Clinical Guidance for Bacterial Contamination and Blood Safety

• The evaluation of a patient suspected of having received a bacterially-contaminated platelet transfusion should include:
  • Culture of any residual component, if available, to confirm the initial result.
  • Blood cultures of the patient, even in the absence of apparent sepsis, to ensure sub-clinically silent infections are not missed.
• Any isolates (i.e., microorganisms obtained from the residual component and/or patient culture) C. This allows detailed studies to determine if the microorganisms are linked.
• Results of the patient's clinical and laboratory workup should be communicated to the transfusion service medical director, who should report findings to the blood collection facility.

No test is 100% sensitive; platelets screened for bacterial contamination will occasionally have false negative results.

• For patients who have received blood or blood components and develop signs or symptoms of bacteremia/sepsis, treating clinicians should continue to evaluate for a potential transfusion reaction.
• The evaluation of a patient with suspected sepsis following platelet transfusion should include:
  • culture of any residual component, if available
  • blood cultures of the patient
• Any isolates should be retained until the case investigation is completed.
• Results of the patient’s clinical and laboratory workup should be communicated to the transfusion service medical director and the medical director of the collection facility; these data will help determine the significance of the initially negative test result.

• Donors with potentially medically significant microorganisms identified may be advised to see their physician for further evaluation. Evaluation of the donor by the physician should begin with a thorough clinical history and physical examination. Follow-up investigations might include blood cultures, cultures of other body sites, and additional tests as appropriate.
• Communication between the blood center physician and the treating clinician should facilitate management of the donor. Identification of a culture indicating endogenous bacteremia will likely result in deferral of the donor from future blood donation. To resume donation, the donor may require clearance by the clinician and the blood center medical director; this could be based on the donor successfully completing treatment.

To address the risk of bacterial contamination, effective March 1, 2004, the AABB adopted standard 5.1.1.1 (Standards for Blood Banks and Transfusion Services, 22nd edition), which requires all accredited institutional members to "implement measures to detect and limit bacterial contamination in all platelet components." The College of American Pathologists has also added a query on such testing to the transfusion medicine checklist of their Laboratory Accreditation Program. View the FDA's most recent guidance for bacterial risk mitigation strategies.

Currently, several methods are approved by the FDA for bacterial risk mitigation among platelet donations. One approach is the implementation of Pathogen Reduction Technology (PRT). Many blood collection centers culture apheresis platelets (derived from single donors) and release the unit after the culture has incubated for at least 36 hours.

To improve bacterial screening and reporting, AABB has provided guidance on standardized definitions for test results, investigation, and product management of implicated platelet units with positive tests, management of other components (co-components) associated with the same donation, and further characterization of detected organisms.

• Promptly notify the transfusing physician with all available information according to local operating procedures by the transfusion service or the facility performing the testing.
• Report all test results to the transfusion service medical director and the transfusing physician as soon as possible.
  • Perform a Gram stain immediately on any retained portion of the unit.
  • Identify the microorganism and perform susceptibility testing promptly.
• Note that post-transfusion patient follow-up care will depend on their clinical status and the transfusing physician's judgment. Direct communication between the medical director of the testing facility, the transfusion service medical director, and between either of these individuals and the transfusing clinician, is important for optimal management of patient care decisions.

• Before performing confirmatory assays, initial test results will include both true and false positives.
  • The initial positive test result may be either true contamination introduced from the donor or during handling, or a false positive result.
• True positive results may occur with a variety of organisms; while many may be of little or no clinical significance to the donor, others may be more significant.
• A true positive result is most often the result of contamination of the platelet unit by skin flora (due to incomplete skin decontamination or because of a skin plug). However, a true positive result can also be the result of organisms that may be of clinical significance to the donor, including those that cause bacteremia. Gram-negative organisms (e.g., coli) most often are due to occult bacteremia.
• All Gram-negative organisms should be considered potentially significant for the donor's health. Gram-positive organisms (e.g., Staphylococcus epidermidis) will likely be skin commensals or environmental contaminants.
  • However, some Gram-positive organisms (e.g., Staphylococcus aureus, Streptococcus pneumoniae) may be from endogenous bacteremia in the donor. For example, an organism such as S. aureus may originate from bacteremia in a patient with incompletely treated osteomyelitis.
  • Additionally, some organisms may have low pathogenicity but may indicate a significant underlying disease (e.g., Streptococcus bovis bacteremia associated with colon cancer).
• Blood collection facilities must notify donors of any medically significant abnormality discovered either during the interview or detected because of laboratory testing, in compliance with standard 5.2.2 of the 33rd edition of Standards for Blood Banks and Transfusion Services of the AABB. Deferral criteria are established by the Food and Drug Administration (FDA), applicable State Department of Health ,regulatory agency or by guidelines from the facility medical director. They are based on the severity and transmissibility of the disease and the availability of a confirmatory test.
• Certain organisms are of public health significance, regardless of their effects on donor health. These organisms require additional consideration and reporting according to local and national guidelines. (See Table: Examples of Organisms of Public Health Significance.)