Clinical Factors Associated with Reinfection versus Relapse in Infective Endocarditis: Prospective Cohort Study

Postoperative Treatment Regimens in Patients With Native Valve Endocarditis due to Staphylococcus aureus Who Undergo Valve Replacement or Repair

Background

There remains a lack of consensus regarding the postoperative treatment regimen in patients with native valve Staphylococcus aureus infective endocarditis who undergo surgical valve replacement or repair.

Methods

We conducted a multicenter retrospective review of patients with S aureus native valve endocarditis who underwent surgical valve replacement or repair at Mayo Clinic Enterprise (Minnesota, Florida, Arizona, and Mayo Clinic Health Systems) between 1 January 2012 and 31 December 2022. Postoperative treatment regimens were classified as either monotherapy with a methicillin-sensitive or methicillin-resistant S aureus active agent or combination therapy that included rifampin and/or gentamicin with either active agent.

Results

Of the 339 patients diagnosed with S aureus native valve endocarditis, 61 underwent surgical valve replacement or repair within the initial 6 weeks of antimicrobial therapy. A total of 12 (20.2%) patients died during the 1-year follow-up period. Between patients postoperatively treated with monotherapy (n = 33) and combination therapy (n = 28), a propensity score-weighted analysis revealed that combination therapy was associated with increased risk of 1-year mortality (P = .039), 6-month relapse (P = .016), and treatment-related adverse events (P < .001).

Conclusions

Among patients treated for native valve infective endocarditis caused by S aureus after valvular surgical intervention, all study outcomes-adverse events and drug-drug interactions, 6-month infective endocarditis relapse, and 1-year mortality-were higher in the combination therapy group than the monotherapy group.

Interventional Treatment of Acute Right Ventricular Outflow Tract Infectious Endocarditis: A Bridge to Surgical or Percutaneous Pulmonary Valve Replacement

BACKGROUND

Infective endocarditis (IE) poses significant risks following percutaneous pulmonary valve implantation (PPVI) or surgical replacement (PVR).

AIMS

This study evaluates the effectiveness of emergency percutaneous treatment in stabilizing patients with severe right ventricular dysfunction or obstructive cardiac shock, allowing for delayed surgical or percutaneous valve replacement.

METHODS

This retrospective study examines 16 patients (age 19.9 [15.1-43.3] years) with right-sided IE treated with primary percutaneous intervention. Data collected included cardiac diagnosis, valve types, pathogens identified, procedural details, and outcomes.

RESULTS

Underlying diagnoses included aortic valve stenosis post-Ross surgery (43%), repaired tetralogy of Fallot (25%), common arterial trunk (18%), and repaired double outlet right ventricle (14%). Valve types varied, with Contegra Ven-Pro (56%) and Melody-valve (25%) being the most common. Diagnosis of IE occurred 66.5 (28.3-87.4) months postlast intervention/surgery, with emergency percutaneous treatment performed 2 (1-17) days postdiagnosis. Clinical presentations included obstructive cardiac shock (50%) and septic shock (25%). Preintervention RVOT velocity was 4.4 (4.2-5) m/s, with severely reduced RV function in 68%. Interventions included balloon dilatation, uncovered or covered stent implantation, and Melody valve implantation. Immediate resolution of RVOT obstruction was achieved in all patients, with significant reductions in RV systolic pressures (mean reduction 42.0 (30.2-50.0) mmHg) and improved RV function. No periprocedural deaths occurred, but one complication was noted. Follow-up included surgical repair (68%) and PPVI (18%). Mortality included one IE relapse and one surgical death.

CONCLUSIONS

Emergency percutaneous interventions can stabilize patients with RVOT obstruction due to IE, enabling delayed surgical or percutaneous interventions.

