Similar genomic patterns of clinical infective endocarditis and oral isolates of Streptococcus sanguinis and Streptococcus gordonii.

Streptococcus gordonii and Streptococcus sanguinis belong to the Mitis group streptococci, which mostly are commensals in the human oral cavity. Though they are oral commensals, they can escape their niche and cause infective endocarditis, a severe infection with high mortality. Several virulence factors important for the development of infective endocarditis have been described in these two species. However, the background for how the commensal bacteria, in some cases, become pathogenic is still not known. To gain a greater understanding of the mechanisms of the pathogenic potential, we performed a comparative analysis of 38 blood culture strains, S. sanguinis (n = 20) and S. gordonii (n = 18) from patients with verified infective endocarditis, along with 21 publicly available oral isolates from healthy individuals, S. sanguinis (n = 12) and S. gordonii (n = 9). Using whole genome sequencing data of the 59 streptococci genomes, functional profiles were constructed, using protein domain predictions based on the translated genes. These functional profiles were used for clustering, phylogenetics and machine learning. A clear separation could be made between the two species. No clear differences between oral isolates and clinical infective endocarditis isolates were found in any of the 675 translated core-genes. Additionally, random forest-based machine learning and clustering of the pan-genome data as well as amino acid variations in the core-genome could not separate the clinical and oral isolates. A total of 151 different virulence genes was identified in the 59 genomes. Among these homologs of genes important for adhesion and evasion of the immune system were found in all of the strains. Based on the functional profiles and virulence gene content of the genomes, we believe that all analysed strains had the ability to become pathogenic.

Morphological characterization of vegetation by real-time three-dimensional transesophageal echocardiography in infective endocarditis: Prognostic impact.

PURPOSE: Vegetation size is a prognostic predictor in infective endocarditis (IE) and guides surgical management. The aim of this study was to evaluate the accuracy of real-time 3-dimensional transesophageal echocardiography (RT3DTEE) compared to 2DTEE in the diagnosis and characterization of vegetation, as well as its potential clinical impact. METHODS: Two hundred and three consecutive patients with IE were recruited (2009-2016) and retrospectively analyzed. Vegetation diameters and area from 68 patients were measured by 2DTEE and RT3DTEE at admission. The association between size and systemic embolisms was evaluated with logistic regression models. Differences in the discriminative power for the best dimensions' cutoff points were assessed by comparing the area under the ROC curves (AUC). RESULTS: Vegetation size and area were larger by RT3DTEE (P < 0.001) than by 2DTEE, and RT3DTEE was especially relevant in the characterization of nonfiliform vegetation, Morphology was strongly associated with friability, being sessile vegetation less likely to embolize, compared to filiform and raceme-shaped ones (15.4% vs 46% vs 50%). Major diameter by RT3DTEE had better embolic predictive performance than 2DTEE (AUC 0.76 [0.57-0.89] vs 0.71 [0.53-0.86]; P = 0.611). The best cutoff points associated with embolic events during the infection were 17 mm for RT3DTEE and 15 mm for 2DTEE. Based exclusively on vegetation size, the proportion of patients meeting a surgical indication according to current guidelines is higher using RT3DTEE. CONCLUSIONS: RT3DTEE allows a better characterization of IE vegetation than 2DTEE, what may have a clinical impact on surgical management and also prognostic due to a more accurate prediction of embolic risk.

Impact of pre-operative antimicrobial treatment on microbiological findings from endocardial specimens in infective endocarditis.

Treatment of infective endocarditis (IE) should be initiated promptly. This might hamper the chances to identify the causative organism in blood cultures. Microbiological sampling of infected valve in patients undergoing surgery might identify the causative organism. The impact of pre-operative antimicrobial treatment on the yield of valve samples is not known. This study evaluated the impact of the duration of the pre-operative antibiotic treatment on valve culture and 16S rRNA PCR findings from resected endocardial samples. Patients meeting the modified Duke criteria of definite or possible IE and undergoing valve surgery due to IE during 2011-2016 were included from Southern Finland. Eighty-seven patients were included. In patients with shorter than 2 weeks of pre-operative antimicrobial treatment, PCR was positive in 91% (n = 42/46) and valve culture in 41% (n = 19/46) of cases. However, in patients who had 2 weeks or longer therapy before operation, PCR was positive in 53% (n = 18/34) and all valve cultures were negative. In 14% of patients, PCR had a diagnostic impact. In blood-culture negative cases (n = 13), PCR could detect the causative organism in ten patients (77%). These included five cases of Bartonella quintana, one Tropheryma whipplei, and one Coxiella burnetii. Long pre-operative antimicrobial treatment was shown to have a negative impact on microbiological tests done on resected endocardial material. After 2 weeks of therapy, all valve cultures were negative, but PCR was positive in half of the cases. PCR aided in diagnostic work-up, especially in blood culture negative cases.

