Impact of a molecular approach to improve the microbiological diagnosis of infective heart valve endocarditis.
BACKGROUND
Even today, infective endocarditis (IE) remains a severe and potentially fatal disease demanding sophisticated diagnostic strategies for detection of the causative microorganisms. Despite the use of appropriate laboratory techniques, classic microbiological diagnostics are characterized by a high rate of negative results.


RESULTS
Broad-range polymerase chain reaction (PCR) targeting bacterial and fungal rDNA followed by direct sequencing was applied to excised heart valves (n=52) collected from 51 patients with suspected infectious endocarditis and from 16 patients without any signs of IE during an 18-month period. The sensitivity, specificity, and the positive and negative predictive values for the bacterial broad-range PCR were 41.2%, 100.0%, 100.0%, and 34.8%, respectively, compared with 7.8%, 93.7%, 80.0%, and 24.2% for culture and 11.8%, 100.0%, 100.0%, and 26.2% for Gram staining. Without exception, database analyses allowed identification up to the (sub)species level comprising streptococcal (n=13), staphylococcal (n=4), enterococcal (n=2), and other signature sequences such as Bartonella quintana and Nocardia paucivorans. Fungal ribosomal sequences were not amplified. All valve tissues of the reference group were negative for both PCR and conventional methods, except one sample that was contaminated by molds.


CONCLUSIONS
Culture-independent molecular methods substantially improve the diagnostic outcome of microbiological examination of excised heart valves. Importantly, this was true not only for fastidious, slow-growing, and/or nonculturable microorganisms but also for easy-to-culture pathogens such as streptococci and staphylococci. Both patient management and empiric antibiotic therapy of IE are likely to benefit from improved knowledge of the spectrum of pathogens now causing IE.
Breitkopf
Claudia
C
Institute of Medical Microbiology, University of Münster Hospital, Münster, Germany.
Hammel
Dieter
D
Scheld
Hans H
HH
Peters
Georg
G
Becker
Karsten
K
D000293:Adolescent; D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000382:microbiology; D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000032:analysis; D004271:DNA, Fungal / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D004697:Endocarditis, Bacterial / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology / Q000601:surgery; D005260:Female; D016469:Fungemia / Q000382:microbiology; D005840:Gentian Violet; D006351:Heart Valves / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016533:Mycological Typing Techniques; D010619:Phenazines; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D012329:RNA, Bacterial / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013194:Staining and Labeling
D004269:DNA, Bacterial; D004271:DNA, Fungal; D004275:DNA, Ribosomal; C035863:Gram's stain; D010619:Phenazines; D012329:RNA, Bacterial; D012331:RNA, Fungal; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D005840:Gentian Violet