Abstract
BACKGROUND: The escalating global crisis of antimicrobial resistance (AMR), particularly among multidrug-resistant (MDR) Gram-negative bacteria (GNB), presents a significant challenge to patient care. Newer β-lactam/β-lactamase inhibitor (BL/BLI) combinations, such as imipenem/cilastatin/relebactam (IMI/REL), have been developed to overcome key resistance mechanisms, including those mediated by KPC and AmpC enzymes, offering new hope for treating severe infections with limited therapeutic options. PATIENTS AND METHODS: This was a retrospective, single-center, observational study of 195 adult patients with GNB bacteraemia who received IMI/REL for at least 48 hours. The patient cohort was characterized by a high comorbidity burden (median Charlson Comorbidity Index of 4) and significant illness severity (median APACHE II score of 14). The most common pathogens were Pseudomonas aeruginosa (63.1%) and Klebsiella pneumoniae (24.6%), with a high proportion of isolates being carbapenem-non-susceptible (77.5%). The primary outcome was clinical success, and secondary outcomes included 30-day all-cause mortality and safety. RESULTS: The overall clinical success rate was 72.82%, and the all-cause 30-day mortality rate was 11.3%. Microbiologic failure occurred in 12.3% of patients, and infection recurrence within 30 days was seen in 8.2%. The safety profile was favourable, with adverse drug reactions reported in 4.1% of patients, leading to treatment discontinuation in only two cases (1.02%). CONCLUSIONS: The findings of this study reinforce the value of IMI/REL as an effective and well-tolerated treatment for severe GNB infections in a complex, real-world patient population. These outcomes compare favourably with published data for other new BL/BLI agents, supporting the targeted use of IMI/REL as a crucial component of modern antibiotic stewardship.