16S rRNA Gene PCR/Sequencing of Heart Valves for Diagnosis of Infective Endocarditis in Routine Clinical Practice.

Sequencing is increasingly used for infective endocarditis (IE) diagnosis. Here, the performance of 16S rRNA gene PCR/sequencing of heart valves utilized in routine clinical practice was compared with conventional IE diagnostics. Subjects whose heart valves were sent to the clinical microbiology laboratory for 16S rRNA gene PCR/sequencing from August 2020 through February 2022 were studied. A PCR assay targeting V1 to V3 regions of the 16S rRNA gene was performed, followed by Sanger and/or next-generation sequencing (NGS) (using an Illumina MiSeq), or reported as negative, depending on an algorithm that included the PCR cycle threshold value. Fifty-four subjects, including 40 with IE, three with cured IE, and 11 with noninfective valvular disease, were studied. Thirty-one positive results, 11 from NGS and 20 from Sanger sequencing, were generated from analysis of 16S rRNA gene sequence(s). Positivity rates of blood cultures and 16S rRNA gene PCR/sequencing of valves were 55% and 75%, respectively (P = 0.06). In those with prior antibiotic exposure, positivity rates of blood cultures and 16S rRNA gene PCR/sequencing of valves were 11% and 76%, respectively (P < 0.001). Overall, 61% of blood culture-negative IE subjects had positive valve 16S rRNA gene PCR/sequencing results. 16S rRNA gene-based PCR/sequencing of heart valves is a useful diagnostic tool for pathogen identification in patients with blood culture-negative IE undergoing valve surgery in routine clinical practice.

Proteoglycan 4 (lubricin) is a highly sialylated glycoprotein associated with cardiac valve damage in animal models of infective endocarditis.

Streptococcus gordonii and Streptococcus sanguinis are primary colonizers of tooth surfaces and are generally associated with oral health, but can also cause infective endocarditis (IE). These species express "Siglec-like" adhesins that bind sialylated glycans on host glycoproteins, which can aid the formation of infected platelet-fibrin thrombi (vegetations) on cardiac valve surfaces. We previously determined that the ability of S. gordonii to bind sialyl T-antigen (sTa) increased pathogenicity, relative to recognition of sialylated core 2 O-glycan structures, in an animal model of IE. However, it is unclear when and where the sTa structure is displayed, and which sTa-modified host factors promote valve colonization. In this study, we identified sialylated glycoproteins in the aortic valve vegetations and plasma of rat and rabbit models of this disease. Glycoproteins that display sTa vs. core 2 O-glycan structures were identified by using recombinant forms of the streptococcal Siglec-like adhesins for lectin blotting and affinity capture, and the O-linked glycans were profiled by mass spectrometry. Proteoglycan 4 (PRG4), also known as lubricin, was a major carrier of sTa in the infected vegetations. Moreover, plasma PRG4 levels were significantly higher in animals with damaged or infected valves, as compared with healthy animals. The combined results demonstrate that, in addition to platelet GPIbα, PRG4 is a highly sialylated mucin-like glycoprotein found in aortic valve vegetations and may contribute to the persistence of oral streptococci in this protected endovascular niche. Moreover, plasma PRG4 could serve as a biomarker for endocardial injury and infection.

Native Valve Infective Endocarditis - the Postoperative Results and Role of the Endocarditis Team. A Single Center Experience.

Background: Infective endocarditis (IE) may present with quite different aspects. Consequently, it's management involves a collaborative approach between several specialties. We analyzed the timing of surgery and the role of the "Endocarditis Team" in patients with IE. Methods: The medical records of patients operated for IE in our center during an 18-year period were retrospectively analyzed for the demographic data, causative agent, imagistic features of the affected valve and systemic lesion extension and postoperative results. Results: Patients age ranged between 7 and 84 years, and in many cases (55.88%) the etiology remained unidentified. The early postoperative complications were not significantly higher in patients operated in emergency compared to those with elective surgery. The overall early postoperative mortality rate was 14.05%, significantly lower in the elective surgery cases (p = 0.001). The long-term follow-up for patients operated between 2008 and 2017 showed a late postoperative death rate of 17.8% (34 patients). Conclusions: Emergency surgery for patients with native valve IE provides in most cases a good chance for a cure, despite the relatively high frequency of postoperative complications and rate of postoperative death. The advances in pre- and post-operative management of IE patients, as well as in surgical techniques and prosthetic valves seem to further improve the outcome.

