Contamination of Cellular Blood Products
Nester, M.D. and Ileana Lopez-Plaza, M.D.
sepsis from a contaminated blood component is a rare but potentially serious
complication of blood transfusion.
Timely recognition and appropriate management of a septic transfusion
reaction can be critical to the well being of the patient.
Several precautions are routinely taken to minimize the
risk of collection or transfusion of a bacterially contaminated blood
product. Standard procedures performed include:
assessment of the donor’s health by history and physical
examination; sterilization of the venipuncture site; sterile collection and
processing techniques; and a visual check of the product by blood bank
personnel prior to issuance of the product.
Despite these measures, bacterial contamination of packed red cells
and platelets does occasionally occur.
estimated rate of bacterial contamination of a unit of packed red blood
cells ranges from 1 per 31,000 to less than 1 per 1 million units (1,2).
Red cells are stored at 1- 4°C
for up to 42 days; organisms that survive at cold temperatures in the
presence of heme and dextrose are the usual pathogens.
Yersinia enterocolitica is
the most common organism associated with septic reactions to red cells.
Several case reports of septic transfusions due to Yersinia
enterocolitica have shown asymptomatic blood donors to be the most
likely source. Organisms which
survive in red cells are most often gram negative types which can produce
endotoxins. Besides Yersinia,
these include Serratia, Pseudomonas,
and Enterobacter species.
Because of these endotoxins, transfused patients may rapidly develop
septic shock. Twenty-one episodes of transfusion-related sepsis reported
between 1987 and 1997 were due to Yersinia
fatality rate in these cases was 52%. Other
organisms reported in cases of red cell transfusion-related sepsis, such as Serratia liquefaciens, have an even greater fatality rate.
key point to remember is that autologous donation has the same risks of
bacterial contamination as allogeneic donation. The literature reports a few cases of Yersinia sepsis in patients who donated autologous blood and then
became septic with transfusion of the product (3). In one case, the patient
was hospitalized in the interim between blood donation and surgery with
Yersinia sepsis. Because the
transfusion service was not informed of this, the unit was later transfused.
If a patient has a known episode of bacteremia, sepsis, or complications
from an ongoing infection and has recently donated autologous blood for an
upcoming surgery, the blood bank should be notified so that the unit of
blood may be appropriately evaluated and, if necessary, discarded.
rate of bacterial contamination from a platelet product is estimated to be 1
in 1000 to 1 in 3600 units (1,4), while the risk of symptomatic sepsis or
septic complications due to bacterial contamination of platelets is between
1 in 2000 and 1 in 12000 random donor units (2).
Fatalities due to bacterial contamination of blood components occurs
three times more often with a platelet product than a unit of red cells (2).
Random donor platelets have a statistically greater risk of
contamination both because the product is pooled from four or more donors,
and because the pooling process requires an open system. Platelet products
are stored at room temperature (20-24°C)
for up to 5 days. Organisms which proliferate in platelets are most often
skin commensals such as Staphylococcus
epidermis and Bacillus
species. These organisms may be
acquired by skin plugs that are collected at the time of venipuncture into
the platelet product. Gram negative organisms have been reported and include
Klebsiella pneumoniae, Serratia
marcescens, Salmonella species, Escherichia
coli and Pseudomonas aeruginosa.
Contamination by these organisms is most often due to asymptomatic
bacteremia in the donor. Fatalities due to platelet contamination implicate gram
positive and gram negative organisms in relatively equal numbers.
Recognition and management of a
transfusion reaction due to bacterial contaminated blood product
The severity of the
reaction may depend on several factors, including the organism involved and
the ability to produce endotoxin, the immune status of the patient, and
whether or not antibiotics are already being administered. In general, reactions to contaminated red cells tend to be
rapid and severe. The patient may develop circulatory collapse and signs of
endotoxic shock during or immediately following the transfusion.
Reactions from contaminated platelets can be much more variable in
their severity, and may manifest during the transfusion, or up to 4 hours
after the unit has been transfused.
Any patient who has a reaction
during infusion of a blood product that includes fever (often greater than 2°C
above baseline), rigors, and/or nausea should be evaluated, and the
transfusion should be stopped. Vomiting or diarrhea may be present.
Dyspnea or cyanosis may rarely be seen.
Hypotension may accompany the reaction.
The patient’s vital signs should be recorded frequently, with
monitoring for the development of oliguria or hypotension.
The blood product and appropriate samples should be sent for a
transfusion reaction evaluation. The
degree of severity of the reaction, as well as the changes in vital signs,
should be conveyed to the blood bank. Such communication will assist the
transfusion medicine physician in deciding if bacterial cultures of the
blood product are warranted, and in guiding the clinician in appropriate
management of the transfusion reaction.
If evidence of circulatory
collapse is present, intravenous hydration with normal saline should be
maintained at a rapid rate to support renal perfusion.
Cultures on the patient’s blood should be drawn, and then
antibiotic coverage for both facultative gram negative and gram positive
organisms should be initiated as soon as possible.
The patient may need to be transferred to an intensive care unit for
close monitoring and blood pressure support.
Obtaining a baseline PT, PTT, fibrinogen, and platelet count is
appropriate, and frequent monitoring of these parameters may be necessary if
signs of DIC develop. All
supportive measures used for a patient in septic shock should be initiated.
Past and future
efforts to prevent transfusion of a bacterially contaminated cellular
Many studies have been undertaken to determine if a test
could be used to consistently detect bacterial contamination of a cellular
blood product. Tests evaluated
have included gram stain and culture, indicator strips to detect changes in
glucose and pH within individual units, endotoxin assays, and
chemiluminescence –linked universal bacterial rRNA probes.
Each of the tests has been found to have limitations, with regard to
one or more of the following: sensitivity, rapid availability, ease, and
cost (4). Use of
antibiotic-labeled probes and microvolume fluorimetry to detect bacteria in
blood products is still in experimental stages, but may prove useful in the
More recently, attention has been
focused on ways to reduce or eliminate bacteria from a cellular blood
product. A simple method
currently used in Europe is to divert the first 30 mL of a collection into a
sampling pouch. Preliminary
data suggest a 75% reduction in risk of bacterial contamination using this
method (6). Psoralen compounds (particularly S-59) and long-wavelength ultraviolet light,
when used in combination, appear to result in photochemical inactivation of
viruses and bacteria. Initial
studies with platelets indicate that the treatment effectively inactivates
high doses of bacteria, and does not significantly compromise in vitro or in
vivo platelet function (7). A
multicenter clinical trial with this treatment is ongoing. In Europe,
researchers are investigating whether methylene blue derivatives will prove
to be suitable photodynamic antimicrobial agents in blood products.
Although the technology of photoinactivation is still in an
experimental phase, it may ultimately eliminate the risk of bacterial
contamination of a cellular blood product, and supplant the need for
detection. Until that time,
however, ongoing recognition and management of a septic transfusion reaction
is the most powerful tool in minimizing the morbidity from such an
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Institute For Transfusion Medicine