Development of broad-range polymerase chain reaction (PCR) bacterial identification in diagnosis of infective endocarditis.

BACKGROUND AND AIMS OF THE STUDY: The study aim was to identify the value of broad-range bacterial PCR in infective endocarditis (IE) of bacterial etiology, and to determine its specificity and sensitivity.

METHODS: Thirty blood samples were taken for analysis from patients with IE (diagnosed according to Duke criteria) and acquired valvular heart disease. Two control groups of patients with (n = 10) or without (n = 15) urinary tract infection were defined. DNA was isolated, and three different primer pairs for the region of the gene coding for 16S rRNA were tested, to determine the most specific pair. Amplification products were analyzed with gel electrophoresis, stained with ethidium bromide, and located under UV light.

RESULTS: Positive blood cultures were found in 25 patients with IE. A typical echocardiography picture with bacterial vegetations was found in all patients with sterile blood cultures, and in 20 patients with positive blood cultures. The highest specificity was found for forward/reverse (F/R) primers, as the relevant amplified PCR product was present in all blood samples with IE, and in four of 10 patients with urinary tract infection.

CONCLUSION: Broad-range PCR in bacterial endocarditis is a rapid, sensitive and inexpensive technique for the detection of bacteria, but is far more prone to contamination than species-specific PCR. However, under controlled conditions, broad-range PCR may be valuable for the identification of non-specific infection, permitting a more rapid clinical diagnosis of endocarditis.