The symptoms of a viral infection and a bacterial infection may be very similar. Some clinical guidelines suggest that the cause of a sore throat is confirmed prior to prescribing antibiotic therapy and only recommend antibiotics for children who are at high risk of non-suppurative complications. A group A streptococcus infection can be diagnosed by throat culture or a rapid test. In order to perform a throat culture, a sample from the throat (obtained by swabbing) is cultured (grown) on a blood agar plate to confirm the presence of group A streptococcus. Throat cultures are effective for people who have a low bacterial count (high sensitivity), however, throat cultures usually take about 48 hours to obtain the results.