Bacterial Diversity in Native Heart Valves in Infective Endocarditis

Background: Infective endocarditis (IE) is an infectious disease caused by the hematogenous dissemination of bacteria into heart valves. Improving the identification of pathogens that cause IE is important to increase the effectiveness of its therapy and reduce the mortality caused by this pathology. Methods: Ten native heart valves obtained from IE patients undergoing heart valve replacements were analyzed. Bacterial invasion in the heart valves was studied by Gram staining of histological sections. Histopathological changes accompanied with bacterial invasion were studied by immunohistochemical analysis of pan-leukocyte marker CD45, platelet marker CD41, and neutrophil myeloperoxidase. The taxonomic diversity of the bacteria was analyzed using 16S rRNA metabarcoding. Results: Gram staining of the histological sections revealed bacterial cells localized on the atrial surface at the leaflet's free edge or on the ventricular surface at the leaflet's base within fibrin deposits in only three of the studied heart valves. Bacterial colonies were co-localized with microthrombi (CD41+ cells) containing single leucocytes (CD45+ cells), represented by segmented neutrophils. As a result of 16S rRNA metabarcoding, we detected the following bacterial genera: Pseudomonas (70% of the studied heart valves), Roseateles (60%), Acinetobacter (40%), Sphingomonas (40%), Enterococcus (30%), Reyranella (20%), Sphingobium (20%), Streptococcus (20%), Agrobacterium (20%), Ralstonia (10%), and Bacillus (10%). Conclusions: A number of opportunistic microorganisms that could not be detected by routine laboratory tests and were not eliminated during antibiotic therapy were identified in the IE-affected heart valves. The obtained results show the importance of 16S rRNA metabarcoding of heart valves removed due to IE not only as an independent diagnostic method but also as a highly accurate approach that complements routine tests for pathogen identification.

Glucose Supplementation Enhances the Bactericidal Effect of Penicillin and Gentamicin on Streptococcus sanguinis Persisters

Background: Streptococcus sanguinis is a leading cause of infective endocarditis (IE), which causes diverse clinical symptoms and even death. Recurrence after treatment is a crucial problem in IE, possibly caused by the presence of "persister" cells, a small bacterial population that can survive antimicrobials. In this study, the residual risk for penicillin G (PCG) and gentamicin (GM), used for treating IE, to induce Streptococcus sanguinis persisters, was investigated. Methods: The bactericidal effects of PCG and GM on S. sanguinis were evaluated. Furthermore, we confirmed whether the S. sanguinis that survived following combination treatment with PCG and GM were persisters. The bactericidal effect of the combination of PCG and GM against S. sanguinis was measured after the addition of glucose or arginine. Results: Following 48 h of treatment with PCG (1600 μg/mL) and GM (64 μg/mL), S. sanguinis survived, albeit with a low bacterial count, indicating the presence of persisters. The addition of glucose or arginine to PCG and GM increased the bactericidal effect on residual persister cells and reduced the number of persister cells. Moreover, the addition of glucose at concentrations of 10 mg/mL or higher was substantially effective in achieving sterilization. Conclusions: Our findings demonstrate that persisters of S. sanguinis that survive antimicrobial treatment may make the treatment of IE challenging, and that combining antimicrobial treatment with glucose is effective for eliminating persisters of S. sanguinis. Taken together, these findings may facilitate the development of novel therapeutic strategies against IE caused by oral streptococcal infection.

Outcomes of Suction Debulking and Surgery in Patients With Isolated Tricuspid Valve Endocarditis

OBJECTIVE

Percutaneous vegetation debulking has been reported to treat tricuspid valve infective endocarditis (TVIE), but data on feasibility compared with conventional surgical strategies are limited. We aimed to compare short-term outcomes of suction debulking with partial venovenous bypass to conventional open surgery in this population.

METHODS

This was a single-center, retrospective study that included all patients with isolated TVIE who underwent suction debulking with partial venovenous bypass or tricuspid valve surgery between January 2010 and December 2022. Patient characteristics, procedural data, and clinical outcomes were compared.

