US Pharm. 2024;49(8):46-48.
Streptococcal pharyngitis, also referred to as strep throat, is one of the most common upper respiratory infections in school-age children and young adults. In the United States, strep throat accounts for approximately 12 million visits annually in outpatient care settings.1 Strep throat is caused by both viruses and bacteria.
If the onset of a sore throat occurs quickly, it may be caused by Streptococcus pyogenes, also known as group A streptococcus (GAS).1 GAS is a gram-positive, nonmotile, coccus bacterium that grows in chains, and it is the most common etiology for acute pharyngitis, accounting for 5% to 15% of all adult cases and 20% to 30% of all pediatric cases.1 Patient complaints and history may include abrupt onset of fever, sore throat, red tonsils, and exposure to someone with the disease within the previous 2 weeks.2
Although there are a large number of healthcare visits each year for streptococcal pharyngitis, the majority of these cases are viral and self-limiting.3,4 This column will briefly cover the epidemiology, symptoms, diagnosis, treatment, and complications of this infection in school-age children and young adults.1,2
Pathogenesis and Epidemiology
GAS is the most common bacterial cause of streptococcal pharyngitis in children and young adults and peaks in winter and early to mid spring.2 GAS pharyngitis is also more common in children or in friends and families with a direct relation to school-age children.5,6
A recent meta-analysis showed that the prevalence of GAS pharyngitis in children aged younger than 5 years was 24%; in those aged younger than 18 years who presented to an outpatient center for treatment, it was 37%.7 However, GAS pharyngitis will typically occur in adults aged younger than 40 years, and the occurrence declines steadily thereafter.8
Many regions of the world with low income and poor infrastructure continue to suffer a high burden of S pyogenes diseases, with millions of deaths annually.9 The majority of these deaths follow the development of rheumatic heart disease (RHD), which remains a concern in both developed and developing countries. In many developed countries, the prevalence of RHD is much lower; however, the majority of S pyogenes–associated deaths are attributed to the clinical manifestations associated with invasive disease.10
Risk Factors
Three factors can increase the risk of strep throat infection:
• Young age: Strep throat occurs most commonly in children.
• Time of year: Although strep throat can occur anytime, it tends to circulate in winter and early spring.
• Crowded settings: Streptococcus bacteria flourish wherever people are in close contact.
Daycare centers, for example, can increase the risk of acquiring a GAS infection, including strep throat.
Symptoms and Diagnosis
Multiple studies have shown that history and physical examination alone fail to aid the physician in accurately diagnosing GAS pharyngitis.9 However, symptoms that consist of a sore throat, abrupt onset of fever, the absence of a cough, or exposure to someone with GAS pharyngitis within the previous 2 weeks may be suggestive of GAS pharyngitis.11,12 Physical examination findings include cervical lymphadenopathy, pharyngeal inflammation, and tonsillar exudate. Palatine petechiae and uvular edema are also suggestive of GAS pharyngitis.11,12
The Infectious Diseases Society of America (IDSA) currently notes that the signs and symptoms of GAS pharyngitis overlap too broadly with other infectious and noninfectious causes to allow for a precise diagnosis to be made based upon history and physical examination alone.6
The IDSA recommends confirmatory bacterial testing in all cases, except when a clear viral etiology is suspected. Diagnostic testing in children aged younger than 3 years is not recommended because both GAS pharyngitis and acute rheumatic fever are rare in this age group. However, children aged younger than 3 years with risk factors, including siblings with GAS pharyngitis, may be considered for testing.6
For those who undergo testing, the IDSA recommends that a rapid antigen detection test (RADT) be employed as the first-line measure to aid the physician in the diagnosis of GAS pharyngitis. Positive tests do not need to be backed up by a throat culture in all age groups due to the highly specific nature of the RADT. A negative RADT should be followed by a throat culture, but this is not needed in adults due to both the low incidence of GAS pharyngitis and acute rheumatic fever seen in this population. Following treatment, a test of cure is not needed but may be considered in special circumstances.6
The diagnosis and management of GAS are optimized with an interprofessional team that can include a primary care provider, emergency department physician, otolaryngologist, nurse practitioner, infectious disease consultant, and internist.
Differential Diagnosis
Streptococcal pharyngitis can be differentiated from many other conditions, including viral pharyngitis, epiglottitis, peritonsillar abscess, retropharyngeal abscess, coxsackievirus (herpangina), influenza, Epstein-Barr virus, and respiratory viruses (e.g., parainfluenza, rhinovirus, adenovirus, and infectious mononucleosis).
The following symptoms suggest that a virus (e.g., colds or flu) is the cause of a sore throat versus a strep throat13:
• Cough
• Runny nose
• Hoarseness (changes in voice)
• Conjunctivitis (also called pink eye).
Complications
Suppurative infections seen with GAS pharyngitis include tonsillopharyngeal cellulitis or abscess, otitis media, sinusitis, necrotizing fasciitis, bacteremia, meningitis, brain abscess, and jugular vein septic thrombophlebitis.1 Nonsuppurative complications of GAS pharyngitis include acute rheumatic fever, poststreptococcal reactive arthritis, scarlet fever, streptococcal toxic shock syndrome, acute glomerulonephritis, and pediatric autoimmune neuropsychiatric disorder associated with GAS.1
Treatment and Management
The main objectives of treatment for GAS pharyngitis are reducing a patient’s duration and severity of symptoms, preventing both acute and delayed complications, and preventing the overspill of the infection to others.
