Albert Ludwig Sigesmund Neisser was a physician and scientist working in Poland who, in 1879, identified the bacterium that causes gonorrhea. Before Neisser’s discovery, physicians and scientists were unsure of what causes gonorrhea, a sexually transmitted infection, or STI, that typically causes genital pain and discharge in those infected. Using newly available microscopy techniques, Neisser examined genital discharge from patients with gonorrhea and observed the bacteria that eventually became known as Neisseria gonorrhoeae, named in his honor. Beyond discovering the bacterial cause of gonorrhea, Neisser also directed a dermatology clinic in Breslau, Poland, and researched other diseases including syphilis and leprosy. In addition to his discoveries, he also experienced scandals and ethical controversies regarding his research practices, which resulted in the implementation of directives regarding informed consent. By identifying the causative agent of gonorrhea, Neisser enabled future physicians and scientists to develop treatments for a disease that can cause infertility and be passed from mother to child causing serious illness in infants.