TROVAFLOXACIN IS A FLUORONAPHTHYRIDONE RELATED TO THE FLUOROQUINOLONES WITH IN VITRO ACTIVITY AGAINST A WIDE RANGE OF GRAM-NEGATIVE AND GRAM-POSITIVE AEROBIC, AND ANAEROBIC MICROORGANISMS. THE BACTERICIDAL ACTION OF TROVAFLOXACIN RESULTS FROM INHIBITION OF DNA GYRASE AND TOPOISOMERASE IV. DNA GYRASE IS AN ESSENTIAL ENZYME THAT IS INVOLVED IN THE REPLICATION, TRANSCRIPTION AND REPAIR OF BACTERIAL DNA. TOPOISOMERASE IV IS AN ENZYME KNOWN TO PLAY A KEY ROLE IN THE PARTITIONING OF THE CHROMOSOMAL DNA DURING BACTERIAL CELL DIVISION. MECHANISM OF ACTION OF FLUOROQUINOLONES INCLUDING TROVAFLOXACIN IS DIFFERENT FROM THAT OF PENICILLINS, CEPHALOSPORINS, AMINOGLYCOSIDES, MACROLIDES, AND TETRACYCLINES. THEREFORE, FLUOROQUINOLONES MAY BE ACTIVE AGAINST PATHOGENS THAT ARE RESISTANT TO THESE ANTIBIOTICS. THERE IS NO CROSS-RESISTANCE BETWEEN TROVAFLOXACIN AND THE MENTIONED CLASSES OF ANTIBIOTICS. THE OVERALL RESULTS OBTAINED FROM IN VITRO SYNERGY STUDIES, TESTING COMBINATIONS OF TROVAFLOXACIN WITH BETA-LACTAMS AND AMINOGLYCOSIDES, INDICATE THAT SYNERGY IS STRAIN SPECIFIC AND NOT COMMONLY ENCOUNTERED. RESISTANCE TO TROVAFLOXACIN IN VITRO DEVELOPS SLOWLY VIA MULTIPLE-STEP MUTATION IN A MANNER SIMILAR TO OTHER FLUOROQUINOLONES.