Transfusion-Transmitted Bacterial Infections (TTBI)

Transfusion-Transmitted Bacterial Infections (TTBI)

• Absence of prior infection with the same pathogen in the recipient is a risk factor for TTBI
• Clinical Presentation: • RBC contamination leads to septic reactions • Gram-negative bacteria produce endotoxins • Symptoms include fever, rigors, hypotension, nausea, and severe complications • Platelet contamination results in fever and chills, often caused by Gram-positive bacteria
• Diagnosis: • Suspect TTBI in patients with post-transfusion fever, chills, rigors, or hypotension • High suspicion level is essential as it can be confused with other reactions
• Microorganisms: • RBC contamination: Gram-negative bacteria • Platelet contamination: Gram-positive cocci • Storage conditions influence the types of bacteria involved
• Incidence: • Rates vary and are often underreported • Hemovigilance programs help improve reporting and reveal higher rates
• Prevention: • Enhanced donor screening • Improved skin disinfection • Pathogen-reduction technologies like the INTERCEPT system

Hemolytic Disease of the Fetus and Newborn

• Destruction of the RBCs of a fetus and neonate by antibodies produced by the mother
• The mother can be stimulated to form RBC Ab naturally (ABO), by previous pregnancy, or transfusion (RBC alloimmunization)
• RhD continues to remain an important cause of incompatibility, although its frequency has been equaled or surpassed by other RBC Ab specificities
• Initial diagnosis of maternal RBC alloimmunization is serologic
• Etiology: • Levine and Stetson: Postulated that mother has been immunized to the father’s antigen through fetomaternal hemorrhage
• Exchange Transfusion: • Indication: Critical levels of Bilirubin • Blood cell products: Group O, RhD-negative/RhD-positive, leukocyte reduced, HgbS negative, CMV safe, irradiated, and Ag-negative for maternal RBC Abs
• Simple Transfusion: • The infant may receive small volume or “top-off” RBC transfusions to correct anemia anytime from after birth to many weeks later
• Management: • Phototherapy:
  • Sufficient to adequately conjugate the bilirubin and lessen the need for transfusion in infants with mild to moderate hemolysis • Intravenous Immune Globulin:
  • Used to treat hyperbilirubinemia of the newborn caused by HDFN
  • Competes with mother’s Abs for the Fc receptors on the macrophages in the infant’s spleen, reducing the amount of hemolysis
• Prevention: • Selection of RBCs for Females: K-negative RBC units for women of childbearing age • Rh Immune Globulin:
  • Given to RhD-negative mothers
  • First dose: 28 weeks’ gestation, recommended by ACOG
  • Second dose: given after delivery of an RhD-positive infant (antenetal); 18 weeks of gestation (3rd trimester)
  • Recommended to give RhIG within 2 hours after delivery (Postpartum)

Autoimmune Hemolytic Anemia

• Immune hemolytic anemia - defined as shortened red blood cell (RBC) survival mediated through the immune response, specifically by humoral antibody

Adverse Metabolic Effects of Transfusion

• The chief metabolic effects of transfusion involve: • Citrate toxicity • Hyperkalemia (increased potassium)

Iron Overload

• Long term complication of frequent RBC transfusion
• Iron accumulation affects functions of heart, liver, endocrine system
• Signs and symptoms: muscle weakness, fatigue, weight loss, mild jaundice, anemia
• After 10 to 15 red cell transfusions, excess iron is present in the liver, heart, and endocrine organs
• Chronic red cell transfusion recipients have the greatest risk for developing iron overload, with a cumulative 50 to 100 red blood cell unit transfusions causing greater morbidity than the underlying anemia
• Therapy: Iron chelation agent

Transfusion-Associated Sepsis (TAS)

• Acute nonimmune transfusion reaction
• Body temperatures usually 2°C or more above normal and rigors that can be accompanied by hypotension
• Occurs when a bacteria-contaminated blood component is transfused
• Abruptness of presentation may be similar to AHTR
• Bacterial endotoxins generated during storage may contribute to TAS-related morbidity and mortality
• Diagnosis: Isolation of the same organism in both the implicated blood bag and the patient’s blood
• Treatment: Discontinue transfusion, supportive, antibiotic therapy