The value of autopsy microbiology

Blood and marrow cultures as indicators of bone contamination in cadaver donors

Of 770 cadaver bone donors evaluated, 185 had positive blood or ilium marrow aspirate cultures. These donors were matched with an immediately preceding or subsequent donor with negative blood and marrow cultures. Donors with cultures positive for skin contaminants only were not included in the study. Samples of the blood and bone marrow, surface swab cultures, and cultures of tissue samples of the excised skeletal tissues were obtained at the time of tissue procurement. There were 88 (48%) donors with similar microbial species recovered from the blood and ilium marrow. These donors had a higher rate of positive bone cultures (30%) than donors with positive blood (15%) or marrow cultures only (11%) or donors with negative blood and marrow culture results (7.3%). Recovery of similar isolates from the blood and marrow had a positive predictive value of 72% for the isolation of the same types of organisms from the excised tissues compared with 38% for donors with positive blood cultures only. Although not absolute predictors of tissue contamination, combined blood and bone marrow cultures were more reliable indicators of tissue contamination than blood cultures alone.