REACTION TO A BACTERIALLY CONTAMINATED PRODUCT (coagulase-negative Staphylococcus)
Blood products can become contaminated with bacteria which can then multiply and cause a severe septic reaction in the recipient. Although this is not a common occurrence, the reaction is potentially life-threatening. Surveillance studies have shown that becteria can be cultured from as many as 1:285 platelet products . However, septic reactions are uncommon; one study reported a risk of 0.01% (7/51,278). Of these there was one contaminated red cell product and no contaminated fresh frozen plasma. It was of interest that 5 occurred in single donor apheresis platelets and one occurred in pooled random donor platelets. From this information it is quite apparent that platelet transfusions are at greater risk for bacterial contamination.
Special concern must be given to platelets since they are stored at room temperature and this can allow small numbers of bacteria to multiply. Another important factor is that those receiving multiple platelets transfusions may be more likely to be immunosuppressed (ie. bone marrow transplant recipients). The effects of bacterial contamination could be fatal in this population. Platelets are currently stored for a maximum of 5 days. However, before 1986 the storage time was 7 days. The FDA reported from 1976-1985, 13 cases of transfusion associated deaths caused by bacterial contamination of platelets . Because of this the FDA in 1986 reduced the maximum storage time from 7 to 5 days.
CAUSES OF CONTAMINATION:
The question arises as to how and where the contamination is occurring. Potential sources can include skin donation site, chronic infection in the donor, asymptomatic donor bacteriemia, faulty or contaminated equipment or contamination during the processing of pooled products. Knowing this, it is understandable that the most common microorganisms responsible for contamination are common skin flora, including Staphylococcus epidermidis, diphtheroids, and Staphylococcus aureus. Gram negative bacteria have also been reported. Some of these like Pseudomonas species, Citrobacter freundii, Escherichia coli, and Yersinia enterocolitica, produce an endotoxin and are cold-growing allowing for multiplication in products stored at cooler temperatures, (ie. red cell) . Yersinia enterocolitica contamination of red cells has been reported in cases where the donor was healthy with asymptomatic gastrointestinal disease .
CLINICAL SYMPTOMS AND LAB EVALUATION:
Clinical signs and symptoms of bacterial contamination include fever, rigors and hypotension. Shock may develop with flushing and dry skin. Abdominal cramps, diarrhea, vomiting and generalized muscle pain also may occur . If any of these symptoms are noted, the transfusion should be stopped and the remaining product returned to the blood bank for further evaluation. This should include routine testing for any transfusion reaction, including clerical check, direct antiglobulin test, and visual inspection for plasma hemoglobin. If the clinical situation is suspicious for septic reaction then the bag (with corresponding gram stain) and the patient should be cultured. One study reported the most valuable test for a definitive diagnosis of this complication is a positive gram stain of the residual contents of the blood bag in question . Blood bag segments should not be used as a source for culture or gram stain.
Treatment with antibiotics should be initiated as appropriate. If severe hypotension is present vasopressors or steroids may be necessary . Attention must be placed on the development of more severe clinical problems such as disseminated intravascular coagulation and renal failure. Components associated with the suspected transfused units should be guarantined and cultured.
Thoughts as to how to prevent bacterial contamination have included reducing the storage time, adding antibiotics to the platelet units, prestorage white blood cell filtration and gram staining all 4-5 day old platelets before transfusion . Low level skin contamination can occur at the site of a scar of a frequent donor. Avoiding this area could be advantageous . Finally, there has been suggestion to perform more detailed questioning of the donor so as to distinguish those at risk for asymptomatic bacteremia .
The patient's blood culture remained negative and she remained stable throughout her hospitalization. It must be noted that she was and had been receiving appropriate antibiotic therapy for one week prior to this event. She continued to do well through this hospital course and was discharged to home with no sequelae.
Sazama K. Bacteria in blood for transfusion. A review. Archives of Pathology and Laboratory Medicine. 118(4): 350-65, 1994, Apr.
Contributed by Patricia A. Aronica, M.D. and Darrell J. Triulzi, M.D.