What to take for sore throat due to allergies
| 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 assist with diagnosis; however, their use is controversial due to insufficient accuracy.[16] The modified Centor criteria are a set of five criteria; the entire score indicates the probability of a streptococcal infection.[10]
One point is given for each of the criteria:[10]
- Swollen and tender cervical lymph nodes
- Tonsillar exudate or swelling
- Absence of a cough
- Temperature >°C (°F)
- 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 act out 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 kid 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 unusual, a negative rapid strep test is sufficient to law 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 law 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
See also: Acute pharyngitis
As the symptoms of streptococcal pharyngitis overlap with other conditions, it can be hard 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 happen 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 little 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 own 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]
Signs and symptoms
The typical signs and symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38°C (°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 unusual but highly specific finding.[10]
Symptoms typically start one to three days after exposure and final 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.
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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, shut 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]
Prognosis
The symptoms of strep throat generally 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 istered.[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:
The economic cost of the disease in the United States in children is approximately $ million annually.[8]
Treatment
Untreated streptococcal pharyngitis generally resolves within a few days.[10] Treatment with antibiotics shortens the duration of the acute illness by about 16hours.[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 assist 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 propose that no antimicrobial treatment be given to healthy adults who own 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 days in comparison to the standard 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]
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