What is the role of throat culture in the workup of pediatric pharyngitis?

Updated: Dec 11, 2018
  • Author: Harold K Simon, MD, MBA; Chief Editor: Russell W Steele, MD  more...
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Answer

A throat culture remains the standard for diagnosis, though results can take as long as 48 hours. Throat culture results are highly sensitive and specific for group A beta-hemolytic streptococci (GABHS), but results can vary according to technique, sampling, and culture media.

Most institutions and clinics have rapid testing, which is useful when immediate therapy is desired. Rapid testing can be highly reliable when used in conjunction with throat cultures. Several rapid diagnostic tests are available. Compared with throat culture, such tests are 70-90% sensitive and 95-100% specific.

Rapid screening followed by culture has become the standard in most institutions, especially in developed countries. In repeated investigations, rapid screening with throat culture backup for rapid screen–negative cases has continued to be the most proven strategy. This approach potentially minimizes unnecessary antibiotic administration by helping limit antibiotic use to cases with positive rapid screen findings or those with subsequent positive culture findings. [6]

This approach arises out of the somewhat low sensitivity and specificity of clinical screening. Although the categorization of clinical differentiators developed by the Infectious Diseases Society of America (IDSA) can assist in clinical management (see Presentation), rapid screening followed by culture remains the best combination when resources are available.

The IDSA added that testing for Group A Streptococcus usually is not recommended for the following: patients with sore throat and accompanying symptoms (e.g., cough, rhinorrhea) that strongly suggest a viral etiology; children aged < 3 years, because acute rheumatic fever is extremely rare in this age group; and asymptomatic household contacts of patients with Group A Streptococcus pharyngitis. [7, 8]


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