In vitro evaluation of S-25930 and S-25932, two new quinolones, against aerobic gram-negative isolates from cancer patients.

The in vitro activity of S-25930 and S-25932, two new 4-quinolones, against 450 aerobic gram-negative organisms isolated from cancer patients was evaluated and compared with the activity of ciprofloxacin, enoxacin, difloxacin (A-56619), and A-56620. Both agents inhibited most members of the family Enterobacteriaceae at concentrations of less than or equal to 2.0 micrograms/ml, but their activity against Pseudomonas aeruginosa was inferior to that of other quinolones. Although considerably less active than ciprofloxacin and A-56620, S-25930 was frequently two- to eightfold more active than S-25932 and was comparable to difloxacin and enoxacin against most isolates.