Determinants and consequences of positive valve culture when cardiac surgery is performed during the acute phase of infective endocarditis.

The optimal timing of cardiac surgery in infective endocarditis (IE) remains debated: Early surgery decreases the risk of embolism, and heart failure, but is associated with an increased rate of positive valve culture. To determine the determinants, and the consequences, of positive valve culture when cardiac surgery is performed during the acute phase of IE, we performed a retrospective study of adult patients who underwent cardiac surgery for definite left-sided IE (Duke Criteria), in two referral centres. During the study period (2002-2016), 148 patients fulfilled inclusion criteria. Median age was 65 years [interquartile range, 53-73], male-to-female ratio was 2.9 (110/38). Cardiac surgery was performed after 14 days [5-26] of appropriate antibiotics. Valve cultures returned positive in 46 cases (31.1%). Factors independently associated with positive valve culture were vegetation size ≥ 10 mm (OR 2.83 [1.16-6.89], P = 0.022) and < 14 days of appropriate antibacterial treatment before surgery (OR 4.68 [2.04-10.7], P < 0.001). Positive valve culture was associated with increased risk of postoperative acute respiratory distress syndrome (37.0% vs. 15.7%, P = 0.008) but was associated neither with an increased risk of postoperative relapse nor with the need for additional cardiac surgery. Duration of appropriate antibacterial treatment and vegetation size are independently predictive of positive valve culture in patients operated during the acute phase of IE. Positive valve culture is associated with increased risk of postoperative acute respiratory distress syndrome.

Investigating the Impact of Early Valve Surgery on Survival in Staphylococcus aureus Infective Endocarditis Using a Marginal Structural Model Approach: Results of a Large, Prospectively Evaluated Cohort.

BACKGROUND: The impact of valve surgery on outcomes of Staphylococcus aureus infective endocarditis (SAIE) remains controversial. We tested the hypothesis that early valve surgery (EVS) improves survival by using a novel approach that allows for inclusion of major confounders in a time-dependent way. METHODS: EVS was defined as valve surgery within 60 days. Univariable and multivariable Cox regression analyses were performed. To account for treatment selection bias, we additionally used a weighted Cox model (marginal structural model) that accounts for time-dynamic imbalances between treatment groups. To address survivor bias, EVS was included as a time-dependent variable. Follow-up of patients was 1 year. RESULTS: Two hundred and three patients were included in the analysis; 50 underwent EVS. All-cause mortality at day 30 was 26%. In the conventional multivariable Cox regression model, the effect of EVS on the death hazard was 0.85 (95% confidence interval [CI], .47-1.52). Using the weighted Cox model, the death hazard rate (HR) of EVS was 0.71 (95% CI, .34-1.49). In subgroup analyses, no survival benefit was observed in patients with septic shock (HR, 0.80 [CI, .26-2.46]), in NVIE (HR, 0.76 [CI, .33-1.71]) or PVIE (HR, 1.02 [CI, .29-3.54]), or in patients with EVS within 14 days (HR, 0.97 [CI, .46-2.07]). CONCLUSIONS: Using both a conventional Cox regression model and a weighted Cox model, we did not find a survival benefit for patients who underwent EVS in our cohort. Until results of randomized controlled trials are available, EVS in SAIE should be based on individualized decisions of an experienced multidisciplinary team. CLINICAL TRIALS REGISTRATION: German Clinical Trials registry (DRKS00005045).

Impact of Valve Culture in the Prognosis of Active Left-sided Infective Endocarditis.

