The strept or other bacteria can cause infection of the throat (called as pharyngitis). Symptoms of tonsillitis and pharyngitis are same. Your physician can do strept test and further better test is throat swab (culture test). Culture test is able to identify all the bacteria including strept, so it is superior than the strept test. Though the report of culture test can take 72 hours to come.
Please feel free for your follow up questions.