RESULTS

Of the 45 patients included, 16 (35.6%) underwent suction debulking and the remainder (64.4%) underwent surgery. Baseline characteristics were comparable, including high rates of preprocedure hemodialysis (11.1%), prior infectious endocarditis (44.4%), intravenous drug use (60.0%), presence of tricuspid bioprostheses (24.4%), and septic shock (40.0%). Suction debulking had a shorter procedure time than surgery (206 [176 to 224] min vs 400 [325 to 487] min, P < 0.001) and was associated with numerically lower rates of various complications including acute kidney injury requiring hemodialysis, limb ischemia, and dysrhythmia requiring pacemaker. Over a mean follow-up period of 473 ± 604 days, recurrent endocarditis (37.5% vs 17.2%, P = 0.25) and the need for reintervention (50.0% vs 17.2%, P = 0.048) were higher with suction debulking. However, all-cause mortality was similar between the groups (12.5% vs 10.3%, P > 0.99).

CONCLUSIONS

Suction debulking can safely be performed in patients with isolated TVIE with shorter procedural times and similar midterm all-cause mortality compared with surgery. Suction debulking may be appropriate initial therapy for this complex population.

Outcomes of Enterococcus faecalis infective endocarditis according to MIC of amoxicillin: a multicentric study

Background

The incidence of Enterococcus faecalis infective endocarditis is increasing over time. Data on the impact of minimum inhibitory concentration (MIC) of amoxicillin on treatment outcomes are scarce. The objective of this study was to describe the epidemiology of E. faecalis infective endocarditis and to evaluate whether the MIC of amoxicillin might influence mortality.

Materials

We retrospectively included all consecutive patients diagnosed with definite E. faecalis infective endocarditis between 2013 and 2020 in 11 French hospitals. We extracted data from the local diagnosis-related group (DRG) database and matched these data with microbiological results. Amoxicillin MIC was determined by Etest strip. The primary endpoints were endocarditis-related mortality and risk factors for endocarditis-related mortality including amoxicillin MIC.

Results

A total of 403 patients with definite E. faecalis infective endocarditis were included. Patients were predominantly male (76.4%) with a median age of 74 years (67-82). Embolic complications occurred in 170 (42.1%) patients. Cardiac surgery was performed in 158 (61.5%) patients. The endocarditis-related mortality rate was 28.3% and the median delay between mortality and onset of hospitalization was 24 (9; 41) days. E. faecalis MIC of amoxicillin was available for 246 (61%) patients. The median MIC was 0.5 mg/L (0.4-0.7). Amoxicillin MIC was not found to be associated with in-hospital mortality. None of the variables included in the multivariate model were identified as a risk factor for mortality and there was no correlation between mortality and the duration of treatment for 4 weeks versus 6 weeks.

Conclusions

Higher amoxicillin MIC was not a risk factor leading to endocarditis-related mortality in definite E. faecalis infective endocarditis. However, further studies are needed to assess the effect of amoxicillin MIC on relapse.

Advancements and Challenges in the Management of Prosthetic Valve Endocarditis: A Review

