Yersinia Infections in Transfusions

  by  makelessnoise 

Yersinia enterocolitica is a human pathogen that affects the G.I. system. It causes fever, diarrhea, and abdominal pains, and can sometimes be mistaken for appendicitis and is usually spread by contact with fecal material. However, it is a very important infection in blood banking, as it is the leading cause of post-transfusion septic infections.

Y. enterocolitica is a common contaminant is stored blood. The bacteria has several adaptions that allow it to thrive under the conditions blood is stored. Yersinia species are siderophilic, meaning they like high-iron environments, as is in stored blood. Y. enterocolitica can survive and even reproduce in temperatures down to -2C, allowing them to grow at the refrigerated temperatures blood is stored. The bacteria use glucose and adenine, found in storage additives, for metabolism and growth, and have an optimal pH of 7.0 – 8.0, and blood is stored around 7.3. It has been shown calcium prevents growth of pathogenic Yersinia but only above 30C, so blood stored with a calcium chelated anticoagulant does not prevent infection.

Y. enterocolitica can cause an asymptomatic infection in the intestines that disseminates to the blood, which is how is eventually contaminates stored blood. Donors who are asymptomatic or who have bacterial counts low enough to not present symptoms are not routinely screened. The bacteria do not actively cause sepsis, but trigger a major generalized inflammatory response, thought to be the result of a cell wall component that strongly binds to and activates macrophages, who initiate a cytokine cascade throughout the body.

Serologic donor testing is expensive and infections caused by Y. enterocolitica is relatively rare. The simplest ways to prevent post-transfusion infections from the bacteria are not allowing donors the give blood if they do not feel well or have any signs of infection, not giving blood older than 3 weeks to susceptible recipients because the  bacteria take 3 to 4 weeks to reach dangerous levels in refrigerated blood, and using pre-storage leukocyte-reducing techniques because the bacteria have a strong affinity for WBCs.

http://www.ncbi.nlm.nih.gov/pubmed/21865196