Septic Transfusion Reactions

PATHOPHYSIOLOGY: The description of the presentation of a septic transfusion reaction should have set off some bells in your head.

That is, if you are someone who has ever practiced clinical medicine.

A patient with the combination of massive hypotension/shock along with a high fever sounds suspiciously like someone with septic shock from an overwhelming bacterial load. Septic reactions, in their worst form, are simply described as the Blood Bank giving someone an instant case of septic shock.

The pathophysiology of shock from bacterial invasion of the bloodstream is beyond the scope of this web site, but I will say that the manifestations of septic reactions from transfusion tend to be worse with gram-negative contamination, due to the very common presence of endotoxin released from those organisms. Endotoxins can have a severe and dramatic effect on body functions and lead to rapid shock and organ failure.

With that being said, you should be aware that the type of blood product being transfused greatly affects whether the contaminating organism is gram-positive or gram-negative. That discussion follows below.

Red Blood Cells

Red Cells, as you probably know, are stored in cold temperatures (1-6 degrees C) for up to 42 days in the liquid state (depending on the anticoagulant/preservative solution used). As such, the organisms that contaminate RBCs must have a pretty good tolerance for cold temperatures in order to proliferate in such an environment. There are several organisms that fit the bill, and almost all of them are gram-negative. These organisms include Yersinia enterocolitica, various Pseudomonas organisms (especially P. fluorescens), Serratia, Escherishia coli, as well as others such as Citrobacter freundii. Stick these bad boys in a bag of cold blood and they are Oh-so-happy!

Platelets

Platelets, unlike RBCs, are stored at room temperature (at 20-24 degrees C for up to five days). As such, the organisms that contaminate platelets are quite fond of growing in an environment similar to the ambient air. These organisms are mostly skin flora, and almost always gram-positive. Staphylococcus aureus and various Streptococcus organisms are most likely in platelet contamination. This does not mean that gram-negative organisms can't grow in platelets, just that they are much less common.

On to the treatment of septic reactions.

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