Nalidixic Acid and Oxolinic Acid in the Treatment of Chronic Bacteriuria

The effects two organic acid antimicrobials, nalidixic acid and oxolinic acid, were compared in vitro and in patients with chronic bacteriuria. Oxolinic acid was found to be more active in inhibiting Enterobacteriaceae, whereas neither agent was very effective against strains of Pseudomonas. Both nalidixic acid and oxolinic acid appeared less active when tested against a higher inoculum of bacterial cells. This difference was more pronounced with nalidixic acid and was most marked when tested in liquid medium. The results of a controlled clinical trial in 54 patients demonstrated that treatment with 2 g/day oxolinic acid was associated with less emergence of resistance during therapy than was the case with 4 g/day nalidixic acid. Although the relative role of these agents in the treatment of chronic bacteriuria remains uncertain, it appears that oxolinic acid, because of its decreased tendency to evoke highly resistant mutants, has distinct potential advantages over nalidixic acid.