Canterbury DHB

Transfusion of Infected Blood

Pathophysiology

Caused by infusion of blood or blood components which are bacterially contaminated due to bacteraemia in the donor, residual bacteria at the donor skin venepuncture site, or contamination in processing.

Platelets which are stored at room temperature are the blood component most likely to cause this type of reaction, with estimated risk of <1:10,000 units transfused overall, and are more associated with gram positive organisms. With RBCs, the risk is <1:250,000. Red cell transfusions are more likely to be contaminated by gram negative organisms that can survive the cold such as Yersinia and Pseudomonas. The exact incidence of this type of reaction is unknown and may be underestimated due to intercurrent illnesses within the recipient. This complication may affect autologous blood.

Clinical Manifestations

• Onset can be dramatic and quick, often within 30 minutes of starting transfusions.
• Acute septic shock: high fevers with or without rigors, hypotension.
• Respiratory distress.
• Nausea, vomiting, and diarrhoea.
• Haemoglobinuria in 20% of patients due to lysis of red cells in the blood bag.
• Symptoms of disseminated intravascular coagulation.
• Gram positive organisms may produce less severe effects with the onset of symptoms developing during or following the transfusion.
• Overall, mortality for bacterially contaminated blood products, including all organisms, is approximately 25% but is higher (approx. 50%) with gram negative organisms.

Laboratory Diagnosis and Evaluation

Perform standard laboratory investigations including culturing of the blood bag contents and the patient’s blood.

Gram stain of the blood bag contents will often reveal the presence of organisms. Organisms that have been found include:

• Yersinia enterocolitica.
• E.coli.
• Serratia sp.
• Pseudomonas sp.
• Klebsiella sp.
• S. aureus.
• S. epidermidis.

Culture of blood should be performed at 4° C, 20° C, and 37° C.

Management and Prevention

This is an urgent situation and after the appropriate cultures have been obtained, IV antibiotics must be given if there is a clinical reason to suspect that infected blood has been transfused. Suitable empiric antibiotics to cover the likely bacteria are gentamicin 5-7 mg/kg IV stat and a broad-spectrum penicillin or cephalosporin.

Observation of the colour of the blood units should be made before transfusing blood, as contaminated blood may be darker and have a purplish discolouration.

Topic Code: 5123