Why are sore throats cultured, and why are antibiotics administered?

Why do physicians order laboratory tests? Reasons include: to make a diagnosis, to confirm a clinical opinion, insecurity, patient and family pressure, concern for liability, to guide therapy, habit.

Case in point. Throat culture.

Sore throat is one of the most common human illnesses. Most are caused by viruses. Fewer than 10% seem to be caused by Streptococcus. But around 10 to 20% of clinically well children, when cultured, have Streptococci found in their throats.

So, if the strep is there with or without symptoms, i.e., disease, where is the evidence for causation?

The standard of care for many decades has been to treat patients with sore throat who are found to have Streptococcus pyogenes with antibiotics, usually penicillin or related drugs.

But the length of time the person with sore throat is symptomatic prior to recovery is four to seven days, whether or not the strep is found and regardless of whether antibiotics are used.

So, why are sore throats cultured, and why are antibiotics administered?

Studies from the 1940s and 1950s found that the rates of acute rheumatic fever following strep throat could be cut from 2% to 1% (not to 0%) by using antibiotics.

So, antibiotics for strep throat became and remain the “standard of practice” to prevent rheumatic fever.

In 2011, the incidence of rheumatic fever in the U.S. is about 1 per 1 million strep throats. Yet, antibiotics are still commonly used to treat sore throats.

Why? Why not?

One million prescriptions for antibiotics for sore throat may prevent one case of rheumatic fever. But they may cause 2,400 cases of significant allergic reactions up to and including anaphylaxis, 50,000 to 100,000 cases of diarrhea and some 100,000 cases of skin rash.

Once an axiom, and still recommended by the American Heart Association, the use of antibiotics to treat strep throat can now be characterized a pseudoaxiom — a false premise, masquerading as truth, and passed down from generation to generation, brainlessly.

Physicians should not prescribe antibiotics for sore throats, or for that matter, acute bronchitis. Nor need they do throat cultures.

They don’t help. They often hurt. First, do no harm.

George Lundberg is a MedPage Today Editor-at-Large and former editor of the Journal of the American Medical Association.

Originally published in MedPage Today. Visit MedPageToday.com for more health policy news.

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  • http://www.bryantsstatisticalconsulting.com Donald Tex Bryant

    Very interesting historical point of view. It seems this is the first time that I have run across this information and it is excellent from an epidemiology POV. Besides the series of adverse effects of the antibiotic perhaps you should include that the consistent prescriptions foster drug resistance from the bacteria.

  • Taylor

    Sorry, but I had strep throat TWICE this year (February and April) and the second time it was absolutely miserable. One day after being on the antibiotic I felt better. If I had not taken the antibiotic I probably would have suffered another 2, 3, 4, or more days. No thanks.

    • http://natickpediatrics.net Rob Lindeman

      Don’t apologize, Taylor, just go back and read Dr. Lundberg’s article carefully. You missed the point.

  • http://natickpediatrics.net Rob Lindeman

    Amen! And AMEN!!!

    • http://theYogadr.com Kathleen

      I second that.
      Amen! and AMEN!!!

  • stitch

    Quite simply, people don’t want to wait a few days to feel better, and antibiotics for strep are the quintessential “magic bullet.” Also keep in mind that many people can no longer afford to take time off from work, no paid sick time, etc. And no child left untested rules penalize schools and students for days missed.

    I agree with you overall, but this is the reality of the world we live in. The new reality is that the strep will become resistant and these expectations will change whether we like it or not.

  • http://natickpediatrics.net Rob Lindeman

    From Cochrane:


    Antibiotics confer relative benefits in the treatment of sore throat. However, the absolute benefits are modest. Protecting sore throat sufferers against suppurative and non-suppurative complications in high-income countries requires treating many with antibiotics for one to benefit. This NNT may be lower in low-income countries. Antibiotics shorten the duration of symptoms by about 16 hours overall.

  • Cindy

    On a macro level this sounds great to me. On a micro level, I will always insist on a strep test for my own. I lost my dear sister to heart damage from a misdiagnosed childhood case of strep and rheumatic fever. She left behind two young children and her death changed the course of many lives. For our family, a routine strep test’s benefits would have far outweighed the cost.

  • primaryMD

    I’m not sure it’s that simple.
    Dr. Robert Centor (of the “Centor score” for sore throats) has written extensively on this subject, and antibiotics can be important for certain patients. He has many posts on the suject:


    We should be judicial in whom we test and treat, but to say that sore throats don’t need antibiotics is an oversimplification.

    • http://petereliasmd.com pheski

      “I’m not sure it’s that simple.”


      Every complex problem has a simple but incorrect solution.

      • Kevin

        well said.

    • Tom Benzoni

      This is the world we created. We prescribe the drugs. We create the expectations. We get paid more when we prescribe (see coding guidelines for low v. moderate).
      We have met the enemy and they are us.
      Tom Benzoni

    • mary mancuso

      I agree. I work at a college health center and see quite of few peritonsilar abscesses every year with negative streps.

      • http://natickpediatrics.net Rob Lindeman

        “…quite of few peritonsilar abscesses every year with negative streps.”

