Multidrug-Resistant versus Extensively Drug-Resistant Gram-Negative Bloodstream Infections in the Intensive Care Unit: A Systematic Review
Quader Naseer, Santosh Singh*, Mohammed Masood and Bhavani Prasad G
ABSTRACT
Background: Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacterial (GNB) bloodstream infections represent a critical challenge in intensive care units (ICUs), leading to prolonged hospitalization, increased organ support, and high mortality. While XDR infections are generally perceived to confer worse outcomes, emerging data suggest that illness severity, host factors, and timeliness of antimicrobial optimization may play a more decisive role.
Objective: To systematically compare the clinical characteristics, interventions, and outcomes of critically ill adult patients with MDR versus XDR Gramnegative bacteraemia in ICU settings.
Methods: A systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed/MEDLINE, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar were searched from January 2010 to December 2024. Observational studies and randomized trials comparing MDR and XDR Gram-negative bloodstream infections in adult ICU patients were included. Data on demographics, severity scores, interventions, and outcomes were extracted. Risk of bias was assessed using the Newcastle–Ottawa Scale.
Results: A total of 18 studies encompassing 3,742 patients were included. XDR infections were consistently associated with higher severity scores, longer ICU and hospital stay, increased ventilator days, and greater need for invasive organ support. Mortality outcomes were heterogeneous; 11 studies reported no significant difference, while 5 studies demonstrated similar or lower mortality in XDR infections, particularly where early targeted antimicrobial therapy was employed. Clinical resolution rates were comparable across resistance phenotypes.
Conclusion: XDR Gram-negative bacteremia in ICU patients is associated with greater illness severity and healthcare resource utilization but does not uniformly result in higher mortality compared to MDR infections. Early diagnosis and prompt antimicrobial optimization appear to mitigate adverse outcomes, underscoring the importance of timely intervention over resistance phenotype alone.
