In this video, Dr. Narendra Saini, MBBS, MD, Internal/General Medicine, will discuss about when is the blood culture necessary. The blood culture should be taken as soon as possible in case of infectious disease. If the infectious disease is of bacterial origin then blood culture is very necessary. After the report of blood culture, the preferred antibiotics are given. Dr. Saini also explains that many times antibiotics are already prescribed and blood culture is advised. Do not switch the antibiotics before the blood culture reports. The fundamental rule for blood culture in any infectious disease is to prescribe antibiotics on the basis of blood culture reports.