In vitro activity and adaptation strategies of eravacycline in clinical Enterococcus faecium isolates from China

Eravacycline (Erava) is a synthetic fluorocycline with potent antimicrobial activity against a wide range of Gram-positive bacteria. This study aimed to investigate the in vitro antimicrobial activity and resistance mechanism of Erava in clinical E. faecium isolates from China. Erava minimum inhibitory concentrations (MICs) against clinical E. faecium isolates-including those resistant to linezolid (LZD) or harboring the tetracycline (Tet) resistance genes was ≤0.25 mg l^-1. Moreover, our data indicated that clinical isolates of E. faecium with Erava MIC 0.25 mg l^-1 were predominantly shown to belong to Sequence-type 78 (ST78) and ST80. The prevalence of Erava heteroresistance in clinical E. faecium strain was 2.46% (3/122). The increased Erava MIC values of heteroresistance-derived E. faecium clones could be significantly reduced by efflux pump inhibitors (EPIs). Furthermore, comparative proteomics results showed that efflux pumps lmrA, mdlA, and mdlB contributed significantly to the acquisition of Erava resistance in E. faecium. In addition, a genetic mutation in 16 S rRNA (G190A) were detected in resistant E. faecium isolates induced by Erava. In summary, Erava exhibits potent in vitro antimicrobial activity against E. faecium, but mutation of Tet target sites and elevated expression of efflux pumps under Erava selection results in Erava resistance.

Eravacycline: A Review in Complicated Intra-Abdominal Infections

Eravacycline (Xerava™), a novel fully synthetic fluorocycline, consists of the tetracyclic core scaffold with unique modifications in the tetracyclic D ring; consequently, it exhibits potent in vitro activity against Gram-positive and -negative bacterial strains expressing certain common tetracycline-specific acquired resistance mechanisms. In vitro, eravacycline exhibits potent activity against a broad spectrum of clinically relevant Gram-positive and -negative aerobic and anaerobic bacteria. Intravenous eravacycline is approved in several countries for the treatment of complicated intra-abdominal infections (cIAIs) in adult patients. In two pivotal double-blind, multinational trials in this patient population, eravacycline (infusion ≈ 1 h) was noninferior to intravenous ertapenem or meropenem at the test-of-cure visit in terms of clinical response rates in all prespecified populations. Eravacycline had an acceptable tolerability profile, with infusion site reactions, nausea, vomiting and diarrhoea the most commonly reported adverse reactions, most of which were of mild to moderate severity. Given its broad spectrum of activity against common clinically relevant pathogens (including those expressing certain tetracycline- and other antibacterial-specific acquired resistance mechanisms) and its more potent in vitro activity and better tolerability profile than tigecycline, eravacycline provides a novel emerging option for the treatment of adult patients with cIAIs, especially as empirical therapy when coverage of resistant pathogens is required.