Abstract
BackgroundThe study aimed to explore the sensitivity and specificity of a novel fast 16S rDNA PCR and sequencing assay for the improved diagnosis of infective endocarditis (IE) in patients with suspected native or prosthetic heart valve (HV) infection over a multi-year period at our cardiovascular center.MethodsSixty-eight patients were prospectively enrolled who underwent HV replacement for suspected or confirmed IE between February 1, 2009 and September 1, 2014. Patient demographics, medical co-morbidities, Duke’s criteria, culture results, and antibiotic therapy were collected by detailed chart reviews. Dual-priming oligonucleotide primers targeted to 500 bps of the V1-V3 region of the 16S rRNA gene were used to perform fast broad-range 16S rDNA PCR and Sanger sequencing on ribosomal DNA extracted from HV tissues. The performance/diagnostic efficiency of the molecular test was evaluated against blood cultures and Gram stain and culture of HV tissue in patients’ with definite IE according to Duke’s criteria.ResultsFifty patients (73.5 %) had definite IE and another 8 (11.8 %) had possible IE according to Duke’s criteria. Cardiac surgery was delayed an average of 15.4 days from the time of the patient’s last positive blood culture, and appropriate antibiotic therapy was given in the pre-operative period. While 44/50 (88 %) patients had a positive blood culture, HV tissue culture was only positive in 23 (46 %) of them. Molecular testing of all HV tissues had sensitivity, specificity, NPV and PPV of 92, 77.8, 77.8 and 92 % compared to 44, 100, 39.1 and 100 % respectively for culture for diagnosis of definite IE. For prosthetic HV tissue, 16S rDNA PCR had sensitivity of 93 % and specificity of 83 % compared to 35 and 100 % respectively for culture. A literature review showed that the diagnostic accuracy of our novel fast broad-range 16S rDNA PCR assay was similar or better than that of previously published studies.ConclusionsThis novel fast broad-range 16S rDNA PCR/sequencing test had superior sensitivity compared to tissue Gram stain and culture for identifying underlying bacterial pathogen in both native and prosthetic valve endocarditis.
Highlights
The study aimed to explore the sensitivity and specificity of a novel fast 16S rDNA PCR and sequencing assay for the improved diagnosis of infective endocarditis (IE) in patients with suspected native or prosthetic heart valve (HV) infection over a multi-year period at our cardiovascular center
Microbiologic diagnosis in IE, which is a cornerstone of the Duke criteria, has classically relied on traditional culture results for isolation of a pathogen(s) from blood or affected heart valve tissue
Because broad-range PCR assays are prone to contamination [21], and primers within the 16S rRNA gene may cross-react with human DNA in clinical samples, we developed a novel, fast broad-range 16S rDNA PCR using unique dual-priming oligonucleotide (DPO) primer to try and increase the sensitivity and specificity of molecular diagnosis of IE [22]
Summary
The study aimed to explore the sensitivity and specificity of a novel fast 16S rDNA PCR and sequencing assay for the improved diagnosis of infective endocarditis (IE) in patients with suspected native or prosthetic heart valve (HV) infection over a multi-year period at our cardiovascular center. The Duke criteria are used to diagnose IE and may help determine whether cardiovascular surgery may be required [3], with almost half (44.9 %) of patients requiring valve surgery [2, 4]. Microbiologic diagnosis in IE, which is a cornerstone of the Duke criteria, has classically relied on traditional culture results for isolation of a pathogen(s) from blood or affected heart valve tissue. Negative culture results are even more prevalent in patients with atypical organisms and prosthetic valve IE due to difficulties in selecting appropriate tissue [6,7,8,9,10]. Identification of the causative pathogen is important for targeting antimicrobial therapy as well as determining prognosis
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