Dr. William Pasteur (d. 1791), a son of Swiss immigrant Dr. Jean Pasteur, opened an apothecary shop on the Duke of Gloucester Street in Williamsburg, Va., in 1759. In 1775 he entered into a partnership with John Minson Galt, who was to practise surgery with Pasteur's assistance. Pasteur later became a director of the Lunatic Hospital in 1790, but served in that capacity for only one month. Pasteur also held several public offices, including justice of the peace for York County, Va., and mayor of Williamsburg (see Blanton, Medicine in Virginia, 321-22).

GW purchased medicines and other items from Pasteur in the early 1770s. GW's financial accounts indicate that Pasteur treated John Parke and Martha Parke Custis (see Ledger A, 299; Ledger B, 4, 61, 96, 120).