Editing Streptococcal pharyngitis (section)

==Diagnosis==
{| class="wikitable" style = "float: right; margin-left:15px; text-align:center"
|+ Modified Centor score
!Points||Probability of Strep||Management
|-
| 1 or fewer|| <10%||No antibiotic or culture needed
|-
| 2        ||11–17%||rowspan="2"|Antibiotic based on culture or RADT
|-
| 3        ||28–35%
|-
| 4 or 5   ||52%||[[Empiric antibiotics]]
|}

A number of scoring systems exist to help with diagnosis; however, their use is controversial due to insufficient accuracy.<ref>{{cite journal|last1=Cohen|first1=JF|last2=Cohen|first2=R|last3=Levy|first3=C|last4=Thollot|first4=F|last5=Benani|first5=M|last6=Bidet|first6=P|last7=Chalumeau|first7=M|title=Selective testing strategies for diagnosing group A streptococcal infection in children with pharyngitis: a systematic review and prospective multicentre external validation study.|journal=Canadian Medical Association Journal |date=6 January 2015|volume=187|issue=1|pages=23–32|pmid=25487666|doi=10.1503/cmaj.140772|pmc=4284164}}</ref> The modified [[Centor criteria]] are a set of five criteria; the total score indicates the probability of a streptococcal infection.<ref name=Review09/>

One point is given for each of the criteria:<ref name=Review09/>
*Absence of a cough
*Swollen and tender cervical lymph nodes
*Temperature >{{convert|38.0|C|F}}
*Tonsillar exudate or swelling
*Age less than 15 (a point is subtracted if age >44)

A score of one may indicate no treatment or culture is needed or it may indicate the need to perform further testing if other high risk factors exist, such as a family member having the disease.<ref name=Review09/>

The [[Infectious Disease Society of America]] recommends against routine antibiotic treatment and considers antibiotics only appropriate when given after a positive test.<ref name="IDSA2012" /> Testing is not needed in children under three as both group A strep and [[rheumatic fever]] are rare, unless a child has a sibling with the disease.<ref name="IDSA2012" />

===Laboratory testing===
A [[throat culture]] is the [[gold standard (test)|gold standard]]<ref>{{Cite book|author1=Smith, Ellen Reid |author2=Kahan, Scott |author3=Miller, Redonda G. |title=In A Page Signs & Symptoms |series=In a Page Series |publisher=Lippincott Williams & Wilkins |location=Hagerstown, Maryland |year=2008 |pages=312 |isbn=978-0-7817-7043-9 }}</ref> for the diagnosis of streptococcal pharyngitis, with a sensitivity of 90–95%.<ref name=Review09/>  A [[rapid strep test]] (also called rapid antigen detection testing or RADT) may also be used. While the rapid strep test is quicker, it has a lower [[sensitivity (tests)|sensitivity]] (70%) and statistically equal [[specificity (tests)|specificity]] (98%) as a throat culture.<ref name=Review09/> In areas of the world where [[rheumatic fever]] is uncommon, a negative rapid strep test is sufficient to rule out the disease.<ref>{{cite journal|last1=Lean|first1=WL|last2=Arnup|first2=S|last3=Danchin|first3=M|last4=Steer|first4=AC|title=Rapid diagnostic tests for group A streptococcal pharyngitis: a meta-analysis.|journal=Pediatrics|date=October 2014|volume=134|issue=4|pages=771–81|pmid=25201792|doi=10.1542/peds.2014-1094|s2cid=15909263}}</ref>

A positive throat culture or RADT in association with symptoms establishes a positive diagnosis in those in which the diagnosis is in doubt.<ref name=IDSAGuideline2002/> In adults, a negative RADT is sufficient to rule out the diagnosis. However, in children a throat culture is recommended to confirm the result.<ref name=IDSA2012/> Asymptomatic individuals should not be routinely tested with a throat culture or RADT because a certain percentage of the population persistently "carries" the streptococcal bacteria in their throat without any harmful results.<ref name=IDSAGuideline2002/>

===Differential diagnosis===
{{See also|Acute pharyngitis}}
As the symptoms of streptococcal pharyngitis overlap with other conditions, it can be difficult to make the diagnosis clinically.<ref name=Review09/> Coughing, nasal discharge, [[diarrhea]], and [[conjunctivitis|red, irritated eyes]] in addition to fever and sore throat are more indicative of a [[viral sore throat]] than of strep throat.<ref name=Review09/> The presence of marked lymph node enlargement along with sore throat, fever, and tonsillar enlargement may also occur in [[infectious mononucleosis]].<ref name="pmid15508538">{{cite journal | author = Ebell MH | title = Epstein-Barr virus infectious mononucleosis | journal = Am Fam Physician | volume = 70 | issue = 7 | pages = 1279–87 | year = 2004 | pmid = 15508538 | url = http://www.aafp.org/afp/20041001/1279.html | url-status = live | archive-url = https://web.archive.org/web/20080724055725/http://www.aafp.org/afp/20041001/1279.html | archive-date = 2008-07-24 }}</ref> Other conditions that may present similarly include [[epiglottitis]], [[Kawasaki disease]], [[acute retroviral syndrome]], [[Lemierre's syndrome]], [[Ludwig's angina]], [[peritonsillar abscess]], and [[retropharyngeal abscess]].<ref name=Got2018>{{cite journal |last1=Gottlieb |first1=M |last2=Long |first2=B |last3=Koyfman |first3=A |title=Clinical Mimics: An Emergency Medicine-Focused Review of Streptococcal Pharyngitis Mimics. |journal=The Journal of Emergency Medicine |date=May 2018 |volume=54 |issue=5 |pages=619–629 |doi=10.1016/j.jemermed.2018.01.031 |pmid=29523424|doi-access=free }}</ref>