NEW ORLEANS, LA—Relebactam showed “strong potential” for restoring the in vitro activity of imipenem against respiratory pathogens that were otherwise non-susceptible to carbapenems, according to research presented at IDWeek 2016. 

“Further development of this compound could provide a valuable therapeutic option for treating infections caused by resistant gram-negative bacilli,” reported Meredith A.M. Hackel, PhD, of IMHA, Inc., in Schaumburg, IL.

Relebactam, formerly MK-7655, is an investigational beta-lactamase inhibitor of class A and class C carbapenemases. Previous research has shown that it can restore the in vitro activity of imipenem (IMI) against Enterobacteriaceae (including those producing KPC) and Pseudomonas aeruginosa (PA).

The study team evaluated its restoration of IMI against gram-negative isolates from respiratory tract infections (RTI) collected in the United States and Canada the course of the 2015 SMART surveillance program.

Participating hospitals collected up to 100 consecutive gram-negative pathogens from respiratory tract infections. Using CLSI broth microdilution, minimum inhibitory concentration (MICs) were identified for 843 PA and 1,141 non-Protease Enterobacteriaceae (NPE). 

Of 258 PA isolates that were not susceptible to IMI, 197 (76%) became IMI-susceptible following addition of relebactam, raising the overall IMI susceptibility of PA isolates to 93%, the study team found. 

“Among 1,141 NPE, 92% (1,051) were susceptible to IMI; of the 90 nonsusceptible isolates, 63 (70%) were rendered susceptible by the addition of relebactam, for a final 98% susceptibility,” Dr. Hackel reported.