Streptococcal Group A Disease

Clinical Background

skin infection

Streptococcus group A causes a broad spectrum of diseases, most commonly causing pharyngitis and tonsillitis.

Epidemiology

Prevalence - streptococcal pharyngitis represents 1-2% of primary care visits and is one of the top 20 reported diseases
Primary bacterial cause of exudative tonsillitis and pharyngitis
Age - most cases occur in patients under 20 years of age
Transmission - direct contact with nasal discharge; seasonally most common in winter or early spring
Organism
- Group A Streptococcus bacteria, gram-positive cocci
- Organism may evoke cross-reacting immune response with human tissue leading to rheumatic fever, rheumatic heart disease and acute glomerulonephritis
  - Acute glomerulonephritis also associated with streptococcal skin disease
  - Rheumatic heart disease and rheumatic fever are associated with streptococcal pharyngitis

Risk Factors

Young age
Presence of tonsils

Clinical Presentation

Primary symptoms - sudden onset sore throat, fever, dysphagia
Constitutional symptoms - headache, nausea, vomiting, abdominal pain
Clinical findings - pharyngeal erythema, tonsillar exudates, anterior cervical adenopathy, palatine petechiae
Complications
- Peritonsillar abscess
- Rheumatic fever
- Glomerulonephritis
- Rheumatic heart disease

Treatment

Antibiotics necessary to eradicate toxin-producing organisms and prevent rheumatic fever

See Also

Staphylococcal Disease

Tests

Tests generally appear in the order most useful for common clinical situations

Test name: DNase-B Antibody

ARUP #: 0050220

Methodology: Nephelometry

Use:

Preferred test in most clinical scenarios; best test for rheumatic chorea since it remains elevated longer

Confirm current or recent group A streptococcal infection in patients suspected of having a non-suppurative complication such as acute glomerulonephritis (AGN) or acute rheumatic fever (ARF)

DNase-B and ASO antibody tests are generally ordered concurrently

Limitations:

Antibiotic therapy decreases antibody levels

Follow-up:

May want to order a throat culture at the same time

Recommend testing acute and convalescent samples taken approximately 2 weeks apart

Antibodies may persist for 2-3 months after infection

Test name: Streptolysin O Antibody (ASO)

ARUP #: 0050095

Methodology: Nephelometry

Use:

Confirm a prior infection with group A streptococcus in patients suspected of having a non-suppurative complication, such as acute glomerulonephritis or acute rheumatic fever

DNase-B and ASO antibody tests are generally ordered concurrently

Limitations:

Not helpful in the diagnosis of the agent of skin infections

Antibiotic therapy decreases elevation of test

Follow-up:

May want to order a throat culture at the same time

Recommend testing acute and convalescent samples taken approximately 2 weeks apart

Antibodies may persist for 6 weeks after infection

Test name: Streptococcus pyogenes, Group A Antibody (Streptozyme®) with Reflex to Titer

ARUP #: 0050642

Methodology: Hemagglutination

Use:

Outdated test

Recommend DNase-B Antibody or Streptolysin O Antibody tests

Limitations:

Follow-up:

Additional Tests Available

Test name: Streptococcus (Group A) Culture

ARUP #: 0060126

Methodology: Standard reference procedures for aerobic bacterial culture and identification

Comments:

Test name: Streptococcus (Group A) Rapid with Reflex to Culture

ARUP #: 0028903

Methodology: Immunoassay with Direct Observation/Culture

Comments:

References

General References

Alcaide ML, Bisno AL. Pharyngitis and epiglottitis. Infect Dis Clin North Am. 2007;21(2):449-69, vii.

Bisno AL. Acute pharyngitis. N Engl J Med. 2001;344(3):205-211.

Bourbeau PP. Role of the microbiology laboratory in diagnosis and management of pharyngitis. J Clin Microbiol. 2003;41(8):3467-3472.

Brook I, Dohar JE. Management of group A beta-hemolytic streptococcal pharyngotonsillitis in children. J Fam Pract. 2006;55(12):S1-11.

Colletti T, Robinson P. Strep throat: guidelines for diagnosis and treatment. JAAPA. 2005;18(9):38-44.

Hahn RG, Knox LM, Forman TA. Evaluation of poststreptococcal illness. Am Fam Physician. 2005;71(10):1949-1954.

Leung AK, Newman R, Kumar A, Davies HD. Rapid antigen detection testing in diagnosing group A beta-hemolytic streptococcal pharyngitis. Expert Rev Mol Diagn. 2006;6(5):761-766.

Shet A, Kaplan EL. Clinical use and interpretation of group A streptococcal antibody tests: a practical approach for the pediatrician or primary care physician. Pediatr Infect Dis J. 2002;21(5):420-426.

References from the ARUP Institute for Clinical and Experimental Pathology Research®

Martins TB, Augustine NH, Hill HR. Development of a multiplexed fluorescent immunoassay for the quantitation of antibody responses to group A streptococci. J Immunol Methods. 2006;316(1-2):97-106.

Martins TB, Hoffman JL, Augustine NH, Phansalkar AR, Fischetti VA, Zabriskie JB, Cleary PP, Musser JM, Veasy LG, Hill HR. Comprehensive analysis of antibody responses to streptococcal and tissue antigens in patients with acute rheumatic fever. Int Immunol. 2008;20(3):445-452.

Martins TB, Veasy LG, Hill HR. Antibody responses to group A streptococcal infections in acute rheumatic fever. Pediatr Infect Dis J. 2006;25(9):832-837.

Medical Reviewers

Carney, Heather, M.D. Assistant Medical Director, Transfusion Services at ARUP Laboratories; Pathology, University of Utah

Fisher, Mark A., Ph.D. Research Instructor, Medical Microbiology Fellow, Department of Pathology, University of Utah

Hill, Harry R., M.D. Group Medical Director, Laboratory of Immunology, ARUP Laboratories, and Executive Director of the ARUP Institute for Clinical and Experimental Pathology; Professor and Division Head, Clinical Pathology, University of Utah

Litwin, Christine, M.D. Medical Director, Immunology at ARUP Laboratories; Professor, Clinical Pathology, University of Utah

Petti, Cathy A., M.D. Medical Director, Infectious Diseases at ARUP Laboratories; Assistant Professor, Pathology and Medicine, University of Utah

Comprehensive Review: September 2008
Last Update: September 2008