Administrative Office
St. Joseph's Hospital Site, L301-10
50 Charlton Avenue East
HAMILTON, Ontario, CANADA L8N 4A6
PHONE: (905) 521-6141
FAX: (905) 521-6142
http://www.fhs.mcmaster.ca/hrlmp/
Issue No. 84
QUARTERLY NEWSLETTER
December 2005
Bacterial Detection in Platelet Products
According to a number of studies published over the past 5 years, the 3 leading causes of
transfusion-associated mortality include: (a) acute hemolytic transfusion reactions; transfusionassociated acute lung injury (TRALI); and bacterial sepsis. Until recently, the bacterial
contamination of blood and blood products, has received very little attention and recent studies
have indicated that the bacterial contamination of blood products is both an under-recognized
and under-reported cause of transfusion-associated morbidity and mortality. In fact, it is quite
likely that bacterial sepsis due to the contamination of blood products is currently the leading
microbiological cause of transfusion related morbidity and mortality.
In light of such issues the American Association of Blood Banks (AABB) has enacted a standard
that requires the blood Transfusion Services in the US to employ methods to limit and detect
bacterial contamination in all platelet components. For all the above reasons, it is very important
for the Transfusion Service to introduce processes to detect bacterial contamination in platelets
prior to transfusion. The latter are stored at 22oC, a temperature that facilitates bacterial growth.
The Transfusion Service of the Hamilton Regional Laboratory Medicine Program (HRLMP) has
looked at a number of different options, keeping in mind the need for sensitivity, specificity, rapid
detection as well as overall cost. Several different systems and processes were evaluated and
their feasibility explored for the detection of bacteria in platelet products. The use of the pH
meter was ultimately agreed upon. The pH method process provides ease of testing, rapid
response and easily interpreted results. Below are the results of the validation/verification
processes that were used.
Twenty random donor platelet units were inoculated with various strains of bacteria in order to
test the efficacy of the pH meter for the detection of bacterial contamination of platelet
concentrates. The platelets used for the inoculation of bacteria were three-day-old human
platelets. Each platelet bag was divided into two aliquots, using a sterile docking device in order
to maintain a closed system. One aliquot served as the control and the other represented test
platelets, inoculated with 1.0 ml of a bacterial suspension. The pH and culture were examined
for 4 consecutive days and the pH was found to be lower than 7.0 in 16 of the 20 (80%)
inoculated units tested. We therefore feel that this approach will result in a significant
improvement in the safety of the platelet products transfused to patients in Hamilton Hospitals.
Based on the above considerations, the HRLMP Transfusion Service will be implementing the
hand held pH meter method for the testing of platelet products for the presence of bacteria, just
prior to being issued for transfusion to the patient. This safeguard will be used in conjunction
with Canadian Blood Services direct culture of apheresis platelets and pooled buffy coat
platelets, when the latter become available within the next 12 months. It is believed that the
introduction of the pH testing for bacterial contamination will provide for improved blood product
safety for the patients receiving platelets at both Hamilton Health Sciences and St. Joseph's
Healthcare.
Selected References:
1. Yomtovian R. Bacterial contamination of blood: lessons from the past and road map for the
future. Transfusion 2004; 44:450-460.
2. Blajchman MA, Goldman M, Baeza, F. Improving the bacteriological safety of platelet
transfusions. Transfusion Medical Review 2004; 18: 11-24.
3. Hillyer CD, Josephson CD, Blajchman MA, Vostal JG, Epstein JS, Goodman JL. Bacterial
contamination of blood components: Risks, strategies, and regulation. Hematology (Am Soc
Hematol Educ Program) 2003; 575-89.
4. Blajchman MA, Beckers EA, Dickmeiss E, Lin L, Moore G, Muylle L. Bacterial detection of
platelets: current problems and possible resolutions. 2005; 19:259-72.
5. Yazer MH, Triulzi DJ. Use of pH meter for bacterial screening of whole blood platelets.
Transfusion 2005; 45: 1133-1137.
Duane Boychuk, Manager;
Anna MacDonald, Senior Technologist; and
Morris Blajchman, MD, FRCP(C), Director
Transfusion Medicine Services
Hamilton Regional Laboratory Medicine Program