Prosthetic valve endocarditis (PVE) is the medical term used to describe a focus of infection involving a valvular substitute within the heart. It is a significant concern in the field of cardiology, and the epidemiology of PVE has seen notable developments over the last five decades. The disease currently affects an older demographic and is becoming increasingly prevalent in patients with transcatheter-implanted valves. It is imperative that we urgently address the significant challenges posed by PVE. It is a disease that has a wide range of potential aetiologies, clinical presentations, and courses. In developed countries, Staphylococcus aureus is now the predominant causative organism, resulting in an aggressive form of disease that frequently afflicts vulnerable or elderly populations. However, it is clear that Enterococcus species present a significant challenge in the context of PVE following TAVR procedures, given their elevated prevalence. The 2023 Duke/International Society for Cardiovascular Infectious Diseases infective endocarditis diagnostic criteria now include significant developments in microbiological and image-based techniques for diagnostic purposes, specifically the incorporation of fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography. These developments unequivocally enhance the diagnostic sensitivity for PVE, while maintaining the specificity. They do so in accordance with the results of studies conducted specifically for the purpose of validation. The lack of rigorous scientific studies and a shortage of funding and resources for research have led to a significant gap in our understanding. Randomized controlled trials could provide invaluable insight and guidance for clinical practice, but they are missing, which represents a major gap. It is clear that there is an urgent need for more research. PVE is a life-threatening condition that must be handled by a multidisciplinary endocarditis team at a cardiac centre in order to improve outcomes. The emergence of innovative surgical techniques has empowered clinicians to steer more patients away from surgical procedures, despite the presence of clear indications for them. A select group of patients can now complete parenteral or oral antimicrobial treatment at home. Additionally, antibiotic prophylaxis is the best option for individuals with prosthetic valves who are going to have invasive dental procedures. These individuals should be given antibiotics beforehand.

Prosthetic Valve Endocarditis: A Retrospective Cohort Study Conducted at "Dr. Carol Davila" Central Military Emergency University Hospital in Bucharest

OBJECTIVE

To evaluate patients with prosthetic valves who developed infective endocarditis by comparing treatment outcomes in both early- and late-onset IE episodes following prosthetic valve replacement surgery. This study sought to conduct a comprehensive assessment of the efficacy of these methodologies. The insights derived from this assessment can be utilized to enhance the quality of care for individuals with infective endocarditis who have undergone prosthetic valve replacement surgery.

RESULTS

During the period of investigation (January 2017-December 2022), 78 patients diagnosed with infective endocarditis (IE) on a prosthetic valve were admitted to the Infectious Diseases Department of the "Dr. Carol Davila" Central Military Emergency University Hospital in Bucharest. In 28 patients (35.8%), the onset of PVE occurred within 12 months of surgery (early onset), whereas in 50 patients (64.2%), the onset occurred more than 12 months after surgery (late onset). The mortality rate was 35.9% (53.6% among the early onset patients and 26% among the late-onset patients). Among patients who received surgical and medical therapy, the mortality rate was 29.6%, whereas among those who received only medical therapy, a 39.2% mortality rate was reported. According to the extracted data, antibiotic therapy was successful in 72.6% of the patients. In contrast, a combination of surgical and drug-based approaches resulted in a cure in 76.1% of patients. The most common etiological agent was Staphylococcus aureus (38.5%), followed by Enterococcus faecalis (26.9%) and Streptococcus mitis (10.3%). The mortality rate of patients infected with S. aureus was 29.2%, indicating the severity of this infectious agent.

CONCLUSIONS

Prosthetic valve endocarditis (PVE) is a serious condition associated with a high mortality rate both in the short and long term. Regardless of the therapy used, the risk of death remains high.

Long-term Oral Suppressive Antimicrobial Therapy in Infective Endocarditis (SATIE Study): An Observational Study

Background

The role of suppressive antimicrobial therapy (SAT) in infective endocarditis (IE) management has yet to be defined. The objective of this study was to describe the use of SAT in an IE referral center and the patients' outcomes.

Methods

We conducted a retrospective observational study in a French IE referral center (Paris). All patients with IE who received SAT between 2016 and 2022 were included.

Results

Forty-two patients were included (36 male [86%]; median age [interquartile range {IQR}], 73 [61-82] years). The median Charlson Comorbidity Index score (IQR) was 3 (1-4). Forty patients (95%) had an intracardiac device. The most frequent microorganisms were Enterococcus faecalis (15/42, 36%) and Staphylococcus aureus (12/42, 29%). SAT indications were absence of surgery despite clinical indication (28/42, 67%), incomplete removal of prosthetic material (6/42, 14%), uncontrolled infection source (4/42, 10%), persistent abnormal uptake on nuclear imaging (1/42, 2%), or a combination of the previous indications (3/42, 7%). Antimicrobials were mainly doxycycline (19/42, 45%) and amoxicillin (19/42, 45%). The median follow-up time (IQR) was 398 (194-663) days. Five patients (12%) experienced drug adverse events. Five patients (12%) presented with a second IE episode during follow-up, including 2 reinfections (different bacterial species) and 3 possible relapses (same bacterial species). Fourteen patients (33%) in our cohort died during follow-up. Overall, the 1-year survival rate was 84.3% (73.5%-96.7%), and the 1-year survival rate without recurrence was 74.1% (61.4%-89.4%).

