Gram Stain, Culture, and Histopathological Examination Findings for Heart Valves Removed because of Infective Endocarditis

Morris, Arthur J.; Drinković, Dragana; Pottumarthy, Sudha; Strickett, Marianne G.; MacCulloch, D; Lambie, Neil; Kerr, A.

doi:10.1086/367842

Cited by 82 publications

(61 citation statements)

References 32 publications

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“…Gram stain of tissue processed in the microbiology laboratory may be more sensitive than histopathological Gram stain of tissue sections, 81% versus 67% in one study; however, in 10% of cases, the histopathology Gram stain detected organisms while the microbiology Gram stain was negative (17). Unfortunately, several studies have shown that culture of valve tissue suffers from low sensitivity and specificity, with positive cultures in only 6% to 26% of endocarditis cases (17,18,25). A microorganism different from that identified by blood culture or valve PCR was detected in 36% (10/28) of positive valve cultures in one study, suggesting a high rate of false positivity of valve culture (25).…”

Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 81%

“…Current recommendations for the diagnosis of endocarditis also recommend culture of valvular tissue, with culture results being used to direct the duration of postoperative antimicrobial therapy (1,6,9). Gram stain of tissue processed in the microbiology laboratory may be more sensitive than histopathological Gram stain of tissue sections, 81% versus 67% in one study; however, in 10% of cases, the histopathology Gram stain detected organisms while the microbiology Gram stain was negative (17). Unfortunately, several studies have shown that culture of valve tissue suffers from low sensitivity and specificity, with positive cultures in only 6% to 26% of endocarditis cases (17,18,25).…”

Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 97%

“…Blood cultures are negative in 2% to 40% of cases of endocarditis, with some studies reporting blood culture-negative rates up to 71% (4,5,(17)(18)(19). The causes of so-called "culture-negative endocarditis" fall into two categories: negative blood cultures due to concomitant or antecedent antibacterial therapy or the presence of an organism that does not grow in routine blood cultures, with the first being more common.…”

Section: Diagnosis Of Culture-negative Endocarditismentioning

confidence: 99%

“…Caution should be exercised when interpreting staining properties of organisms in valves removed from patients on antimicrobial therapy, as bacterial morphologies and stain properties may be altered. Additionally, the presence of organisms in tissue does not necessarily indicate active endocarditis, as clearance of organisms is delayed compared to sterilization of the vegetation (17).…”

Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 99%

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Laboratory Diagnosis of Infective Endocarditis

et al. 2017

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Infective endocarditis is life-threatening; identification of the underlying etiology informs optimized individual patient management. Changing epidemiology, advances in blood culture techniques, and new diagnostics guide the application of laboratory testing for diagnosis of endocarditis. Blood cultures remain the standard test for microbial diagnosis, with directed serological testing (i.e., Q fever serology, Bartonella serology) in culture-negative cases. Histopathology and molecular diagnostics (e.g., 16S rRNA gene PCR/sequencing, Tropheryma whipplei PCR) may be applied to resected valves to aid in diagnosis. Herein, we summarize recent knowledge in this area and propose a microbiologic and pathological algorithm for endocarditis diagnosis. KEYWORDS clinical microbiology, endocarditisD espite recent advances in diagnostic and therapeutic strategies, the mortality of infective endocarditis remains high, with more than one-third of patients affected dying within a year following diagnosis (1, 2). Identification of the specific underlying microbial etiology is essential for optimal patient management; delays in microbial diagnosis may contribute to late initiation of effective antimicrobial therapy, influencing morbidity and mortality. The modified Duke criteria provide a basic scheme for diagnosis and definition of endocarditis and rely on detection of infecting microorganisms in addition to echocardiographic and clinical findings (1, 3). The finding of two (or more) blood cultures positive for a typical microorganism consistent with infective endocarditis is a major criterion for infective endocarditis as is positive Q fever serology (anti-phase I IgG titer of Ն1:800). Echocardiographic findings are also considered but are beyond the scope of the manuscript.The epidemiology of endocarditis, which has shifted in recent years, should guide diagnostic testing. Today, staphylococci and streptococci combined cause ϳ80% of cases. Staphylococcus aureus remains the dominant pathogen, associated with ϳ25% to ϳ30% of cases, while coagulase-negative staphylococci account for ϳ11% of cases (4, 5). Streptococci, primarily viridans group streptococci, cause ϳ30% of cases, with Streptococcus gallolyticus (a Streptococcus bovis group member) being involved in ϳ20% to ϳ50% of streptococcal cases (4, 5). Enterococci, especially Enterococcus faecalis, account for ϳ10% of cases (4, 5). Gram-negative bacilli account for ϳ5% of cases and include the HACEK group organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella species) and, less commonly, non-HACEK Gramnegative bacilli, such as the Enterobacteriaceae and nonfermenting Gram-negative bacilli. Fungi are rare endocarditis causes, with Candida species being the most common. A number of uncultivable or challenging to cultivate organisms cause endocarditis, the most common of which are Coxiella burnetii, Bartonella species, and Tropheryma whipplei.Endocarditis most often involves the aortic or mitral valves, with tricuspid valve involvement accoun...

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Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 81%

Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 97%

Section: Diagnosis Of Culture-negative Endocarditismentioning

confidence: 99%

Section: Evaluation Of Excised Cardiac Valvular Tissuementioning

confidence: 99%

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Laboratory Diagnosis of Infective Endocarditis

et al. 2017

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“…In a recent study, the presence of histological signs of infective endocarditis (IE) correlated with the presence of bacterial DNA in heart valve tissue, and when patients had no histological evidence of IE, PCR amplification was always negative (10). A recent study has shown that the presence of Gramstaining organisms in heart valves of patients cured of IE does not predict the presence of viable organisms (29). However, it has not been determined whether DNA amplification from valve tissue is predictive of an active infectious process.…”

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confidence: 99%

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

et al. 2005

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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.

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