Transfusion transmitted infections (TTI)
|2011–12 Data Summary (n=12)|
|Age||Sex||Day of Transfusion|
|0–4 years||1||Male||5||Week day||12|
|25–34 years||-||Facility Location||Time of Transfusion|
|35–44 years||1||Major City||7||Between 7am and 7pm||4|
|45–54 years||1||Inner Regional||1||Between 7pm and 7am||2|
|55–64 years||1||Outer Regional||-||Unknown||6|
|75+ years||5||Very Remote||-|
|Clinical Outcome Severity||Imputability||Blood Component|
|Life threatening||-||Possible||5||Red cells||6|
|Minor morbidity||1||Confirmed/Certain||2||Fresh Frozen Plasma||-|
|No morbidity||7||Not assessable||4||Cryoprecipitate||-|
|Outcome not available||4||Cryodepleted plasma||-|
|2012–13 Data Summary (n=5)|
|Age||Sex||Day of Transfusion|
|0–4 years||-||Male||-||Week day||4|
|25–34 years||1||Facility Location||Time of Transfusion|
|35–44 years||-||Major City||-||Between 7am and 7pm||-|
|45–54 years||1||Inner Regional||1||Between 7pm and 7am||1|
|55–64 years||-||Outer Regional||-||Unknown||4|
|75+ years||2||Very Remote||-|
|Clinical Outcome Severity||Imputability||Blood Component|
|Life threatening||-||Possible||-||Red cells||2|
|Minor morbidity||1||Confirmed/Certain||1||Fresh Frozen Plasma||-|
|No morbidity||-||Not assessable||3||Cryoprecipitate||-|
|Outcome not available||3||Cryodepleted plasma||-|
- QLD data is unavailable for 2012–13.
- Sex and facility location data is unavailable for NSW.
- Time of transfusion data is unavailable for NSW and SA.
- Data is unavailable for WA.
- Uncategorised refers to those reports where no data was provided.
The National Haemovigilance Program allows the reporting of four distinct TTI categories: bacterial, viral, parasitic and other (such as Creutzfeldt‑Jakob disease).
From 2011–12 to 2012–13, there were 17 suspected cases of TTI reported to the National Haemovigilance Program, all of which were related to bacterial infections. Only three cases reported were confirmed to be TTIs, with two related to the transfusion of platelets and one related to the transfusion of red cells. There were no reports of any TTI resulting from viral or parasitically contaminated components. There was an increase in the reports of suspected TTI from 3 in 2008–09 to 18 in 2009–10, and a decrease to 12 in 2011–12. The number of TTI dropped further in 2012–13 due to the unavailability of QLD data.
|Clinical Outcome Severity||
Excluded / Unlikely
Likely / Probable
Confirmed / Certain
N/A / Not assessable
|Outcome not available|
- Outcome severity and imputability data unavailable for QLD for 2012–13.
- Outcome severity and imputability data unavailable for WA.
In Australia, the mandatory tests provided by the Blood Service for all blood donations are for ABO and Rh(D) blood groups, red cell antibodies, and the following infections: human immunodeficiency virus (HIV) I and II, hepatitis B and C, human T‑lymphotrophic virus (HTLV) I and II, and syphilis. The Blood Service also performs a test for reported residence in, or travel to, an area with malaria. Test results are checked before blood components are released for clinical use or further manufacture. Only donations that have satisfactory blood group results, are non‑reactive for infectious disease screening and meet other defined specifications are released. If an infectious disease screening test is confirmed reactive, the donation is destroyed. The Blood Service notifies donors of any abnormal results on infectious disease and red cell antibody screening once testing is completed, usually within 2 weeks. The donor is advised about the health implications of positive tests.
The viral risk estimates presented in the following table have recently been revised based on Blood Service data from 1 January 2012 to 31 December 2013. These estimates are updated annually. The risk of viral TTI in Australia is exceedingly low. The predicted risk of transmission per unit transfused for HIV, HCV, HTLV and malaria remains substantially less than the 1 in 1 million threshold considered as 'negligible'. The risk for HBV remains very low but has increased to approximately 1 in 468,000 per unit transfused due to the introduction of a more sensible test for HBV DNA. The actual risk of HBV transmission would be predicted to have declined from the point of the new test's implementation in August 2013. To date there have been no reported cases of vCJD in Australia.
|Agent and testing standard||Window Period (Days)||Estimate of residual risk 'per unit'|
|HIV (antibody/ /p24Ag + NAT)||5.9||Less than 1 in 1 million|
|HCV (antibody + NAT)||2.6||Less than 1 in 1 million|
|HBV (HBsAg + NAT)||15.1||Approximately 1 in 468,000|
|HTLV I & II (antibody)||51||Less than 1 in 1 million|
|Variant Creutzfeldt‑Jakob Disease (vCJD) [No testing]||Not available||Possible. Not yet reported in Australia.|
|Malaria (antibody)||7–14||Less than 1 in 1 million|
- The risk estimates for HIV, HCV and HBV are based on Blood Service data from 1 January 2012 to 31 December 2013.
- The HTLV estimates are based on data for the period 1 January 2010 to 31 December 2013.
Australia and many developed countries have developed effective strategies to reduce the bacterial contamination of blood components.
