The bactericidal activity of DR-3355, an optically active isomer of ofloxacin

The bactericidal activity of compound DR-3355, an optically active isomer of ofloxacin, was measured against Escherichia coli, Staphylococcus aureus and S. epidermidis, in nutrient broth and in phosphate-buffered saline. DR-3355 was found to be approximately twice as active as ofloxacin in terms of the concentration at which maximum bacterial kill was achieved. Hence it appears that DR-3355 is twice as active as ofloxacin not only in terms of its ability to inhibit bacterial multiplication but also in its ability to kill bacteria. DR-3355 was found to be active against non-dividing bacteria and did not require either active RNA or protein biosynthesis in order to kill bacteria.