History
Viral and bacterial causes of pharyngitis are similar, and the differentiation of the etiology is difficult based on history and physical examination alone. Signs and symptoms alone cannot be used to rule out or diagnose GAS pharyngitis. [11] Despite this, classic presentations are described below.
-
GAS infection is most common in children aged 4-7 years.
-
Sudden onset is consistent with a GAS pharyngitis. Pharyngitis following several days of coughing or rhinorrhea is more consistent with a viral etiology.
-
Person has been in contact with others diagnosed with GAS or rheumatic fever presenting with symptoms consistent with GAS are more likely to have GAS pharyngitis.
-
Headache is consistent with GAS infection.
-
Cough is not usually associated with GAS infection.
-
Vomiting is associated with GAS infection but may be present in other types of pharyngitis.
-
A history of recent orogenital contact suggests the possibility of gonococcal pharyngitis.
-
A history of rheumatic fever is important when considering treatment.
The Centor criteria have been used in the past as a way to diagnose and treat GAS pharyngitis. [12] These include the following:
-
Fever
-
Anterior cervical lymphadenopathy
-
Tonsillar exudate
-
Absence of cough
One point is awarded for each of the criteria met, with patients scoring 0-1 unlikely to have GAS infection and patients with a score of 4 more likely to have GAS. A clinical diagnosis of GAS infection using these criteria can result in an overestimation of the incidence of streptococcal pharyngitis, as many bacterial and viral cases of pharyngitis can be indistinguishable on clinical grounds. This can lead to an overtreatment of pharyngitis with antibiotics. [13] In adults, the positive predictive value of the Centor criteria for predicting GAS pharyngitis is around 40% if 3 criteria are met, and about 50% if 4 criteria are met. [14] These criteria along with other clinical features should be used to guide treatment for pharyngitis in adults. A modified version of the Centor score, in which age is also taken account (and which is also called the McIsaac score), can be used in diagnosis as well. [15, 16]
Physical
See the list below:
-
Airway patency must be assessed and addressed first.
-
Temperature: Fever is usually absent or low-grade in viral pharyngitis, but fever is not reliable to differentiate viral or bacterial etiologies.
-
Hydration status: Oral intake usually is compromised because of odynophagia; therefore, various degrees of dehydration result.
-
Head, ears, eyes, nose, and throat (HEENT)
Conjunctivitis may be seen in association with adenovirus.
Scleral icterus may be seen with infectious mononucleosis.
Rhinorrhea usually is associated with a viral cause.
Tonsillopharyngeal/palatal petechiae are seen in GAS infections and infectious mononucleosis.
A tonsillopharyngeal exudate may be seen in streptococcal infectious mononucleosis and occasionally in M pneumoniae, C pneumoniae, A haemolyticus, adenovirus, and herpesvirus infections. Therefore, exudate does not differentiate viral and bacterial causes.
Oropharyngeal vesicular lesions are seen in coxsackievirus and herpesvirus. Concomitant vesicles on the hands and feet are associated with coxsackievirus (hand-foot-and-mouth disease).
-
Lymphadenopathy: Tender anterior cervical nodes are consistent with streptococcal infection, whereas generalized adenopathy is consistent with infectious mononucleosis or the acute lymphoglandular syndrome of HIV infection.
-
Cardiovascular: Murmurs should be documented in an acute episode of pharyngitis to monitor for potential rheumatic fever.
-
Pulmonary: Pharyngitis and lower respiratory tract infections are more consistent with M pneumoniae or C pneumoniae, particularly when a persistent nonproductive cough is present.
-
Abdomen: Hepatosplenomegaly can be found in infectious mononucleosis infection.
-
Skin
A sandpapery scarlatiniform rash is seen in GAS infection (see Scarlet Fever). [17]
Maculopapular rashes are seen with various viral infections and with infectious mononucleosis empirically treated with penicillin.
