In Focus
Enhancing bacterial safety of blood components
Addressing residual safety risk and focus on experiences from Japan and Hong Kong
The Bacteria Subgroup of the ISBT Transfusion Transmitted Infectious Diseases Working Party (TTID WP) undertakes activities focused on the enhancement of blood safety and dissemination of knowledge1.
As part of its mission, the Bacteria Subgroup brings together researchers and transfusion medicine professionals from around the world to address emerging and persistent challenges in bacterial safety of blood components. This was exemplified at the ISBT TTID Meeting that was held in Kuala Lumpur, Malaysia, on June 20, 2026, with presentations from the Japanese Red Cross Society and the Hong Kong Red Cross Blood Transfusion Service.
Key Takeaways from Implementing Universal Bacterial Screening with Large Volume Delayed Sampling Customized for Japan’s Medical Environment
The Japanese Red Cross (JRC) supplies approximately 850,000 platelet components (PC) annually to around 3,600 hospitals across the country, including facilities in remote regions. To accommodate this nationwide distribution network, the JRC has adopted a Large Volume Delayed Sampling (LVDS) strategy with bacterial culture of PC shortened to 24 hours. Simultaneously, the PC shelf life was extended from three to five days. Before implementation of universal bacterial screening of PC, 30 transfusion-transmitted bacterial infection (TTBI) cases were documented, including three fatalities, representing approximately two cases per million PC. Serious TTBIs involved pathogenic bacteria such as Staphylococcus aureus, Streptococcus dysgalactiae and Escherichia coli2, providing a strong rationale for introducing universal screening using an LVDS algorithm. This algorithm involves PC sampling 40 hours after blood collection and inoculation of aerobic and anaerobic bottles. Post-sampling, PCs are quarantined for 24 hours before distribution with a negative 24-hour culture result.
Figure 1. Japanese Red Cross Society: Japan's sole blood service provider
If an initial culture is positive, the implicated PC is re-tested. If re-testing is positive, bacteria are identified. If re-testing is negative, the initial result is classified as false positive. During the first 10 months of universal PC screening, no TTBI cases were reported. Sixty-five initially positive cultures comprised 18 false positives and 44 confirmed positives (~1/10,000). Streptococcus and Staphylococcus accounted for approximately 80% of bacteria identified. Screening did not eliminate residual risk: five near-miss events were reported involving 4-day and 5-day PC contaminated with S. aureus, which presented visible aggregates. Continued surveillance, investigation of breakthrough events and visual PC inspection remain essential. The JRC programme offers a valuable model for blood services seeking to balance the benefits of universal PC screening with large-scale component production and distribution. The key lesson is that bacterial safety strategies are most effective when they are carefully designed for the environment in which they must operate.
A Recap of 25-years’ Experience in Bacterial Surveillance Testing – What is Next?
The Hong Kong Red Cross Blood Transfusion Service (HKRC) began systematic bacterial surveillance in 1998–1999 in response to an estimated PC contamination rate of ~1/2,000. Over the subsequent 25 years, the HKRC has progressively implemented other mitigating measures. Initially, testing relied on a single culture bottle, but the system progressively evolved to incorporate aerobic and anaerobic cultures, optimized sampling strategies, and eventually the adoption of LVDS. However, evidence demonstrated that bacterial surveillance cannot eliminate TTBIs. Interestingly, the HKRC experience has included detection of streptococcal species. Isolation of Streptococcus was particularly intriguing because of their association with colorectal cancer and polyps. Thus, PC bacterial screening may occasionally provide clinically relevant information for blood donors. More recently, in addition to an LVDS PC testing algorithm, the HKRC has implemented pathogen reduction of selected PC. Observed changes in the frequency of positive cultures after LVDS has raised the question whether current skin disinfection procedures are effective in reducing bacterial loads on donor skin. This has prompted consideration of future studies comparing alternative antiseptic strategies, including additional alcohol and povidone iodine on top of the current twice applications of alcohol and chlorhexidine. However, there should be a balance between microbiological efficacy and donor experience. Additional disinfection steps could increase exposure time and potentially contribute to skin irritation or allergic reactions, already seen with chlorhexidine. Consequently, any modification of the current HKRC protocol would require prospective evaluation rather than simply extending exposure times. The next phase of bacterial safety may therefore depend on combining increasingly sensitive surveillance technologies with better understanding of bacterial ecology, formation of surface-attached bacterial aggregates known as biofilms, skin microbiology and human factors. The HKRC’s experience illustrates how sustained surveillance over decades can identify residual risks that would remain invisible in shorter studies—and how these observations can guide the next generation of interventions to make PC transfusion safer.
Figure 2. Journey to minimize transfusion transmitted bacterial sepsis in Hong Kong
Final Remarks
Presentations and discussion of the Bacteria Subgroup at the ISBT TTID-WP Meeting highlighted the predominance of S. aureus as a PC contaminant and biofilm formation as persistent challenges for PC safety. As bacteria form biofilms in deeper layers of donor skin, it is important to optimize skin-disinfection protocols. S. aureus microaggregates may appear and disappear during PC storage, and therefore visual inspection remains a critical safety measure. The discussion concluded that no single intervention provides complete bacterial PC safety. Culture screening, pathogen reduction, visual inspection, donor-arm disinfection, manufacturing controls, and quality-control testing should be viewed as complementary layers rather than independent solutions to enhance PC safety. Considerations and challenges of bacterial PC screening and pathogen reduction are discussed in the following articles of the series of the Bacteria Subgroup, authored by Carl MacDonald (retired NHSBT) and Jennifer Bearne (NHSBT), and Richard Benjamin (Cerus Corporation).
References
1. García-Otálora MA, McDonald C, Bearne J, Brown B, Cheng A, Humbrecht C, et al.; ISBT Transfusion‐Transmitted Infectious Diseases Working Party Subgroup on Bacteria. Platelet component safety in the era of new advancements in bacterial screening and pathogen reduction: A congress report of the 2024 ISBT Transfusion-Transmitted Infectious Diseases Working Party, Bacteria Subgroup. Vox Sanguinis. 2025 Aug;120:846-857 2. Satake M, Kozakai M, Matsumoto M, Matsubayashi K, Taira R, Goto N. Platelet safety strategies in Japan: impact of short shelf life on the incidence of septic reactions. Transfusion. 2020;60:731–738.
