Measures to Reduce Nosocomial CMV Transmission
The use of leukocyte-poor blood products, washed frozen red blood cells, and screening of organ donors for CMV antibody are effective measures to reduce nosocomial CMV transmission, while screening of blood recipients helps identify at-risk patients, but routine screening of all healthcare workers is not an evidence-based prevention strategy.
Analysis of Each Measure
1. Use of Leukocyte-Poor Blood for Transfusion: TRUE
- Leukocyte-reduced blood products (<1 x 10^6 leukocytes/unit) are highly effective in preventing transfusion-associated CMV infection in CMV-seronegative recipients 1.
- CMV-seronegative recipients of allogeneic stem cell transplants from CMV-seronegative donors should receive only leukocyte-reduced or CMV-seronegative red cells and leukocyte-reduced platelets 1.
- The putative source of CMV in blood products is the leukocyte, and leukocyte depletion has been shown to be an effective alternative to using seronegative blood products 2.
- Leukocyte depletion effectively prevents transfusion-transmitted CMV because the virus resides in white blood cells 3.
2. Use of Washed Frozen Red Blood Cells for Transfusion: TRUE
- CMV-negative patients should receive only CMV-negative and/or filtered blood products before and after transplantation 1.
- Washed frozen red blood cells remove leukocytes, which are the cellular reservoir for CMV in blood products 4.
- This approach aligns with the principle that removing leukocytes prevents CMV transmission through transfusion 2.
3. Screening of Organ Donors for CMV Antibody: TRUE
- HSCT candidates should be tested for the presence of serum anti-CMV IgG antibodies before transplantation to determine their risk 1.
- The risk of CMV transmission is 20-40% in case of a CMV seropositive donor 1.
- Patients at highest risk of developing CMV disease are seronegative recipients of seropositive donors 5.
- Serological screening of organ donors is a key strategy in preventing primary CMV infection 3.
- The serological status of an organ donor is a major risk factor in developing overt CMV-related disease in immunocompromised individuals 4.
4. Screening of Blood Recipients for CMV Antibody: TRUE
- HSCT candidates should be tested for the presence of serum anti-CMV IgG antibodies before transplantation to determine their risk for primary CMV infection and reactivation 1.
- Screening recipients identifies those at risk who require CMV-negative or leukocyte-reduced blood products 1.
- The serological status of the recipient is essential for determining appropriate prevention strategies 5, 4.
- This screening allows for risk stratification: CMV-seronegative recipients have a 45-86% risk of CMV reactivation if seropositive, and 20-30% risk of CMV disease 1.
5. Screening of All Health Workers for CMV Antibody: FALSE
- No guideline evidence supports routine screening of all healthcare workers for CMV antibody as a nosocomial prevention measure.
- The primary prevention strategy for healthcare workers is standard precautions: wearing gloves when handling blood products or potentially contaminated biologic materials 1.
- HSCT patients who are known to excrete CMV should be placed under standard precautions for the duration of CMV excretion 1.
- The evidence focuses on contact precautions and hand hygiene rather than serological screening of healthcare workers 1.
Key Clinical Pitfalls
- Do not assume that CMV-seropositive recipients require CMV-negative blood products - guidelines do not recommend transfusion of CMV-negative blood products to CMV-positive recipients 1.
- Insufficient data exist to recommend leukocyte-reduced products for CMV-seronegative recipients with CMV-seropositive donors (R-negative, D-positive) 1.
- Recent evidence suggests that in low birthweight infants, most CMV infections are caused by breast milk feeding or congenital transmission rather than transfusion of leucoreduced blood products 6.