Strep throat spreads through close contact with a sick person. To be sure that a person has strep throat, a test called a throat culture is needed. Even without this test, a likely case of strep throat can be known because of the symptoms. Antibiotics can help a person with strep throat. Antibiotics are medicines that kill bacteria. They are used mostly to prevent complication such as rheumatic fever rather than to shorten the length of sickness.