Combination of ofloxacin and other antimicrobial agents

We evaluated the combination of ofloxacin with piperacillin, gentamicin, vancomycin, rifampin, clindamycin, and metronidazole by the checkerboard agar dilution method against 165 isolates which included Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa, Providencia stuartii, Acinetobacter, Staphylococcus aureus, Bacteroides fragilis, and Citrobacter perfringens. Synergy of piperacillin-ofloxacin was demonstrated for 50% and 40% respectively of E. cloacae and P. aeruginosa. Some ofloxacin and piperacillin-resistant isolates were susceptible with the combination. Ofloxacin-gentamicin was indifferent for aerobic gram-negative species. Ofloxacin and vancomycin or gentamicin was indifferent for S. aureus and E. faecalis, but rifampin-ofloxacin showed addition. Combination of ofloxacin and metronidazole or clindamycin or erythromycin was indifferent for aerobic and anaerobic species. Ofloxacin could be combined with piperacillin with benefit against P. aeruginosa, but combination with aminoglycosides is not of benefit.