Tentative interpretative zone diameters for fusidic acid Neosensitabs on Mueller Hinton agar and three blood containing media.

Two hundred and ninety-two staphylococci were tested using fusidic acid Neosensitabs, a semiconfluent inoculum on Mueller Hinton agar and three blood containing agar media in order to investigate the interpretative zone diameters published by the manufacturer (Rosco). Zone diameters were, as expected, smaller on blood containing agar compared with Mueller Hinton agar. Many susceptible strains were intermediate on Danish Blood agar using the current breakpoints. We suggest that the interpretative zone diameters be changed to S>or=32, R<or=30 for Mueller Hinton agar and S>or=24, R<or=22 on blood containing media.