Streptococcal Pharyngitis

Article Author:
John Ashurst
Article Editor:
Laura Edgerley-Gibb
Updated:
3/15/2019 10:13:20 AM
PubMed Link:
Streptococcal Pharyngitis

Introduction

Acute pharyngitis is one of the most common complaints that a physician encounters in the ambulatory care setting, accounting for approximately 12 million visits each year or 1% to 2% of all ambulatory care visits annually.[1] Typically, the incidence peaks during childhood and adolescents and accounts for 50% of all visits annually.[2] Although there are a large number of visits each year for pharyngitis, the majority of these cases are viral and are self-limiting. However, Group A Streptococcus (GAS) is the most common bacterial etiology for acute pharyngitis and accounts for 5% to 15% of all adult cases and 20% to 30% of all pediatric cases. [3],[4],[5]

Etiology

Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a facultative gram-positive coccus that grows in chains.

Epidemiology

GAS is the most common bacterial cause of pharyngitis in children and adolescents with a peak incidence in winter and early spring.[2] GAS pharyngitis is also more common in school-aged children or in those with a direct relation to school-aged children. A recent meta-analysis showed that the prevalence GAS pharyngitis in those less than 18 years old who present to an outpatient center for treatment for a sore throat was 37%, and for children younger than 5, it was 24%.[6] In adults, however, GAS pharyngitis will typically occur before the age of 40 and decline steadily after that.[7]

History and Physical

Multiple studies have shown that history and physical examination alone fail to aid the physician in accurately diagnosing GAS pharyngitis in patients.[8] However, a history that consists of a sore throat, abrupt onset of fever, the absence of a cough, and exposure to someone with GAS pharyngitis within the previous 2 weeks may be suggestive of GAS pharyngitis.[9],[10] Physical exam findings including cervical lymphadenopathy, pharyngeal inflammation, and tonsillar exudate. Palatine petechiae and uvular edema are also suggestive.[9],[10]

Evaluation

The modified Centor criteria is a clinical aid for physicians to determine who to test and treat when GAS pharyngitis is suspected. However, the Infectious Disease Society of American (IDSA) currently notes that the signs and symptoms of GAS pharyngitis overlap too broadly with other infectious and non-infectious causes to allow for a precise diagnosis to be made based upon history and physical alone.

The broad overlap of signs and symptoms seen in bacterial and viral pharyngitis coupled with the inaccuracy of medical providers when distinguishing GAS pharyngitis from other causes, the IDSA recommends confirmatory bacterial testing in all cases except when a clear viral etiology is expected. Diagnostic testing in children younger than 3 is not recommended because both GAS pharyngitis and acute rheumatic fever is rare in this age group. However, children under 3 years of age with risk factors, including but not limited to siblings with GAS pharyngitis, may be considered for testing. [5]

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. In children, 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. Anti-streptococcal antibody titers are not recommended to aid the physician in the acute diagnosis of GAS pharyngitis because the test reflects previous infections.  Following treatment, a test of cure is not needed but may be considered in special circumstances. [5]

Treatment / Management

The main goals of treatment for GAS pharyngitis include reducing a patient’s duration and severity of symptoms, preventing acute and delayed complications, and the preventing the spread of infection to others.

Those with GAS pharyngitis should be treated with either penicillin or amoxicillin given their relatively low cost and low adverse effect profile. Penicillin can be prescribed as either 250 mg twice or three times daily for children and 250 mg 4 times daily for adults. If either the clinician or patient prefers an intramuscular approach for penicillin treatment, then benzathine penicillin G, can be given as a one-time dose of 600,000 units if the patient is less than 27 kg and 1.2 million U if the patient is greater than or equal to 27 kg. If amoxicillin is chosen by the prescriber, then the medication can be given 50 mg/kg, once daily with a maximum of 1000 mg per dose or 25 mg/kg twice a day with a maximum of 500 mg per dose. With either the penicillin or oral amoxicillin route, a total of 10 days of treatment should be completed. [5]

For those with an allergy to penicillin, clindamycin (7 mg/kg/dose, 3 times daily; max = 300 mg/dose; 10 day duration), clarithromycin (7.5 mg/kg/dose. twice daily; max = 250mg/dose; 10 day duration) or azithromycin (12 mg/kg, once daily; max = 500mg/dose; 5 day duration) can be prescribed. A first-generation cephalosporin (cephalexin 20 mg/kg/dose, twice daily, max = 500mg/dose; duration 10 days) can also be used for those patients without an anaphylactoid reaction to penicillin. [5]

As adjunctive therapy for the patient with GAS pharyngitis, the IDSA recommends acetaminophen or an NSAID to control pain associated with the disease or any fever that should develop. Currently, the ISDA does not recommend routine adjunctive therapy with corticosteroids for those with GAS pharyngitis. [5]

Following antibiotic treatment, patients may see the resolution of symptoms within one 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, post-exposure prophylaxis is not recommended unless a patient has a history of acute rheumatic fever, during outbreaks of non-supportive complications, or when GAS infections are seen recurrently in households or close contacts. Prevention of the disease is through proper hand hygiene, and it also is key to halting disease progression within close quarters. [5]

