Delafloxacin: Tolerable, Effective Against Gram-Negative Pathogens for ABSSSI

klebsiella pneuminae
klebsiella pneuminae
Delafloxacin is effective against gram-negative pathogens and has a similar tolerability profile to vancomycin/aztreonam when used in patients with an ASSSSI.
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SAN DIEGO – The anionic fluoroquinolone antibiotic delafloxacin (Baxdela™, Melinta Therapeutics, Inc.) is effective against gram-negative pathogens and features a similar tolerability profile to vancomycin/aztreonam when used in patients with an acute bacterial skin and skin structure infection (ABSSSI), according to results from 2 phase 3 trials presented at IDWeek 2017.

Investigators evaluated outcomes in patients with ABSSSI who received delafloxacin 300 mg IV every 12 hours (in patients with gram-positive pathogens), or delafloxacin 300 mg IV every 12 hours for 3 days with a mandatory blinded switch to oral delafloxacin 450 mg every 12 hours (in patients with gram-negative pathogens), or vancomycin 15 mg/kg IV (actual body weight) with aztreonam between 5 to 14 days. Follow-up for evaluation of outcomes was at 14 days and 21 to 28 days (late follow-up).

At baseline, a total of 1042 patients in the 2 studies had a pathogen, of which 197 (18%) had an isolated gram-negative pathogen. Patients had cellulitis (25%), abscesses (27%), and wound infections (47%). The most common gram-negative isolate was Klebsiella pneumoniae. Ranges of minimum inhibitory concentration [MIC]50, MIC90, and MIC for K pneumoniae were 0.12, 0.25, and 0.03-4 μg/mL.

Compared with patients taking vancomycin/aztreonam, participants prescribed delafloxacin had similar rates of treatment-emergent adverse events (47.7% vs 45.1%, respectively). Gastrointestinal-related events for vancomycin/aztreonam and delafloxacin, including nausea (4.3% vs 6.1%, respectively) and diarrhea (2.0% vs 6.1%, respectively) were the most common treatment-emergent adverse events reported. Discontinuation of treatment because of treatment-emergent adverse events was reported in 2.4% of patients taking vancomycin/aztreonam vs 0.8% of patients receiving delafloxacin.

“Gram-negative bacteria are not as common in skin infections. But they can be serious infections and the most commonly used antibiotics will not treat them. If overlooked, these gram-negative infections lead to increase in hospital stay and cost,” said Sue K. Cammarata, MD, Melinta Therapeutics’ chief medical officer, in an interview with Infectious Disease Advisor.

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“These data presented at IDWeek show that Baxdela provides an IV and oral treatment that covers the most common gram-negative and gram-positive pathogens so that physicians will know that the patients are covered as they await culture results,” concluded Dr Cammarata.


Sue K. Cammarata, MD, is the chief medical officer of Melinta Therapeutics, Inc. All other authors have received either research grants, consulting fees, or are employed by Melinta Therapeutics, Inc. All full listing of disclosures can be viewed here.

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O’Riordan W, Overcash S, Lawrence L, McCurdy SP, Tseng C, Cammarata SK. Outcomes with IV/oral delafloxacin (DLX) compared to vancomycin/aztreonam (VAN/AZ) in treatment of patients (pts) with acute bacterial skin and skin structure infections (ABSSSI) and gram-negative (GN) pathogens. Presented at: IDWeek 2017; October 4-8, 2017; San Diego, CA. Poster 1856.