How strep throat is diagnosed.

DEAR READERS: In yesterday's column, I responded to a reader's question about acute pharyngitis -- inflammation of the throat caused by infection with bacteria or viruses. I was taught that diagnosing and treating a patient with a sore throat was not complicated: The sore throat was caused either by Group A streptococcus ("strep," a kind of bacteria) or by a virus. If a throat culture showed strep, you treated it with penicillin. Simple. But in my view (some colleagues disagree), it's not that simple. The risk from an untreated infection with Group A strep is much lower today in the United States than it was 70 years ago. That means that the value of treatment is reduced. But the chance of side effects from the treatment -- antibiotics -- is not reduced.