Tonsillopharyngitis%20-%20acute Diagnosis
Diagnosis
Conditions Where Lab Tests for Group A Beta-Hemolytic Streptococci are Not Available or Not Practical
- Antibiotics will not be needed for every patient that presents with sore throat
- Antibiotics should not be withheld if the clinical condition is severe or group A beta-hemolytic streptococci (GABS) is suspected
- Modified Centor score can be used to decide on which patients need no testing, lab tests [throat swab or rapid antigen detection test (RADT)] or empiric antibiotic therapy
- Score of 0 to 1 does not require testing or antibiotic therapy
- Patients with score of 2 or 3 require testing, positive results warrant empiric therapy
- Score of ≥4 is at high risk of GABS and empiric therapy is considered
Who Should be Tested for Group A Beta-Hemolytic Streptococci Pharyngitis?
- Clinical presentation of group A beta-hemolytic streptococci and viral pharyngitis greatly overlap
- Patients who have clinical and epidemiological findings suggestive of GABS pharyngitis should be tested for the presence of group A streptococci in the pharynx
- Diagnostic testing of contacts of infected patients is not routinely recommended
FeverPAIN Score
- May be used to assess the need to start antibiotic treatment as well as the severity of throat pain
- High results may indicate streptococcal infection; results should be correlated with Centor criteria score
Centor Criteria
- Used to assess the susceptibility of patients to GABS infection based on the patient’s age and symptoms
- Results may assist in the decision to start antibiotic treatment
- Uses a points system utilizing the following signs/symptoms:
- Fever (>38°C/>100.4°F) (1)
- Absence of cough (1)
- Tender anterior cervical node (1)
- Tonsillar exudate/swelling (1)
- Age 3-14 years (1)
- Age 15-44 years (0)
- Age >44 years (-1)
- Modified total risk based on total acute tonsillopharyngitis score:
Total Score | Risk of GABS |
≥4 | 51-53% |
3 | 28-35% |
2 | 11-17% |
1 | 5-10% |
≤0 | 1-2.5% |
Laboratory Tests
Throat Swab Culture
- Gold standard for confirmation of clinical diagnosis of group A beta-hemolytic streptococci (GABS) pharyngitis
- Recommended for those with history of contact with symptomatic persons with GABS pharyngitis, recurrent GABS infection and symptomatic patients at high risk for rheumatic fever
- If done correctly, culture of a single throat swab on a blood agar plate has a sensitivity of 90-95%
- Less expensive than rapid antigen detection test (RADT) and more readily available
- Results take 24-48 hours
- Does not differentiate between illness and carrier states
- False-negative results may be seen in patients who have received antibiotic therapy shortly before or at the time the swab was obtained
Proper Technique of Obtaining a Throat Swab
- Swab the surface of both the tonsils, tonsillar fossae and posterior pharyngeal wall
- Do not include the mouth, uvula and oropharynx
- Optimally done at onset of symptoms and before antimicrobial therapy is started
Rapid Antigen Detection Test (RADT)
- Developed for the identification of GABS directly from throat swabs
- More expensive than throat swab cultures, but results are available faster (within minutes)
- With sensitivity of 80-90% and specificity of 90-99%
- Does not differentiate between illness and carrier states
- A rapid test can lead to earlier initiation of definitive therapy with the following advantages:
- Reduced risk of spread of GABS
- Reduced acute morbidity associated with illness
- Earlier return of patient to work or school
- A negative RADT result for an adult patient does not need to be confirmed with a throat culture because of the low incidence of streptococcal infection and low risk of rheumatic fever in this age group