Diagnosis of streptococcal tonsillitis in general practice by clinical assessment and by office culture of throat swabs on Streptocult.

In a one-year study 274 general practitioners performed office cultures on Streptocult of throat swabs from 2,699 patients with acute pharyngotonsillitis in order to identify those with beta-haemolytic streptococci in the throat. The finding of group A beta-haemolytic streptococci by laboratory culture of corresponding throat swabs was used as a reference when determining the diagnostic value of either clinical assessment or Streptocult culture for the identification of patients with streptococcal pharyngotonsillitis. Based on 2,150 cases, sensitivity was 70% and 84%, respectively; specificity, 63%, respectively 77%; positive predictive value, 38%, respectively 53%; and negative predictive value, 87%, respectively 94%. Compared to the clinical assessment of the etiology, use of Streptocult resulted in the additional identification of 14% of the patients with group A streptococci and 13% of the patients without this organism present in the throat, as judged by laboratory culture. Overall, 78% of the patients were correctly diagnosed by the use of Streptocult, compared to 65% by clinical assessment. It is concluded that the use of Streptocult in general practice may be of substantial benefit in the identification of patients with group A streptococcal tonsillitis.