1588 - Activity of Imipenem/Relebactam Against Clinical Isolates of P. aeruginosa and K. pneumoniae Collected in Asia/Pacific Countries – SMART 2016-2018

Background: Relebactam (REL) inhibits class A and C β-lactamases and was approved in the USA in combination with imipenem (IMI) and cilastatin for the treatment of complicated intraabdominal and urinary tract infections. We evaluated the activity of IMI/REL against clinical isolates collected in Asia/Pacific as part of the global SMART surveillance program.

Methods: In 2016-2018, 56 clinical laboratories each collected up to 250 consecutive, aerobic and facultative gram-negative pathogens from various infection sources per year. Susceptibility was determined using CLSI broth microdilution and CLSI breakpoints. IMI-nonsusceptible isolates (except from India) were screened for β-lactamase genes.

Results: Among 5501 K. pneumoniae and 4362 P. aeruginosa isolates, 46.6% and 65.3%, respectively, were collected from patients with lower respiratory tract infections, 25.6% and 17.1% from intraabdominal infections, 19.9% and 13.9% from urinary tract infections, and 7.2 and 2.9% from bloodstream infections. No infection source was specified for 0.7% of isolates from either species. 90.7% of collected K. pneumoniae isolates were IMI/REL-susceptible, ranging from 56.8% in India and ~80% in Thailand and Vietnam (~16% MBL-positive) to ≥97% in 7 countries (0-2% MBL-positive). 28.6% (202/707) of IMI-nonsusceptible K. pneumoniae were IMI/REL-susceptible. Of the 425 molecularly characterized IMI-nonsusceptible K. pneumoniae, 187 (44.0%) were MBL/OXA-48-like negative and 83.4% of these (156/187) were IMI/REL-susceptible; 82 isolates (19.3%) were KPC-positive and 91.5% of these (75/82) were IMI/REL-susceptible.
The table shows percent susceptible and percent MBL-positive among all collected P. aeruginosa isolates. 74.3% of IMI-nonsusceptible P. aeruginosa (n=1236) were IMI/REL-susceptible.Table


Conclusion: IMI/REL was active against 91% of K. pneumoniae and 89% of P. aeruginosa isolates collected in Asia/Pacific overall, with higher activity in countries with lower MBL-positive rates. IMI/REL promises to be an important treatment option for IMI-nonsusceptible MBL-negative isolates, including KPC-producing K. pneumoniae.