BACKGROUND: The culture of removed cardiac tissues during cardiac surgery of left-sided infective endocarditis (LSIE) helps to guide antibiotic treatment. Nevertheless, the prognostic information of a positive valve culture has never been explored. METHODS: Among 1078 cases of LSIE consecutively diagnosed in 3 tertiary centers, we selected patients with positive blood cultures who underwent surgery during the active period of infection and in whom surgical biological tissues were cultured (n = 429). According to microbiological results, we constructed 2 groups: negative valve culture (n=218) and concordant positive valve culture (CPVC) (n=118). We compared their main features and performed a multivariable analysis of in-hospital mortality. RESULTS: Patients with CPVC presented more nosocomial origin (32% vs 20%, P = .014), more septic shock (21% vs 11%, P = .007), and higher Risk-E score (29% vs 21%, P = .023). Their in-hospital mortality was higher (35% vs 19%, P = .001), despite an earlier surgery (3 vs 11 days from antibiotic initiation, P < .001). Staphylococcus species (61% vs 42%, P = .001) and Enterococcus species (20% vs 9%, P = .002) were more frequent in the CPVC group, whereas Streptococcus species were less frequent (14% vs 42%, P < .001). Independent predictors for in-hospital mortality were renal failure (odds ratio [OR], 2.6 [95% confidence interval {CI}, 1.5-4.4]), prosthesis (OR, 1.9 [95% CI, 1.1-3.5]), Staphylococcus aureus (OR, 1.8 [95% CI, 1.02-3.3]), and CPVC (OR, 2.3 [95% CI, 1.4-3.9]). CONCLUSIONS: Valve culture in patients with active LSIE is an independent predictor of in-hospital mortality.

Significant variation in heart valve banking practice.

The European Blood Alliance (EBA) Tissue and Cells annual benchmarking exercise identified that in 2014, the heart valve (HV) discard rate in tissue establishments (TEs) run by EBA members was between 19 and 65%. Given this significant discard rate, a decision was taken to carry out a worldwide data-gathering exercise to assess the processing methodology in different TEs. In collaboration with the Foundation of European Tissue Banks, a questionnaire asking for the details on HV processing was sent to TEs worldwide. Nineteen questionnaires were received back from 15 European TEs and 4 non-European TEs. The data provided confirmed a significant discard rate of HVs with 43-50% of aortic valves and 20-32% of pulmonary valves being discarded in 2015. The causes of HV discard varied, with microbiology contamination, anatomical and medical reasons being the main causes. This data-gathering exercise highlighted significant variations in practice in different TEs including how donor suitability is assessed, critical timings for heart retrieval and processing, heart rinsing, HV decontamination protocols and methods of microbiological testing. To reduce the discard rates, there are several aspects of HV banking that could be validated and standardised. Here, we report the findings of this data-gathering exercise. We consider this a first step that will help lead to standardising HV banking.

Validation of microbiological testing in cardiovascular tissue establishments: results of a second international quality-round trial.

The performance of many laboratories can be evaluated by participation in external quality assessment (EQA) schemes. EQA allows for comparison of a laboratory's performance with a source outside the laboratory-either a peer group of laboratories or a reference laboratory. Such EQA schemes do not exist in tissue banking despite the fact that tissue establishments (TE) perform very complex procedures. This paper describes the first ever EQA scheme in the field specifically assessing microbiological aspects in heart valve (HV) banking. Twenty-two TEs participated. Three HV tissue samples were sent to each participating TE-two contaminated with non-pathogenic micro-organisms and a third negative control. The aims were to isolate and identify the micro-organisms present and then to successfully decontaminate the HV tissue using the routine standard operating procedures of the TE. Eight of the TEs were able to isolate and identify all contaminating micro-organisms present, and of these, five also successfully decontaminated the tissue; 13 TEs failed to establish the identity of one or more of the contaminants; five TEs appear to have introduced contamination during the processing or testing of the tissue; and eight failed to successfully decontaminate the HV tissue. This initiative provides TEs with an international benchmark for tissue product microbiology testing. It has identified significant variation in practice and in the ability of different TEs to identify the presence of contamination. There is now work ongoing with the aim of setting up a regular EQA scheme for HV banking.

Clinical utility of echocardiography for the diagnosis of native valve infective endocarditis in Staphylococcus aureus bacteremia.

BACKGROUND: The incidence of Staphylococcus aureus infective endocarditis (IE) is steadily rising due to advances in health care delivery. Routine echocardiography is essential in the management of Staphylococcus aureus bacteremia (SAB). The aim of this retrospective cohort study was to characterize the real-world use of echocardiography in adult patients with SAB and native valve S aureus IE. METHODS: Using an academic hospital microbiological database, all cases of SAB in adults between 2010 and 2016 were identified. Demographic, echocardiographic, and clinical features were recorded. RESULTS: A total of 738 episodes of SAB were identified, of which 504 (68%) patients underwent transthoracic echocardiography (TTE) within 30 days. Of 73 patients with definite IE, 46 (63%) patients had definite IE diagnosed on the initial TTE. An additional 14 (19%) patients had definite IE diagnosed on repeat TTE, 6 (8%) on transesophageal echocardiography (TEE), and 7 (10%) were diagnosed without fulfilling Duke echocardiographic criteria. The yield of repeat TTE was comparable to that of TEE for identifying new vegetations not identified on the initial TTE (17% vs 21%, P = .78). CONCLUSIONS: Most cases of IE in SAB were identified using TTE alone, with repeat TTE improving the diagnostic yield in the setting of clinical decompensation.

