Service evaluation to establish the sensitivity, specificity and additional value of broad-range 16S rDNA PCR for the diagnosis of infective endocarditis from resected endocardial material in patients from eight UK and Ireland hospitals

Abstract

Infective endocarditis (IE) can be diagnosed in the clinical microbiology laboratory by culturing explanted heart valve material. We present a service evaluation that examines the sensitivity and specificity of a broad-range 16S rDNA polymerase chain reaction (PCR) assay for the detection of the causative microbe in culture-proven and culture-negative cases of IE. A clinical case-note review was performed for 151 patients, from eight UK and Ireland hospitals, whose endocardial specimens were referred to the Microbiology Laboratory at Great Ormond Street Hospital (GOSH) for broad-range 16S rDNA PCR over a 12-year period. PCR detects the causative microbe in 35/47 cases of culture-proven IE and provides an aetiological agent in 43/69 cases of culture-negative IE. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the 16S rDNA PCR assay were calculated for this series of selected samples using the clinical diagnosis of IE as the reference standard. The values obtained are as follows: sensitivity = 67 %, specificity = 91 %, PPV = 96 % and NPV = 46 %. A wide range of organisms are detected by PCR, with Streptococcus spp. detected most frequently and a relatively large number of cases of Bartonella spp. and Tropheryma whipplei IE. PCR testing of explanted heart valves is recommended in addition to culture techniques to increase diagnostic yield. The data describing the aetiological agents in a large UK and Ireland series of culture-negative IE will allow future development of the diagnostic algorithm to include real-time PCR assays targeted at specific organisms.

Mycoplasma hominis, a Rare but True Cause of Infective Endocarditis

“…S. epidermidis was retrospectively found to be responsible only for an arterial catheter infection. Broadrange PCR using primers for 16S rDNA and excised heart valves improves the diagnostic outcome of microbiological examinations (5,25,26). Consequently, British guidelines for IE management include positive results of broad-range PCR performed on excised heart valves as a minor criterion for IE (27).…”

“…Consequently, British guidelines for IE management include positive results of broad-range PCR performed on excised heart valves as a minor criterion for IE (27). 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).…”

First Experience of a Multicenter External Quality Assessment of Molecular 16S rRNA Gene Detection in Bone and Joint Infections

“…Microbiological diagnosis remains difficult, mostly for chronic or low-grade infections, and requires prolonged culture conditions after pretreatments such as bead mill processing of perioperative samples (2) or implant sonication (3). Molecular biology provided a diagnostic tool that showed its effectiveness, especially when antibiotics were administered before surgery or when fastidious bacteria were involved, particularly for the diagnosis of endocarditis (4). For BJI diagnosis, broad-range 16S rRNA gene PCR has shown higher, lower, or equivalent sensitivity compared with conventional culture methods, but sometimes to the detriment of specificity (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Molecular identification of pathogens from excised heart valves of infective endocarditis cases

“…There have been several reports evaluating the routine molecular diagnosis of IE using resected valves (Goldenberger et al, 1997, Harris et al, 2014, Miyazato et al, 2012, Gauduchon et al, 2003, Voldstedlund et al, 2008, Rovery et al, 2005, Marin et al, 2007. In these reports, 16S rRNA gene diagnostic criteria (Miller et al, 2016).…”

“…burnetii from blood or infected heart valve with either broad-range 16S rRNA primers (Houpikian et al, 2005) or species-specific primers (Harris et al, 2014 …”