Aztreonam: correlation between disk diffusion and agar plate dilutions susceptibility tests.
Regression lines and error rate-bounded analyses were performed for correlating inhibitory zone diameters with the 30-micrograms aztreonam disk and aztreonam minimal inhibitory concentration for gram-negative aerobic clinical isolates. A correlation coefficient of -0.81 was found for the regression line. Preliminary proposed criteria to distinguish susceptible isolates from resistant ones are: susceptible greater than or equal to 22 mm (MIC less than or equal to 8 micrograms/ml), intermediate 16-21 mm (MIC = 16 micrograms/ml) and resistant less than or equal to 15 mm (MIC greater than or equal to 32 micrograms/ml). Using these criteria, the rates for false-susceptible and false-resistant isolates were zero.
Agar↗