Metronidazole-quinolone combination: antibacterial activity in vitro

Combination of metronidazole and oxolinic or pipemidic acid were tested in vitro against some of the bacteria most commonly responsible for genito-urinary infections (E. coli, K. pneumoniae, Enterob. cloacae, Serratia marcescens, Pr. mirabilis, Pr. morganii, Str. faecalis and 3 strains of Ps. aeruginosa). The metronidazole-oxolinic acid combination was found to be additive or synergistic against E. coli, K. pneumoniae, Enterob. cloacae and Serratia marcescens. The results show that subinhibitory concentrations of oxolinic acid may reveal an activity of metronidazole against aerobic and facultative anaerobic bacteria, under aerobic conditions.