Is it too late to take blood cultures to detect infection once the administration of antibiotics has commenced?

Possibly: If you have been adequately treated for a bacterial infection with an antibiotic that was sensitive to that infection it may be difficult to grow out. If you continue to run a fever, feel ill or had a viral infection than a culture may be helpful. Hospitalized patients with infections get blood cultures if the temperature is over 102 or per the infectious disease protocol of the hospital.Good luck

Blood Cultures: Wow, looks like you are very ill right now so I suspect someone else is asking this question. Blood cultures are certainly not as accurate once antibiotics have been started and nothing may grow. Cultures can be done in what are called resin bottles that will help take the antibiotics out and let bacteria grow. I suspect the patient was too ill and antibiotics needed to be started right away.