IN A SERIES of papers between 1929 and 1932, Fleming1 observed that the growth of certain bacteria was inhibited by the chance introduction into the culture plates of the mold Penicillium rubrum, which is abundantly found in rotted fruit, vegetables and stale decaying matter. However, it was not until 1940 that great interest was stimulated in the field by the comprehensive, enthusiastic reports of Florey2 and Abraham,3 together with their co-workers. Thereafter experimental and clinical studies appeared in the literature confirming the excellent results obtained with penicillin against certain bacterial infections.
For clinical application the mold had to be standardized, and two general methods of assay, or standardization, have been developed.
Oxford, or Florey, Unit.
—Florey and Florey4 employed Staphylococcus aureus plates incubated with Penicillium for twelve to sixteen hours at 37 C. The surrounding zone of bacterial inhibition was observed, and each 24 mm.
YASUNA ER. DANGER OF PENICILLIN THERAPY IN ACTIVE UVEITIS. Arch Ophthalmol. 1947;37(5):598-607. doi:10.1001/archopht.1947.00890220615006