Understanding Blood Culture Collection and Processing

In adults, it is recommended to collect 20 to 30 mls of blood per culture set, ideally distributing about 10 mls into multiple bottles. The common practice of spacing blood culture draws lacks strong supporting evidence, and recent guidelines, including those for endocarditis, reflect this. For pediatric cases, collection should be based on weight, suggesting one to four percent of total blood volume, with pediatric bottles limited to five mls per bottle. Once blood cultures reach the laboratory, automated instruments process them, scanning barcodes to link patient information. Cultures are usually monitored for growth for up to five days, using systems that detect carbon dioxide production as bacteria grow. Techniques differ, with some labs employing fluorometric and others using colorimetric reactions to indicate positivity. Different types of bottles are employed, such as anaerobic and pediatric options, and special considerations must be made for interpreting pediatric bottle results due to potential debris complications.