Evaluation of teicoplanin and vancomycin disk susceptibility tests.

Disk tests with two glycopeptide antibiotics, teicoplanin and vancomycin, were evaluated, and MICs were compared with those of fusidic acid and coumermycin. For tests with 30-micrograms vancomycin disks, we recommend modification of the current zone size standards to less than or equal to 10 mm for resistant and greater than or equal 15 mm for susceptible. For teicoplanin disk tests, 30-micrograms disks are recommended, with zone size interpretive standards of less than or equal to 10 and greater than or equal 14 mm. Since no resistant clinical isolates are available at this time, susceptibility testing of either drug is rarely necessary, and zone size standards are tentative.