Conclusions

SAT was mainly prescribed to patients with cardiac devices because of the absence of surgery despite clinical indication. Five (12%) breakthrough second IE episodes were reported. Prospective comparative studies are required to guide this empirical practice.

C-terminal deletion of RelA protein is suggested as a possible cause of infective endocarditis recurrence with Enterococcus faecium

Infective endocarditis (IE) caused by Enterococcus spp. represents the third most common cause of IE, with high rates of relapse compared with other bacteria. Interestingly, late relapses (>6 months) have only been described in Enterococcus faecalis, but here we describe the first reported IE relapse with Enterococcus faecium more than a year (17 months) after the initial endocarditis episode. Firstly, by multi locus sequence typing (MLST), we demonstrated that both isolates (EF646 and EF641) belong to the same sequence type (ST117). Considering that EF641 was able to overcome starvation and antibiotic treatment conditions surviving for a long period of time, we performed bioinformatic analysis in identifying potential genes involved in virulence and stringent response. Our results showed a 13-nucleotide duplication (positions 1638-1650) in the gene relA, resulting in a premature stop codon, with a loss of 167 amino acids from the C-terminal domains of the RelA enzyme. RelA mediates the stringent response in bacteria, modulating levels of the alarmone guanosine tetraphosphate (ppGpp). The relA mutant (EF641) was associated with lower growth capacity, the presence of small colony variants, and higher capacity to produce biofilms (compared with the strain EF646), but without differences in antimicrobial susceptibility patterns according to standard procedures during planktonic growth. Instead, EF641 demonstrated tolerance to high doses of teicoplanin when growing in a biofilm. We conclude that all these events would be closely related to the long-term survival of the E. faecium and the late relapse of the IE. These data represent the first clinical evidence of mutations in the stringent response (relA gene) related with E. faecium IE relapse.

Epidemiology and Risk Factors of Mycotic Aneurysm in Patients With Infective Endocarditis and the Impact of its Rupture in Outcomes. Analysis of a National Prospective Cohort

Background

Several aspects of the occurrence and management of mycotic aneurysm (MA) in patients with infective endocarditis (IE) have not been studied.

Objectives

To determine the incidence and factors associated with MA presence and rupture and to assess the evolution of those initially unruptured MA.

Methods

Prospective multicenter cohort including all patients with definite IE between January 2008 and December 2020.

Results

Of 4548 IE cases, 85 (1.9%) developed MA. Forty-six (54.1%) had intracranial MA and 39 (45.9%) extracranial MA. Rupture of MA occurred in 39 patients (45.9%). Patients with ruptured MA had higher 1-year mortality (hazard ratio, 2.33; 95% confidence interval, 1.49-3.67). Of the 55 patients with initially unruptured MA, 9 (16.4%) presented rupture after a median of 3 days (interquartile range, 1-7) after diagnosis, being more frequent in intracranial MA (32% vs 3.3%, P = .004). Of patients with initially unruptured MA, there was a trend toward better outcomes among those who received early specific intervention, including lower follow-up rupture (7.1% vs 25.0%, P = .170), higher rate of aneurysm resolution in control imaging (66.7% vs 31.3%, P = .087), lower MA-related mortality (7.1% vs 16.7%, P = .232), and lower MA-related sequalae (0% vs 27.8%, P = .045).