In Australia, the major components of the management strategies for TTI include the pre‑donation questionnaire, identification of factors associated with TTI risk, skin disinfection prior to needle insertion, use of diversion pouches in collection kits to minimise the risk of bacterial infection and screening for antibody, antigen and viral nucleic acids. In April 2008, the Blood Service commenced pre‑release bacterial contamination screening of 100% of platelet components. As a result, there were no confirmed severe cases (such as death, life threatening or severe morbidity) related to platelet transfusion reported in Australia from 2008–09 to 2012–13.
Bacteria screening for platelet donations was rolled out in the UK's National Health Service Blood and Transplant (NHSBT) in 2011. Strategies to reduce the bacterial contamination of blood components are under continual review in the UK. There were two undetermined cases of bacterial TTIs reported to the UK SHOT Program in 2012 and no proven cases in 2013, indicating that bacterial and viral screening is effective in improving the safety of the UK blood supply.
The Blood Service provides guidance on the recognition, investigation and management of transfusion associated sepsis.
- When to suspect this adverse reaction?
Clinical features of transfusion associated sepsis suggesting the possibility of bacterial contamination and/or endotoxin reaction may include rigors, high fever, severe chills, hypotension, tachycardia, nausea and vomiting, dyspnoea, or circulatory collapse during or soon after transfusion.
In severe cases, the patient may develop shock with accompanying renal failure and disseminated intravascular coagulation (DIC). This reaction may be fatal.
Bacterial infections are reported to occur in at least 1:75,000 platelet transfusions and at least 1:500,000 red cell transfusions. Bacterial infection is more common with:
- platelets (as these are stored at room temperature)
- previously frozen components thawed by immersion in a water bath
- red cell components stored for several weeks.
- Usual causes?
Blood components may be contaminated by:
- bacteria from the donor's skin during the collection procedure
- unrecognised bacteraemia in the donor
- contamination from the environment
- contamination during the preparation of components
- contamination of ports during the thawing of frozen products in a water bath
- both gram-positive and gram-negative organisms have been implicated in transfusion associated sepsis with serious morbidity and mortality occurring most frequently with gram-negative bacteria
- organisms capable of multiplying at low temperatures and those using citrate as a nutrient are most often associated with red cell contamination, especially Yersinia enterocolitica.
Request for blood cultures from the patient, and perform culture and Gram Stain on the remainder of the blood component.
The key to diagnosing transfusion related sepsis is culturing the same organism from the patient and component.
Keep the blood bag and giving set (sealed) for further investigation.
- What to do?
Stop transfusion immediately and follow other steps for managing suspected transfusion reactions. Start broad-spectrum antibiotics once cultures have been taken, including cover for staphylococcal infections.
Provide cardiovascular support.
Send blood pack to the Transfusion Service Provider for urgent culture and Gram Stain.
Advise Transfusion Service Provider to notify the Blood Service to ensure quarantining and testing of related components from the same donation/donor.
Case study 1: Transfusion transmitted bacterial infection
A 43 year old female with acute myeloid leukaemia required platelet transfusion for severe thrombocytopenia (platelet count of 5x109/L) following a recent stem cell transplant. Approximately 30 minutes after the commencement of transfusion with a 4 day old leucodepleted pooled platelet concentrate she experienced fever, rigors, distress and vomiting. A transfusion reaction was suspected and the platelet transfusion was ceased. Blood cultures were taken and the patient was commenced on empirical antibiotic therapy with meropenem and vancomycin. The patient had been previously well and bacterial cultures performed several days earlier were negative.
A suspected transfusion transmitted bacterial infection was reported to the hospital blood bank and the Blood Service. The Blood Service immediately initiated a recall of the other components manufactured from the whole blood donations.
Gram stain of the implicated residual platelet component showed Gram positive cocci. Bacterial cultures from the patient and from the residual platelet component were both positive for Staphylococcus aureus.
The Blood Service performs bacterial contamination screening on all platelet components at 24 hours post manufacture and platelets are supplied culture negative to date. Review of the bacterial contamination screening testing of the implicated pooled platelet was negative after 7 days of culture. The red cell and plasma components from the 4 whole blood donations were able to be recalled for culture; they were all negative. The 4 donors were contacted to determine if they remained well post donation; no factors relating to bacterial infection were identified.
This is a high probability case of transfusion transmitted bacterial infection as the patient and residual platelet component cultures were both positive for the same organism following transfusion.
Platelet components are the most likely product to be contaminated due to their storage conditions at room temperature, neutral pH and high glucose concentration. There have been three cases of transfusion transmitted bacterial infection associated with platelets since the implementation of routine bacterial contamination testing of platelets by the Blood Service in April 2008. Implicated organisms included Staphylococcal species, which are well known skin contaminants, and Bacillus species which are an environmental contaminant. In all these cases the bacterial contamination screening performed by the Blood Service was negative after 7 days of culture representing a false negative culture. False negative culture results can occur because the level of bacterial contamination at 24 hours post manufacture can be very low.
This case illustrates the need for treating clinicians to consider the possibility of transfusion transmitted bacterial infection when patients develop symptoms consistent with a severe transfusion reaction during or shortly after transfusion. Suspected transfusion transmitted bacterial infections should be immediately reported to the Blood Service to allow timely recall of other implicated blood components to reduce the risk of other patient harm. A prompt Gram stain on the implicated pack will also assist in the prompt diagnosis and in the targeting of antibiotic therapy.