Gentamicin bioautography assay vs. the microbiological disk test

The use of bioautography for quantitative measurement of gentamicin concentrations was compared with the disk test. Following chromatographic separation and bioautography, gentamicin produced inhibition zones, 2 approximately 7 times larger than the inhibition zones formed by the same amounts of gentamicin in the disk test. Bioautography, therefore, is a more sensitive assay method.