INTERPRETIVE STANDARDS AND QUALITY-CONTROL LIMITS FOR SUSCEPTIBILITY TESTS WITH AMPICILLIN-SULBACTAM COMBINATION DISKS

In vitro studies were performed to evaluate susceptibility tests with disks containing 10 .mu.g of ampicillin plus 10 .mu.g of sulbactam. Interpretive zone standards of .ltoreq. 11 mm (resistant), 12-13 mm (intermediate) and .gtoreq. 14 mm (susceptible) are proposed. A 9-laboratory coordinated study was performed to establish tentative zone size limits for quality control of ampicillin-sulbactam disks. This included data with a new control strain selected to monitor performance of such combination disks.