Streptococcal pharyngitis
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] |
Diagnostic method | Throat culture, strep test[1] |
Differential diagnosis | Epiglottitis, infectious mononucleosis, Ludwig's angina, peritonsillar abscess, retropharyngeal abscess, viral pharyngitis[4] |
Prevention | Handwashing[1] |
Treatment | Paracetamol (acetaminophen), NSAIDs, antibiotics[1][5] |
Frequency | 5 to 40% of sore throats[6][7] |
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]
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.[8]
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.[8] 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.[5]
Strep throat is a common bacterial infection in children.[2] It is the cause of 15–40% of sore throats among children[6][9] and 5–15% among adults.[7] Cases are more common in late winter and early spring.[9] 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.[9]
Other symptoms include: headache, nausea and vomiting, abdominal pain,[10] muscle pain,[11] or a scarlatiniform rash or palatal petechiae, the latter being an uncommon but highly specific finding.[9]
Symptoms typically begin one to three days after exposure and last seven to ten days.[3][9]
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.[7]
-
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.[9] -
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).[12] Other bacteria such as non–group A β-hemolytic streptococci and fusobacterium may also cause pharyngitis.[9][11] 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.[11][13] Dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days.[11] Contaminated food can result in outbreaks, but this is rare.[11] Of children with no signs or symptoms, 12% carry GAS in their pharynx,[6] and, after treatment, approximately 15% of those remain positive, and are true "carriers".[14]
Diagnosis
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.[15] The modified Centor criteria are a set of five criteria; the total score indicates the probability of a streptococcal infection.[9]
One point is given for each of the criteria:[9]
- 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 indicated 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.[9]
The Infectious Disease Society of America recommends against empirical treatment and considers antibiotics only appropriate when given after a positive test.[7] 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.[7]
Laboratory testing
A throat culture is the gold standard[16] for the diagnosis of streptococcal pharyngitis, with a sensitivity of 90–95%.[9] 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.[9] In areas of the world where rheumatic fever is uncommon, a negative rapid strep test is sufficient to rule out the disease.[17]
A positive throat culture or RADT in association with symptoms establishes a positive diagnosis in those in which the diagnosis is in doubt.[18] In adults, a negative RADT is sufficient to rule out the diagnosis. However, in children a throat culture is recommended to confirm the result.[7] 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.[18]
Differential diagnosis
As the symptoms of streptococcal pharyngitis overlap with other conditions, it can be difficult to make the diagnosis clinically.[9] 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.[9] The presence of marked lymph node enlargement along with sore throat, fever, and tonsillar enlargement may also occur in infectious mononucleosis.[19] Other conditions that may present similarly include epiglottitis, Kawasaki disease, acute retroviral syndrome, Lemierre's syndrome, Ludwig's angina, peritonsillar abscess, and retropharyngeal abscess.[4]
Prevention
Tonsillectomy may be a reasonable preventive measure in those with frequent throat infections (more than three a year).[20] However, the benefits are small and episodes typically lessen in time regardless of measures taken.[21][22][23] 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.[7] Treating people who have been exposed but who are without symptoms is not recommended.[7] Treating people who are carriers of GAS is not recommended as the risk of spread and complications is low.[7]
Treatment
Untreated streptococcal pharyngitis usually resolves within a few days.[9] Treatment with antibiotics shortens the duration of the acute illness by about 16 hours.[9] The primary reason for treatment with antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses.[9] Antibiotics prevent acute rheumatic fever if given within 9 days of the onset of symptoms.[12]
Pain medication
Pain medication such as NSAIDs and paracetamol (acetaminophen) helps in the management of pain associated with strep throat.[24] Viscous lidocaine may also be useful.[25] While steroids may help with the pain,[12][26] they are not routinely recommended.[7] Aspirin may be used in adults but is not recommended in children due to the risk of Reye syndrome.[12]
Antibiotics
The antibiotic of choice in the United States for streptococcal pharyngitis is penicillin V, due to safety, cost, and effectiveness.[9] Amoxicillin is preferred in Europe.[27] In India, where the risk of rheumatic fever is higher, intramuscular benzathine penicillin G is the first choice for treatment.[12]
Appropriate antibiotics decrease the average 3–5 day duration of symptoms by about one day, and also reduce contagiousness.[18] They are primarily prescribed to reduce rare complications such as rheumatic fever and peritonsillar abscess.[28] The arguments in favor of antibiotic treatment should be balanced by the consideration of possible side effects,[11] 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.[28][29] Antibiotics are prescribed for strep throat at a higher rate than would be expected from how common it is.[30]
Erythromycin and other macrolides or clindamycin are recommended for people with severe penicillin allergies.[9][7] First-generation cephalosporins may be used in those with less severe allergies[9] and some evidence supports cephalosporins as superior to penicillin.[31][32] Streptococcal infections may also lead to acute glomerulonephritis; however, the incidence of this side effect is not reduced by the use of antibiotics.[12]
Prognosis
The symptoms of strep throat usually improve within three to five days, irrespective of treatment.[18] Treatment with antibiotics reduces the risk of complications and transmission; children may return to school 24 hours after antibiotics are administered.[9] The risk of complications in adults is low.[7] 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.[7]
Complications arising from streptococcal throat infections include:
The economic cost of the disease in the United States in children is approximately $350 million annually.[7]
Epidemiology
Pharyngitis, the broader category into which Streptococcal pharyngitis falls, is diagnosed in 11 million people annually in the United States.[9] It is the cause of 15–40% of sore throats among children[6][9] and 5–15% in adults.[7] Cases usually occur in late winter and early spring.[9]
References
- ^ a b c d e f g h i j k l m n o p "Is It Strep Throat?". CDC. October 19, 2015. Archived from the original on 2 February 2016. Retrieved 2 February 2016.
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- ^ a b c d Shaikh N, Leonard E, Martin JM (September 2010). "Prevalence of streptococcal pharyngitis and streptococcal carriage in children: a meta-analysis". Pediatrics. 126 (3): e557–64. doi:10.1542/peds.2009-2648. PMID 20696723.
- ^ a b c d e f g h i j k l m n o p q r 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.
- ^ a b Harris, AM; Hicks, LA; Qaseem, A (19 January 2016). "Appropriate Antibiotic Use for Acute Respiratory Tract Infection in Adults: Advice for High-Value Care From the American College of Physicians and the Centers for Disease Control and Prevention". Annals of Internal Medicine. 164: 425. doi:10.7326/M15-1840. PMID 26785402.
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- ^ Lindbaek M, Høiby EA, Lermark G, Steinsholt IM, Hjortdahl P (2004). "Predictors for spread of clinical group A streptococcal tonsillitis within the household". Scand J Prim Health Care. 22 (4): 239–43. doi:10.1080/02813430410006729. PMID 15765640.
- ^ Rakel, edited by Robert E. Rakel, David P. (2011). Textbook of family medicine (8th ed.). Philadelphia, PA.: Elsevier Saunders. p. 331. ISBN 9781437711608. Archived from the original on 2017-09-08.
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- ^ Smith, Ellen Reid; Kahan, Scott; Miller, Redonda G. (2008). In A Page Signs & Symptoms. In a Page Series. Hagerstown, Maryland: Lippincott Williams & Wilkins. p. 312. ISBN 0-7817-7043-2.
- ^ Lean, WL; Arnup, S; Danchin, M; Steer, AC (October 2014). "Rapid diagnostic tests for group A streptococcal pharyngitis: a meta-analysis". Pediatrics. 134 (4): 771–81. doi:10.1542/peds.2014-1094. PMID 25201792.
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- ^ 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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