Evaluating the in Vitro Efficacy of Imipenem-Relebactam against Carbapenem-Resistant Gram-Negative Bacteria: A Comparative Analysis of Clinical Isolates

Abstract

Background: Antimicrobial resistance (AMR) is an increasing worldwide health issue with Gram-negative, carbapenem and colistin-resistant microorganisms. Gram-negative Rods (GNRs) resistance to carbapenems has emerged as a significant issue in medical facilities that gives rise to morbidity and mortality. Imipenem-relebactam (IMI-REL) a combination of the carbapenem, imipenem and the new release bactam-based, 2-lactamase inhibitor relebactam has demonstrated potential to defeat resistance in multidrug-resistant (MDR) pathogens.

Purpose: This study was intended to test the in vitro activity of IMI-REL against the carbapenem-resistant GNR isolates on clinical samples by the modified Kirby-Bauer disk diffusion test.

Methods: The study was a cross-sectional study conducted at the Armed Forces Institute of Pathology (AFIP), Rawalpindi, in June 2022 through January 2023. Total 210 clinical isolates of carbapenem-resistant GNRs were gathered and the susceptibility to IMI-REL was determined. The resistance rates were grouped in terms of patient age, gender and specimen type.

Findings: Of 210 isolates, 63.8 % were sensitive , 29 % resistant and 7.2 % intermediate sensitive to IMI-REL. The highest resistance was documented in isolates of invasive respiratory specimens. There was stratification analysis showed that resistance patterns varied significantly depending on the type of specimen.

Conclusion: IMI-REL showed considerable in vitro efficacy against carbapenem-resistant isolates of GNR, which suggests that the antibiotic can be used in the treatment of MDR infections, especially in severely ill patients. More clinical trials are necessary to support these findings and allow it to be used in the treatment plans.