About 50% to 80% of pharyngitis, or sore throat, symptoms are viral in origin and include a variety of viral pathogens. These pathogens are predominantly rhinovirus, influenza, adenovirus, coronavirus, and parainfluenza. Less common viral pathogens include herpes, Epstein-Barr virus, human immunodeficiency virus (HIV), and coxsackievirus. More severe cases tend to be bacterial and may develop after an initial viral infection.
The most common bacterial infection is Group A beta-hemolytic streptococci, which causes 5% to 36% of cases of acute pharyngitis. Other bacterial etiologies include Group B & C streptococci, Chlamydia pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Candida, Neisseria meningitidis, Neisseria gonorrhoeae, Arcanobacterium haemolyticum, Fusobacterium necrophorum, and Corynebacterium diphtheriae. Environmental allergies and chemical exposures may also cause acute pharyngitis.
In 2010, there were 1.814 million emergency department visits for pharyngitis, of which 692,000 were for patients under the age of 15. Most cases of pharyngitis occur in children under the age of 5. Adults can also develop the disorder but at a lower rate. Globally, pharyngitis rates are very high chiefly in countries where antibiotics are overprescribed.
Bacteria and viruses can cause direct invasion of the pharyngeal mucosa. Certain viruses like rhinovirus can cause irritation secondary to nasal secretions. In almost all cases, there is a local invasion of the pharyngeal mucosa which also results in excess secretion and edema.
The history and physical examination should look for findings consistent with uncomplicated pharyngitis and exclude other potentially serious and life-threatening illnesses. Clinical manifestations frequently include fever, tonsillar exudates, painful cervical adenopathy, pharyngeal erythema, and ear pain. Uncomplicated infectious pharyngitis, both viral and bacterial, typically is self-limited to 5 to 7 days, is not progressive, is bilateral, does not have trismus, and does not have evidence of airway obstruction (stridor).
If viral in etiology, associated symptoms often include coughing, rhinorrhea, conjunctivitis, headache, and a rash. Group A beta-hemolytic streptococcal pharyngitis typically has an acute onset, lacks signs of a viral upper respiratory infection such as a cough or rhinorrhea, and is associated with fever, tonsillar exudates, and cervical adenopathy. Pharyngitis due to Epstein-Barr virus, otherwise known as infectious mononucleosis, can cause headaches, fever, tonsillar hypertrophy, lymphocytosis, atypical lymphocytes. Myalgia and fatigue are commonly reported symptoms. IMN can have both anterior and posterior cervical lymphadenopathy. Patients can have persistent lymphadenopathy and fatigue for up to 3 weeks. It is important to assess for hepatomegaly or splenomegaly. If a morbilliform rash develops after amoxicillin for presumed Group A beta-hemolytic streptococci, one should suspect infectious mononucleosis.
A retropharyngeal abscess is characterized by neck stiffness and pain with neck extension. For epiglottitis, look for stridor as a symptom. F. necrophorum is the bacterium that causes Lemierre's syndrome, or internal jugular vein thrombophlebitis. If there has been orogenital contact by the patient, consider N. gonorrhoeae. Acute retroviral syndrome due to HIV may be associated with fever and non-exudative pharyngitis.
A variety of clinical decision rules have been developed to improve the diagnosis of Group A beta-hemolytic streptococcal pharyngitis and to guide testing and treatment. The Centor Score is one of the most commonly used, particularly for adult patients.
Centor Criteria (1 point for each) for Group A Beta-hemolytic Streptococci:
More likely in 5 to 15 years of age and not valid under 3 years old.
Point Totals and Recommended Actions: 0-1: No testing or antibiotics.2-3: Rapid antigen test. 4: No testing, empiric antibiotics.
White blood cell counts have minimal value in the differentiation of viral versus bacterial etiologies of pharyngitis. A lymphocytosis (greater than 50%) or increased atypical lymphocytes (greater than 10%) may suggest infectious mononucleosis.
Rapid antigen detection tests (RADT) are very specific for Group A beta-hemolytic streptococci, but their sensitivity varies widely, from about 70% to 90%. If the test is positive, treatment should be initiated. If it is negative, particularly in children, a throat culture should be obtained and should guide treatment.
Throat cultures have been the ideal standard for diagnosis, but their sensitivity is variable and is influenced by many factors. These factors include the bacterial burden, site of collection (the tonsillar surface is best), culture medium, and culture atmosphere.
