Answer: A Surgeon

Joseph Lister was a 19th century surgeon best known for his pioneering work in the field of antiseptic surgery. Prior to Lister’s extensive study of surgical procedures, practices, and post-operational mortality, the most widely held belief in regard to post-surgical infection was that the air quality in the surgical suite and hospital were responsible for the health of the patient (and the rate of post-op infections). While hospital air quality was, and remains, an important component of maintaining safety for both the staff and the patient, we now know that microbial contamination is the source of infections.

While a professor of surgery at the University of Glasgow, the work of Louis Pasteur (made famous by his contributions to the field of microbial study and food safety) came to Lister’s attention. Building on Pasteur’s work and cross-applying it to surgical conditions, Lister demonstrated that, contrary to the popular belief at the time, practices like surgeons and nurses washing their hands and sterilizing surgical implements led to a radical decrease in post-op infections.

The mouthwash Listerine, introduced in 1879, was named after Joseph Lister in honor of his work in antisepsis. Other honorary namings include the pathogenic bacterial genus Listeria and the slime mold genus Listerella.