How to culture units involved in a transfusion reaction investigation

A Blood Bank Supervisor at a hospital in Ohio asks for advice on how to culture units involved in a transfusion reaction investigation. Some questions he has are as follows:

1. How should the sample be obtained from the bag (including disinfection methods)?
2. What media should be set up?
3. Should the culture be set up on plates or using blood culture bottles (or both)?

They recently had a case where blood culture bottles were used for working up a platelet reaction. The bottles were positive for Streptococcus salivarius and for Micrococcus. The donor center requested the product bag, which had negative culture results.

The following comments have been submitted in response.

ADDENDA Feb. 15, 2010

1. A highly experienced physician in North Carolina reports that in his practice, bacterially contaminated platelet products are typically suspected in two settings:
   1. the result of either visual examination of the product bag
      
      
   2. an adverse transfusion reaction suspected of being related to bacteria

In the majority of cases, identification of any bacteria will be performed in either a hospital clinical microbiology laboratory or a commercial laboratory. Standard operating procedures should be established for the handing of a suspected contaminated unit. Methods will vary and depend on the systems already in place at those facilities for routine bacterial identification. Use of a culture system that is FDA cleared for the quality control of platelets is preferred, but is not always readily available in a hospital setting. The use of a liquid culture system and or an agar based system are both capable of identifying bacteria of clinical significance. Ideally, samples should be investigated in replicates and grown in both an aerobic and an aerobic environment. The presence of multiple organisms suggests contamination during the culture process. The vast majority of confirmed contaminated platelet bags only grow one organism. When in doubt repeat the culture. The greater the volume that is cultured, the greater the sensitivity. Sampling of the bag should be performed aseptically. This can be accomplished with a sterile connection device or with the use of a sample site coupler. Septums and culture bottle caps should be cleaned with alcohol, however, some labs might also choose to employ either tincture of iodine or chlorhexidine followed by an alcohol wipe.

ADDENDA March 8, 2010

2. A Canadian colleague reports that the Canadian Public Health Agency has provided guidelines on when and how to culture. These guidelines can be viewed HERE.

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