Evaluation of the Association Between ABO and Rh Blood Groups and the Pathogens of Bloodstream Infections

Objective: This study aimed to investigate the relationship between ABO and Rh blood groups and bloodstream infections caused by Gram-positive bacteria, Gram-negative bacteria, and yeasts, and to explore whether blood group polymorphisms contribute to susceptibility to infection.Materials and Methods: A retrospective case–control study was conducted among 2,618 hospitalized patients between May 2021 and May 2024. The case group included 270 patients with positive blood cultures, and the control group comprised 2,348 patients without bloodstream infections. Blood group typing was performed using the DiaMED-ID Micro Typing System® by gel centrifugation method, and microbiological identification was carried out using the BD Phoenix™ M50 automated system. Antimicrobial susceptibility testing followed EUCAST guidelines. Statistical analyses assessed the relationship between blood groups, microorganism types, and clinical variables.Results: The median age of patients with positive blood cultures was significantly higher than that of culture-negative patients (76 vs. 53 years, p < 0.001). The most common blood groups were A Rh-positive (38.7%) and O Rh-positive (30.5%). Among culture-positive patients, blood group A was the most frequent (45.9%), followed by O (30.7%), B (14.1%), and AB (9.3%). The most common pathogens were Staphylococcus aureus (19.3%), Escherichia coli (18.9%), and Enterococcus spp. (18.5%). No statistically significant association was found between ABO/Rh blood groups and bloodstream infection or pathogen distribution. A non-significant trend toward association was observed for Escherichia coli (p = 0.093).Conclusion: ABO and Rh blood groups were not significantly associated with bloodstream infection risk or pathogen distribution. Further studies are needed to clarify potential host-pathogen interactions