Background: Bloodstream infections (BSI) cause significant morbidity and mortality in solid organ transplant (SOT) recipients. There are few data regarding the contribution of multidrug-resistant organisms (MDROs) to these infections. Objectives: We evaluated the resistance-percentage of MDRO BSIs in SOT recipients and assessed associated mortality. Methods: A systematic review Data sources: MEDLINE and Embase databases up to January 2024. Study eligibility criteria: Studies of adult SOT recipients that quantify MDRO BSI resistance-percentage and/or associated crude mortality. MDROs studied were carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPA), third-generation-cephalosporin-resistant Enterobacterales (3GCR-E), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). Participants: Adult SOT recipients with a microbiologically confirmed BSI. Interventions: Not applicable. Risk of bias assessment: Newcastle Ottawa Scale. Methods of data synthesis: MDRO BSI resistance-percentage and mortality outcomes were reported as median (IQR) and crude mortality (%), respectively. Results: Of 945 studies identified, 52 were included. Most were retrospective (41/52) and/or single centre (37/52), and liver transplantation was the most studied SOT type (22/52). High resistance-percentages of BSIs were noted, ranging from 13.6% CRE for Enterobacterales to 59.2% CRAB for Acinetobacter baumannii. Resistance-percentage trends decreased over time, but these changes were not statistically significant. Asia had highest resistance-percentages for MRSA (86.2% [IQR 77.3-94.6%]), 3GCR-E (59.5% [IQR 40.5-66.7%]) and CRE (35.7% [IQR 8.3-63.1%]). North America had highest VRE resistance-percentages (77.7% [IQR 54.6-94.7%]). Crude mortality was 15.4-82.4% and was consistently higher than non-MDRO BSIs. Conclusions: MDRO BSIs resistance-percentages were high for all pathogens studied (IQR 24.6-69.4%) but there was geographical and temporal heterogeneity. MDRO BSIs were associated with high mortality in SOT recipients. Microbiological and clinical data in this vulnerable population were incomplete, highlighting the need for robust international multi-centre studies.

The authors have declared no competing interest.

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