Continuing Education Activity

Group A streptococcus is a Gram-positive, non-motile bacteria that is the most common etiology for acute pharyngitis accounting for 5 to 15 percent of all adult cases and 20 to 30 percent of all pediatric cases. Patient history may include an abrupt onset of fever, sore throat, and exposure to someone with the disease within the previous two weeks. The following activity emphasizes the essential knowledge necessary for interprofessional team members to have while treating patients with streptococcal pharyngitis.

Objectives:

• Review the evaluation of a patient with suspected streptococcal pharyngitis.
• Summarize the treatment of streptococcal pharyngitis.
• Describe the complications of streptococcal pharyngitis.
• Describe the value of improving care coordination among the interprofessional team to educate patients on proper hand hygiene to prevent the spread of infection.

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 annually 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 of 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] However, in adults, 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 are 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 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 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 (Behçet 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 diagnose 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 are optimized with an interprofessional team that can include a primary care provider, emergency department physician, otolaryngologist, 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 preventing the spread of infection to others. The outcome of patients treated promptly with antibiotics is excellent, with recovery in a few days. It is important to educate the patient on proper hand hygiene to prevent the spread of infection to others. Patients should be informed that there is a small risk of developing glomerulonephritis or rheumatic fever. [11][12] [Level 5]