G. ZIMMERMANN¹, J. SIGLE¹, A. MENDEZ², S. MAURER ², A. SIDEROW<sup>1

1</sup>Blood Donation Center SRK Aargau-Solothurn, Switzerland, ²Haemovigilance Department, Kantonsspital Aarau, Switzerland

Background: There are very few reported cases of red blood cell concentrate (RBC) transfusion related sepsis with K.pneumoniae. The course of the infection is usually severe with a high mortality. Case Report: An 83 year old patient was admitted to the ER due to dyspnoea and melaena; laboratory results showed anaemia (Hb 58g/l). The patient had history of upper gastrointestinal bleeding and was under anticoagulant treatment. In total 9 RBC were administered during his hospitalization. 1h after transfusion of the 3 RBC the patient developed fever. The immunohaematologic work-up showed no incompatibility; in the blood culture of the transfusion bag grew K.pneumoniae within 24h of transfusion. However, the patient’s blood cultures taken at the time of reaction remained negative. Because of the positive blood cultures of the transfusion bag and persistent fever, consecutive blood cultures of the patient were taken which turned positive 72h after the transfusion reaction. The patient was transferred to the ICU due to progressively sepsis signs and haemodynamic instability. The sepsis treatment consisted of Ceftriaxon und Bactrim. The patient recovered and was discharged 13 days after the transfusion reaction. Antibiogram and molecular typing showed that the 2 Klebsiella strains obtained from the RBC and patient were identical. The cultures of the serothek of the index blood donation remained negative; the cultures of the returned-back Q-Plasma remained also negative, as well as the eubacterial PCR conducted after centrifugation of this plasma. The donor of the RBC had no history of invasive interventions or symptoms of respiratory or urinary tract infections. Repeated blood cultures of the donor obtained 1 week and 5 months after the transfusion reaction remained negative. Conclusions: We present a case of severe transfusion-related sepsis with K.pneumoniae due to a RBC transfusion. In spite of thoroughly examinations the source of the contamination could not be identified. Of note, initial blood cultures of the patient remained negative which stresses the significance of repeated blood cultures if clinical symptoms persist or cultures of the blood bag turn positive.