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Assessment of polymicrobial interactions in bacterial isolates from transfused platelet units associated with sepsis
Christopher A Kerantzas1, Jacob Merwede2, Edward L Snyder1
1Department of Laboratory Medicine, Yale University, New Haven, Connecticut, USA.
Background:
In 2019 the Centers for Disease Control and Prevention (CDC) reported a series of 4 transfusion reactions that resulted from contamination of apheresis platelet products. Products involved in all 4 cases were contaminated with Acinetobacter calcoaceticus-baumannii complex (ACBC) and in 3 products Staphylococcus saprophyticus was found as well. CDC investigation found that bacterial isolates from the cases were genetically related and suggested a common source of contamination. The contamination of blood products with ACBC is rare and polymicrobial contamination of blood products even less common. ACBC and S. saprophyticus have been observed to adhere to one another and sediment out of suspension in vitro, a process referred to as coaggregation, and we hypothesized that there was an interaction between the strains from these cases that contributed to their co-contamination of blood products.
Study Design And Methods:
To test the hypothesis of bacterial interaction, we performed coaggregation experiments and observed the growth characteristics of ACBC and S. saprophyticus strains recovered from contaminated blood products involved in a subset of the CDC cases.
Results:
An increase in S. saprophyticus CFU concentration was observed after several days of co-culture with ACBC in LB and plasma; however, no other findings suggested coaggregation or augmentative growth interaction between the bacterial strains.
Conclusion:
Ultimately, an interaction between ACBC and S. saprophyticus that could help explain their co-occurrence and growth in contaminated platelet units was not found; however future studies of potential interactions may be warranted.
Insights
Researchers investigated bacterial interactions in contaminated platelet products. They found no evidence of coaggregation or growth enhancement between Acinetobacter calcoaceticus-baumannii complex and Staphylococcus saprophyticus, despite their co-occurrence in transfusion reactions.
Area of Science:
- Microbiology
- Infectious Diseases
- Blood Safety
Background:
- In 2019, the CDC reported transfusion reactions due to contaminated apheresis platelet products.
- Four cases involved contamination with Acinetobacter calcoaceticus-baumannii complex (ACBC) and Staphylococcus saprophyticus.
- Bacterial isolates were genetically related, suggesting a common contamination source.
Purpose of the Study:
- To test the hypothesis that bacterial interaction contributes to co-contamination of blood products.
- To investigate potential coaggregation and augmentative growth between ACBC and S. saprophyticus.
Main Methods:
- Co-culture experiments were performed with ACBC and S. saprophyticus strains from contaminated blood products.
- Bacterial growth characteristics and coaggregation were observed in vitro.
Main Results:
- S. saprophyticus concentration increased after co-culture with ACBC in LB and plasma.
- No coaggregation or significant augmentative growth interaction was observed between the strains.
Conclusions:
- Bacterial interaction does not appear to explain the co-occurrence of ACBC and S. saprophyticus in contaminated platelet units.
- Further research into potential interactions may be warranted.
