The activity of enoxacin against clinical bacterial isolates in comparison with that of five other agents, and factors affecting that activity

The activity of enoxacin against 362 clinical bacterial isolates in comparison with norfloxacin, nalidixic acid, ampicillin, latamoxef (moxalactam) and gentamicin was tested by an agar dilution method. Typical MICs for enterobacteria lay between 0.12 and 1.0 mg/l. Enterobacter spp. and Serratia spp. tended to be more resistant. Enoxacin was also active against Pseudomonas aeruginosa (mean MIC 0.5 mg/l) and highly active against fastidious Gram-negative aerobes. Typical MICs for Staphylococcus aureus were 1-2 mg/l while streptococci were more resistant (16-32 mg/l). Enoxacin had no useful activity against Bacteroides fragilis and Clostridium perfringens. Enoxacin was generally more active at pH 8 than pH 6, and in broth than in urine. It was bactericidal in its action. Daily serial passage from growth in broth containing enoxacin caused decreased sensitivity which was limited to four- to 16-fold greater than the original MIC. Enoxacin was about half as active as norfloxacin against enterobacteria, equally active against staphylococci, and some two to four times less active against streptococci.