Streptococcal pharyngitis

Streptococcal pharyngitis, also known as strep throat, is an infection of the back of the throat including the tonsils caused by group A streptococcus (GAS).[1] Common symptoms include fever, sore throat, red tonsils, and enlarged lymph nodes in the neck.[1] A headache, and nausea or vomiting may also occur.[1] Some develop a sandpaper-like rash which is known as scarlet fever.[2] Symptoms typically begin one to three days after exposure and last seven to ten days.[2][3]

Streptococcal pharyngitis
Other names	Streptococcal tonsillitis, streptococcal sore throat, strep
A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in a 16-year-old.
Specialty	Infectious disease
Symptoms	Fever, sore throat, large lymph nodes[1]
Usual onset	1–3 days after exposure[2][3]
Duration	7–10 days[2][3]
Causes	Group A streptococcus[1]
Risk factors	Sharing drinks or eating utensils[4]
Diagnostic method	Throat culture, strep test[1]
Differential diagnosis	Epiglottitis, infectious mononucleosis, Ludwig's angina, peritonsillar abscess, retropharyngeal abscess, viral pharyngitis[5]
Prevention	Handwashing,[1] covering coughs[4]
Treatment	Paracetamol (acetaminophen), NSAIDs, antibiotics[1][6]
Frequency	5 to 40% of sore throats[7][8]

Strep throat is spread by respiratory droplets from an infected person.[1] It may be spread directly or by touching something that has droplets on it and then touching the mouth, nose, or eyes.[1] Some people may carry the bacteria without symptoms.[1] It may also be spread by skin infected with group A strep.[1] The diagnosis is made based on the results of a rapid antigen detection test or throat culture in those who have symptoms.[9]

Prevention is by washing hands and not sharing eating utensils.[1] There is no vaccine for the disease.[1] Treatment with antibiotics is only recommended in those with a confirmed diagnosis.[9] Those infected should stay away from other people for at least 24 hours after starting treatment.[1] Pain can be treated with paracetamol (acetaminophen) and nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen.[6]

Strep throat is a common bacterial infection in children.[2] It is the cause of 15–40% of sore throats among children[7][10] and 5–15% among adults.[8] Cases are more common in late winter and early spring.[10] Potential complications include rheumatic fever and peritonsillar abscess.[1][2]

Signs and symptoms

The typical signs and symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38 °C (100 °F), tonsillar exudates (pus on the tonsils), and large cervical lymph nodes.[10]

Other symptoms include: headache, nausea and vomiting, abdominal pain,[11] muscle pain,[12] or a scarlatiniform rash or palatal petechiae, the latter being an uncommon but highly specific finding.[10]

Symptoms typically begin one to three days after exposure and last seven to ten days.[3][10]

Strep throat is unlikely when any of the symptoms of red eyes, hoarseness, runny nose, or mouth ulcers are present. It is also unlikely when there is no fever.[8]

• 
  Mouth wide open showing the throat
  A throat infection which on culture tested positive for group A streptococcus. Note the large tonsils with white exudate.
• 
  Mouth wide open showing the throat
  Note the petechiae, or small red spots, on the soft palate. This is an uncommon but highly specific finding in streptococcal pharyngitis.[10]
• 
  A set of large tonsils in the back of the throat, covered in white exudate.
  A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in an 8-year-old.

Cause

Strep throat is caused by group A β-hemolytic Streptococcus (GAS or S. pyogenes).[13] Other bacteria such as non–group A β-hemolytic streptococci and fusobacterium may also cause pharyngitis.[10][12] It is spread by direct, close contact with an infected person; thus crowding, as may be found in the military and schools, increases the rate of transmission.[12][14] Dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days.[12] Contaminated food can result in outbreaks, but this is rare.[12] Of children with no signs or symptoms, 12% carry GAS in their pharynx,[7] and, after treatment, approximately 15% of those remain positive, and are true "carriers".[15]

Diagnosis

Modified Centor score

Points	Probability of Strep	Management
1 or fewer	<10%	No antibiotic or culture needed
2	11–17%	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.[16] The modified Centor criteria are a set of five criteria; the total score indicates the probability of a streptococcal infection.[10]

One point is given for each of the criteria:[10]

• Absence of a cough
• Swollen and tender cervical lymph nodes
• Temperature >38.0 °C (100.4 °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.[10]

The Infectious Disease Society of America recommends against empirical treatment and considers antibiotics only appropriate when given after a positive test.[8] 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.[8]

Laboratory testing

A throat culture is the gold standard[17] for the diagnosis of streptococcal pharyngitis, with a sensitivity of 90–95%.[10] 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 (70%) and statistically equal specificity (98%) as a throat culture.[10] In areas of the world where rheumatic fever is uncommon, a negative rapid strep test is sufficient to rule out the disease.[18]

