Infections caused by drug-resistant bacteria are a global public health threat causing serious illness and even death. Strains of the bacterium Enterococcus faecium (E. faecium) are generally harmless in healthy people, but can be pathogenic in immunocompromised or severely ill patients. E. faecium strains from hospital environments have acquired resistance to commonly used antibiotics, including those used to treat serious infections, making these infections especially challenging to treat.