Interpretative criteria and quality control parameters for telithromycin disc diffusion susceptibility tests

In vitro studies were carried out with 4175 Gram-positive clinical isolates, comparing telithromycin broth microdilution MICs with disc diffusion zone diameters. Provisional interpretive criteria for testing staphylococci were > or =23 mm for susceptible and < or =19 mm for resistant. Because pneumococci and other streptococci require increased CO(2), the corresponding zone sizes are 3 mm smaller (> or =20 mm and < or =16 mm). Two collaborative studies were performed in order to propose the following quality control limits: 24-30 mm for Staphylococcus aureus ATCC 25923 and 27-33 mm for Streptococcus pneumoniae ATCC 49619.