[First Isolation of Coxiella burnetii in Turkey from a Patient with Endocarditis; Antigen Production and Phase Change Study]. / Endokarditli Bir Olgudan Coxiella burnetii'nin Türkiye'de Ilk Izolasyonu; Antijen Üretimi ve Faz Degisimi Çalismasi.

Coxiella burnetii is the causative agent of Q fever, a zoonotic infection. The bacteria is a gram-negative, pleomorphic, coccobacilli and capable to survive and proliferate within the host cell's phagolysosome. There are two morphological cell types of C.burnetii including small and large cell variants. C.burnetii is divided into phase I and phase II serologically variants according to LPS structure in the cell wall. Phase I is the natural phase found in infected animals or humans and is highly infectious. Phase II is not very infectious and could be obtained only in laboratories after serial passages in cell cultures or embryonated egg cultures. Q fever can be asymptomatic (in 50% of the cases), acute or chronic. Major presentations of acute Q fever are flu-like illness, pneumonia, and hepatitis, whereas the chronic form presents mainly as infective endocarditis. The aim of this study was to obtain C.burnetii phase II variant from C.burnetii phase I variant by a phase change study. In this study, C.burnetii was isolated by cell culture method from the heart valve tissue of a Q fever endocarditis case. C.burnetii phase I antigen for the indirect fluorescent antibody test (IFAT) was prepared from the isolated strain. For the isolation and identification of C.burnetii, heart valve tissue of the patient was homogenized and DNA was extracted by tissue extraction kit. C.burnetii DNA in the valve tissue was determined by real-time PCR (Rt-PCR). This C.burnetii DNA positive specimen was inoculated into Vero cells by shell vial centrifugation method. The scraped Vero cells were fixed on the slides after one week of incubation and IFAT was performed using C.burnetii phase I IgG positive sera, bacteria that were grown in and surrounding the Vero cells stained apple green were determined microscopically. Infected cells were disrupted by freeze and thaw method to obtain bacterial suspension. The DNA obtained from the bacterial suspension was again found to be positive for C.burnetii by Rt-PCR. Isolation sample was found to be positive in PCR at an earlier cycle compared to heart tissue sample, thus the bacterial growth was also confirmed with PCR. 16S ribosomal RNA gene of our isolate was amplified by PCR using 27F and 1492 primers and then sequenced. The DNA sequences were compared with reference DNA sequences of GeneBank; and the nucleotide sequence of the 16S ribosomal RNA gene of our isolate was found to be 99% similar to C.burnetii strain ATCC VR-615 an accession number NR104916. Serial cell culture passages of the isolated strain were performed to obtain C.burnetii phase II variant from C.burnetii phase I variant. After each passage, presence of phase change was investigated by IFAT using C.burnetii phase I and phase II IgG positive sera. At the end of 17 cell culture passages, phase change could not be observed. C.burnetii phase I IFAT antigen was prepared from the obtained bacterial suspension. In this study, we presented the isolation and identification of C.burnetii by cell culture, molecular and serological methods from the heart valve of a patient with endocarditis for the first time in our country.

Aspergillus flavus native valve endocarditis following combined liver and renal transplantation: Case report and review of the literature.

Aspergillus endocarditis is a rare infection that occurs most commonly in patients with prior cardiac surgery but cases in post-transplant recipients without prior cardiac surgery have been reported. Diagnosis is often delayed and requires high index of suspicion. We here report a case of Aspergillus endocarditis in solid organ transplant recipient.

Is the Unyvero i60 ITI multiplex PCR system a promising test in the diagnosis of infective endocarditis from heart valves?

