In vitro susceptibility comparisons and recommendations for oxolinic acid.

Minimal inhibitory concentration and disk diffusion susceptibility studies were carried out with oxolinic acid to determine a recommended disk content for disk susceptibility testing. Regression curve analyses were performed with disks containing 1, 2, and 5 mug of oxolinic acid. Data suggest that the 5-mug disk more satisfactorily fulfills requirements for susceptibility testing than the 1- or 2-mug disks evaluated. Ultraviolet spectral analysis studies for absorption maxima and extinction coefficients were done to verify the authenticity and concentration of oxolinic acid in the aqueous solutions studied.