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    Centor Score (Modified/McIsaac) for Strep Pharyngitis

    Estimates probability that pharyngitis is streptococcal, and suggests management course.


    Use only in patients with recent onset (≤3 days) acute pharyngitis.

    When to Use
    Why Use

    Children with pharyngitis, primarily; the risk of GAS decreases significantly with age into adulthood.

    • The Modified Centor Criteria (or McIsaac Score) correlate directly with risk of positive throat culture for GAS.
    • New 2012 Guidelines from the IDSA no longer recommend empiric treatment for patients alone; they recommend testing patients that are at higher risk for strep pharyngitis, but not giving antibiotics until a rapid test is positive or a throat culture is positive.
    • The “Modified” criteria include an age component, along with “tonsillar swelling” as part of the rule. GAS is incredibly rare in patients under 3 and less common in older adults, so this can help risk stratify patients for clinicians.
    • Most cases of pharyngitis are viral in origin, and with the rare incidence of rheumatic fever, along with the questionable benefits of early antibiotics to prevent sequelae like peritonsillar abscess, antibiotics are prescribed much less often. Steroids (like dexamethasone) and NSAIDS often provide similar pain relief and resolution of symptoms to antibiotics.

    Most pharyngitis is viral and does not respond to antibiotic treatment. The Centor Criteria attempt to predict which patients will have culture-confirmed streptococcal infections of their pharynx to help determine which patients to test in the first place.

    About the Creator
    Dr. Robert M. Centor
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    Creator Insights


    Steroids and NSAIDS improve symptoms; antibiotics are often indicated in streptococcal pharyngitis, but do not prevent the suppurative complications of it like peritonsillar abscess.


    Addition of the assigned points.


    Dr. Robert M. Centor

    From the Creator

    Why did you develop the Centor Score? Was there a clinical experience that inspired you to create a this tool for clinicians?
    In 1979, while working in the "non-acute" adult emergency room, a resident asked me how to evaluate a sore throat patient. Having just finished my residency, I started to give a definitive answer, but had a moment of humility and told him that I did not know. We made a treatment decision at the time, and I went to the library to learn more. A wonderful microbiologist agreed to do some throat cultures for us, and I developed a questionnaire. Our goal was to see if clinical findings could stratify the probability that an adult (16 and older in our ER) patient had group A Strep.

    What pearls, pitfalls and/or tips do you have for users of the Centor Score? Are there cases when it has been applied, interpreted, or used inappropriately?
    We studied adults, and thus have always been wary of applying it to children. More recently, we have published a review that shows that pre-adolescent pharyngitis has many differences from adolescent/young adult pharyngitis. McIsaac has developed an adjustment for age which might be appropriate for pre-adolescents.

    Please do not use this score if the patient does not have a recent onset acute pharyngitis (3 days or less). Some have erred in using this for any throat discomfort.

    What recommendations do you have for health care providers once they have the Centor Score result? Are there any adjustments or updates you would make to the score given recent changes in medicine?
    Our recent research suggests that our Score stratifies not just group A strep, but also groups C&G strep and Fusobacterium necrophorum. Because we believe that we should treat all of these bacteria, we favor narrow antibiotics (preferably penicillin, amoxicillin or a narrow spectrum cephalosporin) for scores of 3 or 4. Depending on clinical assessment, we sometimes will also treat the 2s. Zeros and 1s need no testing or antibiotics. All patients should be told that pharyngitis is generally self limited and should improve over the next 2-5 days. If symptoms worsen, then the differential diagnosis broadens and the score is not longer relevant. Major red flags include rigors and inability to swallow secondary to pain. These patients need further evaluation, and likely hospitalization.

    Any further research you're working on related to resource utilization and sore throat?
    We continue to study the importance of Fusobacterium necrophorum, an obligate anaerobe that causes endemic pharyngitis in adolescents and young adults. This bacteria is very important because it is the most common cause of peritonsillar abscess in the 15-30 age group, and the primary cause of Lemierre Syndrome.

    About the Creator

    Robert M. Centor, MD, is the retired regional dean for the Huntsville Regional Medical and professor of medicine in the Division of General Internal Medicine at the University of Alabama at Birmingham. He researches medical decision-making and has published widely in the diagnosis and management of adult sore throats. Dr. Centor is also Chair Emeritus of the Board of Regents for the American College of Physicians.

    To view Dr. Robert M. Centor's publications, visit PubMed

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