Streptococcal pharyngitis


Group A Streptococcus, Streptococcus pyogenes, is responsible for 5-15% of cases of pharyngitis in adults and 20-30% of cases and children.

Referred to as strep throat.

It occurs most commonly among children between the ages of five and 15 years.

The incidence is higher in winter and early spring in temporal climates.

Causes acute illness and post infectious glomerulonephritis and acute rheumatic fever.

Rheumatic fever is a leading cause of acquired heart disease among children in resource poor parts of the world, and is currently uncommon in most developed countries.

Sore throat is the most common presentation and onset is often abrupt.

Aside from sore throat, symptoms may include: fever, chills, headache, malaise and in children abdominal pain and nausea and vomiting.

Occasionally this process is associated with scarlet fever, with a papulr erythematous rash that spares the face, may be accentuated in skin folds and may eventually desquamate.

The presence of cough, coryza, an conjunctivitis suggest alternative diagnoses such as a viral infection.

Sore throat is usually severe and is often worse on one side.

Prolonged and severe unilateral pain may be associated with a peritonsillar or retropharyngeal abscess.

Exudative pharyngitis due to streptococcal infection is rare among children younger than three years of age.

In children younger than three years of age this infection may manifest as generalized lymphadenopathy,coryza and excoriated nares.

Fever generally resolves within 3-5 days.

Sore throat usually resolves within one week.

Clinical diagnosis is unreliable.

Signs and symptoms range from mild sore throat to severe exudative pharyngitis with high fever.

Probability of positive throat culture or rapid antigen test is 3% or less for patients with no clinically suggestive symptoms and 30-50% with all of the suggestive clinical criteria.

Throat cultures and rapid antigen tests should not be done in the absence of clinically suggestive criteria.

Carrier state of Streptococcus pyogenes in approximately 10% of school age children and less frequently in other age groups.

Carrier state can persist for week-months and associated with very low risk of infection or transmission to others.

Throat cultures and rapid antigen tests reserved for patients with clinically suggestive disease.

Laboratory confirmation of the diagnosis is based on a positive throat culture or a rapid antigen detection test of a throat swab specimen.

The posterior pharynx and tonsils should be the site of swabbing (but not the tongue, lips or buccal mucosa) increasing the sensitivity of both the culture and rapid antigen detection test.

Serum antibodies to streptolysin O or DNase B levels are useful for retrospective diagnosis, and provide support for diagnosis of acute rheumatic fever and poststreptococcal glomerulonephritis, but are not helpful in the management of a diagnosis of acute disease, since titers do not increase until 7-14 days after the onset of infection, reaching a peak in 3-4 weeks.

Rapid antigen detection tests for Streptococcus pyogenes seek to detect acid extraction of cell wall carbohydrate antigen and detect that antigen with specific anti-body.

Rapid detection of Streptococcus pyogenes with DNA sequence hybridization studies or polymerase chain reaction assays are also available.

Rapid antigen detection tests have a sensitivity of 70-90%, and the sensitivity is dependent on the clinical likelihood of streptococcal infection in the test population.

Rapid antigen detection tests have a specificity of 95% or greater and a positive result obviates the need for culture.

If a rapid antigen test is negative, a throat culture is recommended since it is a more sensitive test.

Infection may be indistinguishable from many other infectious disease and include: Bacteria-Group C streptococci, Anaerobic organisms, Fusobacterium, Neisseria, Corynebacterium, Yersinia, Mycoplasma, Treponema, and Chlamydophilia: Viral-Rhinovirus, Coronavirus, Adenovirus, Influenza, Parainfluenza, Coxsackievirus, Herpes simplex, Epstein-Barr, Cytomegalovirus, and HIV.

Is a self-limited disease in the vast majority of patients.

Post-streptococcal glomerulonephritis is not prevented by antibiotic treatment.

Antibiotic treatment associated with a 80% reduction in the incidence of acute rheumatic fever, as compared with no antibiotic treatment.

Antibiotics reduce the risk of otitis media, and peritonsillar abscess, the suppurative complications of the infection.

In the absence of antibiotic treatment, throat cultures remain positive for up to six weeks in 50% of patients.

Effective antibiotic therapy results in a negative throat culture within 24 hours in more than 80% of individuals.

Prior to return to school, children should receive antibiotics for 24 hours.

Early administration of antibiotics also shortens duration of symptoms.

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