Secondary bacterial culture of platelets to mitigate transfusion-associated sepsis: A 3-year analysis at a large academic institution.

BACKGROUND: In 2019, the United States Food and Drug Administration published its final recommendations to mitigate bacterial contamination of platelets. We sought to evaluate our secondary bacterial culture (SBC) strategy in light of those recommendations. STUDY DESIGN AND METHODS: A retrospective analysis was conducted of SBC data (October 2016-2019) at our institution. SBC was performed upon receipt (Day 3 after collection); 5 mL of platelet product was inoculated aseptically into an aerobic bottle and incubated at 35°C for 3 days. For 8 months, a 10-mL inoculum was trialed. No quarantine was applied. All positive cultures underwent Gram staining and repeat culture of the platelet product (if available). A probable true positive was defined as concordant positive culture between the initial and repeat culture. The incidence of probable true- and false-positive cultures were reported descriptively and differences evaluated by sampling volume. RESULTS: Over 3 years, 55 896 platelet products underwent SBC, yielding 30 initial positive results (approx. 1/1863 platelets); 25 (83.3%) signaled within 24 hours of SBC. The rates of probable true positive, false positive, and indeterminate for 5 mL were 0.027% (1/3771), 0.002% (1/45 251) and 0.018% (1/5656), respectively. The respective rates for 10 mL were 0.018% (1/5323), 0.07% (1/1521), and 0%. Seven of eight (87.5%) false-positive SBCs occurred with a 10-mL inoculum. No septic transfusion reactions were reported. CONCLUSION: SBC continues to interdict bacterially contaminated units of platelets. Our findings suggest higher rates of false positivity using large-volume inocula.

Implementation of secondary bacterial culture testing of platelets to mitigate residual risk of septic transfusion reactions.

BACKGROUND: Bacterial contamination of platelets remains a major transfusion-associated risk despite long-standing safety measures in the United States. We evaluated an approach using secondary bacterial culture (SBC) to contend with residual risk of bacterial contamination. STUDY DESIGN AND METHODS: Phased implementation of SBC was initiated in October 2016 for platelets (all apheresis collected) received at our institution from the blood donor center (Day 3 post collection). Platelet products were sampled aseptically (5 mL inoculated into an aerobic bottle [BacT/ALERT BPA, BioMerieux, Inc.]) by the blood bank staff upon receipt, using a sterile connection device and sampling kit. The platelet sample was inoculated into an aerobic blood culture bottle and incubated at 35°C for 3 days. The cost of SBC was calculated on the basis of consumables and labor costs at time of implementation. RESULTS: In the 13 months following implementation (October 6, 2016, to November 30, 2017), 23,044/24,653 (93.47%) platelet products underwent SBC. A total of eight positive cultures were detected (incidence 1 in 2881 platelet products), seven of which were positive within 24 hours of SBC. Coagulase negative Staphyloccus spp. were identified in four cases. Five of the eight cases were probable true positive (repeat reactive) and interdicted (cost per averted case was US$77,935). The remaining three cases were indeterminate. No septic transfusion reactions were reported during the observation period. CONCLUSION: We demonstrate the feasibility of SBC of apheresis platelets to mitigate bacterial risk. SBC is lower cost than alternative measures (e.g., pathogen reduction and point-of-release testing) and can be integrated into workflow at hospital transfusion services.

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

BACKGROUND: Bacterial contamination and associated septic transfusion reactions (STRs) remain the leading infectious risk to the blood supply. We sought to characterize the risk and clinical presentation of blood culture-positive transfusion reactions (BCPTRs) and STRs at our institution. STUDY DESIGN AND METHODS: A retrospective analysis was conducted of all suspected transfusion reactions reported to the transfusion service at a 1000-bed tertiary academic medical center from January 2009 to September 2016. Routine investigation included review of the clinical presentation, Gram stain, and bacterial culture of residual blood from the transfused product or associated blood bag. BCPTRs were defined by the presence of a positive bacterial culture in the blood product and/or recipient. STRs met definitive Centers for Disease Control and Prevention hemovigilance criteria for transfusion-transmitted infection, with definite imputability and concordant bacterial culture of the blood product and recipient. RESULTS: A total of 688,514 blood products were transfused during the study period, 3170 transfusion reactions were reported, and 18 (0.57%) were BCPTRs of which seven (0.22%) were STRs. Fifteen of 18 (83.3%) BCPTRs and six of seven (85.7%) were associated with transfusion of apheresis platelets. Major symptoms and signs of BCPTRs included chills (67%), fever (61%), and nausea and vomiting (50%). Four of seven (57.1%) STRs were classified as severe or life-threatening. CONCLUSION: BCPTRs are rare yet potentially serious. The signs and symptoms of BCPTRs, and associated STRs, are not specific, posing risk of misclassification. Challenges surrounding reporting and case ascertainment underscore the need for laboratory measures to address residual risk of contamination.