Diagnosis and Management of Group A Streptococcal Pharyngitis
SUMMARY:
Group A streptococcal (GAS) pharyngitis is a common cause of community acquired infection and can lead to severe acute and long-term complications when left untreated. While rates of GAS infections decreased markedly during the COVID-19 pandemic, the CDC reports an increase in infections in the past year (2022-2023), including invasive, severe disease, and GAS infections in the elderly. Diagnosis and treatment of GAS remains critical to prevent post-GAS complications such as rheumatic fever and glomerulonephritis.
Clinical Presentation
- GAS is the most common bacterial cause of acute pharyngitis and is responsible for 5% to 15% of sore throats in adults
- Signs and symptoms include:
- Acute onset sore throat
- Fever
- Pharyngeal Edema | Erythema |Tonsillar exudates
- Tender anterior cervical lymphadenopathy
- Hard palate petechiae
- Less commonly: Abdominal pain | Nausea/emesis | Headache | Rash
- History of exposure is an important risk factor
- Symptoms that are less consistent with GAS pharyngitis include: Rhinorrhea | Hoarseness | Cough | Conjunctivitis
Diagnosis
- Diagnosis should not be made on clinical presentation alone
- Scoring criteria such as the “Centor Score” can help determine who should be tested based on clinical presentation, but should not replace diagnostic testing
- Patients with clinical symptoms consistent with GAS pharyngitis should undergo rapid antigen detection testing (RADT)
- Throat cultures are recommended for children and adolescents with negative RADT
- Adults have a low pre-test probability for GAS pharyngitis and back up throat cultures are generally not recommended in most cases if RADT is negative
- If RADT is positive further testing is unnecessary given RADT’s high specificity
- Anti-streptococcal antibody titers are not recommended for routine diagnosis of acute infections
- Positive antibody titers reflect past but not current infections
- Differential diagnosis includes: Viral pharyngitis | COVID-19 | Viral URIs | Mono/EBV | Acute HIV | Gonococcal pharyngitis | HSV | Group C streptococcus
- Positive RADT does not distinguish between carriage and acute infection
Treatment
- Without treatment GAS is generally a self-limited disease
- The goals of prompt antibiotic treatment of GAS include
- Decrease length and severity of symptoms
- Prevent acute and long term complications
- Decrease transmission risk
- GAS pharyngitis is the only commonly occurring form of acute pharyngitis for which antibiotic therapy is indicated
- Treatment within 9 days of the onset of illness is effective in preventing acute rheumatic fever (ARF)
- Antibiotic treatment is not effective in preventing poststreptococcal glomerulonephritis
- Adjunctive therapy includes: NSAIDs | Tylenol | Topical anesthetics for sore throat | Lozenges
- Steroids are not recommended
Antibiotics
- First line therapy
- Penicillin: 250 mg 4 times daily or 500 mg twice daily for 10 days | Penicillin-resistant GAS has never been documented
- Amoxicillin: 1g once daily or 500 mg twice daily for 10 days | Once daily dosing my increase adherence
- Benzathine penicillin G: 1,200,000 U IM given once | Preferred for patients unlikely to complete a 10 day course of antibiotics
Penicillin Allergic Patients
- 1st generation cephalosporin (for those not anaphylactically sensitive) for 10 days
- Cephalexin: 500 mg twice daily
- Cefadroxil: 1g daily
- Clindamycin: 300 mg TID for 10 days
- Clarithromycin: 250 mg twice daily or 10 days
- Azithromycin: 500 mg daily for 5 days
Group A Strep Carriers
- Patients with recurrent episodes of GAS pharyngitis in close succession should prompt consideration of GAS carriage
- GAS carriers are unlikely to spread GAS pharyngitis and are at little to no risk of developing complications
- GAS carriage is difficult to eradicate and should only be considered in specific clinical settings
- During a community outbreak of acute rheumatic fever, acute poststreptococcal glomerulonephritis, or invasive GAS infection
- During an outbreak of GAS pharyngitis in a closed or partially closed community
- In the presence of a family or personal history of acute rheumatic fever
- In a family with excessive anxiety about GAS infections
- When tonsillectomy is being considered only because of carriage.
Complications
- Suppurative: Tonsillopharyngeal cellulitis | Abscess | Otitis media | Sinusitis | Mastoiditis
- Nonsuppurative: Acute rheumatic fever | Reactive arthritis | Scarlet fever | Glomerulonephritis | Streptococcal toxic shock syndrome
- If patients fail to improve with antibiotics, then alternative causes of pharyngitis OR suppurative complication of GAS pharyngitis should be looked for
Follow Up
- Patients treated for Group A Streptococcal pharyngitis should generally begin to feel better within 24 to 48 hours of starting antibiotic therapy
- Patients should complete the full course of antibiotics to ensure complete eradication of the bacteria and prevent recurrence
- A repeat test for cure is not recommended for patients who have improved
- May be considered in special populations (e.g., patients at high risk of acute rheumatic fever or recurrent GAS infection)
- Diagnostic testing or empiric treatment of asymptomatic household contacts is not routinely recommended
- Patients may return to work or school when they are
- Afebrile
- Have taken antibiotics for 24 hours
KEY POINTS:
- Group A Streptococcal pharyngitis is the most common cause of bacterial pharyngitis in adults
- Throat culture or RADT should be used to confirm the diagnosis of GAS pharyngitis
- Antibiotics are recommended for the treatment of Group A Streptococcal pharyngitis to reduce the duration and severity of symptoms, prevent complications, and reduce the risk of transmission to others
- Penicillin is the first-line agent for most patients with Group A Streptococcal pharyngitis
- Patients should complete the full course of antibiotics to prevent recurrence and complications.
Learn More – Primary Sources
CDC: Increase in Invasive Group A Strep Infections, 2022–2023
