He looked sick—really sick. He was sitting on a stretcher in an ER bay, flushed, breathing a bit quickly, but his youth seemed to compensate for the acuity of his illness, and he didn’t feel nearly as bad has he looked. His fever was 104, his systolic blood pressure was in the 90s, his heart was racing. He’d had a sore throat recently, and rather than getting better started to feel weak, tired, and feverish. His mom finally dragged him in when he wouldn’t stop shivering. His blood work was not normal, and his chest X-ray looked as if he’d inhaled a box full of cotton balls.
Sore throat is a common problem in primary care. Most of the time it is caused by one of the many cold viruses that continuously circulate, but there’s a catch. Strep throat is an infection caused by caused by a bacterium called group A beta-hemolytic streptococcus (GAS). It can lead to a number of complications, the most important of which is rheumatic fever. Rheumatic fever has a mortality rate approaching 5% and used to be a common cause of severe heart valve disease in the US, but has become much more rare with the use of antibiotics to treat strep throat.
Strep throat with white exudates on the tonsils (public domain)
Deciding whether or not a patient with a sore throat has strep is one of the daily problems of primary care medicine. Rapid strep tests aren’t all that good. Cultures are very good but take time, and in an acute care setting you often can’t count on a patient to follow up on test results. For a couple of decades, clinicians have used the Centor criteria as a decision tool. It’s not a perfect tool, but if a patient meets all four criteria, they are about 56% likely to have strep on a culture, and if they only have one, they only have a 6.5% chance of having strep. This decision tool helps avoid the overuse of antibiotics in patients who are unlikely to have a bacterial infection.
Unless we’re wrong.
It turns out that the Dr. Centor is a well-known medical blogger, but more important, he hasn’t stopped looking at the sore throat problem. He has just published a report in the Annals of Internal Medicine looking at the microbiology of sore throats, and the results may have a significant impact on how we approach the problem.
The patient I told you about at the beginning of this post did not have strep. He grew Fusobacterium necrophorum from his blood. This anaerobic bacterium had made its way from his throat into his internal jugular vein and from there had spread to several of his other organs. He was a very, very ill young man (but he did fully recover). Septic internal jugular thrombophlebitis due to F. necrophorum is known as “Lemierre’s syndrome” and was thought to be relatively rare, partly due to the heavy use of empiric antibiotics for sore throats. It has been suggested that as we have become more conservative with antibiotic use, Lemierre’s has become more common. Whether this is true or not, Dr. Centor’s report suggests that the risk of Lemierre’s may be much higher than we think.
Centor looked at a number of studies of adolescents and young adults with sore throats and found that a significant percentage of people who tested negative for strep had F. necrophorum in their throat. In fact, it appears that infection with F. necorphorum may be as common as strep in this group.
There are a number of unanswered questions, including what the real risk of Lemierre’s may be, but these findings may end up having significant clinical implications. We don’t have any rapid tests for this bacteria, so we have to evaluate risk and use the available data to make intelligent clinical decisions. Strep is most often treated with penicillin and related drugs. These same drugs are generally effective against F. necrophorum, but it is not uncommon to use macrolides such as azithromycin (Zithromax) as an alternative agent. These drugs do not kill F. necrophormus and I’m going to think twice before using them as an alternative to penicillin.
The evolving story of sore throats is a great example of the changing nature of medical science, and the translation of research into clinical practice. This is what makes it fun.
Centor RM (2009). Expand the pharyngitis paradigm for adolescents and young adults. Annals of internal medicine, 151 (11), 812-5 PMID: 19949147
Centor RM, Witherspoon JM, Dalton HP, Brody CE, & Link K (1981). The diagnosis of strep throat in adults in the emergency room. Medical decision making : an international journal of the Society for Medical Decision Making, 1 (3), 239-46 PMID: 6763125
Bliss SJ, Flanders SA, & Saint S (2004). Clinical problem-solving. A pain in the neck. The New England journal of medicine, 350 (10), 1037-42 PMID: 14999116