Conclusions

MA occurred in 2% of the patients with IE. Half of the Mas occurred in an intracranial location. Their rupture is frequent and associated with poor prognosis. A significant proportion of initially unruptured aneurysms result from rupture during the first several days, being more common in intracranial aneurysms. Early specific treatment could potentially lead to better outcomes.

Recurrence of bacteremia and infective endocarditis according to bacterial species of index endocarditis episode

PURPOSE

In patients surviving infective endocarditis (IE) recurrence of bacteremia or IE is feared. However, knowledge is sparse on the incidence and risk factors for the recurrence of bacteremia or IE.

METHODS

Using Danish nationwide registries (2010-2020), we identified patients with first-time IE which were categorized by bacterial species (Staphylococcus aureus, Enterococcus spp., Streptococcus spp., coagulase-negative staphylococci [CoNS], 'Other' microbiological etiology). Recurrence of bacteremia (including IE episodes) or IE with the same bacterial species was estimated at 12 months and 5 years, considering death as a competing risk. Cox regression models were used to compute adjusted hazard ratios of the recurrence of bacteremia or IE.

RESULTS

We identified 4086 patients with IE; 1374 (33.6%) with S. aureus, 813 (19.9%) with Enterococcus spp., 1366 (33.4%) with Streptococcus spp., 284 (7.0%) with CoNS, and 249 (6.1%) with 'Other'. The overall 12-month incidence of recurrent bacteremia with the same bacterial species was 4.8% and 2.6% with an accompanying IE diagnosis, while this was 7.7% and 4.0%, respectively, with 5 years of follow-up. S. aureus, Enterococcus spp., CoNS, chronic renal failure, and liver disease were associated with an increased rate of recurrent bacteremia or IE with the same bacterial species.

CONCLUSION

Recurrent bacteremia with the same bacterial species within 12 months, occurred in almost 5% and 2.6% for recurrent IE. S. aureus, Enterococcus spp., and CoNS were associated with recurrent infections with the same bacterial species.

Risk of Infective Endocarditis Post-transcatheter Pulmonary Valve Replacement Versus Surgical Pulmonary Valve Replacement: A Systematic Review

Pulmonary valve replacement (PVR) is the most common cardiac operation in adult patients with congenital heart disease (ACHD). It can improve right ventricular outflow tract (RVOT) obstruction, typically due to pulmonary valve stenosis or regurgitation. PVR can be performed surgically (open-heart) and through a transcatheter (percutaneous) method, which is minimally invasive and is associated with shorter hospitalization stays. However, following PVR, infectious endocarditis (IE) can complicate the recovery process and increase mortality in the long term. IE is a rare but deadly multi-organ system condition caused by microorganisms traversing the bloodstream from a specific entry point. It can have many presentations, such as splinter hemorrhages, fevers, and vegetation on valves that lead to stroke consequences. This paper aims to evaluate the differences in the rate, etiology, manifestations, treatment, and outcomes of IE following surgical and transcatheter PVR, as the goal is to perform a procedure with few complications. In both approaches, Staphylococcus aureus was the most common microorganism that affected the valves, followed by Streptococcus viridians. Research has shown that surgical pulmonary valve replacement (SPVR) has a decreased risk of IE following surgery compared to TPVR. However, TPVR is preferred due to the reduced overall risk and complications of the procedure. Despite this, the consensus on mortality rates does differ. Future research should consider the type of valves used for transcatheter pulmonary valve replacement (TPVR), such as Melody valves versus Edward Sapien valves, as their IE rates vary significantly.

