Detection of streptococcal deoxyribonucleic acid with polymerase chain reaction in excised valvular tissue of rheumatic heart disease patients.

Abstract

Introduction: Rheumatic heart disease (RHD) is traditionally attributed to cumulative valvular injury from the recurrent episodes of acute rheumatic fever. An alternative hypothesis is that streptococcal antigenic material may persist within cardiac valves, perpetuating chronic inflammation. This study aimed to test this by detecting streptococcal deoxyribonucleic acid (DNA) in excised rheumatic valvular tissue.

Methods: We prospectively included 15 patients with RHD and 5 non-RHD controls undergoing valve replacement surgery. Patients with active rheumatic activity or infective endocarditis were excluded. Valvular tissue was subjected to nucleic acid extraction and polymerase chain reaction using universal 16S ribosomal ribonucleic acid primers, with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal control.

Results: All the samples amplified with GAPDH primers, confirming DNA integrity. However, no bacterial DNA was detected in RHD or control valves. Histopathology consistently revealed chronic inflammation, fibrosis, hyalinization, and dystrophic calcification in RHD valves.

Conclusions: Streptococcal bacterial DNA was not detected in the excised cardiac valvular tissues of RHD patients, suggesting that chronic bacterial persistence is unlikely to be the cause of ongoing valvular inflammation. The study, however, is limited by its small sample size.