Estimation of bacterial risk in extending the shelf life of PLT concentrates from 5 to 7 days.
BACKGROUND
The use of bacterial culture to prevent bacterial contamination of blood components has renewed interest for extending the shelf life of PLT concentrates to 7 days after collection.


METHODS
This study was therefore conducted to determine the residual risk of bacterial contamination in PLT concentrates at the end of 5 and 7 days after collection in a center where all PLT concentrates are routinely screened by taking samples on Day 2 for culture. PLT units with no growth after 48 hours were sampled a second time on Day 5 or Day 7 after collection, followed by inoculation into aerobic culture bottles. The inoculated bottles were then monitored for up to 7 days at 35 degrees C in an automatic monitoring and detection system.


RESULTS
During a 16-month study period, a total of 6020 PLT concentrates were tested 5 days (Group A, n=3010) and 7 days (Group B, n=3010) after collection. Four units in each group (0.133%) were found to be contaminated. In 6 units, bacteria were seen on direct Gram stain. In addition, 5 of the associated RBC units grew the same organisms on culture. The organisms include three coagulase-negative staphylococci and five Propionibacterium acnes. The positive rate of routine short-term bacterial culture was 0.035 percent during the same study period.


CONCLUSIONS
Despite routine short-term bacterial culture, a significant risk of bacterial contamination remains at 5 and 7 days after collection. For now, the shelf life of PLT concentrates should remain 5 days.
Lee
C K
CK
Hong Kong Red Cross Blood Transfusion Service and Center of Infection and Department of Microbiology, the University of Hong Kong, Hong Kong. ckleea@ha.org.hk
Ho
P L
PL
Lee
K Y
KY
Cheng
W W
WW
Chan
N K
NK
Tsoi
W C
WC
Lin
C K
CK
D001419:Bacteria / Q000254:growth & development*; D001769:Blood / Q000382:microbiology*; D001792:Blood Platelets / Q000382:microbiology*; D001793:Blood Preservation; D015169:Colony Count, Microbial; D006801:Humans; D012307:Risk Factors; D013997:Time Factors