New tetracycline antibiotic effective in acute bacterial skin and skin-structure infections


Background: Acute bacterial skin and skin-structure infections (ABSSSIs) continue to account for substantial morbidity and health care burden, with the emergence of drug-resistant pathogens further complicating their management. Omadacycline is a new once-daily tetracycline with in vitro activity against a wide range of causative agents of ABSSSI, including Streptococcus pyogenes, Staphylococcus aureus (including methicillin-resistant strains, or MRSA), and Enterococcus spp.

Study design: Phase 3, randomized, double-blind, double-dummy, placebo-controlled trial.

Setting: A total of 55 sites in the United States, Peru, South Africa, and Europe.

Synopsis: The trial recruited 645 adults with a qualifying ABSSSI (such as wound infection, cellulitis or erysipelas, or major abscess) with evidence of an inflammatory response (white blood cell count at least 10,000 cells/mm3 or 4,000 cells/mm3 and below, immature neutrophils at least 15%, lymphatic involvement, or oral or rectal temperature greater than 38.0° C or less than 36.0° C). Exclusion criteria included infections associated with chronic skin lesions and clinically significant liver or renal insufficiency or immunocompromised state. All patients received either omadacycline or linezolid IV with the option to switch to the oral preparation of the respective drugs after at least 3 days of therapy.

Omadacycline was noninferior to moxifloxacin with respect to early clinical response (84.8% vs. 85.5%, respectively) and posttreatment clinical response rates (86.1% vs. 83.6%). Efficacy was similar for methicillin-susceptible or methicillin-resistant Staphylococcus aureus, the most common isolated pathogens. Frequency of adverse events (primarily gastrointestinal) was also similar in the two groups. Mean duration of IV therapy was 4.4 days, and mean duration of oral therapy was 5.5 days in the omadacycline group.

Bottom line: Omadacycline provides similar clinical benefit as linezolid in the treatment of ABSSSIs.

Citation: O’Riordan W et al. Omadacycline for acute bacterial skin and skin-structure infections. N Eng J Med. 2019;380:528-38.

Dr. Manian is a core educator faculty member in the department of medicine at Massachusetts General Hospital and an associate professor of medicine at Harvard Medical School, Boston.

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