Frequently, I see patients who believe they know their diagnosis long before they hear it from me.  One of the most common self-diagnoses comes from parents who bring their sore-throated children in to see me.  I start most of my office visits by asking, “What’s going on?”  I hope that this question will elicit a response consisting of a list of symptoms which allows me to compile a mental picture of possible diagnoses.  When a child with a sore throat sits in front of me, though, the parent often answers my question with, “I think she’s got strep throat.”  Sometimes this parent gets it right; sometimes this parent gets it wrong.  I need more information to decide.
Knowing a little more about strep throat can help enlighten us.  The bacteria causing strep throat has the name Streptococcus pyogenes, which becomes “strep” when shortened.  (As an aside, we scientists and physicians feel very smart when we get to use fancy names, like Streptococcus pyogenes, derived from old or obsolete languages.  That’s why, for no apparent reason, we call the belly button the “umbilicus” and use the word “pruritic” for itchy.  Any yahoo off the street can say “itchy belly button,” but it sounds super smart to say “pruritic umbilicus,” even though it means exactly the same thing.  But I digress.)
Strep throat occurs when the bacteria Streptococcus pyogenes gets in the back of throat and grows.  Most people who have strep got it from someone else.  Strep throat has three classic signs: fever, a red throat, and swollen lymph nodes in the front of the neck.  Those with strep throat usually have a headache and poor appetite also.  In general, those with strep do not exhibit any of the following symptoms: cough, runny nose, itchy eyes, or swollen lymph nodes in the back of the neck.  These are all symptoms of a viral infection.  The problem with all this information, though, lies in that strep throat does not always follow the above rules, so deciding who has strep throat and who has a viral infection mimicking strep throat can be difficult.
Interestingly, physicians don’t treat strep throat in order to make the patient get better sooner.  The vast majority of the time, someone with strep throat who seeks no treatment will fall ill for three-to-five days, but then will get better rapidly.  In fact, if someone with strep doesn’t get antibiotics within the first 36 hours of becoming sick, the antibiotics will have no effect on the length of the illness.  Someone with strep who gets antibiotics within 24-36 hours of becoming sick will shorten the length of their symptoms by about 1 day.  Really, we treat strep throat in order to prevent possible complications, especially rheumatic fever, which can lead to permanent damage to the heart valves.
Even though the complications of strep throat can pose serious problems, we don’t want to treat all people with a sore throat for strep.  Antibiotics, one of the three most important advancements in the history of medicine, have saved countless lives and prevented a near-infinite number of cases of rheumatic fever, but also come with their own risks.  (The other two are sanitized water and vaccines, but that’s a discussion for another day.)  Penicillin, the antibiotic of choice for strep throat, can cause life-threatening allergic reactions or a severe colon infection called C. diff colitis.  Giving penicillin to a patient with a viral throat infection exposes that patient to risk of an allergy or colitis for no benefit.
Usually, the McIsaac Rule can decide whether a patient with a sore throat needs antibiotics or not.  The McIsaac Rule gives a patient with a sore throat points.  You get one point each for having absent cough, a red throat, swollen glands at the front of the neck, or fever.  Zero or one point means the infection is viral and no antibiotic should be given.  Patients with two or three points should have a strep test in the office to decide whether they require antibiotics or not.  Patients with four points should be given an antibiotic without the bother of being tested.
Is the parent who says “I think she has strep throat” correct?  If the child has no fever, a runny nose, and a cough, the chances of finding strep throat are so slim that a visit to my office could likely have been avoided, as the poor kid has a virus.  I will likely advise ibuprofen, Tylenol, and salt water gargles to help with the throat pain.  If, however, the sore-throated child has had a fever and no cough or runny nose, the parent is likely correct and the visit to my office could prevent something as severe as rheumatic fever.  I can say one thing for certain about this hypothetical child, though – whether or not they leave my office with a prescription for an antibiotic, they will definitely leave with a sticker.  I’ve got nothing against bribery.