In vitro activity of omadacycline against pathogens isolated from Mainland China during 2017-2018

Antibiotic resistance of bacterial pathogens isolated in China is a major concern. Omadacycline is a novel tetracycline derivative that has been approved for use in skin infections and community-acquired pneumonia. This study was conducted to determine the in vitro activity of omadacycline against a large collection of patient isolate medical centers across Mainland China. A total of 1041 recent clinical isolates are obtained from patients hospitalized in 29 provinces and municipalities across China. The in vitro activity of omadacycline and comparator agents was assessed using the microbroth dilution methodology. Omadacycline was active against methicillin-susceptible and -resistant Staphylococcus aureus with MIC₉₀ values of 0.25 and 1 mg/L, respectively. All isolates of Enterococcus faecalis and Enterococcus faecium, including vancomycin-resistant isolates, were inhibited by ≤ 0.25 mg/L of omadacycline. It was active against Streptococcus pneumoniae irrespective of susceptibility to penicillin or macrolides (MIC₉₀ =0.12 mg/L). The minimum inhibitory concentration (MIC) distribution of omadacycline was nearly identical against (extended-spectrum beta-lactamases) ESBL-positive, ESBL-negative, and carbapenemase-producing Escherichia coli (MIC₉₀ = 4 mg/L). Omadacycline also showed good activity against Acinetobacter baumannii, inhibiting all isolates at ≤ 8 mg/L. Against Hemophilus influenzae and Moraxella catarrhalis, the MICs of omadacycline were low and not influenced by the presence of β-lactamase. Overall, the activity of omadacycline was very good against isolates commonly associated with skin infections and pneumonia, and the susceptibility of Chinese isolates was similar to that reported for these pathogens from large surveillance studies outside China. This suggests that omadacycline could be an option for treatment of these infections in Chinese patients.