Pharyngitis is defined as an infection or irritation of the pharynx or tonsils (see the image below). The etiology is usually infectious, with most cases being of viral origin and most bacterial cases attributable to group A streptococci (GAS). Other causes include allergy, trauma, toxins, and neoplasia.
It is difficult to distinguish viral and bacterial causes of pharyngitis on the basis of history and physical examination alone. Nevertheless, the following factors may help rule out or diagnose GAS pharyngitis:
GAS infection is most common in children aged 4-7 years
Sudden onset is consistent with GAS pharyngitis; pharyngitis after several days of coughing or rhinorrhea is more consistent with a viral etiology
Contact with others who have GAS or rheumatic fever with symptoms consistent with GAS raises the likelihood of GAS pharyngitis
Headache is consistent with GAS infection
Cough is not usually associated with GAS infection
Vomiting is associated with GAS infection, though not exclusively so
Recent orogenital contact suggests possible gonococcal pharyngitis
A history of rheumatic fever is important
Centor criteria for GAS pharyngitis include the following:
Fever (1 point)
Anterior cervical lymphadenopathy (1 point)
Tonsillar exudate (1 point)
Absence of cough (1 point)
A score of 0-1 makes GAS infection unlikely; a score of 4 makes it likely. In adults, the positive predictive value of these criteria is around 40% if 3 criteria are met and about 50% if 4 criteria are met.
Physical examination includes the following:
Assessment of airway patency
Head, ears, eyes, nose, and throat – Conjunctivitis, scleral icterus, rhinorrhea, tonsillopharyngeal/palatal petechiae, tonsillopharyngeal exudate, oropharyngeal vesicular lesions
Lymphadenopathy (cervical or generalized)
See Clinical Presentation for more detail.
Laboratory studies that may be helpful include the following:
Group A beta-hemolytic streptococcal rapid antigen detection test (preferred diagnostic method in emergency settings)
Throat culture (criterion standard for diagnosis of GAS infection [90-99% sensitive])
Mono spot (up to 95% sensitive in children; less than 60% sensitive in infants)
Gonococcal culture if indicated by the history
Imaging studies generally are not indicated for uncomplicated viral or streptococcal pharyngitis. However, the following may be considered:
Lateral neck film in patients with suspected epiglottitis or airway compromise
Soft-tissue neck CT if concern for abscess or deep-space infection exists
A throat swab may also be done.
See Workup for more detail.
Prehospital care usually is not necessary for uncomplicated pharyngitis unless airway compromise is an issue. Intubation should not be attempted unless the patient stops breathing spontaneously.
Emergency measures may include the following:
Assess and secure the airway, if necessary
Assess the patient for signs of toxicity, epiglottitis, or oropharyngeal abscess
Evaluate hydration status, and rehydrate as necessary
Assess for GAS infection if clinically suspected
Most cases, whether viral or bacterial, are relatively benign and self-limited. Management of GAS infection, when indicated, includes the following:
Do not treat patients without a positive culture or positive rapid antigen detection test result
Perform a rapid antigen detection test if GAS is clinically suspected on the basis of the history and physical examination; if test results are positive, begin antibiotic therapy
Patients who are positive for all 4 Centor criteria can often be treated with antibiotics without antigen testing or cultures
Household contacts of patients with GAS infection or scarlet fever should be treated for a full 10 days of antibiotics without testing only if they have symptoms consistent with GAS; asymptomatic contacts should not be treated
If the diagnosis is in doubt or the above criteria are not met, initiation of antibiotic therapy should await rapid antigen test or culture results
Pharyngitis is defined as an infection or irritation of the pharynx and/or tonsils. The etiology is usually infectious, with most cases being of viral origin. These cases are benign and self-limiting for the most part. Bacterial causes of pharyngitis are also self-limiting, but are concerning because of suppurative and nonsuppurative complications. Other causes include allergy, trauma, toxins, and neoplasia. 
The most significant bacterial agent causing pharyngitis in both adults and children is GAS infection (Streptococcus pyogenes); this is shown in the image below.
Physical findings of GAS are shown in the image below.
Mycoplasma pneumoniae, Chlamydia pneumoniae, and Arcanobacterium haemolyticus are other bacterial causes of pharyngitis, but these pathogens are rare. Antibiotics covering atypical pathogens should not routinely be used to treat pharyngitis. 
The main ED concerns with pharyngitis are to rule out more serious conditions, such as epiglottitis or peritonsillar abscess, and to diagnose group A beta-hemolytic streptococcal (GABHS) infections. Airway obstruction is also of utmost importance for the ED physician treating pharyngitis.
