CDC, Red Cross warn of bacterial blood infections
Viral agents not only concern
Public health officials are launching a national effort to detect transfusion-related bacterial infections, implementing a new surveillance approach that will focus on heightening clinical suspicion.
’The big problem with this has been lack of clinician identification,” says Susan Cookson, MD, a medical epidemiologist in the Centers for Disease Control and Prevention hospital infections program. ’With heightened clinical awareness we will be able to get a true idea of how significant this is, and once we have that, develop ways to try and prevent it.”
The primary infectious agent of concern is Yersinia enterocolitica, a bacteria that can cause asymptomatic infection in donors, survive easily in banked blood, and then cause life-threatening sepsis in patients receiving transfusions. While much effort has been made to upgrade detection of viral agents like HIV and hepatitis C, only passive surveillance is in place to record such bacterial infections. Even without actively seeking reports, the CDC has been apprised of 20 cases of Yersinia enterocolitica-contaminated red blood cells infecting patients. The cases occurred in 14 different states from April 1987 through June 1996.
Recipient’s illness may cloud etiology
But there are concerns that these cases are only the tip of the proverbial iceberg, as many such infections may not be traced back to contaminated blood. Transfusion recipients may often be severely ill, and clinicians could ascribe adverse reactions to the patient’s immune-compromised state, Cookson notes.
’We think of it as more of a sequela of the underlying condition, but it may actually be a result of bacterial contamination of blood,” Cookson tells Hospital Infection Control. ’Increased awareness will probably make us realize that this is much more of a problem than we had previously thought.”
To heighten identification the CDC is working with the American Red Cross and the American Association of Blood Banks to try to determine the rate of contamination, and to develop and distribute a standardized definition of adverse patient reactions to transfusion of bacterially contaminated blood.
The symptoms of the 20 known patients who received Y. enterocolitica-contaminated blood included 16 who developed chills; 14 with fevers; 13 with hypotension; and seven who developed disseminated vascular coagulopathy. In all, 12 (60%) died after transfusion.
Plans call for heightening awareness among clinicians, requesting that once such symptoms appear in patients they send the blood unit to the microbiology lab to be cultured for bacterial contamination. Blood supplies that are found contaminated are then to be sent to the CDC for confirmation, Cookson says.
Ongoing problems include the lack of practical screening mechanisms for bacteria in blood at donation. Even questioning donors will not identify asymptomatic cases. No symptoms were reported by donors in 40% of the known cases, but the remainder reported diarrhea or abdominal pain near the time of donation. Donors now are asked if they are sick, but officials are concerned that extending that to, say, diarrhea in the last 30 days could eliminate many healthy donors from the blood supply. Improved surveillance may result in more detailed approaches for screening donors and identifying patient groups that may be at particular risk of infection with bacteria-contaminated blood.
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