An Algorithm for a Selective use of Throat Swabs in the Diagnosis of Group: A Streptococcal Pharyngo-Tonsillitis in General Practice

Abstract

A prospective evaluation was made of an algorithm for a selective use of throat swabs in patients with sore throat in general practice. The algorithm states that a throat swab should be obtained (a) in all children younger than 15 years; (b) in patients aged 15 years or more who have pain on swallowing and at least three of four signs (enlarged or hyperaemic tonsils; exudate; enlarged or tender angular lymph nodes; and a temperature ≥ 38°C); and (c) in adults aged 15–44 years with pain on swallowing and one or two of the four signs, but not both cough and coryza. Group A streptococci were found by laboratory culture in 30% of throat swabs from 1783 patients. Using these results as the reference, the algorithm was 95% sensitive and 26% specific, and assigned 80% of the patients to be swabbed. Its positive and negative predictive values in this setting were 36% and 92%, respectively. It is concluded that this algorithm may be useful in general practice.

Key Words:

• algorithm
• general practice
• group A streptococci
• pharyngitis
• sore throat
• throat swabs
• tonsillitis