A doctor will usually take a throat culture to determine the presence of the streptococcal bacteria in the throat. This is done by swiping the throat area with a cotton swab that is then analyzed in a laboratory. If the strep bacteria are present, your doctor will prescribe antibiotics. If you are given antibiotics, follow the course completely to avoid future complications. It may take several days until the throat culture comes back from the laboratory, but delaying treatment for that time will not increase the risks of developing rheumatic fever.