Efficiency of combination therapy versus monotherapy for the treatment of infections due to carbapenem-resistant Gram-negative bacteria: a systematic review and meta-analysis.

backgroundFor resistant Gram-positive bacteria, evidence suggests that combination therapy is more effective. However, for resistant Gram-negative bacteria, no consensus has been reached. This study aims to comprehensively summarize the evidence and evaluate the impact of combination versus monotherapy on infections caused by carbapenem-resistant Gram-negative bacteria (CRGNB).

methodsA systematic search was conducted in PubMed, Cochrane library, Web of Science, and Embase up to June 15, 2024, to identify relevant studies. This study included comparisons of monotherapy and combination therapy for treating infections caused by CRGNB. Topical antibiotics (i.e., inhalational or intratracheal administration) and monotherapy with sulbactam/relebactam was excluded. The primary outcome was mortality, and the secondary outcomes were clinical success and microbiological eradication. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated in order to systematically assess effect of treatment on mortality, clinical success and microbiological eradication. Subgroup analyses, publication bias tests, and sensitivity analyses were also performed.

resultsA total of 62 studies, including 8342 participants, were analyzed, comprising 7 randomized controlled trials and 55 non-randomized studies. Monotherapy was associated with higher mortality (OR = 1.29, 95%CI: 1.11-1.51), lower clinical success (OR = 0.74, 95%CI: 0.56-0.98), and lower microbiological eradication (OR = 0.71, 95%CI: 0.55-0.91) compared to combination therapy for CRGNB infections. Specifically, patients with carbapenem-resistant Enterobacteriaceae (CRE) infections receiving monotherapy had higher mortality (OR = 1.50, 95%CI: 1.15-1.95), comparable clinical success (OR = 0.57,95%CI: 0.28-1.16), and lower microbiological eradication (OR = 0.48,95%CI:0.25-0.91) than those receiving combination therapy. For carbapenem-resistant Acinetobacter baumannii (CRAB) infections, no significant differences were observed in mortality (OR = 1.15.95%CI: 0.90-1.47), clinical success (OR = 0.95,95%CI: 0.74-1.24) and microbiological eradication (OR = 0.78,95%CI: 0.54-1.12).

conclusionsMonotherapy or combination therapy is controversial. The systematic review and meta-analysis suggested that monotherapy is associated with higher mortality, lower clinical success, and lower microbiological eradication for treating infection caused by CRGNB. The available evidence suggests that treatment should be selected based on the specific bacteria and antibiotic used. Monotherapy for CRE infections may lead to adverse outcomes. For CRAB infections, no significant differences were found between combination therapy and monotherapy. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022331861.