Low bacterial contamination rate in platelet components following primary culture screening: a Saudi Arabian experience.

BACKGROUND

Platelet storage at room temperature (20-24° C) with agitation facilitates bacterial proliferation. Despite global standards for culture-based screening, there is a lack of component-level contamination data within the Saudi Arabian context.

METHODS

We conducted a retrospective review of 28,416 post-donation platelet components at the Riyadh regional laboratory (2020-2021) to determine the culture-confirmed bacterial contamination rate. Screening for bacterial contamination utilized the BacT/ALERT® VIRTUO system at 24 ± 2 h post-collection. The primary outcome was to measure the confirmed contamination rate per 1,000 components; secondary outcomes included the positive predictive value (PPV) of initial screening and organism distribution. Screen-positive units were quarantined and underwent a formal confirmation algorithm via repeat culture and subculture.

RESULTS

Out of 28,416 components, 49 (0.17%) were initially screen-positive. Twenty-five cases were culture-confirmed, yielding a contamination rate of 0.88 per 1,000 components (95% CI: 0.54-1.23) and a Positive Predictive Value (PPV) of 51.0%. Skin commensals predominated, led by Staphylococcus epidermidis (28.0%) and Corynebacterium spp. (16.0%).

CONCLUSION

The confirmed contamination rate aligns with international benchmarks for primary culture programs. These findings suggest that implementing advanced strategies like Large-Volume Delayed Sampling (LVDS) or near-issue secondary testing could further reduce the residual risk posed by slow-growing skin flora.