Why are sore throats cultured, and why are antibiotics administered?

Why do physicians order laboratory tests? Reasons include: to make a diagnosis, to confirm a clinical opinion, insecurity, patient and family pressure, concern for liability, to guide therapy, habit.

Case in point. Throat culture.

Sore throat is one of the most common human illnesses. Most are caused by viruses. Fewer than 10% seem to be caused by Streptococcus. But around 10 to 20% of clinically well children, when cultured, have Streptococci found in their throats.

So, if the strep is there with or without symptoms, i.e., disease, where is the evidence for causation?

The standard of care for many decades has been to treat patients with sore throat who are found to have Streptococcus pyogenes with antibiotics, usually penicillin or related drugs.

But the length of time the person with sore throat is symptomatic prior to recovery is four to seven days, whether or not the strep is found and regardless of whether antibiotics are used.

So, why are sore throats cultured, and why are antibiotics administered?

Studies from the 1940s and 1950s found that the rates of acute rheumatic fever following strep throat could be cut from 2% to 1% (not to 0%) by using antibiotics.

So, antibiotics for strep throat became and remain the “standard of practice” to prevent rheumatic fever.

In 2011, the incidence of rheumatic fever in the U.S. is about 1 per 1 million strep throats. Yet, antibiotics are still commonly used to treat sore throats.

Why? Why not?

One million prescriptions for antibiotics for sore throat may prevent one case of rheumatic fever. But they may cause 2,400 cases of significant allergic reactions up to and including anaphylaxis, 50,000 to 100,000 cases of diarrhea and some 100,000 cases of skin rash.

Once an axiom, and still recommended by the American Heart Association, the use of antibiotics to treat strep throat can now be characterized a pseudoaxiom — a false premise, masquerading as truth, and passed down from generation to generation, brainlessly.

Physicians should not prescribe antibiotics for sore throats, or for that matter, acute bronchitis. Nor need they do throat cultures.