Differential Diagnosis

Infectious Causes[5]

  • Respiratory viruses (parainfluenza, rhinovirus, coxsackievirus, adenovirus etc)
  • Arcanobaceterium haemolyticum
  • Mycoplasma species
  • Chlamydia species
  • Corynebacterium diphtheria
  • Acute HIV infection
  • Neisseria gonorrhoeae
  • Treponema pallidum
  • Epstein-Barr virus
  • Fusobacterium necrophorum

Non-infectious Causes[5]

  • Allergies
  • Gastroesophageal reflux disease
  • Exposure to second-hand smoke
  • Trauma
  • Autoimmune disorders (Behcet Syndrome, Kawasaki, etc)
  • Foreign body

Complications

Suppurative complications seen with GAS pharyngitis include tonsillopharyngeal cellulitis or abscess, otitis media, sinusitis, necrotizing fasciitis, bacteremia, meningitis, brain abscess, and jugular vein septic thrombophlebitis. Non-suppurative complications of GAS pharyngitis include acute rheumatic fever, post-streptococcal reactive arthritis, scarlet fever, streptococcal toxic shock syndrome, acute glomerulonephritis, and pediatric autoimmune neuropsychiatric disorder associated with group A streptococci (PANDAS).

Pearls and Other Issues

Because physicians cannot accurately diagnosis GAS pharyngitis based solely on history and physical exam, the IDSA recommends confirmatory bacterial testing with a rapid antigen detection test.

The treatment of choice for confirmed GAS pharyngitis is either penicillin or amoxicillin. For those with an allergy to penicillin, then clindamycin, clarithromycin, or azithromycin can be used.

A test of cure is only recommended in special patient populations and should not be employed routinely.

Enhancing Healthcare Team Outcomes

The diagnosis and management of GAS is with a multidisciplinary team that includes an emergency department physician, nurse practitioner, infectious disease consultant and an internist. The goal of treatment for GAS is to lower the patient’s duration and severity of symptoms, preventing acute and delayed complications, and the preventing the spread of infection to others. The outcome of patients treated promptly with antibiotcs is excellent with recovery in a few days. It is important to educate the patient on proper hand hygiene to prevent spread of infection to others. Patients should be informed that there is a small risk of developing glomerulunephritis or rheumatic fever. [11][12](Level V)


References

[1] Schappert SM,Rechtsteiner EA, Ambulatory medical care utilization estimates for 2006. National health statistics reports. 2008 Aug 6     [PubMed PMID: 18958997]
[2] Danchin MH,Rogers S,Kelpie L,Selvaraj G,Curtis N,Carlin JB,Nolan TM,Carapetis JR, Burden of acute sore throat and group A streptococcal pharyngitis in school-aged children and their families in Australia. Pediatrics. 2007 Nov     [PubMed PMID: 17974731]
[3] Pichichero ME, Group A streptococcal tonsillopharyngitis: cost-effective diagnosis and treatment. Annals of emergency medicine. 1995 Mar     [PubMed PMID: 7864482]
[4] Tsevat J,Kotagal UR, Management of sore throats in children: a cost-effectiveness analysis. Archives of pediatrics     [PubMed PMID: 10401800]
[5] Shulman ST,Bisno AL,Clegg HW,Gerber MA,Kaplan EL,Lee G,Martin JM,Van Beneden C, Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2012 Nov 15     [PubMed PMID: 23091044]
[6] Shaikh N,Leonard E,Martin JM, Prevalence of streptococcal pharyngitis and streptococcal carriage in children: a meta-analysis. Pediatrics. 2010 Sep     [PubMed PMID: 20696723]
[7] Andr� M,Odenholt I,Schwan A,Axelsson I,Eriksson M,Hoffman M,M�lstad S,Runehagen A,Lundborg CS,Wahlstr�m R, Upper respiratory tract infections in general practice: diagnosis, antibiotic prescribing, duration of symptoms and use of diagnostic tests. Scandinavian journal of infectious diseases. 2002     [PubMed PMID: 12587619]
[8] Shulman ST,Bisno AL,Clegg HW,Gerber MA,Kaplan EL,Lee G,Martin JM,Van Beneden C, Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2012 Nov 15     [PubMed PMID: 22965026]
[9] Choby BA, Diagnosis and treatment of streptococcal pharyngitis. American family physician. 2009 Mar 1     [PubMed PMID: 19275067]
[10] Ebell MH,Smith MA,Barry HC,Ives K,Carey M, The rational clinical examination. Does this patient have strep throat? JAMA. 2000 Dec 13     [PubMed PMID: 11147989]
[11] Leung TN,Hon KL,Leung AK, Group A Streptococcus disease in Hong Kong children: an overview. Hong Kong medical journal = Xianggang yi xue za zhi. 2018 Dec;     [PubMed PMID: 30416105]
[12] Vekemans J,Gouvea-Reis F,Kim JH,Excler JL,Smeesters PR,O'Brien KL,Van Beneden CA,Steer AC,Carapetis JR,Kaslow DC, The path to group A Streptococcus vaccines: WHO research and development technology roadmap and preferred product characteristics. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2019 Jan 8;     [PubMed PMID: 30624673]