PCR Detection of Bacteria on Cardiac Valves of Patients with Treated Bacterial Endocarditis

Abstract

We used broad-range PCR amplification and sequencing to detect and identify bacterial DNA in 156 valves of patients treated for infective endocarditis (IE). Bacterial DNA was found more frequently in patients who underwent valve replacement while on antibiotic treatment for IE (60%) than in patients who had completed antibiotic treatment for IE (37%; P ‫؍‬ 0.02). We found specific bacterial DNA in valves removed from 11 of 30 patients who had completed antibiotic treatment for IE. Six had no histological evidence of IE. The presence of DNA was significantly correlated with the presence of histologic lesions (P ‫؍‬ 0.001) and with the presence of bacteria detected by Gram staining (P < 0.001). Bartonella and streptococci were detected for much longer after antibiotic treatment by PCR than other species (P ‫؍‬ 0.047 and 0.04, respectively), and coagulase-negative staphylococci were detected for much shorter periods (P ‫؍‬ 0.02). The finding that bacterial DNA was more likely to be detected in valves of patients with active IE than in patients who had completed antibiotic treatment for IE shows that bacterial DNA is cleared slowly. There was no significant correlation between the duration of antibiotic therapy and the presence of bacterial DNA in valves. Since the persistence of bacterial DNA in valves does not necessarily indicate the persistence of viable bacteria, the detection of bacterial DNA in valves from IE patients should be interpreted with caution, in particular in those patients with a past history of treated IE.

Mycoplasma hominis, a Rare but True Cause of Infective Endocarditis

“…Physicians have to take into account the results of broad-range 16S rDNA PCR in IE for an appropriate choice of antibiotics (26). However, contamination and persistence of positive PCR several years after treatment of IE limit the use of broad-range PCR as a major criterion for IE diagnosis (28,29). A delay between the appearance of clinical symptoms and identification of M. hominis as the causative agent was highlighted in a series of mediastinitis observations where the mean delay between obtaining sample and microbiological diagnosis was 9.1 days (21).…”

Laboratory Diagnosis of Infective Endocarditis

“…Long-term persistence of bacterial DNA has been reported in patients who have completed a full course of antibiotic therapy, in some cases several years after diagnosis of endocarditis. In one study, PCR was more likely to be positive in valves with histologic evidence of endocarditis, although PCR was positive in 23% (7/30) of patients with a history of endocarditis but no histological findings consistent with active endocarditis, suggesting that bacterial DNA may persist even after resolution of tissue lesions (35). Conversely, results can be falsely negative due to the presence of PCR inhibitors, the presence of microbial nucleic acid below the limit of detection of the assay being used, or sampling error since microorganisms are often not homogenously distributed in resected valves.…”

Analysis of 525 Samples To Determine the Usefulness of PCR Amplification and Sequencing of the 16S rRNA Gene for Diagnosis of Bone and Joint Infections

“…(20,24,40,56,58,61) or to investigate pathogens associated with destabilized hip prostheses (27). This approach has been successfully applied, mainly on cardiac valves, for the diagnosis of endocarditis, allowing the detection of bacteria despite antibiotic therapy and for negative cardiac valve culture (5,19,50) due to fastidious bacteria such as Mycoplasma spp. or Tropheryma whipplei (15,17).…”