Etiology of Sore Throat
Sore throat results from infection; the most common cause is
Rarely, an abscess or epiglottitis is involved; although uncommon, these disorders are of particular concern because they may compromise the airway.
Tonsillopharyngitis is predominantly a viral infection; a lesser number of cases are caused by bacteria.
The respiratory viruses Overview of Viral Respiratory Infections Viral infections commonly affect the upper or lower respiratory tract. Although respiratory infections can be classified by the causative virus (eg, influenza), they are generally classified... read more (rhinovirus, adenovirus, the influenza virus, coronavirus, respiratory syncytial virus) are the most common viral causes, but occasionally Epstein-Barr virus Infectious Mononucleosis Infectious mononucleosis is caused by Epstein-Barr virus (EBV, human herpesvirus type 4) and is characterized by fatigue, fever, pharyngitis, and lymphadenopathy. Fatigue may persist weeks or... read more (the cause of mononucleosis), herpes simplex Herpes Simplex Virus (HSV) Infections Herpes simplex viruses (human herpesviruses types 1 and 2) commonly cause recurrent infection affecting the skin, mouth, lips, eyes, and genitals. Common severe infections include encephalitis... read more , cytomegalovirus Cytomegalovirus (CMV) Infection Cytomegalovirus (CMV, human herpesvirus type 5) can cause infections that have a wide range of severity. A syndrome of infectious mononucleosis that lacks severe pharyngitis is common. Severe... read more , HIV Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more (as a primary infection), or coronavirus SARS-CoV-2 (the cause of COVID-19 COVID-19 COVID-19 is a respiratory illness caused by the novel coronavirus SARS-CoV-2. Infection may be asymptomatic or have symptoms ranging from mild upper respiratory symptoms to acute respiratory... read more ) is involved.
The main bacterial cause of sore throat is group A beta-hemolytic streptococci (GABHS Streptococcal Infections Streptococci are gram-positive aerobic organisms that cause many disorders, including pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis. Symptoms vary with the organ... read more ), which, although estimates vary, causes perhaps 10 to 25% of all sore throats in adults and slightly more in children. GABHS is a concern because serious poststreptococcal sequelae (eg, rheumatic fever, glomerulonephritis, abscess) may occur.
Uncommon bacterial causes include gonorrhea Gonorrhea Gonorrhea is caused by the bacterium Neisseria gonorrhoeae. It typically infects epithelia of the urethra, cervix, rectum, pharynx, or conjunctivae, causing irritation or pain and purulent... read more , diphtheria Diphtheria Diphtheria is an acute pharyngeal or cutaneous infection caused mainly by toxigenic strains of the gram-positive bacillus Corynebacterium diphtheriae and rarely by other, less common... read more , mycoplasma Mycoplasmas Mycoplasmas are ubiquitous bacteria that differ from other prokaryotes in that they lack a cell wall. Mycoplasma pneumoniae is a common cause of pneumonia, particularly community-acquired... read more , and chlamydial infection Chlamydia Three species of Chlamydia cause human disease, including sexually transmitted infections and respiratory infections. Diagnosis depends on species; culture, nucleic acid amplification... read more .
An abscess in the pharyngeal area (peritonsillar Peritonsillar Abscess and Cellulitis Peritonsillar abscess and cellulitis are acute pharyngeal infections most common among adolescents and young adults. Symptoms are severe sore throat, trismus, "hot potato" voice, and uvular... read more , parapharyngeal Parapharyngeal Abscess A parapharyngeal abscess is a deep neck abscess. Symptoms include fever, sore throat, odynophagia, and swelling in the neck down to the hyoid bone. Diagnosis is by CT. Treatment is antibiotics... read more , and, in children, retropharyngeal Retropharyngeal Abscess Retropharyngeal abscesses, most common among young children, can cause sore throat, fever, neck stiffness, and stridor. Diagnosis requires lateral neck x-ray or CT. Treatment is with endotracheal... read more ) is uncommon but causes significant throat pain. The usual causative organism is GABHS.
Epiglottitis Epiglottitis Epiglottitis is a rapidly progressive bacterial infection of the epiglottis and surrounding tissues that may lead to sudden respiratory obstruction and death. Symptoms include severe sore throat... read more , perhaps better termed supraglottitis, used to occur primarily in children and usually was caused by Haemophilus influenzae type B (HiB). Now, because of widespread childhood vaccination against HiB, supraglottitis/epiglottitis has been almost eradicated in children; more cases occur in adults. Causal organisms in children and adults include Streptococcus pneumoniae, Staphylococcus aureus, nontypeable H. influenzae, Haemophilus parainfluenzae, beta-hemolytic streptococci, Branhamella catarrhalis, and Klebsiella pneumoniae. HiB is still a cause in adults and unvaccinated children.
