In vitro activity of A-56619 and A-56620 against multi-resistant and routine clinical isolates.

A-56619 and A-56620 are two new quinolone compounds that are currently being studied. They were found to be active against multi-resistant and routine isolates of Staphylococcus aureus, enterobacteria, aminoglycoside-sensitive and resistant strains of Pseudomonas aeruginosa. Most of the enterobacteria were inhibited by 0.5-1 mg/l of A-56620. A-56619 was less active, concentrations of 1-4 mg/l being needed for 90% inhibition. Both the compounds were active at concentrations of 0.5-1 mg/l against staphylococci, including multi-resistant S. aureus. The MIC90 for P. aeruginosa was 1-2 mg/l for A-56620 and 8 mg/l for A-56619.