Prosthetic valve endocarditis caused by Pseudomonas aeruginosa with variable antibacterial resistance profiles: a diagnostic challenge

Clinical characteristics and outcomes in pseudomonas endocarditis: a systematic review of individual cases : Systematic review of pseudomonas endocarditis

BACKGROUND

The landscape of Pseudomonas infective endocarditis (IE) is evolving with the widespread use of cardiac implantable devices and hospital-acquired infections. This systematic review aimed to evaluate the emerging risk factors and outcomes in Pseudomonas IE.

METHODS

A literature search was performed in major electronic databases (PubMed, Scopus, and Google Scholar) with appropriate keywords and combinations till November 2023. We recorded data for risk factors, diagnostic and treatment modalities. This study is registered with PROSPERO, CRD42023442807.

RESULTS

A total of 218 cases (131 articles) were included. Intravenous drug use (IDUs) and prosthetic valve endocarditis (PVE) were major risk factors for IE (37.6% and 22%). However, the prosthetic valve was the predominant risk factor in the last two decades (23.5%). Paravalvular complications (paravalvular leak, abscess, or pseudoaneurysm) were described in 40 cases (18%), and the vast majority belonged to the aortic valve (70%). The mean time from symptom onset to presentation was 14 days. The incidence of difficult-to-treat resistant (DTR) pseudomonas was 7.4%. Valve replacement was performed in 57.3% of cases. Combination antibiotics were used in most cases (77%), with the aminoglycosides-based combination being the most frequently used (66%). The overall mortality rate was 26.1%. The recurrence rate was 11.2%. Almost half of these patients were IDUs (47%), and most had aortic valve endocarditis (76%).

CONCLUSIONS

This review highlights the changing epidemiology of Pseudomonas endocarditis with the emergence of prosthetic valve infections. Acute presentation and associated high mortality are characteristic of Pseudomonas IE and require aggressive diagnostic and therapeutic approach.

A Hole in the Heart, a Hole in the Defenses: A Case of Pseudomonas Endocarditis

Infective endocarditis (IE) is a rare but serious infection of the cardiac endothelium. This case report presents a rare instance of left-sided Pseudomonas aeruginosa endocarditis in an immunocompetent patient without traditional risk factors for IE. Pseudomonas endocarditis is uncommon and usually associated with specific factors. The patient in this case was a 30-year-old male with end-stage renal disease, receiving hemodialysis through a tunneled dialysis catheter, who developed a fever. Blood cultures confirmed P. aeruginosa as the causative agent, which prompted the administration of appropriate antibiotics and the removal of the catheter. However, subsequent imaging revealed significant damage to the mitral valve. Despite timely mitral valve replacement and aggressive medical treatment, the patient's condition worsened, and he ultimately succumbed to the infection. This case also emphasizes the necessity of timely diagnosis and intervention. In this patient, by the time it was diagnosed and managed, significant mitral valve damage had already occurred. Therefore, it should be considered a differential diagnosis even in patients with no risk factors and should be managed vigorously. Pseudomonas endocarditis is associated with high mortality, and successful treatment often requires a combination of antipseudomonal antibiotics due to the organism's ability to develop resistance. Surgical intervention, such as valve replacement, is frequently necessary. This case underscores the importance of considering P. aeruginosa infection, even in patients without traditional risk factors for IE. Early diagnosis, appropriate antibiotic therapy, and timely surgical intervention are critical for improving outcomes in Pseudomonas endocarditis cases.

Gut microbiota, blood metabolites, and left ventricular diastolic dysfunction in US Hispanics/Latinos

BACKGROUND

Left ventricular diastolic dysfunction (LVDD) is an important precursor of heart failure (HF), but little is known about its relationship with gut dysbiosis and microbial-related metabolites. By leveraging the multi-omics data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a study with population at high burden of LVDD, we aimed to characterize gut microbiota associated with LVDD and identify metabolite signatures of gut dysbiosis and incident LVDD.

RESULTS

We included up to 1996 Hispanic/Latino adults (mean age: 59.4 years; 67.1% female) with comprehensive echocardiography assessments, gut microbiome, and blood metabolome data. LVDD was defined through a composite criterion involving tissue Doppler assessment and left atrial volume index measurements. Among 1996 participants, 916 (45.9%) had prevalent LVDD, and 212 out of 594 participants without LVDD at baseline developed incident LVDD over a median 4.3 years of follow-up. Using multivariable-adjusted analysis of compositions of microbiomes (ANCOM-II) method, we identified 7 out of 512 dominant gut bacterial species (prevalence > 20%) associated with prevalent LVDD (FDR-q < 0.1), with inverse associations being found for Intestinimonas_massiliensis, Clostridium_phoceensis, and Bacteroide_coprocola and positive associations for Gardnerella_vaginali, Acidaminococcus_fermentans, Pseudomonas_aeruginosa, and Necropsobacter_massiliensis. Using multivariable adjusted linear regression, 220 out of 669 circulating metabolites with detection rate > 75% were associated with the identified LVDD-related bacterial species (FDR-q < 0.1), with the majority being linked to Intestinimonas_massiliensis, Clostridium_phoceensis, and Acidaminococcus_fermentans. Furthermore, 46 of these bacteria-associated metabolites, mostly glycerophospholipids, secondary bile acids, and amino acids, were associated with prevalent LVDD (FDR-q < 0.1), 21 of which were associated with incident LVDD (relative risk ranging from 0.81 [p = 0.001, for guanidinoacetate] to 1.25 [p = 9 × 10-5, for 1-stearoyl-2-arachidonoyl-GPE (18:0/20:4)]). The inclusion of these 21 bacterial-related metabolites significantly improved the prediction of incident LVDD compared with a traditional risk factor model (the area under the receiver operating characteristic curve [AUC] = 0.73 vs 0.70, p = 0.001). Metabolite-based proxy association analyses revealed the inverse associations of Intestinimonas_massilliensis and Clostridium_phoceensis and the positive association of Acidaminococcus_fermentans with incident LVDD.

