IN-VITRO ACTIVITY OF BAY-12-8039, A NEW FLUOROQUINOLONE, AGAINST SPECIES REPRESENTATIVE OF RESPIRATORY-TRACT PATHOGENS

The in vitro antibacterial activity of BAY 12-8039, a novel 8-methoxy- quinolone, was compared with those of other quinolones, amoxicillin/cl avulanate, cefuroxime and erythromycin against species commonly implic ated in respiratory tract infections as well as viridans group strepto cocci. The new compound was highly active against methicillin-suscepti ble staphylococci (MIC90 0.125 mu g/ml), penicillin-susceptible and pe nicillin-resistant pneumococci (MIC90 0.5 and MIC50 0.25 mu g/ml, resp ectively), penicillin-susceptible and penicillin-resistant viridans gr oup streptococci (MIC90 0.5 and 0.25 mu g/ml, respectively), group A s treptococci (MIC,, 0.25 mu g/ml), M. catarrhalis (MIC90 0.125 mu g/ml) and H. influenzae (MIC90 0.063 mu g/ml), irrespective of beta-lactama se production. It was, however, less active against methicillin-resist ant staphylococci (MIC50 and MIC90, 2 and 4 mu g/ml, respectively). Th e new compound demonstrated bactericidal activity at concentrations 2, 4, 8 times the MIC against representative isolates of the above colle ction. At a concentration of eight times the MIG, the frequency of spo ntaneous resistance ranged from 2.5 x 10(-7) to <4 x 10(-8). These res ults suggested that BAY 12-8039 would be a promising agent for the era dication of respiratory tract pathogens and that clinical trials asses sing its efficacy for the management of infections caused by these org anisms are warranted. (C) 1998 Elsevier Science B.V./International Soc iety of Chemotherapy. All rights reserved.