Periodontitis increases risk of viable bacteria in freshly drawn blood donations

The aim of the study was to determine if periodontitis, which often causes transient bacteraemia, associates with viable bacteria in standard blood donations.

This was a cross-sectional study of 60 self-reported medically healthy blood donors aged over 50 years. According to standard procedures, whole blood was separated by fractionation into plasma, buffy-coat, and red blood cell (RBC)-fractions. The buffy-coat was screened for bacterial contamination using BacT/ALERT. Samples from plasma and RBC-fractions were incubated anaerobically and aerobically at 37°C for 7 days on trypticase soy blood agar (TSA). For identification, colony polymerase chain reaction was performed using primers targeting 16S rDNA.

From 62% of the donors with periodontitis, bacterial growth was observed on at least 1 out of 4 plates inoculated with plasma or RBCs, whereas only 13% of plates inoculated with plasma or RBCs from periodontally healthy controls yielded bacterial growth (relative risk 6.4, 95% CI: 2.1; 19.5; p=0.0011). None of the donors tested positive for bacterial contamination using BacT/ALERT. Cutibacterium acnes was found in 31% of the donations from donors with periodontitis and in 10% of the donations from periodontally healthy donors. In addition, Staphylococcus species, Bacillus mycoides, Aggregatibacter aphrophilus, and Corynebacterium kroppenstedtii were detected.

Periodontitis increased the risk of bacterial contamination of blood products. Contaminating bacteria are often associated with the RBC-fraction. As the BacT/ALERT test is generally performed on platelet products, routine screening fails to detect many occurrences of viable bacteria in the RBC-fraction.