Louis Pasteur was a historical figure. He was a renowned scientist.
In 2266, Dr. Roger Korby was described by Spock as the "Louis Pasteur of archaeological medicine." Korby's translations of the medical records from the Orion ruins revolutionized immunization techniques. (TOS: "What Are Little Girls Made Of?")
Pasteur's name was among the choices The Doctor considered in giving himself, as stated in a discussion with Kes. This name was among other medical revolutionaries such as Pyong Ko, Jarvik and Schweitzer. (VOY: "Fury")
In the script for DS9: "Distant Voices", for Dr. Julian Bashir's surprise birthday party in 2371, the crew of Deep Space 9 had the choices narrowed down to two different holosuite programs: a Greek palace on Mount Olympus or Louis Pasteur's house in Paris. This scene does not appear in the aired episode.