Results of a phase 2 study comparing two doses of delafloxacin to tigecycline in adults with complicated skin and skin-structure infections

Abstract number: P1794

O'Riordan W., Surber J., Manos P., Mehra P., Babazadeh S., Hopkins S., Burak E.

Objectives: Delafloxacin (DFX) is an investigational fluoroquinolone active against a variety of Gram-positive bacteria, including methicillin- and quinolone-resistant strains of Staphylococcus aureus (MRSA, QRSA). Two doses of DFX were compared to a standard dose of tigecycline (TIG) in patients with complicated skin and skin structure infections (cSSSI).

Methods: A multicentre, randomised, double-blind trial enrolled adults with the following: wound infections following surgery, trauma, burns or animal/insect bites; abscesses; or cellulitis. Patients were randomised 1:1:1 to receive either DFX 300 mg IV BID, DFX 450 mg IV BID, or TIG, 100 mg IV×1, followed by 50 mg IV BID; randomisation was stratified by infection type. Duration of therapy was 5 to 14 days. The primary efficacy analysis, performed on the clinically evaluable (CE) population at the Test-of-Cure (TOC) visit (14 to 21 days after the final dose of study drug), compared the clinical response rates in the DFX and TIG arms. Clinical response rates in the two DFX treatment arms were also compared. The Fisher exact test was used for the comparisons.

Results: Of the 150 patients randomised, 68% were male; the mean age was 40±14.5 yrs. Thirty-six percent had cellulitis, 33% had abscesses and 31% had wound infections; 111 (74%) patients had pathogens identified at baseline. S. aureus (95) was the most frequent isolate; 72% (68/95) were MRSA (MIC90 values, in mcg/mL, were as follows: DFX = 0.06, TIG = 0.12, ciprofloxacin = 16, levofloxacin = 4, linezolid = 1). Overall, the most frequent adverse events were nausea, vomiting and diarrhoea; the 300 mg BID DFX arm was the best tolerated of the regimens.

Conclusions: DFX, dosed at either 300 mg BID or 450 mg BID, was as effective as TIG 50 mg BID when used to treat adults with a variety of cSSSIs, including those caused by MRSA and QRSA.