The aim of this study was to evaluate the new commercial Unyvero i60 ITI multiplex PCR system (Curetis, Holzgerlingen, Germany) on native cardiac valves in comparison with made in-house 16S rRNA PCR amplification (91E/13BS primers) and conventional microbiological techniques. Forty-four patients (30 men, 14 women) with suspected infective endocarditis (IE) were included in this evaluation corresponding to 30 aortic valves and 14 mitral valves. IE was definite for 40 patients using the modified Duke criteria. 16S rRNA PCR amplification was successful in 22 patients (55%). The Unyvero i60 ITI cartridge yielded a positive result in 16 patients (40%). Among the 40 cases, the etiological agent was not included in the panel of Unyvero i60 ITI cartridge for 14 cases. Moreover, for S. aureus, the Unyvero i60 ITI cartridge quickly yielded the susceptibility to meticillin. The result of the experiment was available after 5 hours whereas 16S rRNA PCR amplification-sequencing needs 14 hours of manipulation. If the manufacturer incorporates new targets able to detect more endocarditis agents such as viridans streptococci, the Unyvero i60 ITI cartridge may be a promising and easy-to-use test.

Comparison of automated and conventional microbiological examination of donated human cardiac tissue in heart valve banking.

Most tissue banks use the conventional method; however, the automated method has advantages over the conventional method. The aim of this study was to compare the conventional and automated methods of culture in human cardiac tissue using an artificial contamination model. Myocardial samples were contaminated with sequential concentration (104 to 10-1 CFU/mL) with Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans. Cultures were obtained from solution were the fragment was immersed and minced tissue, before and after the routine decellularization solution, with automated and conventional culture methods. Automated and conventional methods were compared and a p value ≤ 0.05 was considered significant. Staphylococcus aureus presented a significantly higher growth in the automated method, as well as faster than the conventional (p < 0.05). The positivity for growth in the automated method was higher in concentrated inoculum (> 102 CFU/mL) (p < 0.05). The growth in the automated method was significantly faster than conventional when inoculum concentration was above 103 CFU/mL. The automated culture method is faster than conventional method with a higher positivity in a contaminated model of myocardial and transport solution used in tissue banks.

Bioburden in transport solutions of human cardiovascular tissues: a comparative evaluation of direct inoculation and membrane filter technique.

All cardiac allograft tissues are under potential contamination, requiring a validated terminal sterilization process or a minimal bioburden. The bioburden calculation is important to determine the bacterial burden and further decontamination and disinfection strategies for the valve processing. The aim of this study was to determine the bioburden from transport solution (TS) of heart valves obtained from non-heart-beating and heart-beating donors in different culture methods. The bioburden from TS was determined in 20 hearts donated for valve allograft tissue using membrane filter (MF) and direct inoculation. Tryptic soy agar and Sabouraud plates were incubated and colonies were counted. Ninety-five percent of samples from this study were obtained from heart-beating donors. The warm ischemic time period for heart was 1.06 ± 0.74 h and the cold ischemic time period was 25.66 ± 11.16 h. The mean TS volume was 232.68 ± 96.67 mL (48.5-550 mL). From 20 samples directly inoculated on TSA agar plates, 2 (10%) were positive. However, when MF was used, from 20 samples in TSA, 13 (65%) were positive with a mean count of 1.36 ± 4.04 CFU/mL. In Sabouraud plates, the direct inoculation was positive in 5 samples (25%) with a mean count of 0.24 ± 0.56 CFU/mL. The use of MF increased the positivity to 50% (10 samples from a total of 20) with a mean of 0.28 ± 0.68 CFU/mL. The positivity was superior using MF in comparison with direct inoculation (p < 0.05). The bioburden of TS is low and MF is the technique of choice due to higher positivity.

Contribution of Streptococcus mutans Strains with Collagen-Binding Proteins in the Presence of Serum to the Pathogenesis of Infective Endocarditis.

