Fleming first presented penicillin to which club in February 1929?

Fleming first presented penicillin to the Medical Research Club on 13 February 1929.

The presentation described his work at St Mary’s Hospital, where he had observed that a Penicillium mould inhibited nearby Staphylococcus bacteria. His talk was titled “A medium for the isolation of Pfeiffer’s bacillus,” reflecting his immediate interest in using penicillin to suppress unwanted bacteria in laboratory cultures.

The discovery received little attention at the time. Fleming’s report was later published in the British Journal of Experimental Pathology in 1929, but the medical potential of penicillin was not widely recognised for another decade. The club was not the Royal Society or a pathology society; those are plausible-sounding but incorrect alternatives.

Fleming’s early presentation should also be distinguished from the later Oxford work of Howard Florey, Ernst Chain and their colleagues, who developed methods for concentrating and mass-producing penicillin.