Contemporary Features and Management of Endocarditis

Infective endocarditis is a rare but devastating disease. Morbidity and mortality rates have failed to improve despite new technological advances. The disease has evolved over time with new significant populations at risk-most notably those with prosthetic valves or implantable cardiovascular devices. These devices pose new challenges for achieving a timely and accurate diagnosis of infection. While the modified Duke criteria is accepted as the gold standard for diagnosing native valve endocarditis, it has been shown to have significantly inferior sensitivity when it comes to identifying infections related to right-heart endocarditis, prosthetic valves, and indwelling cardiac devices. Additionally, prosthetic valves and cardiovascular implantable electronic devices can exhibit shadowing and artifact, rendering transthoracic echocardiography and transesophageal echocardiography results inconclusive or even normal. Having a keen awareness of the varying clinical presentations, as well as emerging valvular imaging modalities such as F-fluorodeoxyglucose cardiac positron-emission tomography plus computed tomography, promises to improve the evaluation and diagnosis of infective endocarditis. However, indications for appropriate use of these studies and guidance on modern clinical management are still needed.

Multiple Recurrent Infective Endocarditis Secondary to Streptococcus mitis Bacteremia Despite Proper Antibiotic and Surgical Treatment

Infective endocarditis (IE) is a rare and potentially fatal disease. It is an infection of the endocardium of the heart and heart valves. One of the major complications faced by patients who have recovered from a first episode of IE is recurrent IE. Risk factors for recurrent IE include intravenous (IV) drug use, prior episodes of IE, poor dentition, recent dental procedures, male gender, age over 65, prosthetic heart valve endocarditis, chronic dialysis, positive valve culture(s) obtained at the time of surgical intervention, and persistent postoperative fever. We present a case of a 40-year-old male with a history of former IV heroin use who experienced multiple episodes of recurrent IE caused by the same pathogen, Streptococcus mitis. This recurrence occurred despite the patient completing the appropriate course of antibiotic therapy, undergoing valvular replacement, and maintaining drug abstinence for two years. This case highlights the challenges associated with identifying the source of infection and emphasizes the need to develop guidelines for surveillance and prophylaxis against recurrent IE.

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6–8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

New Perspectives for Prosthetic Valve Endocarditis: Impact of Molecular Imaging by FISHseq Diagnostics

BACKGROUND

The microbial etiology of prosthetic valve infective endocarditis (PVE) can be difficult to identify. Our aim was to investigate the benefit of molecular imaging technique fluorescence in situ hybridization (FISH) combined with 16S rRNA-gene polymerase chain reaction (PCR) and sequencing (FISHseq) for the analysis of infected prosthetic heart valves.

METHODS

We retrospectively evaluated the diagnostic outcome of 113 prosthetic valves from 105 patients with suspected PVE, treated in 2003-2013 in the Department of Cardiac Surgery, Charité University Medicine Berlin. Each prosthetic valve underwent cultural diagnostics and was routinely examined by FISH combined with 16S rRNA gene PCR and sequencing. We compared classical microbiological culture outcomes (blood and valve cultures) with FISHseq results and evaluated the diagnostic impact of the molecular imaging technique.

RESULTS

Conventional microbiological diagnostic alone turned out to be insufficient, as 67% of preoperative blood cultures were noninformative (negative, inconclusive, or not obtained) and 67% of valve cultures remained negative. FISHseq improved the conventional cultural diagnostic methods in PVE in 30% of the cases and increased diagnostic accuracy. Of the valve culture-negative PVE cases, FISHseq succeeded in identifying the causative pathogen in 35%.

CONCLUSIONS

FISHseq improves PVE diagnostics, complementing conventional cultural methods. In addition to species identification, FISH provides information about the severity of PVE and state of the pathogens (eg, stage of biofilm formation, activity, and localization on and within the prosthetic material). As a molecular imaging technique, FISHseq enables the unambiguous discrimination of skin flora as contaminant or infectious agent.

Left ventricular pseudoaneurysm secondary to recurrent mitral prosthetic valve endocarditis

An 86-year-old man who had undergone two mitral valve replacements developed heart failure due to prosthetic valve infection and left ventricular pseudoaneurysm (LVPA). LVPA due to infective endocarditis is rare and caused by the abscess formation in the left ventricular myocardium. Infective endocarditis caused by enterococci requires attention to relapse.