A positive throat culture or RADT in association with symptoms establishes a positive diagnosis in those in which the diagnosis is in doubt.[19] In adults, a negative RADT is sufficient to rule out the diagnosis. However, in children a throat culture is recommended to confirm the result.[8] 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.[19]

Differential diagnosis

As the symptoms of streptococcal pharyngitis overlap with other conditions, it can be difficult to make the diagnosis clinically.[10] Coughing, nasal discharge, diarrhea, and red, irritated eyes in addition to fever and sore throat are more indicative of a viral sore throat than of strep throat.[10] The presence of marked lymph node enlargement along with sore throat, fever, and tonsillar enlargement may also occur in infectious mononucleosis.[20] Other conditions that may present similarly include epiglottitis, Kawasaki disease, acute retroviral syndrome, Lemierre's syndrome, Ludwig's angina, peritonsillar abscess, and retropharyngeal abscess.[5]

Prevention

Tonsillectomy may be a reasonable preventive measure in those with frequent throat infections (more than three a year).[21] However, the benefits are small and episodes typically lessen in time regardless of measures taken.[22][23][24] Recurrent episodes of pharyngitis which test positive for GAS may also represent a person who is a chronic carrier of GAS who is getting recurrent viral infections.[8] Treating people who have been exposed but who are without symptoms is not recommended.[8] Treating people who are carriers of GAS is not recommended as the risk of spread and complications is low.[8]

Treatment

Untreated streptococcal pharyngitis usually resolves within a few days.[10] Treatment with antibiotics shortens the duration of the acute illness by about 16 hours.[10] The primary reason for treatment with antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses.[10] Antibiotics prevent acute rheumatic fever if given within 9 days of the onset of symptoms.[13]

Pain medication

Pain medication such as NSAIDs and paracetamol (acetaminophen) helps in the management of pain associated with strep throat.[25] Viscous lidocaine may also be useful.[26] While steroids may help with the pain,[13][27] they are not routinely recommended.[8] Aspirin may be used in adults but is not recommended in children due to the risk of Reye syndrome.[13]

Antibiotics

The antibiotic of choice in the United States for streptococcal pharyngitis is penicillin V, due to safety, cost, and effectiveness.[10] Amoxicillin is preferred in Europe.[28] In India, where the risk of rheumatic fever is higher, intramuscular benzathine penicillin G is the first choice for treatment.[13]

Appropriate antibiotics decrease the average 3–5 day duration of symptoms by about one day, and also reduce contagiousness.[19] They are primarily prescribed to reduce rare complications such as rheumatic fever and peritonsillar abscess.[29] The arguments in favor of antibiotic treatment should be balanced by the consideration of possible side effects,[12] and it is reasonable to suggest that no antimicrobial treatment be given to healthy adults who have adverse reactions to medication or those at low risk of complications.[29][30] Antibiotics are prescribed for strep throat at a higher rate than would be expected from how common it is.[31]

Erythromycin and other macrolides or clindamycin are recommended for people with severe penicillin allergies.[10][8] First-generation cephalosporins may be used in those with less severe allergies[10] and some evidence supports cephalosporins as superior to penicillin.[32][33] These late-generation antibiotics show a similar effect when prescribed for 3-7 days in comparison to the standard 10-days of penicillin when used in areas of low rheumatic heart disease.[34] Streptococcal infections may also lead to acute glomerulonephritis; however, the incidence of this side effect is not reduced by the use of antibiotics.[13]

Prognosis

The symptoms of strep throat usually improve within three to five days, irrespective of treatment.[19] Treatment with antibiotics reduces the risk of complications and transmission; children may return to school 24 hours after antibiotics are administered.[10] The risk of complications in adults is low.[8] In children, acute rheumatic fever is rare in most of the developed world. It is, however, the leading cause of acquired heart disease in India, sub-Saharan Africa and some parts of Australia.[8]

Complications arising from streptococcal throat infections include:

• Acute rheumatic fever[11]
• Scarlet fever[35]
• Streptococcal toxic shock syndrome[35][36]
• Glomerulonephritis[37]
• PANDAS syndrome[37]
• Peritonsillar abscess[8]
• Cervical lymphadenitis[8]
• Mastoiditis[8]

The economic cost of the disease in the United States in children is approximately $350 million annually.[8]

Epidemiology

Pharyngitis, the broader category into which Streptococcal pharyngitis falls, is diagnosed in 11 million people annually in the United States.[10] It is the cause of 15–40% of sore throats among children[7][10] and 5–15% in adults.[8] Cases usually occur in late winter and early spring.[10]

