The in vitro activities of GAR-936, the 9-t-butylglycylamido derivative of
minocycline, were compared with those of doxycycline, minocycline, acid tet
racycline against 527 gram-positive clinical isolates. GAR-936 inhibited al
l strains, including those resistant to other tetracyclines, at concentrati
ons of less than or equal to 2 mu g/ml, except two strains of JE; diphthero
ids for which the MIC was 4 mu g/ml.