- Author: John R Acerra, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD more...
GABHS rapid antigen detection test
This is the preferred method for diagnosing GAS infection in the emergency department because of difficulties with culture follow-up. (See the image below.)
Only patients with a high clinical likelihood of GAS pharyngitis should be tested. Patients with a Centor score of 0-1 should be treated symptomatically without testing.
Antigens are specific, but sensitivities vary. The sensitivity of the GABHS rapid antigen detection test is 70-90%, and the specificity is 90-100%, depending on the manufacturer.[17, 18, 19, 20] Children with a negative antigen test should have a follow-up culture unless the antigen being used in the office has been shown to be as sensitive as a culture.
The use of a GABHS rapid antigen detection test can decrease the use of unnecessary antibiotics in pediatric patients when used properly.
Adults do not need follow-up culture after a negative antigen test because of the low incidence of GAS in this population.
This is the criterion standard for diagnosis of GAS infection (90-99% sensitive). Although less expensive than the rapid antigen detection test, it is not be the best test to use in the emergency department because of difficulty with follow-up. The guidelines that recommend cultures for GAS screening are aimed at office-based practices and not the emergency department.
Patients can be treated up to 9 days after onset of symptoms to prevent acute rheumatic fever, so immediate antibiotic therapy is not crucial if patients can be easily contacted for follow-up should a culture become positive.
Additional tests include the following:
Mono spot is up to 95% sensitive in children (less than 60% sensitivity in infants)
Peripheral smear may show atypical lymphocytes in infectious mononucleosis 
Perform gonococcal culture as indicated by history
A complete blood count (CBC), erythrocyte sedimentation rate (ESR), and C-reactive protein have a low predictive value and usually are not indicated 
See the list below:
Imaging studies generally are not indicated for uncomplicated viral or streptococcal pharyngitis.
Lateral neck film should be taken in patients with suspected epiglottitis or airway compromise.
Soft tissue neck CT can be used if concern for abscess or deep-space infection exists; however, peritonsillar abscess is almost always a clinical diagnosis. Imaging is rarely needed for diagnosis.
See the list below:
The procedure for a throat swab is to vigorously rub a dry swab over the posterior pharynx and both tonsils, obtaining a sample of exudate. If any exudate is obtained, then transport it dry (not in a liquid medium).
Alcaide AL, Bisno AL. Pharyngitis and epiglottitis. Infect Dis Clin North Am. 2006. 21:449-469.
Twefik TL, Al Garni M. Tonsillopharyngitis: Clinical highlights. J of Otolaryngology. 2005. 34:
Mostov PD. Treating the immunocompetent patient who presents with an upper respiratory infection: pharyngitis, sinusitis, and bronchitis. Prim Care. 2007 Mar. 34(1):39-58. [Medline].
Pichichero ME, Casey JR. Systematic review of factors contributing to penicillin treatment failure in Streptococcus pyogenes pharyngitis. Otolaryngol Head Neck Surg. 2007 Dec. 137(6):851-857. [Medline].
[Guideline] Gerber MA, Baltimore RS, Eaton CB, et al. Prevention of rheumatic fever and diagnosis and treatment of acute Streptococcal pharyngitis: a scientific statement from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the Council on Cardiovascular Disease in the Young, the Interdisciplinary Council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research: endorsed by the American Academy of Pediatrics. Circulation. 2009 Mar 24. 119(11):1541-51. [Medline].
Centers for Disease Control and Prevention. Summary of notifiable diseases, United States, 1997. MMWR Morb Mortal Wkly Rep. 1998 Nov 20. 46(54):ii-vii, 3-87. [Medline].
Kalra MG, Higgins KE, Perez ED. Common Questions About Streptococcal Pharyngitis. Am Fam Physician. 2016 Jul 1. 94 (1):24-31. [Medline].
Shaikh N, Swaminathan N, Hooper EG. Accuracy and precision of the signs and symptoms of streptococcal pharyngitis in children: a systematic review. J Pediatr. 2012 Mar. 160(3):487-493.e3. [Medline].
Centor RM, Allison JJ, Cohen SJ. Pharyngitis management: defining the controversy. J Gen Intern Med. 2007 Jan. 22(1):127-30. [Medline].
