Blog | Friday, February 28, 2014

Cognitive errors in considering pharyngitis

Since prior to my entrance to medical school, common wisdom for treating sore throats involved the prevention of rheumatic fever. Since group A strep pharyngitis is the cause of most acute rheumatic fever, all efforts have focused on treating group A strep. Studies in the 1950s showed that penicillin treatment decreased the probability of patients developing rheumatic fever.

The prevailing theory in the 50s and 60s, that we should diagnose group A strep and ignore all other pharyngitis etiologies, persists to the present. Guidelines focus on the group A strep diagnostic problem. Articles investigating inappropriate use of antibiotics for upper respiratory infections lump pharyngitis in with bronchitis and other upper respiratory complaints. Those studies criticize physicians who provide antibiotics to patients who do not have a positive test for group A strep (either a rapid test or a culture).

The prevailing construct assumes that sore throats are sore throats regardless of age. Many pharyngitis experts are actually streptococcal experts who focus on group A strep. Many pharyngitis experts are pediatricians who focus on pre-adolescent pharyngitis. They hold any other potential bacterial pathogen to a higher standard of proof that group A strep.

When one carefully reads the pharyngitis literature, especially the literature on complications and other bacterial pathogens, one finds an interesting observation. Pre-adolescent pharyngitis actually is predominantly group A strep or viral, but adolescent (here I will use a loose definition of ages 15-30) pharyngitis has more varied bacterial etiologies.

We published the first article describing group C streptococcal pharyngitis as endemic and symptomatic in adolescents. Multiple other articles, primarily from college student health, have also documented this finding. The best randomized controlled trial of penicillin in adults found that group C pharyngitis patients had 1 day less symptoms when treated with penicillin.

More recently Fusobacterium necrophorum is gaining attention, primarily because of outstanding work in Denmark and England. I recently published an article that uses published data to estimate that the complications (peritonsillar abscesses and Lemierre syndrome) from this organism are more dangerous and more devastating than those from group A strep in this country.

Lemierre syndrome is much more common as a complication of adolescent pharyngitis than is acute rheumatic fever. It is deadlier and causes significant disabilities in some patients.

Yet current guidelines lump all pharyngitis into one bucket and only address group A streptococcal pharyngitis. Rapid tests only detect group A pharyngitis. These guidelines now mention group C and Fusobacterium but opine that we do not have enough evidence to worry about them.

Obviously I argue that we cannot wait for complete evidence in addressing adolescent Fusobacterium pharyngitis. Lack of evidence for addressing adolescent pharyngitis differently is not equivalent to evidence that we should not treat adolescent pharyngitis differently.

Not all medical questions have sufficient evidence to make good decisions. We physicians must purposefully extrapolate from what we know about pathophysiology and then make rational decisions. I submit that if we knew that an adolescent had Fusobacterium pharyngitis we would have a logical and defensible reason to treat with antibiotics, specifically penicillin. But we do not have a readily available diagnostic test for Fusobacterium necrophorum because it is a difficult to grow anaerobic bacteria.

So we must ask ourselves how much “overtreatment” with penicillin is tolerable to prevent 1 patient developing a peritonsillar abscess or worse yet Lemierre syndrome. Very few organisms show sensitivity to penicillin in 2014. Fortunately strep (both group A and group C) and Fusobacterium remain sensitive.

Current criticism of treating adolescent pharyngitis based on signs and symptoms alone represents (in my mind) a cognitive error. Our lack of prospective studies definitively answering this question should not exclude a logical approach to trying to prevent a rare but extraordinarily serious infection.
