Highlights: (1) An acyltransferase (*atf3*) is prevalent in ST258 *K. pneumoniae*; (2) Expression of *atf3* enhances glycolysis, increasing bacterial ATP production and ROS; (3) With *atf3*, the airway metabolome was altered with greater glucose consumption; (4) *K. pneumoniae* expressing *atf3* has a competitive advantage in vivo