Streptococcus mutans, a major pathogen of dental caries, is considered one of the causative agents of infective endocarditis (IE). Recently, bacterial DNA encoding 120-kDa cell surface collagen-binding proteins (CBPs) has frequently been detected from S. mutans-positive IE patients. In addition, some of the CBP-positive S. mutans strains lacked a 190-kDa protein antigen (PA), whose absence strengthened the adhesion to and invasion of endothelial cells. The interaction between pathogenic bacteria and serum or plasma is considered an important virulence factor in developing systemic diseases; thus, we decided to analyze the pathogenesis of IE induced by S. mutans strains with different patterns of CBP and PA expression by focusing on the interaction with serum or plasma. CBP-positive (CBP+)/PA-negative (PA-) strains showed prominent aggregation in the presence of human serum or plasma, which was significantly greater than that with CBP+/PA-positive (PA+) and CBP-negative (CBP-)/PA+ strains. Aggregation of CBP+/PA- strains was also observed in the presence of a high concentration of type IV collagen, a major extracellular matrix protein in serum. In addition, aggregation of CBP+/PA- strains was drastically reduced when serum complement was inactivated. Furthermore, an ex vivo adherence model and an in vivo rat model of IE showed that extirpated heart valves infected with CBP+/PA- strains displayed prominent bacterial mass formation, which was not observed following infection with CBP+/PA+ and CBP-/PA+ strains. These results suggest that CBP+/PA-S. mutans strains utilize serum to contribute to their pathogenicity in IE.

AtlA Mediates Extracellular DNA Release, Which Contributes to Streptococcus mutans Biofilm Formation in an Experimental Rat Model of Infective Endocarditis.

Host factors, such as platelets, have been shown to enhance biofilm formation by oral commensal streptococci, inducing infective endocarditis (IE), but how bacterial components contribute to biofilm formation in vivo is still not clear. We demonstrated previously that an isogenic mutant strain of Streptococcus mutans deficient in autolysin AtlA (ΔatlA) showed a reduced ability to cause vegetation in a rat model of bacterial endocarditis. However, the role of AtlA in bacterial biofilm formation is unclear. In this study, confocal laser scanning microscopy analysis showed that extracellular DNA (eDNA) was embedded in S. mutans GS5 floes during biofilm formation on damaged heart valves, but an ΔatlA strain could not form bacterial aggregates. Semiquantification of eDNA by PCR with bacterial 16S rRNA primers demonstrated that the ΔatlA mutant strain produced dramatically less eDNA than the wild type. Similar results were observed with in vitro biofilm models. The addition of polyanethol sulfonate, a chemical lysis inhibitor, revealed that eDNA release mediated by bacterial cell lysis is required for biofilm initiation and maturation in the wild-type strain. Supplementation of cultures with calcium ions reduced wild-type growth but increased eDNA release and biofilm mass. The effect of calcium ions on biofilm formation was abolished in ΔatlA cultures and by the addition of polyanethol sulfonate. The VicK sensor, but not CiaH, was found to be required for the induction of eDNA release or the stimulation of biofilm formation by calcium ions. These data suggest that calcium ion-regulated AtlA maturation mediates the release of eDNA by S. mutans, which contributes to biofilm formation in infective endocarditis.

Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves.

BACKGROUND: Bacterial endocarditis is a recognised disease in humans and animals. In humans, infection with Coxiella burnetii can cause endocarditis, but this has not been investigated thoroughly in animals. Endocarditis in cattle is a common post-mortem finding in abattoirs and studies have identified Trueperella pyogenes as a major cause. Despite exposure of cattle to C. burnetii, the significance of this particular bacterium for development and progression of endocarditis has not been studied in detail. Cardiac valves of cattle affected with endocarditis (n = 100) were examined by histology, fluorescence in situ hybridization (FISH) and real time quantitative polymerase chain reaction (PCR). Serum was examined for anti-C. burnetii antibodies by enzyme-linked immunosorbent assay (ELISA). RESULTS: Serology revealed that 70% of the cattle were positive for antibodies to C. burnetii, while PCR analysis identified 25% of endocarditis valve samples as being positive. C. burnetii was not detected by FISH, probably due to the low infection levels. Most cattle had chronic valvular vegetative endocarditis with lesions being characterised by a core of fibrous tissue covered by significant amounts of fibrin, sometimes with areas of liquefaction, and with a coagulum covering the surface. In a few cases, including the case with the highest infection level, lesions were characterized by extensive fibrosis and calcification. Histologically, bacteria other than C. burnetii were observed in most cases. CONCLUSIONS: The presence of C. burnetii DNA is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes-like bacteria were present in the inflamed valves; a bacterium able to induce the observed lesions. Heart valves of normal cattle should be investigated to assess if C. burnetii may be present without preexisting lesions.

Surgical Treatment for Infective Endocarditis: A Single-Centre Experience.

