Interventions Implemented to Reduce the Risk of Transmission of Bacteria by Transfusion in the English National Blood Service

Abstract

Background: Bacterial contamination remains a significant problem in transfusion medicine. A National Health Service Blood and Transplant (NHSBT) study and surveillance data indicated skin commensals derived from the skin of the donor are the major contaminants of blood components. NHSBT therefore explored two interventions: improved donor arm disinfection and diversion. Methods: Improved donor arm disinfection: Commercial and in-house methods of disinfection were evaluated. Swabs at the venepuncture site were taken before and after disinfection and the reduction in bioburden determined. Diversion: Special collection bags were manufactured to allow the initial volume of blood to flow into a pouch, representing the diversion pouch and then the next flow of blood into another pouch representing the collection bag. Pouches were screened for the presence of bacteria. The reduction in bacterial contamination was then determined. Results: A two-step commercial procedure (Donor Prep Kit; DPK) consisting of 70% isopropyl alcohol followed by tincture of iodine was shown to be a best practice procedure (2-min procedure). A 99.79% reduction was obtained, and this method was 10 times more effective than current practice at that time. The DPK was shown in a field trial to increase donor waiting time. A second study was initiated to find a more rapid procedure. ChloraPrep®, consisting of 2% chlorhexidine gluconate and 70% isopropyl alcohol, was shown to have equivalent disinfection efficiency as the DPK, but only took 1 min to perform. In 2006, ChloraPrep was introduced as the national method of donor arm disinfection. Diversion was shown to give a 47% reduction in contamination and was introduced nationally in 2002. Conclusion: Improved donor arm disinfection and diversion are effective, low-cost interventions, but do not eliminate all bacterial transmissions. In 2011, bacterial screening of platelet components was introduced by NHSBT to further increase the safety of the blood supply.

Evaluation of an ethidium monoazide–enhanced 16S rDNA real‐time polymerase chain reaction assay for bacterial screening of platelet concentrates and comparison with automated culture

“…The results obtained from screening 2050 time‐expired PLT packs by EMA‐enhanced 16S rDNA real‐time PCR were in agreement with those generated by BacT/ALERT in that no sample was confirmed positive in either assay. The observed low prevalence of bacterial contamination (<0.048%) in these PLT concentrates is consistent with recent reports from other countries and confirms the efficacy of improved donor skin disinfection and diversion techniques …”

The epidemiology of bacterial culture–positive and septic transfusion reactions at a large tertiary academic center: 2009 to 2016

“…Mechanisms of contamination are well described, and include improper skin decontamination, donor bacteremia, and contamination of equipment and consumables before collection . Preventative measures have been adopted over the past decade to contend with bacterial risk; these include use of diversion pouches, standardized disinfection practices (i.e., cleaning of collection site), and—specific to PLT transfusions—bacterial culture and expanded use of single‐donor (apheresis) collections . Collectively, these measures have succeeded in decreasing the number of transfusions of bacterially contaminated products as reflected by an estimated 60% to 83% decline in transfusion‐associated fatalities …”

Microbial safety of cellular therapeutics—lessons from over ten years’ experience in microbial safety of platelet concentrates

“…The main keystones include careful donor selection and procedures such as the selection of the venepuncture site, effective skin disinfection, separation of the first volume from the blood donation (predonation sampling, also called diversion) and the consistent monitoring of the bag systems. Collectively, these have proven very effective in reducing the rates of bacterial contamination and associated septic transfusions reactions by 50 to 75% . Nonetheless, the residual contamination risk is approximately 1 in 10 000 transfused PCs with nonfatal reactions occurring in 1 in 100 000 and fatal reactions in 1 in 500 000 transfused PCs, respectively, further action is needed .…”