Assessment of in vitro interactions between delafloxacin and other antimicrobials against multi-drug resistant <i>Pseudomonas aeruginosa</i> strains

Novel therapeutic interventions are required to address the critical antimicrobial resistance caused by multidrug-resistant <i>Pseudomonas aeruginosa</i> (MDR-PA) infections. This study examines the impact of combining delafloxacin with antibiotics on MDR-PA isolated from various samples. The minimum inhibitory concentrations (MICs) of delafloxacin, alone and in combination with other antibiotics, were determined against forty distinct MDR-PA isolates using the broth microdilution method. Time-kill curve assays were used to determine the bactericidal and synergistic effects of delafloxacin alone and in combination with other antibiotics <i>in vitro</i> against the selected five strains. Our studies showed delafloxacin exhibited four times greater in-vitro activity against MDR-PA strains than levofloxacin compared with both MIC₅₀ and MIC₉₀ results. Delafloxacin + tobramycin and delafloxacin + ceftazidime/avibactam showed synergy in two out of five strains tested at concentrations equal to the MIC. The outcomes of this research also suggest that these combinations may replace therapy for MDR-PA strains.