Utility of Detecting sof Gene as Evidence of Streptococcus pyogenes Infection in Acute Rheumatic Fever.

Objective: To determine the diagnostic accuracy of polymerase chain reaction-based detection of sof gene compared to throat swab culture for S. pyogenes infection in patients with acute rheumatic fever and those with recurrence of rheumatic activity.

Methods: 40 patients between 3 to 18 years of age, with clinical diagnosis of acute rheumatic fever or new activity in established rheumatic heart disease were included. The amplicon of 228bp of sof gene was detected using a polymerase chain reaction-based technique and the results were compared with throat swab culture for Streptococcus pyogenes.

Results: 10 patients had a positive throat swab culture and 11 had sof gene detected. The sensitivity and specificity of the test was 100% and 96.7%, respectively compared to throat swab culture (P=0.001). The positive predictive value and the negative predictive value was 90.9% and 100% respectively.

Conclusion: Polymerase chain reaction-based detection of sof gene provides an alternative to throat swab culture in diagnosing activity in Acute Rheumatic Fever or established Rheumatic heart disease.