Tonsillopharyngitis%20-%20acute Diagnosis

GABS Pharyngitis Testing

• Clinical presentation of GABS 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

Conditions Where Lab Tests for GABS 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 GABS is suspected
• Modified Centor score or FeverPAIN 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

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%

FeverPAIN Score

• May be used to assess the need to start antibiotic treatment as well as the severity of throat pain
• Uses a point system utilizing the following signs/symptoms:
  • Fever during the previous 24 hours (1)
  • Exudates on tonsils (1)
  • Presentation to a physician within 3 days after onset of symptoms (1)
  • Severely inflamed tonsils (1)
  • Absence of cough or coryza (1)
• Total risk based on total acute tonsillopharyngitis score

  Total Score	Risk of GABS
  ≤2	0-20% (low risk)
  3	30-50% (medium risk)
  ≥4	>50% (high risk)

• High results may indicate streptococcal infection; results should be correlated with Centor criteria score

Throat Swab Culture

• Gold standard for confirmation of clinical diagnosis of 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 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
• May be considered in patients with modified Centor criteria scores ≥3 or when 2 viral features (eg fever,  tonsillar exudate/swelling, swollen anterior cervical nodes, absence of cough) are present
• 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

Other Tests

• Testing for other etiologies (eg coronavirus disease 2019 [COVID-19], influenza, dengue, etc) will be helpful as antiviral therapies might be needed in high-risk individuals
  • Rapid testing or reverse transcriptase-polymerase chain reaction (RT-PCR) test should be used to identify, isolate and treat patients who are suspected of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection
  • In some places, rapid test kits for influenza and other respiratory viral infections may be available
  • Dengue testing may be considered in febrile patients with erythematous throat