PRELIMINARY INTERPRETIVE CRITERIA FOR IN-VITRO SUSCEPTIBILITY TESTING OF CP-99219 BY DILUTION AND DISK DIFFUSION METHODS

CP-99219 is a navel 7-[3-azabicyclo (3.1.0) hexyl] quinolone that possesses activity against a wide variety of aerobic and anaerobic pathogens. The disk diffusion test results (5-mu g CP-99219 disks) were compared with CP-99229 minimum inhibitory concentrations (MICs) using 445 contemporary clinical isolates, including 210 strains that were resistant to ciprofloxacin (MICs, greater than or equal to 4 mu g/ml). A high correlation was observed between methods (r = 0.97), and the proposed conservative zone diameter interpretive criteria were selected primarily from the regression equation as follows: susceptible at greater than or equal to 15 mm (less than or equal to 2 mu g/ml, preferred) and resistant at less than or equal to 10 mm (greater than or equal to 8 mu g/ml); or susceptible at greater than or equal to 19 mm (less than or equal to 1 mu g/ml) and resistant at less than or equal to 14 mm (greater than or equal to 4 mu g/ml). Using these criteria, the occurrence of false-resistant and false-susceptible disk diffusion test results should remain rare (less than or equal to 1.5%).