Apparatus for measuring zones of inhibition.

The apparatus described is a device allowing rapid measurement of susceptibility zone diameters obtained by the Kirby-Bauer method. The device consists of a series of radially arranged strips upon the lid of a microbiologic plate. The strips are transparent, labeled with the antibiotic tested, and slightly movable circumferentially. The strips being as wide as the diameter separating susceptible from resistant organisms, the device allows rapid classification of zone diameters into those indicating susceptibiltiy as well as resistance of orgainisms to the antibiotic tested.