PHILADELPHIA, PA—Eravacycline, a novel antibacterial agent, demonstrated high in vitro activity against Gram-negative pathogens, including multidrug-resistant isolates, a study reported at IDWeek 2014.

“Eravacycline is a novel fluorocycline, and is not affected by common mechanisms leading to tetracycline resistance,” reported Marie Abdallah, MD, from Infectious Diseases, SUNY Downstate Medical Center, Brooklyn, NY, and colleagues. These mechanisms include acquired efflux systems and ribosomal protection proteins.

Dr. Abdallah and colleagues tested the activity of eravacycline against Gram-negative bacterial pathogens isolated from single patients across 11 hospitals in Brooklyn and Queens, NY, from November 2013 to January 2014. Isolates underwent susceptibility testing by dilution techniques according to CLSI methodology, and cephalosporin-resistant isolates were screened by PCR for the presence of blaKPC,blaOXA-23-type, and blaOXA-24-type.

Susceptibility to cephalosporins and carbapenems were evaluated for 2866 E. coli isolates (87% and 99.8% susceptibility, respectively, 2 with blaKPC), 944 Klebsiella pneumonia isolates (67% and 86% susceptibility, respectively, 13% with blaKPC), 216 Enterobacter spp. (75% and 95% susceptibility, respectively, 3% with blaKPC), and 158 Acinetobacter baumannii isolates, (34% and 31% susceptibility, respectively).

The MIC50 and MIC90 values for eravacycline among 125 isolates of K. pneumoniae with blaKPC were 0.5 and 1.0μg/mL, respectively. The MIC50 and MIC90 values for 96 isolates of A. baumannii resistant to carbapenems, were 0.5 and 2μg/mL, respectively.

Researchers concluded eravacycline is a novel antibacterial agent with excellent in vitro activity against E. coli, K. pneumoniae, Enterobacter spp. and A. baumannii, including multidrug-resistant isolates. Also, its activity was also sustained against tetracycline-resistant isolates, and MICs were generally 1 dilution lower than tigecycline for K. pneumoniae and Enterobacter spp. Further, its activity against multidrug-resistant A. baumannii was 4-fold more than that of tigecycline, researchers added.