Aspergillus endocarditis: Diagnostic criteria and predictors of outcome, A retrospective cohort study.

BACKGROUND: Fungal Endocarditis (FE), a relatively rare disease, has a high rate of mortality and is associated with multiple morbidities. Aspergillus endocarditis (AE) is severe form of FE. Incidence of AE has increased and is expected to rise due to an increased frequency of invasive procedures, cardiac devices and prosthetic valves together with increased use of immune system suppressors. AE lacks most of the clinical criteria used to diagnose infective endocarditis (IE), where blood culture is almost always negative, and fever may be absent. Diagnosis is usually late and in many cases is made post-mortem. Late or mistaken diagnosis of AE contribute to delayed and incorrect management of patients. In the current study we aimed to describe the clinical, laboratory and imaging characteristics of AE, to identify predictors of early diagnosis of this serious infection. METHODS: Patients with definite/possible IE, as diagnosed by the Kasr Al-Ainy IE Working Group from February 2005 through June 2016, were reviewed in this study. We compared the demographic, clinical, laboratory and imaging criteria of AE patients to non-fungal IE patients. RESULTS: This study included 374 patients with IE in which FE accounted for 43 cases. Aspergillus was the most common fungus (31 patients; 8.3%) in the patient group. Lack of fever and acute limb ischemia at presentation were significantly associated with AE (p < 0.001, p = 0.014, respectively). Health care associated endocarditis (HAE) and prosthetic valve endocarditis (PVE) were the only significant risk factors associated with AE (p < 0.001 for each). Mitral, non-valvular, and aortotomy site vegetations, as well as aortic abscess/pseudoaneurysm, were significantly associated with AE (p = 0.022, p = 0.004, p < 0.001, and p < 0.001, respectively). Through multivariate regression analysis, HAE, PVE, aortic abscess/pseudoaneurysm, and lack of fever were strongly linked to AE. The probability of an IE patient having AE with HAE, PVE, and aortic abscess/pseudoaneurysm, but no fever, was 0.92. In contrast, the probability of an IE patient having AE with fever, native valve IE, but no health-care associated IE and no abscess/pseudoaneurysm, was 0.003. Severe sepsis and mortality in the Aspergillus group were higher as compared to the non-fungal group (p = 0.098 and 0.097, respectively). Thirteen AE patients died during hospitalization. PVE, the use of single versus dual antifungal agents, severe heart failure, and severe sepsis were significant predictors of mortality (p = 0.008, 0.012, 0.003, and 0.01, respectively). CONCLUSION: To our knowledge, this is the first study to address diagnostic criteria for AE. Through multivariate regression analysis, absence of fever, HAE, PVE, and aortic abscess/pseudoaneurysm were strong predictors of AE. Use of these criteria my lead to earlier diagnoses of AE. Early treatment of AE patients with voriconazole in combination with other antifungal agents may be possible based on the previously mentioned criteria, which may facilitate better patient outcomes.

Influence of Inoculum Effect on the Efficacy of Daptomycin Monotherapy and in Combination with ß-Lactams against Daptomycin-Susceptible Enterococcus faecium Harboring LiaSR Substitutions.

Enterococcus faecium isolates that harbor LiaFSR substitutions but are phenotypically susceptible to daptomycin (DAP) by current breakpoints are problematic, since predisposition to resistance may lead to therapeutic failure. Using a simulated endocardial vegetation (SEV) pharmacokinetic/pharmacodynamic (PK/PD) model, we investigated DAP regimens (6, 8, and 10 mg/kg of body weight/day) as monotherapy and in combination with ampicillin (AMP), ceftaroline (CPT), or ertapenem (ERT) against E. faecium HOU503, a DAP-susceptible strain that harbors common LiaS and LiaR substitutions found in clinical isolates (T120S and W73C, respectively). Of interest, the efficacy of DAP monotherapy, at any dose regimen, was dependent on the size of the inoculum. At an inoculum of ∼109 CFU/g, DAP doses of 6 to 8 mg/kg/day were not effective and led to significant regrowth with emergence of resistant derivatives. In contrast, at an inoculum of ∼107 CFU/g, marked reductions in bacterial counts were observed with DAP at 6 mg/kg/day, with no resistance. The inoculum effect was confirmed in a rat model using humanized DAP exposures. Combinations of DAP with AMP, CPT, or ERT demonstrated enhanced eradication and reduced potential for resistance, allowing de-escalation of the DAP dose. Persistence of the LiaRS substitutions was identified in DAP-resistant isolates recovered from the SEV model and in DAP-resistant derivatives of an initially DAP-susceptible clinical isolate of E. faecium (HOU668) harboring LiaSR substitutions that was recovered from a patient with a recurrent bloodstream infection. Our results provide novel data for the use of DAP monotherapy and combinations for recalcitrant E. faecium infections and pave the way for testing these approaches in humans.

