Broad‐range PCR and sequencing in routine diagnosis of infective endocarditis

Abstract

The aim was to evaluate "16S rDNA PCR and sequencing" (PCR) for identification of bacterial DNA in heart valves in routine diagnosis of infective endocarditis (IE). Heart valves from 74 patients with suspected infective endocarditis, and 16 controls were analysed by histology, culture and PCR. Results from blood culture served as the gold standard. Patients were classified according to the Duke criteria. The final classification resulted in 57 definitive cases of IE, 7 possible, and 10 cases without IE. Sensitivity of valve culture was 26% and specificity 62%. Sensitivity of PCR was 72% and specificity 100%. In patients who had received antibiotic treatment for less than 5 days before surgery, sensitivity of culture and PCR were comparable. In patients who had received antibiotic treatment for more than 5 days, sensitivity of valve culture was markedly reduced compared to sensitivity of PCR. In three of seven blood-culture-negative cases PCR was positive, including two cases with non-cultivable bacteria. No PCR samples were contaminated, whereas 35% of valve-culture samples were contaminated. PCR is more sensitive and specific than valve culture, and a valuable supplement to the existing analyses of valve tissue. PCR is necessary to identify the full spectrum of pathogens causing IE. In contrast to sensitivity of culture, sensitivity of PCR was independent of length of antibiotic treatment before surgery.

High Frequency of Tropheryma whipplei in Culture-Negative Endocarditis

“…Similar to earlier reports from northern countries (2,14,34), these fastidious pathogens were considerably less prevalent in our series, since we identified B. quintana, C. burnetii, Granulicatella-Abiotrophia spp., and bacteria of the HACEK group in only three (1.2%), two (0.8%), four (1.6%), and two (0.8%) cases, respectively. Epidemiologic, geographic, and climatic conditions might influence the prevalence of infectious agents (4,34). For example, the high rate of IE due to Q fever near Marseille correlated with an exposure to dust contaminated by C. burnetii from animal reservoirs (25), whereas Q fever in Germany is quite rare, especially in urban regions.…”

“…Thus, molecular methods for the identification of microorganisms that are difficult to grow are particularly important (11,16,28,34), and the detection of causative pathogens by molecular methods has been suggested to be added to the main Duke criteria for IE (20,26).…”

Broad‐Range PCR for Detection and Identification of Bacteria

“…and of T. whipplei were detected in these valves. Similar findings were made in other studies of heart valve PCR: at the time of operation, most patients were treated with antibiotics and valve cultures were often negative, and among the cases detected by PCR but not by culture were pretreated cases and infections by fastidious bacteria (16,89,153).…”

“…These include excised heart valves in suspected bacterial endocarditis (16,50,89,153), bloodstream infections in neonates or hematologyoncology patients (69,80,103,110,138), cerebrospinal fluid in suspected meningitis or shunt infections (32,73,134,158,167), bone samples or synovial fluid samples in osteomyelitis or septic arthritis (40, 41, 127), vitreous or aqueous fluid in intraocular infections (152), tissue or pus from brain or spinal abscesses (75,115), amniotic fluid in chorioamnionitis or preterm labor (34,58), and various other scenarios.…”

Evaluation of Commercial Universal rRNA Gene PCR plus Sequencing Tests for Identification of Bacteria and Fungi Associated with Infectious Endocarditis

“…Consistently high diagnostic sensitivity has been reported (12,14,21,22). On the other hand, PCR is considered to be prone to false-positive results due to contamination of DNA extraction and PCR reagents (2) and also due to false-negative results as a result of PCR inhibitors coeluting with the DNA (8).…”