Visual identification of bacterially contaminated red cells.

Area of Science:

• Transfusion Medicine
• Microbiology
• Blood Safety

Background:

• Increasing reports of transfusion-acquired Yersinia enterocolitica bacteremia, including fatal cases, highlight a critical risk in blood transfusion.
• Yersinia enterocolitica poses a significant threat, necessitating improved methods for detecting bacterial contamination in blood products.

Purpose of the Study:

• To investigate the potential for visual detection of Yersinia enterocolitica contamination in red blood cell units.
• To determine if a color change in blood bags can serve as an indicator of bacterial growth.

Main Methods:

• Whole blood units were inoculated with Yersinia enterocolitica serotype O:3 at various concentrations.
• Inoculated units were processed into AS-3 preserved red blood cells (RBCs).
• Bacterial growth, color changes, and oxygen levels (pO2) in RBC units and attached sample segments were monitored.

Main Results:

• Yersinia enterocolitica grew in RBC units at concentrations ≥10 colony-forming units/mL.
• A noticeable darkening of RBC units, attributed to hemolysis and decreased pO2, occurred in contaminated units.
• Contaminated units showed color changes by Day 35, 1.5-2 weeks after bacterial detection, while sample segments remained sterile.

Conclusions:

• Visual inspection of RBC unit color, compared to segment color, can identify gross Yersinia enterocolitica contamination before transfusion.
• The observed color change is not exclusive to Yersinia and has been noted in other bacterial sepsis cases, suggesting broader applicability.
• This visual detection method holds potential to reduce the incidence of posttransfusion bacterial sepsis.