Evaluation of Sore Throat
History of present illness should note the duration and severity of sore throat.
Review of systems should seek important associated symptoms, such as runny nose, cough, and difficulty swallowing, speaking, or breathing. The presence and duration of any preceding weakness and malaise (suggesting mononucleosis) are noted.
Past medical history should seek history of previous documented mononucleosis (recurrence is highly unlikely). Social history should include inquiring about close contact with people with documented GABHS infection, risk factors for gonorrhea transmission (eg, recent oral-genital sexual contact), and risk factors for HIV acquisition (eg, unprotected intercourse, multiple sex partners, IV drug abuse).
General examination should note fever and signs of respiratory distress, such as tachypnea, dyspnea, stridor, and, in children, the tripod position (sitting upright, leaning forward with neck hyperextended and jaw thrust forward).
During direct pharyngeal examination, erythema, exudates, and any signs of swelling around the tonsils or retropharyngeal area should be noted. Whether the uvula is in the midline or appears pushed to one side should also be noted.
If supraglottitis/epiglottitis is suspected and if patients (particularly children) have stridor, pharyngeal examination should be done cautiously because it, particularly when a tongue blade is inserted, may trigger complete airway obstruction. Ideally, examination should be done in an operating room and with a flexible fiberoptic laryngoscope,. Adults with no respiratory distress may be examined but also with care.
The neck is examined to check for enlarged, tender lymph nodes. The abdomen is palpated to check for splenomegaly, which may occur in patients with mononucleosis Infectious Mononucleosis Infectious mononucleosis is caused by Epstein-Barr virus (EBV, human herpesvirus type 4) and is characterized by fatigue, fever, pharyngitis, and lymphadenopathy. Fatigue may persist weeks or... read more .
The following findings in patients with a sore throat are of particular concern:
Stridor or other sign of respiratory distress
Muffled, “hot potato” voice
Visible bulge in the pharynx
Interpretation of findings
Supraglottitis/epiglottitis Epiglottitis Epiglottitis is a rapidly progressive bacterial infection of the epiglottis and surrounding tissues that may lead to sudden respiratory obstruction and death. Symptoms include severe sore throat... read more and pharyngeal abscess Parapharyngeal Abscess A parapharyngeal abscess is a deep neck abscess. Symptoms include fever, sore throat, odynophagia, and swelling in the neck down to the hyoid bone. Diagnosis is by CT. Treatment is antibiotics... read more pose a threat to the airway and must be differentiated from simple tonsillopharyngitis Tonsillopharyngitis Sore throat is pain in the posterior pharynx that occurs with or without swallowing. Pain can be severe; many patients refuse oral intake. Sore throat results from infection; the most common... read more , which is uncomfortable but not acutely dangerous. Clinical findings help make this distinction.
With supraglottitis/epiglottitis, severe throat pain and dysphagia begin abruptly, usually with no preceding upper respiratory infection (URI) symptoms. Children often drool and have signs of toxicity. Sometimes (more often in children), patients have respiratory manifestations, with tachypnea, dyspnea, stridor, and sitting in the tripod position. If examined, the pharynx almost always appears unremarkable.
Pharyngeal abscess and tonsillopharyngitis may cause pharyngeal erythema, exudate, or both. However, some findings are more likely to occur in one condition or the other:
Pharyngeal abscess: Muffled, “hot potato” voice (speaking as if a hot object is being held in the mouth) and visible focal swelling in the posterior pharyngeal area (often with deviation of the uvula)
Tonsillopharyngitis: Often URI symptoms (eg, runny nose, cough)
Although tonsillopharyngitis is easily recognized clinically, its cause is not. Manifestations of viral and GABHS Streptococcal Infections Streptococci are gram-positive aerobic organisms that cause many disorders, including pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis. Symptoms vary with the organ... read more infection overlap significantly, although URI symptoms are more common with a viral cause. In adults, clinical criteria that increase suspicion of GABHS as a cause include
Fever or history of fever
Absence of cough
Adults with 1 or no criteria may reasonably be presumed to have viral illness. If ≥ 2 criteria are present, the likelihood of GABHS is high enough to warrant testing (1 Reference Sore throat is pain in the posterior pharynx that occurs with or without swallowing. Pain can be severe; many patients refuse oral intake. Sore throat results from infection; the most common... read more ) but probably not high enough to warrant antibiotics, but this decision needs to be patient-specific (ie, threshold for testing and treatment may be lower in those at risk because of diabetes or immunocompromise). In children, testing usually is done. Although this approach is reasonable, not all experts agree on when to test for GABHS and when antibiotic treatment is indicated.
