On the Antibacterial Action of Cultures of a Penicillium
1929
A laboratory paper reporting that a mould contaminant on a staphylococcus culture plate had dissolved the colonies around it. Fleming grew the mould in broth, filtered it, and tested the filtrate against a range of bacteria, recording which were inhibited and which were not. He reports the filtrate did not harm white blood cells or animals, and suggests it as a tool for isolating certain bacteria in culture and possibly as an antiseptic for wounds.