|Year : 2012 | Volume
| Issue : 2 | Page : 212-214
Detection of bacterial growth in blood components using oxygen consumption as a surrogate marker in a tertiary oncology setup
PD Chavan1, VG Bhat2, S Ojha3, RS Kelkar2, SB Rajadhyaksha3, AN Marathe4
1 Laboratory Manager, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410 210
2 Composite Lab, ACTREC, Department of Microbiology, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410 210
3 Transfusion Medicine, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410 210
4 Blood Bank Officer, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410 210
|Date of Submission||10-Jan-2012|
|Date of Acceptance||04-Mar-2012|
|Date of Web Publication||28-May-2012|
V G Bhat
Composite Lab, ACTREC, Department of Microbiology, ACTREC, Tata Memorial Centre, Kharghar, Navi Mumbai 410 210
Source of Support: None, Conflict of Interest: None
Microbiological contamination of blood and blood products is a well-recognised transfusion risk. This study was performed in the blood bank of our oncology centre, with an objective to detect bacterial contamination in our blood products using oxygen consumption as a surrogate marker [Pall Enhanced Bacterial Detection System (eBDS)]. Results revealed that the percentages of failed units were 1.16% for random donor platelets (RDP), 0.81% for single donor platelets (SDP) and 2.94% for packed red blood cells (PRBCs), of which one RDP and one SDP grew coagulase-negative staphylococcus, while one PRBC culture grew Gram-positive bacilli.
Keywords: Bacterial contamination, eBDS, platelets, red cells
|How to cite this article:|
Chavan P D, Bhat V G, Ojha S, Kelkar R S, Rajadhyaksha S B, Marathe A N. Detection of bacterial growth in blood components using oxygen consumption as a surrogate marker in a tertiary oncology setup. Indian J Med Microbiol 2012;30:212-4
|How to cite this URL:|
Chavan P D, Bhat V G, Ojha S, Kelkar R S, Rajadhyaksha S B, Marathe A N. Detection of bacterial growth in blood components using oxygen consumption as a surrogate marker in a tertiary oncology setup. Indian J Med Microbiol [serial online] 2012 [cited 2019 Jun 20];30:212-4. Available from: http://www.ijmm.org/text.asp?2012/30/2/212/96695
| ~ Introduction|| |
Microbiological contamination of blood and blood products is a well-recognised transfusion risk contributing to the morbidity and mortality associated with blood transfusions.  The risk of transmission of bacterially contaminated blood components is manifold higher than the combined risk of common transmissible viruses. 
While interventions in the form of improved technology, refrigeration/freezing of blood products, improved phlebotomy practices, etc. have generally reduced the incidence of bacterial contamination in blood components,  however, it still remains an important concern, with an overall prevalence ranging from 0.04 to 2.0%.  It is particularly relevant in platelets because of the possibility of even small numbers of bacteria multiplying to clinically significant levels during the storage period of 5 days at room temperatures of 20-24°C.  The infectious risk from transfused platelets has been estimated to range from 1 of 2000-3000 whole-blood derived, random donor platelets (RDP), and apheresis-derived, single donor platelets (SDP). , Significant clinical events have been estimated to occur in approximately 1 in 25,000 for platelet transfusions and 1 in 250,000 for red blood cell (RBC) transfusions,  and this may be an underestimation. Mortality rates associated with bacterial contamination of platelets have ranged from 1 in 17,000 for RDP to 1 in 61,000 for SDPs.  Bacterial contamination may be introduced into blood products through skin flora during collection, or during manipulations while processing, or occasionally may be present in donor blood.  Bacteria implicated in infections associated with platelet and red cell transfusion include coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus spp., Bacillus spp. and propionibacteria among Gram-positive bacteria, and Serratia spp., Yersinia More Details enteocolitica, Acinetobacter spp., Pseudomonas spp. and members of the Enterobacteriaceae group. 
