[Diagnosis of streptococcal tonsillitis in the pediatric department with the help of antigen detection test].

INTRODUCTION

The aim was to examine the validity in the paediatric hospital department of an antigen detection test (ADT) for the diagnosis of streptococcal tonsillitis.

MATERIAL AND

METHODS

A prospective multicenter study including three Danish paediatric hospital departments was performed from May 1, 1998 to April 30, 1999. In 353 children aged 0-14 years the result of the ADT, Clearview Strep A, was compared with the result obtained with cultivation in an aerobic culture and the clinical parameters: hyperaemia, swelling, coating, adenitis and a temperature > or = 38.5 degrees C. In 126 patients the results of the ADT were also compared with white blood cell count (WBC), neutrofil count (NC) and C-reactive protein (CRP).

RESULTS

The prevalence of Group A Streptococci (GAS) from culture was 15%. Sensitivity, specificity, positive and negative predictive value of ADT were 67%, 95%, 72% and 94%, respectively. The positive predictive value of the ADT was significantly lower in patients aged 0-4 years than in patients aged > or = 5 years (p = 0.02). The prevalence of positive ADT was significantly higher in patients with heavy growth of GAS than in patients with moderate or sparse growth (p = 0.01). The prevalence of adenitis (p = 0.003) and coating (p = 0.003) was significantly raised in ADT-positive patients. In patients with growth of Group A Streptococci in cultivation in an aerobic culture the prevalence of adenitis (p = 0.006) and elevated CRP (p = 0.03) was significantly raised.

DISCUSSION: The sensitivity of 67% for the ADT is not satisfactory. However, in our opinion, this is not a sufficient argument against using ADT. It was a problem that the result of the ADT was sometimes difficult to read. Adjustment of the test procedure and the use of easy readable and high-sensitive optical immunoassay tests would probably improve the results significantly. Until the results of such studies exist, we suggest that the method of cultivation in an aerobic culture is used in the case of negative ADT, at least in patients with pronounced symptoms and/or clinical signs of streptococcal tonsilitis (adenitis and coating).