Background: Our blood center began routine screening of Single Donor Platelets, Pheresis (SDP) for bacteria on December 15, 2003 using aerobic culture bottles with the BacT Alert® 3D System. SDP units are held a minimum of 24 hours prior to sampling and then are labeled and released while the culture bottles are incubated for five days.
Case Study: A 77-year old female donated a SDP and concurrent Plasma. Pre-donation platelet count was 328 x103/μL and hemoglobin level was 15.0 g/dL. Collection was uneventful with no error codes received from the equipment. Sample for was obtained on day-1, inoculated in an aerobic culture bottle, and incubated. The inoculated bottle showed growth of bacteria at 19.6 hours of the culture period. SDP had not been distributed and was recultured. Repeat culture was performed on day-2 and it also showed growth at 13.4 hours. The concurrent plasma was thawed and cultured and did not show any growth. A gram stain of the positive culture bottle revealed gram-positive cocci in chains that were later identified as Streptococcus viridans. The donor was notified of the culture results. The donor denied any skin rash or infection, sore throat, fractures, heart or lung conditions. She denied fever, chills or any acute illness. Her chronic conditions included hypertension treated with Lisinopril. She was also receiving thyroid replacement for hypothyroidism and Asiphex for gastro esophageal reflux disease (GERD). She denied any GI or GU symptoms. The culture results were mailed to the donor so that she could share them with her personal physician. The donor is a frequent apheresis donor and has donated 54 SDPs over the past seven years. Three previous donations immediately prior to the current donation were found to be negative after 5-day culture. On day 18, the donor felt weak and tired but without fever or other symptoms and she went to see her physician. The physician obtained a blood culture that grew bacteria the next day. Further testing identified the organism as Streptococcus salivarius, a viridans species. Donor was then hospitalized for five days to begin intravenous Ceftriaxone. Further antibiotic treatment was given at home via a peripherally inserted central (PIC) line. The donor had a three-year history of a benign heart murmur. The PIC line was removed with the completion of the antibiotic treatment on day 65. The donor remained asymptomatic throughout the treatment. Two trans-thoracic and two trans-esophageal echocardiograms were negative for bacterial endocarditis. However, mild idiopathic hypertrophic subaortic stenosis was discovered. The donor had dental work done two months prior to the time the bacteremia was found. However, she had one SDP donation that was culture negative after the dental work. The cause of the donor’s bacteremia remains obscure.
Discussion: Although the screening of Platelets, Pheresis is for the protection of the patient who will receive the product, this case shows that the detection of the bacteria also may benefit the donor. In our case, aymptomatic Streptococcus viridans bacteremia would not have been recognized if it were not detected by culturing her SDP. The donor was grateful for the information that lead to the early detection of blood stream infection that resulted in successful treatment. The donor continues to ask that she be able to donate when eligible.