This guidance is intended to assist sponsors in the clinical development of new antibacterial drugs. Specifically, the guidance explains the FDA’s current thinking about possible streamlined development programs and clinical trial designs for antibacterial drugs to treat serious bacterial diseases in patients with an unmet medical need, including patients who have a serious bacterial disease for which effective antibacterial drugs are limited or lacking. Antibacterial drugs that are pathogen-focused can be developed for the treatment of serious bacterial diseases in patients who have an unmet medical need.