        Those, you treat

      • http://briarcroft.wordpress.com/ Emily Gibson

        The ENTs sometimes culture the abscess contents and it is a junk bag of gram negative bacteria but rarely group A strep is present. The standard of care in our community is Augmentin post-tonsillar abscess I&D.

  • http://petereliasmd.com pheski

    I get and agree with the point, but I have one quibble with the presentation.

    It would be more pertinent to cite the 2011 incidence of rheumatic fever separately for treated and untreated strep throats. Without this, one cannot really calculate a NNT (number of alleged strep throats needed to treat) to prevent a case of rheumatic fever.

    • Kristin

      WORD. Statistical analysis needs to be clean.

  • Dan

    From the cochrane review mentioned earlier:

    3. Symptoms
    Throat soreness and fever were reduced using antibiotics by about half. The greatest difference was seen at Day 3. The number needed to treat (NNT) to prevent one sore throat at Day 3 was less than six; at Week 1 it was 21.

    4. Subgroup analyses of symptom reduction
    Antibiotics were more effective against symptoms at Day 3 (RR 0.58; 95% CI 0.48 to 0.71) if throat swabs were positive for Streptococcus, compared to RR 0.78; 95% CI 0.63 to 0.97 if negative. Similarly at week 1, RRs 0.29; 95% CI 0.12 to 0.70 for positive, and 0.73; 95% CI 0.50 to 1.07 for negative swabs.


    So antibiotics allow for 1 less day of missed school / work.

    In addition, intuition tells me the patient less contagious earlier — and I’ve seen strep go from family member to family member multiple times.

  • http://www.atlas.md Josh

    I looked, and it’s the recomendation of both the infectious disease society of America as well as the CDC to treat. I mean, how do you explain that your child now needs dialysis and a new heart valve because we didn’t treat his sore throat.




  • http://doctorstevenpark.com Steven Park. MD

    There are always exceptions to the rule, but for most cases of throat pain, antibiotics are not needed. Often throat pain can be from reflux. If you ask patients what they did the day or night before, they’ll typically tell you that they ate later than usual or had a drink just before bedtime. Extra acid in the stomach can reflux up into the throat, causing severe throat pain. Alcohol can also relax your throat muscles, leading to more obstructions. Since most people stop breathing intermittently, vacuum pressures in the throat can exacerbate reflux even more.

    Many patients are also placed on a Z-Pak for convenience, and the majority feel better within 12-24 hours, even if they never had a bacterial infection. This is from the anti-reflux properties of the macrolides—they help stomach emptying, which lessens throat inflammation and irritation. The anti-inflammatory property of the macrolides can be due to this mechanism.

    Many women are also placed on antibiotics for throat pain just before their periods. This is due to a similar process—lower levels of progesterone just before women’s periods lessen upper airway muscle tone, which promotes more frequent obstructions and arousals, leading to more reflux. I got over 100 comments from women on a post I did about this subject:


  • http://doctorstevenpark.com Steven Park. MD

    Just to clarify my last comment…obvious bacterial infections should be treated. Sometimes it can lead to abscesses or other serious infections. Having extra large tonsils from infections can also obstruct your breathing at night and bring about temporary sleep apnea. But I often see patients placed on antibiotics when the physical exam is completely normal.

  • http://natickpediatrics.net Rob Lindeman

    While we’re at it, would anybody care to comment on the wisdom of trying to eradicate Strep. pyogenes from the throats of colonized children?

  • Dan Davie

    Sadly, our patients will never understand or accept “NNT” arguments when their kids has fever, won’t eat and is crying from a sore throat. Not after decade after decade of so many doctors giving antibiotics out so injudiciously.

  • http://briarcroft.wordpress.com Emily Gibson

    In my college health center population, sore throat is one of our most common complaints. We treat only when the rapid Group A strep test is positive, which is about 10% of the time, just as Dr. Lundberg says. A large percentage of these individuals are quite toxic with their symptoms of high fever and painful obstructing exudative tonsils. This is a reasonable and humane standard of care given the suffering caused by severe strep tonsillitis. The improvement is almost always dramatic within 24 hours–we know because we check them. This is worth something to a student who can’t miss more than a day of classes/homework/exams without significant consequence. It makes a difference to me that the decreased Group A strep shedding in the treated individual is much less in the intimate environment of dorms and classrooms. Although it is probably not impacted by antibiotic treatment, we have seen a number of cases of post-group A strep glomerulonephritis which can be a devastating illness. Lowering the risk of transmission of the virulent strains is worth it in my experience.

    Antibiotics are hazardous substances, no question, and need to be treated as such. Certain common upper respiratory tract bacteria can cause significant morbidity and mortality in susceptible individuals. Dr. Lundberg, I won’t apologize for treating group A strep pharyngitis.

  • Dr Josh

    Amen, thanks Emily

  • Tpetrusick

    I do throat cultures to not prescribe antibiotics.

