Tuesday, April 14, 2015

Recent Annals of Internal Medicine paper on the microbiology of sore throats

The lead author of the paper was Robert M. Centor, MD, the blogger at DB's Medical Rants. I found some of the findings in the study surprising. Form the paper:

Patients: 312 students aged 15 to 30 years presenting to a student health clinic with an acute sore throat and 180 asymptomatic students.

Measurements: Polymerase chain reaction testing from throat swabs to detect 4 species of bacteria and signs and symptoms used to calculate the Centor score.

Results: Fusobacterium necrophorum was detected in 20.5% of patients and 9.4% of asymptomatic students. Group A β-hemolytic streptococcus was detected in 10.3% of patients and 1.1% of asymptomatic students. Group C/G β-hemolytic streptococcus was detected in 9.0% of patients and 3.9% of asymptomatic students. Mycoplasma pneumoniae was detected in 1.9% of patients and 0 asymptomatic students. Infection rates with F. necrophorum, group A streptococcus, and group C/G streptococcus increased with higher Centor scores (P less than 0.001).

What I get from these findings is that the Centor score predicts “sick” patients with bacterial sore throats who need to be treated, but not necessarily just group A strep infections.

Why treat such patients in the first place? Thinking has shifted in the last few decades. In the days of my training it was mainly to prevent rheumatic fever. The effect of treatment on resolution of symptoms was felt to be modest at best. Over time, as rheumatic fever all but disappeared from the developed world, a more minimalist view began to emerge as illustrated in this talk from a few years ago. But in recent years we have seen the re-emergence of suppurative complications, particularly Lemierre’ssyndrome. This may be due to more restrictive antibiotic use over time or the increasing use of macrolides, which have no activity against the most likely pathogen, Fusobacterium necrophorum.

I believe the article makes a good case to treat “sick” (and presumably bacterial) sore throats in adolescents and adults based on clinical criteria (and not with a macrolide). It is becoming apparent, however, as minimalist thinking weighs in, that this view is not without controversy.

For some insightful discussions on the article see postings here and here.

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