References

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3. Jr, [edited by] Allan H. Goroll, Albert G. Mulley (2009). Primary care medicine : office evaluation and management of the adult patient (6th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 1408. ISBN 9780781775137. Archived from the original on 2016-09-15.CS1 maint: extra text: authors list (link)
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8. Shulman, ST; Bisno, AL; Clegg, HW; Gerber, MA; Kaplan, EL; Lee, G; Martin, JM; Van Beneden, C (Sep 9, 2012). "Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis: 2012 Update by the Infectious Diseases Society of America". Clinical Infectious Diseases. 55 (10): e86–102. doi:10.1093/cid/cis629. PMID 22965026.
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22. van Staaij BK, van den Akker EH, van der Heijden GJ, Schilder AG, Hoes AW (January 2005). "Adenotonsillectomy for upper respiratory infections: evidence based?". Archives of Disease in Childhood. 90 (1): 19–25. doi:10.1136/adc.2003.047530. PMC 1720065. PMID 15613505.
23. Burton, MJ; Glasziou, PP; Chong, LY; Venekamp, RP (19 November 2014). "Tonsillectomy or adenotonsillectomy versus non-surgical treatment for chronic/recurrent acute tonsillitis" (PDF). The Cochrane Database of Systematic Reviews (11): CD001802. doi:10.1002/14651858.CD001802.pub3. PMID 25407135.
24. Morad, Anna; Sathe, Nila A.; Francis, David O.; McPheeters, Melissa L.; Chinnadurai, Sivakumar (17 January 2017). "Tonsillectomy Versus Watchful Waiting for Recurrent Throat Infection: A Systematic Review". Pediatrics. 139 (2): e20163490. doi:10.1542/peds.2016-3490. ISSN 0031-4005. PMC 5260157. PMID 28096515. Archived from the original on 13 August 2017.
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26. "Generic Name: Lidocaine Viscous (Xylocaine Viscous) side effects, medical uses, and drug interactions". MedicineNet.com. Archived from the original on 2010-04-08. Retrieved 2010-05-07.
27. Wing, A; Villa-Roel, C; Yeh, B; Eskin, B; Buckingham, J; Rowe, BH (May 2010). "Effectiveness of corticosteroid treatment in acute pharyngitis: a systematic review of the literature". Academic Emergency Medicine. 17 (5): 476–83. doi:10.1111/j.1553-2712.2010.00723.x. PMID 20536799.
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30. Hildreth, AF; Takhar, S; Clark, MA; Hatten, B (September 2015). "Evidence-Based Evaluation And Management Of Patients With Pharyngitis In The Emergency Department". Emergency Medicine Practice. 17 (9): 1–16, quiz 16–7. PMID 26276908.
31. Linder JA, Bates DW, Lee GM, Finkelstein JA (November 2005). "Antibiotic treatment of children with sore throat". J Am Med Assoc. 294 (18): 2315–22. doi:10.1001/jama.294.18.2315. PMID 16278359.
32. Pichichero, M; Casey, J (June 2006). "Comparison of European and U.S. results for cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis". European Journal of Clinical Microbiology & Infectious Diseases. 25 (6): 354–64. doi:10.1007/s10096-006-0154-7. PMID 16767482.
33. van Driel, ML; De Sutter, AI; Habraken, H; Thorning, S; Christiaens, T (11 September 2016). "Different antibiotic treatments for group A streptococcal pharyngitis". The Cochrane Database of Systematic Reviews. 9: CD004406. doi:10.1002/14651858.CD004406.pub4. PMC 6457741. PMID 27614728.
34. Altamimi, Saleh; Khalil, Adli; Khalaiwi, Khalid A; Milner, Ruth A; Pusic, Martin V; Al Othman, Mohammed A (15 August 2012). "Short-term late-generation antibiotics versus longer term penicillin for acute streptococcal pharyngitis in children". Cochrane Database of Systematic Reviews (8): CD004872. doi:10.1002/14651858.CD004872.pub3. PMID 22895944.
35. "UpToDate Inc". Archived from the original on 2008-12-08.
36. Stevens DL, Tanner MH, Winship J, et al. (July 1989). "Severe group A streptococcal infections associated with a toxic shock-like syndrome and scarlet fever toxin A". N. Engl. J. Med. 321 (1): 1–7. doi:10.1056/NEJM198907063210101. PMID 2659990.
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Classification	D ICD-10: J02.0 ICD-9-CM: 034.0 DiseasesDB: 12507
External resources	MedlinePlus: 000639 eMedicine: med/1811