Differentials
Streptococcus pyogenes pharyngitis
SIGNS / SYMPTOMS
Rapid onset with prominent sore throat and fever.
Headache and gastrointestinal symptoms are frequent.
Red throat and enlarged tonsils covered by yellow or blood-tinged exudate.
Enlarged and tender cervical lymphadenopathy.
Some patients have a fine papular rash with circumoral pallor and strawberry tongue (scarlet fever).[46]
INVESTIGATIONS
Positive throat culture is the definitive test for Streptococcus pyogenes diagnosis.
Rapid antigen detection tests can confirm the presence of group A streptococci carbohydrate antigen on a throat swab within minutes. However, the sensitivity of these tests is between 70% and 90% compared with blood agar plate culture.
Acute epiglottitis
SIGNS / SYMPTOMS
Acute fulminating course of high fever, sore throat, and rapidly progressing respiratory obstruction.
Drooling is usually present, and patient maintains hyperextended neck in attempt to maintain open airways.[47]
INVESTIGATIONS
Direct visualization of the epiglottis shows cherry-red swollen area.
A lateral radiograph of soft tissue of the neck shows enlarged epiglottis protruding from the anterior wall of the hypopharynx (thumb sign).
Usually caused by Haemophilus influenzae b which, like diphtheria, should be vaccine-preventable.
Infectious mononucleosis
SIGNS / SYMPTOMS
Prominent tonsillar enlargement with exudate and cervical lymphadenopathy.
Hepatomegaly and splenomegaly usually present.
Rash and generalized fatigue occur as part of infectious mononucleosis syndrome.[48]
INVESTIGATIONS
Positive heterophil antibody test or positive serologic test for Epstein-Barr virus.
Infectious mononucleosis type illnesses can also be caused by cytomegalovirus, toxoplasmosis, HIV seroconversion, and some other pathogens.
Acute necrotizing ulcerative gingivitis (Vincent angina)
SIGNS / SYMPTOMS
Periodontal disease associated with spirochetes and fusobacteria.
Necrosis and ulceration of the gingiva between the teeth, with adherent grayish pseudomembrane covering the gingiva.
Fever, malaise, and lymphadenopathy.
INVESTIGATIONS
Dark-field microscopy of debris from the pseudomembrane shows spirochetes.
Staphylococcal or streptococcal impetigo
SIGNS / SYMPTOMS
Typically affects skin of the face or extremities that have been traumatized.
Tiny vesicles or pustules form initially and develop into small blisters that rupture, forming a honey-colored, crusted plaque.
Little or no pain. No surrounding erythema, and constitutional symptoms are generally absent.
INVESTIGATIONS
Bacteriologic culture or microscopy shows staphylococci or streptococci.
Mumps
SIGNS / SYMPTOMS
Most recognizable by painful bilateral parotid swelling without sore throat or exudate/pseudomembrane.
Often clinically distinguishable from diphtheria, but facial and neck swelling can look similar and the incidence of both conditions is increased in populations with low vaccine coverage.
INVESTIGATIONS
Diagnosis (and discrimination from diphtheria) is often clinical, but polymerase chain reaction (PCR) of buccal swabs and serology (IgM) detection can provide laboratory confirmation.
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