This study was performed in the blood bank of our oncology centre with a haematopoietic stem cell transplant unit. The objective of this study was to detect bacterial contamination in our blood products - RDPs, SDPs and packed red blood cells (PRBCs) - using oxygen consumption as a surrogate marker. This in turn would enable us to reduce the incidence of transfusion transmitted infections in a setting such as ours with immunocompromised transplant patients.
| ~ Materials and Methods|| |
RDPs, SDPs and PRBCs meant for transfusion in haematopoietic stem cell transplant patients were collected between October 2008 and July 2010 at the Department of Transfusion Medicine and tested by the Pall Enhanced Bacterial Detection System (eBDS). The system uses an oxygen analyser to measure the percentage of oxygen in the headspace gas of the sample pouch. If bacteria are present in the blood component sample, then their metabolic activity and proliferation during incubation results in a measurable decrease in the oxygen content of the sample and the air within the sample pouch. The system recommends use of apheresis and whole-blood derived platelets and leucocyte-reduced red cell components for testing. Briefly, the method was as follows: The representative sample was collected and filled up to the mark on the testing pouch using sterile connecting device (SCD) and sealed. The sample pouch was placed on the platelet agitator horizontally at 35°C in the incubator for 30 h. The percent O 2 in the headspace of the sample pouch on oxygen analyser was measured after 30 h. Results were interpreted by the system as PASS or FAIL based on the level of oxygen consumption after 30 h of incubation at 35°C.
All failed units were then tested for bacterial culture on Bactec 9050 system (BD diagnostics, Franklin Lakes NJ, USA). All failed platelet and PRBC units were quarantined. Confirmed culture positives were discarded and culture negatives taken back on stock.
| ~ Results|| |
A total of 258 RDPs, 246 SDPs and 272 PRBCs were tested by using eBDS (M/S PALL Life Sciences - Pall Medical, Portsmouth, England). The results are displayed in [Table 1].
|Table 1: No. of blood components tested with failed units and units positive for bacterial growth|
Click here to view
Percentages of failed units were 1.16% for RDPs, 0.81% for SDPs and 2.94% for PRBCs. Of the three RDPs which failed eBDS, two failed to show any growth on bacterial culture and one RDP (0.38%) grew coagulase-negative Staphylococcus.
Similarly, of the two SDPs which failed eBDS, one SDP (0.4%) had shown contamination with coagulase-negative Staphylococcus and the other one showed no growth. Only one PRBC (0.36%) out of eight PRBCs sent for culture showed contamination with Gram-positive bacilli, which was not identified, and the other units did not grow bacteria.
| ~ Discussion|| |
Various methods have been used for the detection of bacterial contamination in blood products. These include Gram stain, pH testing, automated blood culture systems like Bactec, BacTAlert and the VersaTrek systems and the Pall eBDS systems amongst others , While the most definitive marker indicative for bacterial contamination would be isolation of the microorganism by bacterial culture, systems like the eBDS could be useful where facilities for culture may not be present, and also because the system is small, compact and portable. In addition, the test procedure is cheaper and does not require a high level of technical expertise as compared to microbiological testing. We found higher rates of positivity in the eBDS systems as compared to the other studies. One study by Blajchman et al.  found a contamination rate of 0.07% for RDP and 0.23% for SDPs, whereas another study by Barrett et al.  found contamination rates of 0.03% for SDPs and 0.003% for PRBCs. So, there was some disparity with respect to platelets and a wider disparity with respect to PRBCs in our study [Table 1]. This could be attributed to the fact that our RDPs and PRBCs are not leucodepleted at source as compared to universally leucodepleted products used in other studies.  Unlike RDPs and PRBCs, all SDPs are leucodepleted at source and thus are less prone to false-positive results. In the Indian setting, probably due to cost restraints, universal leucodepletion at source is not a general practice and could be the major reason for false positivity. The organisms isolated in our study, viz. coagulase-negative staphylococci and Gram-positive bacilli, were similar to the spectrum of organisms isolated in other studies. 
| ~ Conclusion|| |
The eBDS system may be used as a screening method for detection of bacterial contamination in SDPs and RDPs; however, it is associated with false positivity. Further studies with a larger sample size are warranted to assess the usefulness of the eBDS system to detect bacterial contamination in blood components.
| ~ References|| |
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