In vitro activity of DJ-6783 (a keto carboxylic acid) compared with six other orally administered antimicrobial...

DJ-6783 is a new keto carboxylic acid having an expanded antimicrobial activity when compared with nalidixic acid or cinoxacin. Its usable activity includes the following: Enterobacteriaceae (MIC90, less than or equal to 0.06-4.0 micrograms/ml), Acinetobacter species (MIC90, 0.25-1.0 microgram/ml), Pseudomonas species (MIC90, 1.0-2.0 micrograms/ml), P. aeruginosa (MIC90, 16 micrograms/ml), Staphylococcus species (MIC90, 1.0-32 micrograms/ml), Haemophilus influenzae (MIC900, less than or equal to 0.06 microgram/ml), and Neisseria species (MIC90 less than or equal to 0.06 microgram/ml). The Streptococcus species were resistant to DL-6783 with MIC50 ranging from 16 to greater than 32 micrograms/ml. The drug appears to be bactericidal, minimally influenced by increasing inocula, but resistant mutants can be selected by serial subinhibitory concentration passages of strains in DJ-6783. The resulting resistant organisms also have higher MICs to related drugs such as norfloxacin, cinoxacin, and nalidixic acid. DJ-6783 was the most active organic acid not having structural characteristics of the fluorinated 4-quinolones.