Shulman ST, Bisno AL, Clegg HW, Gerber MA, Kaplan EL, Lee G, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012 Nov 15. 55(10):1279-82. [Medline].
Wagner FP, Mathiason MA. Using centor criteria to diagnose streptococcal pharyngitis. Nurse Pract. 2008 Sep. 33(9):10-2. [Medline].
McIsaac WJ, Goel V, To T, Low DE. The validity of a sore throat score in family practice. CMAJ. 2000 Oct 3. 163 (7):811-5. [Medline].
Fine AM, Nizet V, Mandl KD. Large-scale validation of the Centor and McIsaac scores to predict group A streptococcal pharyngitis. Arch Intern Med. 2012 Jun 11. 172 (11):847-52. [Medline]. [Full Text].
Gerber MA. Diagnosis and treatment of pharyngitis in children. Pediatr Clin North Am. 2005 Jun. 52(3):729-47, vi. [Medline].
Lemierre's syndrome, reemergence of a forgotten disease: a case report. Cases J. 2009 Mar 10. 2:6397. [Medline]. [Full Text].
Tanz RR, Gerber MA, Kabat W, Rippe J, Seshadri R, Shulman ST. Performance of a rapid antigen-detection test and throat culture in community pediatric offices: implications for management of pharyngitis. Pediatrics. 2009 Feb. 123(2):437-44. [Medline].
Gerber MA, Shulman ST. Rapid diagnosis of pharyngitis caused by group A streptococci. Clin Microbiol Rev. 2004 Jul. 17 (3):571-80, table of contents. [Medline].
Tanz RR, Gerber MA, Kabat W, Rippe J, Seshadri R, Shulman ST. Performance of a rapid antigen-detection test and throat culture in community pediatric offices: implications for management of pharyngitis. Pediatrics. 2009 Feb. 123 (2):437-44. [Medline].
Del Mar CB, Glasziou PP, Spinks AB. Antibiotics for sore throat. Cochrane Database Syst Rev. 2006 Oct 18. CD000023. [Medline].
Nakhoul GN, Hickner J. Management of adults with acute streptococcal pharyngitis: minimal value for backup strep testing and overuse of antibiotics. J Gen Intern Med. 2013 Jun. 28 (6):830-4. [Medline].
Ayanruoh S, Waseem M, Quee F, Humphrey A, Reynolds T. Impact of rapid streptococcal test on antibiotic use in a pediatric emergency department. Pediatr Emerg Care. 2009 Nov. 25(11):748-50. [Medline].
Pelucchi C, Grigoryan L, Galeone C, Esposito S, Huovinen P, Little P, et al. Guideline for the management of acute sore throat. Clin Microbiol Infect. 2012 Apr. 18 Suppl 1:1-28. [Medline].
Patel NN, Patel DN. Acute exudative tonsillitis. Am J Med. 2009 Jan. 122(1):18-20. [Medline].
Cohen JF, Cohen R, Levy C, et al. Selective testing strategies for diagnosing group A streptococcal infection in children with pharyngitis: a systematic review and prospective multicentre external validation study. CMAJ. 2015 Jan 6. 187(1):23-32. [Medline]. [Full Text].
Del Mar CB, Glasziou PP, Spinks AB. Antibiotics for sore throat (Review). The Cochrane Collaboration. 2007. (1):1-41.
Hayward G, Thompson MJ, Perera R, Glasziou PP, Del Mar CB, Heneghan CJ. Corticosteroids as standalone or add-on treatment for sore throat. Cochrane Database Syst Rev. 2012 Oct 17. 10:CD008268. [Medline].
Tasar A, Yanturali S, Topacoglu H, Ersoy G, Unverir P, Sarikaya S. Clinical efficacy of dexamethasone for acute exudative pharyngitis. J Emerg Med. 2008 Nov. 35(4):363-7. [Medline].
Shephard A, Smith G, Aspley S, et al. Randomised, double-blind, placebo-controlled studies on flurbiprofen 8.75 mg lozenges in patients with/without group A or C streptococcal throat infection, with an assessment of clinicians' prediction of 'strep throat'. Int J Clin Pract. 2015 Jan. 69(1):59-71. [Medline].
Muller D, Lindemann T, Shah-Hosseini K, et al. Efficacy and tolerability of an ectoine mouth and throat spray compared with those of saline lozenges in the treatment of acute pharyngitis and/or laryngitis: a prospective, controlled, observational clinical trial. Eur Arch Otorhinolaryngol. 2016 Apr 28. [Medline].