Those with GAS pharyngitis should be treated with either penicillin or amoxicillin, given their relatively low cost and low adverse effects. Penicillin can be prescribed as either 250 mg twice or three times daily for children and 250 mg four times daily for adults. If amoxicillin is chosen by the clinician, then the medication can be given 50 mg/kg once daily with a maximum of 1,000 mg per dose or 25 mg/kg twice a day with a maximum of 500 mg per dose. If either of these therapies is chosen, a total of 10 days of treatment should be completed.1,6
For those with an allergy to penicillin, clindamycin (7 mg/kg three times daily; maximum 300 mg/dosage; 10-day duration), clarithromycin (7.5 mg/kg twice daily; maximum 250 mg/dosage; 10-day duration), or azithromycin (12 mg/kg once daily; maximum 500 mg/dosage; 5-day duration) can be prescribed. A first-generation cephalosporin (cephalexin 20 mg/kg twice daily; maximum 500 mg/dosage; 10-day duration) can also be used for patients without an anaphylactoid reaction to penicillin.1,6
There has never been a report of a clinical isolate of GAS bacteria that is resistant to penicillin or cephalosporins. However, resistance to azithromycin, clarithromycin, and clindamycin is well known and varies geographically and temporally.
As supportive therapy for the patient with GAS pharyngitis, the IDSA recommends acetaminophen or a nonsteroidal anti-inflammatory drug to control pain associated with the illness or any fever that should arise. Although steroids are effective in relieving pain in acute pharyngitis, the benefits must be balanced with possible adverse drug effects. Currently, the IDSA does not recommend routine adjunctive therapy with corticosteroids for those with GAS pharyngitis.1,6
After the antibiotic treatment, patients may see the disappearance of symptoms within 1 to 3 days and may return to work or school after 24 hours of treatment. A test of cure is not recommended after a course of treatment unless a patient has a history of acute rheumatic fever or another GAS complication. Likewise, postexposure prophylaxis is not recommended unless a patient has a history of acute rheumatic fever, during outbreaks of nonsuppurative complications, or when GAS infections are seen recurrently in households or close contacts. Prevention of the illness is through proper hand hygiene, and it also is key to halting disease progression within close quarters.1,6
It is important to educate the patient on proper hand hygiene to prevent the spread of infection to others. Patients should also be informed that there is a small risk of developing glomerulonephritis or rheumatic fever.14,15
REFERENCES
1. Ashurst JV, Gibb-Edgerley L. Streptococcal pharyngitis. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2024 Jan-. www.ncbi.nlm.nih.gov/books/NBK525997.
2. Danchin MH, Rogers S, Kelpie L, et al. Burden of acute sore throat and group A streptococcal pharyngitis in school-aged children and their families in Australia. Pediatrics. 2007;120(5):950-957.
3. Pichichero ME. Group A streptococcal tonsillopharyngitis: cost-effective diagnosis and treatment. Ann Emerg Med. 1995;25(3):390-403.
4. Tsevat J, Kotagal UR. Management of sore throats in children: a cost-effectiveness analysis. Arch Pediatr Adolesc Med. 1999;153(7):681-688.
5. Brouwer S, Rivera-Hernandez T, Curren BF, et al. Pathogenesis, epidemiology and control of group A Streptococcus infection. Nat Rev Microbiol. 2023;21:431-447.
6. Shulman ST, Bisno AL, Clegg HW, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012;55(10):1279-1282.
7. Shaikh N, Leonard E, Martin JM. Prevalence of streptococcal pharyngitis and streptococcal carriage in children: a meta-analysis. Pediatrics. 2010;126(3):e557-e564.
8. André M, Odenholt I, Schwan A, et al. Upper respiratory tract infections in general practice: diagnosis, antibiotic prescribing, duration of symptoms and use of diagnostic tests. Scand J Infect Dis. 2002;34(12):880-886.
9. Shulman ST, Bisno AL, Clegg HW, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012;5(10):e86-e102.
10. Carapetis JR, Steer AC, Mulholland EK, Weber M. The global burden of group A streptococcal diseases. Lancet Infect Dis. 2005;5(11):685-694.
11. Choby BA. Diagnosis and treatment of streptococcal pharyngitis. Am Fam Physician. 2009;79(5):383-390.
12. Ebell MH, Smith MA, Barry HC, et al. The rational clinical examination. Does this patient have strep throat? JAMA. 2000;284(22):2912-2918.
13. CDC. Sore throat basics. April 17, 2024. www.cdc.gov/sore-throat/about. Accessed July 2, 2024.
14. Leung TN, Hon KL, Leung AK. Group A Streptococcus disease in Hong Kong children: an overview. Hong Kong Med J. 2018;24(6):593-601.
15. Vekemans J, Gouvea-Reis F, Kim JH et al. The path to group A Streptococcus vaccines: World Health Organization research and development technology roadmap and preferred product characteristics. Clin Infect Dis. 2019;69(5):877-883.
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