A heterophile antibody, or Monospot, test is 70% to 92% sensitive and 96% to 100% specific. This test for infectious mononucleosis is commonly available, but the ideal standard is to use Epstein-Barr virus serology. The test's sensitivity is lessened by testing early in the course of the illness (1 to 2 weeks) and by the age of the patient (less than 12 years).
For gonococcal origin, use a culture. Thayer-Martin agar is most commonly used. For Candida, test with a potassium hydroxide preparation or Sabouraud agar.
A chest X-ray is not needed for routine cases. If airway compromise is suspected, a lateral neck X-ray should be obtained.
A CT scan may help identify a peritonsillar abscess.
Antibiotics for pharyngitis are usually used for patients with Group A beta-hemolytic streptococcal pharyngitis. Antibiotics may shorten the duration of symptoms by 16 to 24 hours and prevent rheumatic fever. Older data suggest 1 in 400 untreated cases of strep pharyngitis. Antibiotics should only be used for Group A beta-hemolytic streptococci-positive patients, particularly if they are children, based on a positive culture or a rapid antigen detection test. A 10-day course of oral penicillin is recommended to ensure the eradication of bacterial carriage and the prevention of rheumatic fever. 
Treatment options for Group A beta-hemolytic streptococcal pharyngitis include oral treatment with penicillin V or oral amoxicillin. Cephalosporins, macrolides, and clindamycin may also be used. Intramuscular penicillin is also a treatment option. Resistance may develop during treatment with azithromycin and clarithromycin, and it is not considered a first-line antibiotic for this indication. In patients with a mild penicillin allergy, cephalosporins can be used. In patients with a history of anaphylaxis to penicillin, azithromycin or clindamycin can be used. The disease is no longer infectious after 24 hours of antibiotics.
Single-dose corticosteroids like dexamethasone may be given to reduce the severity of symptoms, although the evidence for this approach is limited. Symptomatic treatment with gargles and acetaminophen or non-steroidal anti-inflammatory drugs should be recommended. Use caution in the setting of severe dehydration. For patients with infectious mononucleosis, contact sports should be avoided for 6 to 8 weeks due to the risk of splenic rupture.
In developing countries, over 20 million individuals are affected by group B streptococci and develop acute rheumatic fever. This disorder is the leading cause of death in young people. Other complications as a result of streptococcal pharyngitis include peritonsillar abscesses, acute glomerulonephritis, and toxic shock syndrome. Mortality from pharyngitis is rare but does occur if the airway is compromised.
Most cases of pharyngitis resolve within 7 to 10 days. Treatment failures are usually due to antibiotic resistance, poor compliance, and untreated close contacts.
Complications of bacterial pharyngitis include:
Household members of patients with group A streptococci should be treated with a full 10-day course of antibiotics without any prior testing only if they present with symptoms. Asymptomatic individuals require no treatment.
Patients must complete a full course of antibiotics, follow up with a primary care provider, wash their hands, rest, and remain hydrated.
Antibiotics are typically overused in the treatment of acute pharyngitis. As most cases are due to a viral etiology, and antibiotics will not alter the patient's course.
The management of pharyngitis is an interprofessional. Once the patient is discharged, follow up is required by the nurse, pharmacist or healthcare provider. Follow-up cultures are not necessary in patients without symptoms. All patients with pharyngitis should be educated on the use of antibiotics. Patients should be told not to use antibiotics empirically because the cause is most often viral. Hand washing and maintenance of good personal hygiene is important to prevent spread to others in the home. To prevent recurrence, immunization should be recommended against the flu virus and diphtheria. All patients must be told about the importance of compliance with antibiotic treatment. Further, patients should be told to use salt water gargles and adhere to a liquid diet until the symptoms subside. If the patient has a fever or pain, acetaminophen is recommended. Finally, parents should be told not to give young children aspirin for fever. (Level V)
The majority of pharyngitis cases recover spontaneously within 7-10 days. Failures may occur if the cause is bacterial and antibiotics were either never prescribed, or there was the presence of antibiotic resistance, or there was a lack of patient compliance with treatment. Most cases of streptococcal pharyngitis improve within 24-48 hours of treatment. However, the flu-like symptoms may persist for 5-10 days. Mortality in the US is very rare but can occur from upper airway obstruction. Complications from pharyngitis are reported in less than 1% of patients and may include otitis media, pneumonia, nephritis, and meningitis. (Level V)
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