Final answer:
Blood culture samples should be observed for a minimum of 18 hours after starting the enrichment culture, allowing for the growth and identification of bacterial colonies.
Step-by-step explanation:
Blood culture samples should be observed for a minimum of 18 hours after starting the enrichment culture. It is preferred to observe them for one day after starting the enrichment culture.
Observing the samples allows for the growth and identification of bacterial colonies, which can provide important information for diagnosing infections. After the observation period, subculture samples can be taken for further analysis.