Brucella endocarditis in a non-endemic area presenting as pyrexia of unknown origin.

A 67-year-old man with type 2 diabetes mellitus and hypertension since 7 years presented with a 3-month history of low-grade fever and malaise. Cardiac auscultation revealed the presence of an ejection systolic murmur in the primary aortic area. Most of the investigations for febrile illness were reported normal. His two-dimensional (2D) echocardiogram revealed a calcified aortic valve with mild aortic stenosis. In view of the prolonged fever and calcified aortic valve with mild aortic stenosis, a transoesophageal echocardiogram was performed, which showed small vegetation noted on right coronary cusp about 2.2 mm with free independent mobility. Blood culture was positive for Brucella spp from all the three venepuncture sites. Medical therapy for brucellosis was given with ciprofloxacin, doxycycline, co-trimoxazole and streptomycin, resulting in complete recovery. Brucella endocarditis is a rare, mostly ignored and missed clinical infection. It requires a high index of clinical suspicion for prompt diagnosis and treatment.

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.

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.

Infectious endocarditis with five localisations--case reports.

Infectious endocarditis is defined as an infection of the endocardial surface area of the heart which can include one or more cardiac valves, mural endocardium or a septal defect. We present the case of a patient, aged 8, hospitalized in Hemato-Oncology Department with pontine glioma, who was also diagnosed with infectious endocarditis in five locations.

Sortase A promotes virulence in experimental Staphylococcus lugdunensis endocarditis.

Staphylococcus lugdunensis is a commensal of humans and an opportunistic pathogen. It can cause an aggressive form of infective endocarditis in healthy humans akin to Staphylococcus aureus. Here we compared the virulence of the genome-sequenced S. lugdunensis strain N920143 to S. aureus in an experimental rat endocarditis model. N920143 caused a milder course of disease with lower levels of bacteraemia and smaller endocardial vegetations than S. aureus strain Newman. However, vegetations were comparable to those produced by S. aureus MRSA strain COL. Little is known about virulence factors of S. lugdunensis as systems to manipulate the bacterium genetically are currently limited. Here, we report a method for electroporation of S. lugdunensis with plasmid DNA and demonstrate that the low efficiency of transformation is due to the activity of a conserved type I restriction-modification system. To streamline the transformation process, we constructed SL01B, an E. coli strain expressing the hsdM/hsdS genes of N920143. Modified plasmid DNA isolated from SL01B transformed S. lugdunensis strains from clonal complexes 1 and 2 efficiently. A deletion mutant of N920143 lacking sortase A was significantly less virulent than the wild-type in the endocarditis model. Mutants defective in single surface proteins Fbl or vWbl were not significantly different from the wild-type but showed trends towards reduced virulence.

Biodegradation of the outer silicone insulation of endocardial leads.

BACKGROUND: Silicone catheter insulation, larynx prostheses undergo biodegradation. The aims of the study were to verify the conviction that outer silicone lead insulation is biostable and inert in addition to determining the role of macrophages (M) and Staphylococcus aureus (S aureus) strains in the silicone lead insulation degradation. METHODS AND RESULTS: Leads removed from 8 patients because of infective and noninfective indications were analyzed with stereomicroscope and classified according to Banacha abrasion classification, and additional analysis using scanning electron microscope was performed. The examination revealed excavations of different shape and depth in the abraded areas. Fresh silicone-insulated lead was cut into fragments. The fragments were cultured with RAW 264.7 macrophage cell line for 9 weeks. Additional lead fragments were placed with S aureus strains: ATCC 25923, ATCC 29213, and K9328H. Lead fragments were also cocultured with the bacterial strains and RAW M. In scanning electron microscope analysis, diminution in silicone was observed. All S aureus strains provoked insulation damage after 9 weeks. The lowest level of degradation of insulation concerned ATCC 25923. Silicone lead fragments in cocultures presented a further gone level of silicone biodegradation. CONCLUSIONS: S aureus, macrophages separately, and S aureus and macrophages cocultures initiate the biodegradation of silicone insulation. Differences in the level of biodegradation between strains of S aureus were observed, with the most aggressive reaction toward silicone visible in the cocultures. In vivo silicone biodegradation is initiated by tearing among surfaces of the lead insulation, macrophages may be the crucial cells for the process that may be aggravated by pathogen colonization.