Rarer causes of tonsillopharyngitis should be considered when the following are present:
Posterior cervical or generalized adenopathy, hepatosplenomegaly, and fatigue and malaise present for > 1 week : Infectious mononucleosis Infectious Mononucleosis Infectious mononucleosis is caused by Epstein-Barr virus (EBV, human herpesvirus type 4) and is characterized by fatigue, fever, pharyngitis, and lymphadenopathy. Fatigue may persist weeks or... read more
No URI symptoms but possible recent oral-genital contact: Pharyngeal gonorrhea Gonorrhea Gonorrhea is caused by the bacterium Neisseria gonorrhoeae. It typically infects epithelia of the urethra, cervix, rectum, pharynx, or conjunctivae, causing irritation or pain and purulent... read more
A dirty-gray, thick, tough membrane on the posterior pharynx that bleeds if peeled away: Diphtheria Diphtheria Diphtheria is an acute pharyngeal or cutaneous infection caused mainly by toxigenic strains of the gram-positive bacillus Corynebacterium diphtheriae and rarely by other, less common... read more (rare in the United States)
If supraglottitis/epiglottitis is considered possible after evaluation, specific testing is required. Patients who do not appear seriously ill and have no respiratory symptoms may have plain lateral neck x-rays to look for edematous epiglottis. However, these x-rays are subject to false-positive interpretation because patient positioning may be imperfect (not a perfectly lateral view) or the x-ray is taken during expiration. Also, a child who appears seriously ill or has stridor or any other respiratory symptoms should not be transported to the x-ray suite. Such patients (and those with positive or equivocal x-ray findings) should usually have flexible fiberoptic laryngoscopy. (CAUTION: Examination of the pharynx and larynx may precipitate complete respiratory obstruction in children, and the pharynx and larynx should not be directly examined except in the operating room, where the most advanced airway intervention is available.)
Pearls & Pitfalls
Many abscesses are managed clinically, but if location and extent are unclear, immediate CT of the neck should be done.
In tonsillopharyngitis, throat culture is the most reliable way to differentiate viral infection from GABHS. To balance timeliness of diagnosis, cost, and accuracy, one strategy in children is to do a rapid strep screen in the office and treat if positive, and if negative, send a formal culture to a laboratory for testing. In adults, because other bacterial pathogens may be involved, throat culture for all bacterial pathogens is appropriate for those meeting clinical criteria described previously (tonsillar exudate, tender lymphadenomegaly, fever or history of fever, absence of cough).
Testing for mononucleosis, gonorrhea, or HIV infection is done only when clinically suspected.
1. Fine AM, Nizet V, Mandl KD: Large-scale validation of the Centor and McIsaac scores to predict group A streptococcal pharyngitis. Arch Intern Med 172 (11):847–852, 2012. doi:10.1001/archinternmed.2012.950
Treatment of Sore Throat
Specific conditions are treated. Patients with severe symptoms of tonsillopharyngitis may be started on a broad-spectrum antibiotic (eg, amoxicillin/clavulanate) pending culture results.
Symptomatic treatments such as warm saltwater gargles and topical anesthetics (eg, benzocaine, lidocaine, dyclonine) may help temporarily relieve pain in tonsillopharyngitis, but patients should be instructed to avoid doses of topical anesthetics that result in toxicity. Patients in severe pain (even from tonsillopharyngitis) may require short-term use of opioids, preferably in liquid preparations.
Corticosteroids (eg, dexamethasone, 10 mg IM) are occasionally used—for example, for tonsillopharyngitis that appears to pose a risk of airway obstruction (eg, due to mononucleosis) or very severe tonsillopharyngitis symptoms.
Most sore throats are caused by viral tonsillopharyngitis.
It is difficult to clinically distinguish viral from bacterial causes of tonsillopharyngitis.
Abscess and epiglottitis are rare but serious causes.
Suspect epiglottitis if patients have a severe sore throat and a normal-appearing pharynx.
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