Tuesday, November 4, 2008

Strep, antibiotics, and acute rheumatic fever

“My throat is killing me” was the first thing Mr. Jones said on seeing me in the office on Monday. He had developed a sore throat on Friday of the past week, and after suffering through the weekend and not improving, he broke down and made an appointment. While he wasn't sure what I could offer him – he didn't think he had strep throat1 - he was miserable and subconsciously hoped I might give him an antibiotic anyway and he would get better sooner. He wanted relief. Swallowing was still exceptionally painful and, while he admitted loving ice cream, he was clearly tired of eating only ice cream.

I could sense his frustration, but before falsely raising his expectations for antibiotics and disappointing him further I felt compelled to tell him that, while I would do the best I could to help him feel better, antibiotics at that point would unlikely shorten the course even if he had strep throat.

“Thanks Doc,” Mr. Jones joked, feigning for the door before sitting back down.

I explained that strep throat generally resolves on its own within five days (more than a week is unusual), and in the few studies suggesting that antibiotics can shorten the course (only by a day or two), antibiotics were started within the first forty-eight hours of symptoms.

I reassured Mr. Jones, though, that all hope was not lost and that there are in fact potential benefits to being diagnosed late with strep throat and delaying the start of antibiotics. Studies suggest that starting antibiotics late, at least two days after the onset of symptoms, is actually associated with a much lower risk of its recurrence during the same strep season.

“So I'm better off not having started antibiotics?” Mr. Jones asked.

While guidelines do not recommend delaying antibiotics in strep throat, the theory behind doing so is to provide the body the time to better develop antibodies to the bacteria, a stronger immune reaction, and memory for protection the next time the person is exposed.

“Why bother then to take antibiotics at all?”

As discussed, antibiotics started early have the ability to shorten the course of strep throat. Antibiotics also decrease the transmission of strep throat to close contacts, including family members. Studies performed with penicillin (still considered the first line treatment for strep throat), show that patients are minimally contagious within twenty-four hours of starting antibiotics.

“Sure, but...”

The main reason for administering antibiotics in strep throat, however, is to prevent acute rheumatic fever. Acute rheumatic fever is an inflammatory, autoimmune (the body attacking itself) reaction that can develop in untreated strep throat. “…the immune system [normally] works by recognizing constant and variable patterns on ‘foreign’ materials and microbes that don’t originate in the host and targeting these invaders and the cells that harbor them for destruction and elimination.” (from A.B.’s entry “Biology of a Cure for HIV,”) In acute rheumatic fever the immune system confuses the patterns on the bacteria with those on tissues in the body, including the heart. Long term damage to the heart and heart valves are potential, severe complications of acute rheumatic fever. (The fear with a vaccine against strep throat, that the body will attack itself, is a large reason why such a vaccine is not yet available.)

Acute rheumatic fever is thankfully rare in the United States although it is more common worldwide. It primarily affects children between 5 and 15 years of age, but can infrequently strike adults, particularly those previously affected. Some people, due to the genetics of their immune systems, are more predisposed to rheumatic fever in the setting of certain ‘rheumatogenic’ strains of strep bacteria. (The reason for the age discrimination, therefore, may be that most adults predisposed to acute rheumatic fever have already revealed themselves as such as children.)

“Sounds scary, but you just said acute rheumatic fever is rare in the U.S., especially for an adult, and that strep throat will go away in a few days anyway. Again, I'm confused, why should I bother with antibiotics?”

Given the severity of potential complications of acute rheumatic fever, the benefits of antibiotics are thought to outweigh the risks. Amazingly, starting the antibiotics even up to nine days after the onset of symptoms (and by then the sore throat has likely already resolved) still prevents acute rheumatic fever. A study conducted on military recruits discovered the phenomenon.

There is the potential for other rare complications of strep throat in adults, such as an extension of the infection, scarlet fever and streptococcal toxic shock syndrome.

“Yes, but don't forget I'm not so sure I have strep,” Mr Jones added.

After discussing further with Mr. Jones his symptoms, examining him and ruling out potential complications, I had to agree that I didn't think he had strep throat. Not unexpectedly most sore throats are viral, and strep throat makes up maybe less than 10% (one in ten) of sore throats that present to doctors. Do we give antibiotics to everyone? (for further reading on the forces at play in administering antibiotics, "Antibiotics and the common cold")

Mr. Jones, however, had enough symptoms that I couldn't be sure that he didn't have strep throat, and I recommended we evaluate further. Even the most experienced doctors are notoriously unable to reliably diagnose who has strep throat by only history and exam.

How then do doctors evaluate sore throats and determine who has strep and who needs antibiotics? A blog entry for another day, but Mr. Jones ended up on throat culture having strep throat.


1Strep throat (streptococcal pharyngitis): an infection of the throat by a particular type of bacteria, Group A streptococcus.

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