Fleming described his penicillin discovery to which club on 13 February 1929?

Fleming described his penicillin discovery to the Medical Research Club on 13 February 1929. His presentation was titled “A medium for the isolation of Pfeiffer’s bacillus” and explained that the mould’s substance could inhibit certain bacteria.

The Medical Research Club was a London scientific discussion society whose meetings gave researchers a venue to present new work. Fleming’s talk focused partly on the practical laboratory value of penicillin: because it inhibited many Gram-positive bacteria but not Haemophilus influenzae, it could help isolate organisms that were resistant to it.

The presentation attracted little immediate attention, and the discovery was not rapidly developed into a treatment. Fleming published his findings later in 1929 in the British Journal of Experimental Pathology, but penicillin was difficult to purify and produce in useful quantities. The club is sometimes confused with the Royal Society or with medical organizations involved later in penicillin research; neither was the audience for this 13 February presentation.