Background A considerable proportion of patients with acute infective endocarditis require surgical treatment. The aim of this study was to collate our short- and medium-term results of surgical treatment of infective endocarditis and to compare the results in native and prosthetic endocarditis. Method Total 254 operations for infective endocarditis from January 2008 to May 2015 were included in this retrospective study. There were 182 operations for native valve endocarditis and 72 for prosthetic valve endocarditis. Patient characteristics, operative details, complications, and mortality were registered. Results The endocarditis was left sided in 247 operations (146 aortic, 78 mitral, and 23 double-valve) and right-sided in 7 (5 tricuspid and 2 pulmonary). Twenty-two patients (8.7%) died within 30 days (7.7% with native valve endocarditis and 11.1% with prosthetic valve endocarditis, p = 0.31). Severe perioperative complications occurred in 99 of 254 operations (39%). Overall cumulative survival at 1 and 5 years was 86% and 75%, respectively, and it was not significantly different for native and prosthetic endocarditis (p = 0.31). Eighteen patients (8%) had one (n = 16) or two (n = 2) recurrent episodes of endocarditis requiring surgery. Conclusion Surgery for infective endocarditis is still associated with a high early mortality rate and a considerable complication rate. Long-term outcome is acceptable. In our study population, morbidity and mortality were not significantly different in native and prosthetic endocarditis.

[Endocarditis of mitral and aortic prosthetic heart valves caused by Aggregatibacter aphrophilus]. / Le cas clinique du mois. Endocardite à Aggregatibacter aphrophilus sur prothèses valvulaires.

We present the case of an acute endocarditis of mitral and aortic prosthetic heart valves caused by Aggregatibacter aphrophilus (Haemophilus aphrophilus-paraphrophilus). This third report in the literature emphasizes the diagnostic work-up and the role of positron emission tomography combined with computed tomography in this setting. The specificities of endocarditis due to the HACEK group (Haemophilus spp., Aggregatibacter, Cardiobacterium hominis, Eikenella corrodens and Kingella spp.) and the specific microbiological data and therapeutic options pertinent to this germ are discussed.

Nous rapportons la troisième observation clinique de la littérature d'une endocardite sur prothèses mécaniques mitrale et aortique due à l'Aggregatibacter aphrophilus (Haemophilus aphrophilus-paraphrophilus). Le pathogène récemment rebaptisé Aggregatibacter aphrophilus fait partie du groupe HACEK (Haemophilus spp., Aggregatibacter, Cardiobacterium hominis, Eikenella corrodens and Kingella spp.) impliqué dans des endocardites valvulaires de diagnostic difficile. Cette histoire clinique est l'occasion d'une revue de la littérature et des spécificités de ce pathogène. Elle met en exergue la contribution de la tomographie à émission de positons combinée à une tomodensitométrie dans le diagnostic et le suivi. Elle démontre, avec un recul de plus de deux ans, l'efficacité du traitement médical dans certaines endocardites sur prothèse.

Shear-Resistant Binding to von Willebrand Factor Allows Staphylococcus lugdunensis to Adhere to the Cardiac Valves and Initiate Endocarditis.

BACKGROUND: Staphylococcus lugdunensis is an emerging cause of endocarditis. To cause endovascular infections, S. lugdunensis requires mechanisms to overcome shear stress. We investigated whether platelets and von Willebrand factor (VWF) mediate bacterial adhesion to the vessel wall and the cardiac valves under flow. METHODS: S. lugdunensis binding to VWF, collagen, and endothelial cells was studied in a parallel flow chamber in the absence and presence of platelets. In vivo adhesion of S. lugdunensis was evaluated in a mouse microvasculature perfusion model and a new mouse model of endocarditis. RESULTS: Contrary to other coagulase-negative staphylococci, S. lugdunensis bound to VWF under flow, thus enabling its adhesion to endothelial cells and to the subendothelial matrix. In inflamed vessels of the mesenteric circulation, VWF recruited S. lugdunensis to the vessel wall. In a novel endocarditis mouse model, local inflammation and the resulting release of VWF enabled S. lugdunensis to bind and colonize the heart valves. CONCLUSIONS: S. lugdunensis binds directly to VWF, which proved to be vital for withstanding shear forces and for its adhesion to the vessel wall and cardiac valves. This mechanism explains why S. lugdunensis causes more-aggressive infections, including endocarditis, compared with other coagulase-negative staphylococci.