Culture-Based Bacterial Detection Methods

Although culture remains the gold standard for bacterial detection and identification, its sensitivity in detecting bacterial contamination of blood products is affected by numerous factors including the growth characteristics of the contaminating organism, timing of specimen procurement, specimen volume, and degree of initial bacterial contamination. Numerous studies of culture-based detection systems have been performed. These have demonstrated that the timing of specimen collection is critically important to test sensitivity: cultures obtained on the day of collection invariably fail to demonstrate bacterially contaminated units that could develop clinically significant overgrowth during storage. Because of the small sample volume normally obtained, reliable detection requires time for the organisms to proliferate to levels at which sampling would include adequate numbers of the organism. Currently, most detection system manufacturers recommend at least a 24-hour incubation period prior to sampling.