of rapidly progressing blood and bone cancer.

Littlejohn underwent four rounds of chemotherapy and went into remission. But by June, her cancer had returned, and she resumed treatment. With her immune system waning due to the chemotherapy, Littlejohn contracted an infection caused by the bacteria Pseudomonas aeruginosa. But the bacteria causing her infection had evolved to evade many common antibiotics that would normally have cured her. Littlejohn’s doctors treated her with colistin, a last-resort antibiotic used for hard-to-treat infections. But even the colistin was not effective against the bacteria.

By October, the infection spread to her lungs and then to her bloodstream. A year after her cancer diagnosis, […]