Surgical implantation of a biventricular pacing system via lower half mini sternotomy.

We present a case of surgical implantation of biventricular epicardial pacing leads and a defibrillating patch via lower half mini sternotomy. Although median sternotomy is routinely used for this purpose, lower half mini sternotomy could provide the surgeon with the same surgical field exposure and a faster post operative recovery.

Contribution of the enterococcal surface protein Esp to pathogenesis of Enterococcus faecium endocarditis.

The enterococcal surface protein Esp, specifically linked to nosocomial Enterococcus faecium, is involved in biofilm formation. To assess the role of Esp in endocarditis, a biofilm-associated infection, an Esp-expressing E. faecium strain (E1162) or its Esp-deficient mutant (E1162Δesp) were inoculated through a catheter into the left ventricle of rats. After 24 h, less E1162Δesp than E1162 were recovered from heart valve vegetations. In addition, anti-Esp antibodies were detected in Esp-positive E. faecium bacteremia and endocarditis patient sera. In conclusion, Esp contributes to colonization of E. faecium at the heart valves. Furthermore, systemic infection elicits an Esp-specific antibody response in humans.

Post-transcoronary ethanol septal ablation (TESA) infective endocarditis complicated by a ventricular septal defect.

A 52-year-old man was referred to the cardiology outpatient service with exertional angina and shortness of breath due to hypertrophic obstructive cardiomyopathy. He underwent transcoronary ethanol septal ablation (TESA) with successful procedural outcome. The patient returned to hospital with a 3-week history of intermittent fever and a positive blood culture showing Staphylococcus aureus, sensitive to flucloxacillin. Transoesophageal echocardiography on admission demonstrated vegetation on interventricular septum and a repeated scan 10 days later demonstrated Doppler flow across the interventricular septum, confirming the presence of a small ventricular septal defect. This patient was successfully managed with 6 weeks of intravenous antibiotics and remained well at 1-year follow-up.

Analysis of the impact of early surgery on in-hospital mortality of native valve endocarditis: use of propensity score and instrumental variable methods to adjust for treatment-selection bias.

BACKGROUND: The impact of early surgery on mortality in patients with native valve endocarditis (NVE) is unresolved. This study sought to evaluate valve surgery compared with medical therapy for NVE and to identify characteristics of patients who are most likely to benefit from early surgery. METHODS AND RESULTS: Using a prospective, multinational cohort of patients with definite NVE, the effect of early surgery on in-hospital mortality was assessed by propensity-based matching adjustment for survivor bias and by instrumental variable analysis. Patients were stratified by propensity quintile, paravalvular complications, valve perforation, systemic embolization, stroke, Staphylococcus aureus infection, and congestive heart failure. Of the 1552 patients with NVE, 720 (46%) underwent early surgery and 832 (54%) were treated with medical therapy. Compared with medical therapy, early surgery was associated with a significant reduction in mortality in the overall cohort (12.1% [87/720] versus 20.7% [172/832]) and after propensity-based matching and adjustment for survivor bias (absolute risk reduction [ARR] -5.9%, P<0.001). With a combined instrument, the instrumental-variable-adjusted ARR in mortality associated with early surgery was -11.2% (P<0.001). In subgroup analysis, surgery was found to confer a survival benefit compared with medical therapy among patients with a higher propensity for surgery (ARR -10.9% for quintiles 4 and 5, P=0.002) and those with paravalvular complications (ARR -17.3%, P<0.001), systemic embolization (ARR -12.9%, P=0.002), S aureus NVE (ARR -20.1%, P<0.001), and stroke (ARR -13%, P=0.02) but not those with valve perforation or congestive heart failure. CONCLUSIONS: Early surgery for NVE is associated with an in-hospital mortality benefit compared with medical therapy alone.