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Visual identification of bacterially contaminated red cells
D M Kim1, M E Brecher, L A Bland
1Mayo Clinic, Rochester, Minnesota.
Abstract:
There have been increasing numbers of reports of transfusion-acquired Yersinia enterocolitica bacteremia (including several fatal cases). Fifteen units of whole blood were inoculated with various concentrations of Y. enterocolitica serotype 0:3 and processed into AS-3 preserved red cells (RBCs). Consistent growth of the organism was found at inoculum concentrations greater than or equal to 10 colony-forming units per mL. In all 13 units of RBCs that supported the growth of Y. enterocolitica, a darkening in color (due to hemolysis and a decrease in pO2) was observed in the bag. The attached sample segments, which were sealed from the main unit, remained sterile and did not darken. This color change was apparent in all the contaminated units by Day 35, which was 1.5 to 2 weeks after the bacteria were first detected in cultures of the blood. Hence, by comparison of the color of the segment tubing with that of the unit itself, units grossly contaminated with Y. enterocolitica can be identified prior to transfusion. Moreover, review of photographs on file at the Centers for Disease Control revealed this dramatic color change in 2 units of blood that caused transfusion-transmitted sepsis (Enterobacter agglomerans and an unidentified gram-negative bacillus, not Yersinia sp.), which demonstrated that the color change was not limited to Y. enterocolitica. This method of visual identification of contaminated units of blood could decrease the incidence of posttransfusion bacterial sepsis.
Insights
Transfusion-acquired Yersinia enterocolitica bacteremia can be detected by a visual color change in red blood cell (RBC) units. This simple method can help prevent bacterial sepsis from contaminated blood transfusions.
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.