Testing for Strep Laryngitis
Strep laryngitis is exceedingly rare, and testing for Group A Streptococcus (GAS) should not be performed when hoarseness is the predominant symptom, as this strongly suggests a viral etiology rather than streptococcal infection. 1
When NOT to Test
The presence of hoarseness is a key clinical feature that argues strongly against GAS pharyngitis and indicates testing should be avoided:
- Hoarseness, cough, rhinorrhea, conjunctivitis, oral ulcers, or viral exanthem are overt viral features that make GAS pharyngitis highly unlikely 1, 2
- Testing patients with these viral features unnecessarily increases healthcare costs and leads to inappropriate antibiotic use 2
- Up to 70% of patients with sore throats receive unnecessary antibiotics, while only 20-30% actually have GAS pharyngitis 1, 3
If Testing is Warranted Despite Hoarseness
If clinical judgment dictates testing is still necessary (which would be unusual with hoarseness present), the diagnostic approach depends on age:
For Children and Adolescents (Ages 3-18):
- Perform a Rapid Antigen Detection Test (RADT) first 1, 2
- If RADT is negative, obtain a backup throat culture because RADTs have 80-90% sensitivity and can miss 10-20% of true infections 1, 2, 4
- Proper swabbing technique is critical: swab both tonsillar surfaces (or tonsillar fossae) and the posterior pharyngeal wall 1, 2
- Culture plates should be incubated at 35°C-37°C for 18-24 hours, with re-examination at 48 hours if initially negative 1
For Adults:
- Perform RADT only—backup throat culture after negative RADT is not necessary 1, 2
- Adults have only 5-10% prevalence of GAS pharyngitis and extremely low risk of acute rheumatic fever, making the risk-benefit ratio favor this approach 3
- The high specificity of RADT (≥95%) means false-positive results are rare, allowing confident treatment decisions on positive results 1, 2
For Children Under 3 Years:
- Do not test for GAS pharyngitis unless there are specific risk factors such as an older sibling with confirmed GAS infection 1, 2
- Acute rheumatic fever is rare in this age group, making testing unnecessary 1
Common Pitfalls to Avoid
- Do not treat based on clinical appearance alone without laboratory confirmation—this leads to massive antibiotic overuse 2, 3
- Do not use anti-streptococcal antibody titers for diagnosis of acute pharyngitis—these reflect past infections, not current ones 1, 2
- Do not test or treat asymptomatic household contacts, even with a history of recurrent infections 3, 5
- Recent antibiotic use can cause false-negative results if antibiotics were given shortly before specimen collection 2
Penicillin Allergy Considerations
If GAS is confirmed and the patient has penicillin allergy:
- For patients without anaphylaxis history: Use a first-generation cephalosporin 1, 3
- For patients with immediate hypersensitivity to penicillin: Use clindamycin or azithromycin 3, 6
- Azithromycin (12 mg/kg once daily for 5 days in children) has been shown to be clinically and microbiologically superior to penicillin V at Days 14 and 30 6