Diagnosis
In developing countries, one third of pharyngitis cases are cases by GAS. The majority of cases are caused by viral infections that do not benefit from antibiotic treatment. Distinguishing viral pharyngitis from bacterial pharyngitis is difficult but important – without treatment 0.3 - 3% of episodes of GAS pharyngitis will precipitate a case of ARF.
A wide range of scoring tools and diagnostic criteria for identifying GAS pharyngitis have been developed – the majority in high resource settings. One of the most commonly used scoring system is the Centor Score, assigning points for tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough and history of fever. Applicability of the Centor Score to low resource settings where ARF is common remain a subject of ongoing study. There is some evidence that clinical presentation of sore throats varies significantly between low income settings, which may limit utility of clinical scoring tools.
Rapid antigen detection tests may be used to inform diagnosis of GAS pharyngitis, though are often not available in settings with a high incidence of ARF. Throat swabs for culture remain the gold standard test for diagnosis of GAS pharyngitis. Microbiology facilities may not be widely available and results take days, limiting the usefulness of throat swabs in acute pharyngitis.
Treatment
Treatment of GAS pharyngitis with an appropriate antibiotic within 9 days of symptoms reduces the attack rate of ARF following GAS pharyngitis by up to 80%. Antibiotic treatment in this critical window is known as primary prophylaxis of ARF.
In many parts of the world, primary prophylaxis is considered an essential step to control of ARF and RHD at population level. Large scale programs to provide primary prophylaxis have been undertaken in New Zealand and in other countries. Policy details are provided in the ‘Control’ section of this site.
Guidelines for management of pharyngitis have been developed in different regions and countries, listed below. Guidelines from high resource countries with a low incidence of ARF tend to recommend against antibiotic treatment of sore throat. These guidelines should not be used in settings with a high incidence of ARF.
Australia
Infants and children; acute management of sore throat. Clinical practice guidelines for New South Wales, 2014
Canada
Treatment of group A streptococcal pharyngitis recommendations, written by the Infectious Diseases and Immunization Committee in 1997.
Europe
Guideline for the management of acute sore throat: ESCMID Sore Throat Guideline Group, published by the European Society for Clinical Microbiology and Infectious Diseases in 2014
New Zealand
Group A streptococcal sore throat management guideline, 2014 update and algorithm developed by the New Zealand Heart Foundation and the Cardiac Society of Australia and New Zealand.
Southern Africa
Guideline for the management of upper respiratory tract infections, written by the Infectious Diseases Society of Southern Africa in 2004
United States of America
Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Also guidance on the prevention of rheumatic fever and diagnosis and treatment of acute streptococcal pharyngitis by the American Heart Association in 2009
Global
The Integrated Management of Childhood Illness (IMCI) program in Africa includes sore throat guidelines to guide treatment by nursing and community health staff.
The vast majority of these guidelines recommend treatment of GAS pharyngitis with penicillin, given orally or intramuscularly. Given the challenges of adherence, a single intramuscular dose of benzathine penicillin G (BPG) is often recommended in areas with a high incidence of ARF. Erythromycin is generally suggested as an alternative for patients with a proven history of hypersensitivity reaction to penicillin.
Antibiotic resistance
Doctors are sometimes worried that treating too many sore throats with antibiotics will cause antibiotic resistance. Use of penicillin to treat sore throats has not been associated with penicillin resistance in GAS; no GAS isolate has ever demonstrated penicillin resistance. The mechanism of this persistent sensitivity to penicillin is poorly understood but has been maintained for many decades with widespread use.
There is the potential for over-use of antibiotics for pharyngitis to contribute to resistance in other bacteria, particularly if penicillin or amoxicillin were replaced by broader-spectrum, often more expensive, antibiotics were used. For example, Streptococcus pneumonia is a major cause of pneumonia which has demonstrated resistance to penicillin following widespread overuse of antibiotics to treat viral infection. It is important that systems to support rational prescribing and accurate diagnosis of GAS are in place and updated regularly. The use of broad spectrum antibiotics for pharyngitis should be discouraged.