A study by Jo et al indicated that in the diagnosis of GAS pharyngitis, the following five signs are significantly associated with the disease, as determined through multivariate logistic regression analysis: pharyngeal hemorrhage (adjusted odds ratio [aOR] = 3.90), palatal hemorrhage (aOR = 2.18), rash (aOR = 2.08), tonsillar swelling (aOR = 1.69), and enlarged cervical nodes (aOR = 1.58). [18]
Causes
See the list below:
-
Bacterial pharyngitis
Group A beta-hemolytic streptococci (GABHS): The classic clinical picture includes a fever, temperature of greater than 101.5°F; tonsillopharyngeal erythema and exudate; swollen, tender anterior cervical adenopathy; headache; emesis in children; palatal petechiae; midwinter to early spring season; and absent cough or rhinorrhea. [17, 19]
Group C, G, and F streptococci may be indistinguishable clinically from GAS infection. Acute glomerulonephritis is an extremely unusual complication of group C streptococcal pharyngitis, but a relationship between group G streptococcal pharyngitis and acute glomerulonephritis has not be established. Acute rheumatic fever has not been described as a complication of either. They may be associated with food-borne outbreaks. The benefit of antibiotic therapy with these types of streptococci is unproven at this time. [7]
Arcanobacterium (Corynebacterium) haemolyticus is more common in young adults and is very similar to GAS infection, including a similar scarlatiniform rash. Patients often have a cough. Occasional outbreaks have been reported.
M pneumoniae in young adults presents with headache, pharyngitis, and lower respiratory symptoms. Approximately 75% of patients have a cough, which is distinctive from GAS infection.
C pneumoniae has a clinical picture similar to that of M pneumoniae. Pharyngitis usually precedes the pulmonary infection by about 1-3 weeks.
Neisseria gonorrhoeae is a rare cause of pharyngitis. A careful history is important since infection usually follows orogenital contact. It may be associated with severe systemic infection.
Corynebacterium diphtheriae is rare in the United States. A foul-smelling gray-white pharyngeal membrane may result in airway obstruction.
-
Viral pharyngitis [4]
Adenovirus: The distinguishing feature of an adenovirus infection is conjunctivitis associated with pharyngitis (pharyngoconjunctival fever). It is the most common etiology in children younger than 3 years.
Herpes simplex: Vesicular lesions (herpangina), especially in young children, are the hallmark. In older patients, pharyngitis may be indistinguishable from GABHS infection.
Coxsackieviruses A and B: These infections present similarly to herpes simplex, and vesicles may be present. If vesicles are whitish and nodular, it is known as lymphonodular pharyngitis. Coxsackievirus A16 may cause hand-foot-and-mouth disease, which presents with 4- to 8-mm oropharyngeal ulcers and vesicles on the hands and feet, and, occasionally, on the buttocks. The oropharyngeal ulcers and vesicles resolve within 1 week.
Epstein-Barr virus (EBV): Clinically known as infectious mononucleosis, it is extremely difficult to distinguish from GAS infection. Exudative pharyngitis is prominent. Distinctive features include retrocervical or generalized adenopathy and hepatosplenomegaly. Atypical lymphocytes can be seen on peripheral blood smear. Viral cultures from washings are about 20% sensitive in adults.
CMV: Presentation of CMV is similar to the presentation of infectious mononucleosis. Patients tend to be older, are sexually active, and have higher fever and more malaise. Pharyngitis may not be a prominent complaint.
HIV-1: This is associated with pharyngeal edema and erythema, common aphthous ulcers, and a rarity of exudates. Fever, myalgia, and lymphadenopathy also are found.
-
Other causes of pharyngitis
Oral thrush is due to candidal species, usually in patients who are immunocompromised. It may be common in young children and presents with whitish plaques in the oropharynx.
Other causes include dry air, allergy/postnasal drip, chemical injury, gastroesophageal reflux disease (GERD), smoking, neoplasia, and endotracheal intubation.
A rare but life-threatening cause of pharyngitis in young adults is Lemierre's syndrome. This condition is usually caused by the anaerobic bacterium, Fusobacterium necrophorum, and is characterized by a oropharyngeal infection with evidence of septic thrombophlebitis. The incidence is approximately one in a million, but it should be considered when a critically ill patient presents with pharyngitis. [20]
-
Streptococcus pyogenes at 100X magnification.
-
Rapid antigen detection test for group A beta-hemolytic streptococci.
-
Posterior pharynx with petechiae and exudates in a 12-year-old girl. Both the rapid antigen detection test and throat culture were positive for group A beta-hemolytic streptococci.
