Detection of Bacterial DNA in Cardiac Vegetations by PCR After the Completion of Antimicrobial Treatment for Endocarditis

PCR with broad-range primers for prokaryotic 16S rRNA genes was used to identify bacterial DNA in tissue from patients undergoing valve replacements following a previous episode of infective endocarditis (IE). Of eight valves investigated, bacterial DNA was detected in three from patients for whom IE had been treated by antibiotic therapy 5, 12 and 18 months previously. The demonstration of bacterial DNA within resected heart valves suggests either recurrence of infection, treatment failure or the persistence of bacterial debris within the cardiac vegetation. There may also be implications for routine use of PCR in the diagnosis of infection.