BACTERIAL-CONTAMINATION OF PLATELETS AT A UNIVERSITY HOSPITAL - INCREASED IDENTIFICATION DUE TO INTENSIFIED SURVEILLANCE

BACKGROUND: A cluster of bacterial contamination of platelets occurred at a university hospital in a one-month period. This unusual clusteri ng allowed us to examine the likely mechanism of contamination and cli nical sequelae. METHODS: We reviewed medical records of patients recei ving random donor platelet transfusions to determine numbers of platel ets transfused, reactions reported, and episodes of bacterial contamin ation. We also reviewed procedures at the collecting blood agencies an d the hospital blood bank. RESULTS: Four patients received bacterially contaminated platelets during June and July 1991. The rates of report ed platelet transfusion reactions increased significantly (P<0.001) fr om September 1989 through July 1991 (study period); in addition, the r ate of contamination of platelets during June and July 1991 was 23-fol d higher than during die previous 21 months (P<0.001). Surveillance me thodology changed dramatically during the study period, contributing t o the recognition of the current cluster. Pathogens isolated from the contaminated platelet pools were Bacillus cereus, Staphylococcus epide rmidis, or Pseudomonas aeruginosa in titers ranging from 10(6) to 10(8 ) colony forming units/mL. Four constituent individual platelet units identified as the probable cause of the outbreak (including one postep idemic episode) were significantly older (mean age, 4.8 days) than 106 randomly selected individual platelet units (mean age, 3.7 days; P = 0.04). Platelet pools were transfused an average of 2.5 hours after po oling. Review of blood collection and platelet preparation practices d id not identify breaks in procedure or technique that could have cause d contamination. CONCLUSIONS: Increased awareness of platelet transfus ion reactions by clinical staff and routine culturing of all platelets associated with tranfusion reactions will identify contaminated plate lets. Identification of contaminated platelets is necessary to treat a ffected patients appropriately and to determine the prevalence of and risk factors for contaminated platelets (Infect Control Hosp Epidemiol 1994;15:82-87).