With infectious pharyngitis, bacteria or viruses may directly invade the pharyngeal mucosa, causing a local inflammatory response. Other viruses, such as rhinovirus and coronavirus, can cause irritation of pharyngeal mucosa secondary to nasal secretions. 
Streptococcal infections are characterized by local invasion and release of extracellular toxins and proteases. In addition, M protein fragments of certain serotypes of GAS are similar to myocardial sarcolemma antigens and are linked to rheumatic fever and subsequent heart valve damage. The prevalence rates of these serotypes of GAS have been becoming rarer over the past several years. Acute glomerulonephritis may result from antibody-antigen complex deposition in glomeruli. 
Children experience more than 5 upper respiratory infections (URIs) per year and an average of one streptococcal infection every 4 years. The occurrence in adults is about one half that rate. The most significant bacterial agent causing pharyngitis in both adults and children is GAS infection (Streptococcus pyogenes), and the most common viruses are rhinovirus and adenovirus. GAS is most prevalent in late fall through early spring. 
The incidence of pharyngitis is higher internationally. Antibiotic resistance may be more prevalent in some countries because of overprescription of antibiotics. Note, however, that despite this, there has never been a documented case of GAS resistant to penicillin anywhere in the world. 
A study by Banigo et al reported that the reduction in the number of tonsillectomies performed in England (28,309 in 1990/1991 vs 6327 in 2013/2014) correlates with an increase in the number of hospital admissions in that country for acute tonsillitis and pharyngitis and with an increase in invasive group A beta-hemolytic streptococcal (GABHS) infections. Indeed, over the course of the 1990/1991 to 2013/2014 period, the number of invasive GABHS infections rose more than two-fold in children aged 14 years or younger. 
In the developing world, an estimated 20 million people are affected by acute rheumatic fever and rheumatic heart disease, making this the leading cause of cardiac death during the first 5 decades of life. This incidence of rheumatic heart disease is dramatically lower in most developed countries, but localized outbreaks have occurred in the Western world. Despite this, new cases of rheumatic heart disease in the United States are extremely rare.  The US Centers for Disease Control and Prevention (CDC) stopped tracking the incidence of rheumatic heart disease in the United States in 1994, when the incidence dropped to less than 1 case per million US general population. 
Other sequelae of streptococcal pharyngitis include acute glomerulonephritis, peritonsillar abscess, and toxic shock syndrome.
Mortality from pharyngitis is rare but may result from one of its complications, most notably airway obstruction.
Pharyngitis occurs with much greater frequency in the pediatric population. Approximately 15-30% of sore throats in children are caused by group A beta-hemolytic streptococcal (GABHS) infections, compared with 5-15% of adults. [1, 7]
The peak incidence of bacterial and viral pharyngitis occurs in the school-aged child aged 4-7 years, with GABHS occurring primarily in patients aged 5-15 years. Pharyngitis, especially GAS infection, is rare in children younger than 3 years.
In a study of 3098 pediatric patients with pharyngitis, Nishiyama et al found the prevalence of GAS pharyngitis to be 1.2% in patients below age 1 year and 3.9% in patients aged 1 year. 
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John R Acerra, MD Assistant Professor, Department of Emergency Medicine, Hofstra North Shore-LIJ School of Medicine; Director, International Emergency Medicine Fellowship, North Shore-LIJ Health System
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
Jeter (Jay) Pritchard Taylor, III, MD Assistant Professor, Department of Surgery, University of South Carolina School of Medicine; Attending Physician, Clinical Instructor, Compliance Officer, Department of Emergency Medicine, Palmetto Richland Hospital
Jeter (Jay) Pritchard Taylor, III, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Columbia Medical Society, Society for Academic Emergency Medicine, South Carolina College of Emergency Physicians, South Carolina Medical Association
Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Employed contractor – Chief Editor for Medscape.
Jerry R Balentine, DO, FACEP, FACOEP Vice President, Medical Affairs and Global Health, New York Institute of Technology; Professor of Emergency Medicine, New York Institute of Technology College of Osteopathic Medicine
Jerry R Balentine, DO, FACEP, FACOEP is a member of the following medical societies: American College of Emergency Physicians, New York Academy of Medicine, American College of Osteopathic Emergency Physicians, American Association for Physician Leadership, American Osteopathic Association
Disclosure: Nothing to disclose.
Mark W Fourre, MD Associate Clinical Professor, Department of Surgery, University of Vermont School of Medicine; Program Director, Department of Emergency Medicine, Maine Medical Center
Disclosure: Nothing to disclose.
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