Fleming-Dutra KE, Hersh AL, Shapiro DJ, et al. Prevalence of Inappropriate Antibiotic Prescriptions Among US Ambulatory Care Visits, 2010-2011. JAMA. 2016 May 3. 315 (17):1864-73. [Medline].
Linder JA, Stafford RS. Antibiotic treatment of adults with sore throat by community primary care physicians: a national survey, 1989-1999. JAMA. 2001 Sep 12. 286 (10):1181-6. [Medline].
Barnett ML, Linder JA. Antibiotic prescribing to adults with sore throat in the United States, 1997-2010. JAMA Intern Med. 2014 Jan. 174 (1):138-40. [Medline].
Matthys J, De Meyere M, van Driel ML, De Sutter A. Differences among international pharyngitis guidelines: not just academic. Ann Fam Med. 2007 Sep-Oct. 5(5):436-43. [Medline].
Van Howe RS, Kusnier LP 2nd. Diagnosis and management of pharyngitis in a pediatric population based on cost-effectiveness and projected health outcomes. Pediatrics. 2006 Mar. 117(3):609-19. [Medline].
Pichichero ME. Pathogen shifts and changing cure rates for otitis media and tonsillopharyngitis. Clin Pediatr (Phila). 2006 Jul. 45(6):493-502. [Medline].
Pichichero M, Casey J. Comparison of European and U.S. results for cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis. Eur J Clin Microbiol Infect Dis. 2006 Jun. 25(6):354-64. [Medline].
Brook I. Overcoming penicillin failures in the treatment of Group A streptococcal pharyngo-tonsillitis. Int J Pediatr Otorhinolaryngol. 2007 Oct. 71(10):1501-8. [Medline].
Logan LK, McAuley JB, Shulman ST. Macrolide treatment failure in streptococcal pharyngitis resulting in acute rheumatic fever. Pediatrics. 2012 Mar. 129(3):e798-802. [Medline].
Depdham D, Rao S, Hitchcock K. Should you treat carriers of pharyngeal group A strep?. J Fam Pract. 2008. 57:
Altamimi S, Khalil A, Khalaiwi KA, Milner R, Pusic MV, Al Othman MA. Short versus standard duration antibiotic therapy for acute streptococcal pharyngitis in children. Cochrane Database Syst Rev. 2009 Jan 21. CD004872. [Medline].
Korb K, Scherer M, Chenot JF. Steroids as adjuvant therapy for acute pharyngitis in ambulatory patients: a systematic review. Ann Fam Med. 2010 Jan-Feb. 8(1):58-63. [Medline]. [Full Text].
Hayward G, Thompson M, Heneghan C, Perera R, Del Mar C, Glasziou P. Corticosteroids for pain relief in sore throat: systematic review and meta-analysis. BMJ. 2009 Aug 6. 339:b2976. [Medline]. [Full Text].
Wing A, Villa-Roel C, Yeh B, Eskin B, Buckingham J, Rowe BH. Effectiveness of Corticosteroid Treatment in Acute Pharyngitis: A Systematic Review of the Literature. Acad Emerg Med. 2010. 17(5):476-483.
Boggs W. What antibiotic strategy is best for adults with acute sore throat? Medscape Medical News. January 27, 2014; Accessed February 4, 2014. Available at http://www.medscape.com/viewarticle/820008.
Huttner B. Antibiotic prescription for sore throat or the legacy of Mr X2.. Lancet Infect Dis. 2014 Jan 16. [Medline].
Little P, Stuart B, Hobbs FD, Butler CC, Hay AD, Delaney B, et al. Antibiotic prescription strategies for acute sore throat: a prospective observational cohort study. Lancet Infect Dis. 2014 Jan 16. [Medline].
Snow V, Mottur-Pilson C, Cooper RJ, et al. Principles of appropriate antibiotic use for acute pharyngitis in adults. Ann Intern Med. 2001 Mar 20. 134 (6):506-8. [Medline].
Schappert SM, Rechtsteiner EA. Ambulatory medical care utilization estimates for 2006. Natl Health Stat Report. 2008 Aug 6. 1-29. [Medline].