  • Paulo Tavares

    I allways prescribe one week of oral Amoxicilin for isolated amigdalitis. My main concern is post.streptococal glomerulonephritis, not the tonsils themselves.
    Amoxicilin does not reach the large bowel and so does not cause diarrea or promotes resistance to other intestinal bacteria.
    No need to spend time and money on strep tests.
    Amoxicilin is cheap and the toxic dose is orally unreachable.
    It should be allways prescribed before endodentistry.
    The exception is very young children for the risk of amputating a meningitis.

    • http://petereliasmd.com pheski

      1. I am not aware of evidence that antibiotic treatment of strep reduces the incidence of PSGN.
      2. Amoxicillin most certainly does cause diarrhea.

      • Paulo Tavares

        1. After a diagnosis of PSGN you shoud treat the patient and all close contacts. All PSGN come from non-treated S. infections. Genetic predisposition may be important. Balancing the severity of a possible PSGN and the inocuity of 1 week of simple Amoxicilin, I favor treatment.
        2. Simple Amoxicilin does not cause diarrhea! The clavulamic acid assotiation does.

        • JustADoc

          I guess I’ll have to tell all my patients that had diarrhea after amoxicillin that they were not actually having diarrhea.

    • Tom Benzoni

      Interestingly, amoxicillin is a gram negative drug, developed for E coli and H flu. It’s breadth makes it a poor choice for a gram positive infection.
      The fact that it is commonly used does not make it the right choice.
      Tom Benzoni

      • Paulo Tavares

        Amoxicilin has all the spectrum of Penicilin V (that is out of the market) plus some more. It’s 100% absorption in the small bowell turn it into equal to EV Ampicilin.
        The coverage of Haemophilus is an advantage in pan ORL infections that are comon in children and in general prophilaxis in splenectomised and other immunocompromised patients.
        It’s an excelent prophilatic antibiotic, and it’s prophilaxis our main concern when “treating” amigdalitis.

  • http://www.medrants.com Robert Centor, MD

    I know Dr. Lundberg and both like him and respect him. However, he misses the point here. I will write a long post on my blog soon to explain his oversimplification of this rather complex problem.

    Sore throats in adolescents and young adults are dangerous; strep throat benefits symptomatically from antibiotics; antibiotics decrease the risk of peritonsillar abscess; antibiotics decrease the probability of spread.

    And, oh by the way, we should worry about more that group A strep when developing a testing/treatment strategy.

    More to follow …

  • Tom Benzoni

    Can anyone on this blog dig up the numbers for fatal reactions to penicillin and to other antibiotics, by year?
    I ask because I think there is a developing body of legal risk.
    Lawyers are learning our weak points. Soon there will be cases lost wherein the doctor gave an antibiotic with fatal results without a positive strep screen. Pay up.
    Then there will be a case with injury and a positive screen. This is a big area, backsaw this is the opportunity to combine NNT with NNH and the legal theory Loss of Opportunity.
    This is being stoked by the cancer screening controversy (screen positive, disease negative, harm in the middle.)
    Tom Benzoni

  • Patricia

    My daughter gets symptomatic strep infections rather frequently. She is very accurate at self-diagnosis, but a strep test is always performed before she is treated. During one infection, she knew that if she was tested, it would be positive, and as a health care worker, she would be sent home. She felt that she was simply too busy to miss work. She wore a mask religiously and stayed away from patients as much as possible. In the afternoon of day two, she went to the doctor, tested positive, and she started antibiotics. By the early morning of day 3, I was in the ED with her as she received IV antibiotics and steroids for acute epiglottitis. She had stridor when breathing and could not even swallow her own saliva; it was a scary couple of hours.

    It may not be evidence-based medicine, but my daughter is getting tested and treated at the first sign of a possible strep infection.

  • Nancy Biernacki

    In the mid-forties, I remember being so sick with sore throats and the doctor made many house calls and painted my throat with iodine. In early July of that year I had my tonsils out and within two weeks I was diagnosed with Rheumatic fever/St. Vitus Dance/heart involvement/joint involvement and was on complete bed rest. I realy lost my years from 7 years old to 13 years because I kept getting relapses. When my children complained of a sore throat, I had their throats cultured almost immediately. I did not want them to be sick like I was.

  • ACM

    There is alot that I agree with regarding this subject, and as an Urgent Care physician I see my fair share of sore throats.

    However, as a parent, I went through a 2 year ordeal with a toddler who was misdiagnosed as having JRA when it was rheumatic fever all along. Multple long-distance trips to pediatric specialists, painful invasive testing, mental anguish, and a gastric ulcer from nsaids are just a sampling of what we endured for 2 years… all because a strep test was not performed. A shot of bicillin cured him.

  • Prof.Pedant

    I used to get a sore throat at least, and often twice, a winter. If it got bad I would go to the physician. Then a friend told me about gargling with grocery store or drug store purchased hydrogen peroxide (i.e. a diluted version, not the rocket fuel). Since then I have two or three times a winter felt a sore throat seeming to come on and have gargled with hydrogen peroxide – and over the last twenty years I have not had a single sore throat that lasted more than a few hours.

    (I also kill athletes foot with a soak in ordinary household vinegar. Take that Tinactin!!!!)

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