In vitro evaluation of A-56619 and A-56620, two new quinolones

The in vitro activities of two new aryl-fluoroquinolones (A-56619 and A-56620) were compared with those of ciprofloxacin, ofloxacin, enoxacin, and norfloxacin. All six quinolones had broad spectra of antibacterial activity; the streptococci, Pseudomonas maltophilia, and Pseudomonas cepacia were the least susceptible. A-56619, A-56620, and chloramphenicol had similar activity against anaerobic bacteria. With both drugs, a low frequency of resistant variants (less than 10(-8)) was observed. By regression analysis, A-56619 MICs correlated best with ofloxacin MICs and A-56620 was most similar to ciprofloxacin.