Norfloxacin and the antibacterial γ pyridone β carboxylic acids

Abstract

Norfloxacin (MK0366), a new γ pyridone β carboxylic acid, was tested in parallel with nalidixic acid against 1450 bacterial isolates (enterobacteria, haemophilus, pseudomonas, enterococci, and staphylococci) most of which were ampicillinresistant. Only 12 isolates (2 of klebsiella, 2 of enterobacter, 4 of acinetobacter, and 1 of pseudomonas were norfloxacin-resistant (MIC >8 mg/l). In contrast 134 enterobacteria, 5 acinetobacter and all the pseudomonas and Gram-positive cocci were nalidixic acid-resistant. Sixty-two per cent of enterobacteria were inhibited by < 0·06 mg/l of norfloxacin, of which 2–8 mg/l inhibited 90% of the pseudomonas and Gram-positive strains.