CONCLUSION

In this study of US Hispanics/Latinos, we identified multiple gut bacteria and related metabolites linked to LVDD, suggesting their potential roles in this preclinical HF entity. Video Abstract.

Triple Threat: Triple Pathogen Endocarditis

Polymicrobial endocarditis is rare but is seen in those with risk factors like diabetes mellitus, structural heart disease, congenital heart defects, prosthetic devices, and intravenous drug use. We report the case of a 30-year-old woman with a past medical history of chronic Hepatitis C and IV drug use who presented with a one-week history of generalized weakness, subjective fevers, lower extremity abscesses, and occasional chest pain. Blood cultures were positive for Streptococcus anginosus, Gemella hemolysans, and Pseudomonas aeruginosa. A transthoracic echocardiogram revealed a very large tricuspid valve vegetation and severe tricuspid regurgitation. Her course was complicated by a complete heart block, septic pulmonary emboli, acute hypoxic respiratory failure, and cardiogenic shock meeting the criteria for early surgical intervention. She underwent an emergency tricuspid valve replacement and pacemaker implantation. During the operation, it became evident that her valve was destroyed with vegetation. A week after the operation, her ejection fraction had improved to 50% and she only exhibited mild tricuspid valve regurgitation. Six weeks later, she was in a stable condition and presented for follow-up. Surgery is necessitated in nearly 50% of Gemella endocarditis cases, 62% of cases with S. anginosus group, and approximately 56% of P. aeruginosa cases. To our knowledge, this is the only case of polymicrobial endocarditis caused by G. hemolysans, S. anginosus, and P. aeruginosa.

Genetic and environmental determinants of surface adaptations in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a well-studied Gram-negative opportunistic bacterium that thrives in markedly varied environments. It is a nutritionally versatile microbe that can colonize a host as well as exist in the environment. Unicellular, planktonic cells of P. aeruginosa can come together to perform a coordinated swarming movement or turn into a sessile, surface-adhered population called biofilm. These collective behaviours produce strikingly different outcomes. While swarming motility rapidly disseminates the bacterial population, biofilm collectively protects the population from environmental stresses such as heat, drought, toxic chemicals, grazing by predators, and attack by host immune cells and antibiotics. The ubiquitous nature of P. aeruginosa is likely to be supported by the timely transition between planktonic, swarming and biofilm lifestyles. The social behaviours of this bacteria viz biofilm and swarm modes are controlled by signals from quorum-sensing networks, LasI-LasR, RhlI-RhlR and PQS-MvfR, and several other sensory kinases and response regulators. A combination of environmental and genetic cues regulates the transition of the P. aeruginosa population to specific states. The current review is aimed at discussing key factors that promote physiologically distinct transitioning of the P. aeruginosa population.

Cellular mechanisms and molecular pathways linking bitter taste receptor signalling to cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction in heart diseases

Heart diseases and related complications constitute a leading cause of death and socioeconomic threat worldwide. Despite intense efforts and research on the pathogenetic mechanisms of these diseases, the underlying cellular and molecular mechanisms are yet to be completely understood. Several lines of evidence indicate a critical role of inflammatory and oxidative stress responses in the development and progression of heart diseases. Nevertheless, the molecular machinery that drives cardiac inflammation and oxidative stress is not completely known. Recent data suggest an important role of cardiac bitter taste receptors (TAS2Rs) in the pathogenetic mechanism of heart diseases. Independent groups of researchers have demonstrated a central role of TAS2Rs in mediating inflammatory, oxidative stress responses, autophagy, impulse generation/propagation and contractile activities in the heart, suggesting that dysfunctional TAS2R signalling may predispose to cardiac inflammatory and oxidative stress disorders, characterised by contractile dysfunction and arrhythmia. Moreover, cardiac TAS2Rs act as gateway surveillance units that monitor and detect toxigenic or pathogenic molecules, including microbial components, and initiate responses that ultimately culminate in protection of the host against the aggression. Unfortunately, however, the molecular mechanisms that link TAS2R sensing of the cardiac milieu to inflammatory and oxidative stress responses are not clearly known. Therefore, we sought to review the possible role of TAS2R signalling in the pathophysiology of cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction in heart diseases. Potential therapeutic significance of targeting TAS2R or its downstream signalling molecules in cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction is also discussed.

Pseudomonas aeruginosa: Infections, Animal Modeling, and Therapeutics

Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen which causes many severe acute and chronic infections with high morbidity, and mortality rates as high as 40%. What makes P. aeruginosa a particularly challenging pathogen is its high intrinsic and acquired resistance to many of the available antibiotics. In this review, we review the important acute and chronic infections caused by this pathogen. We next discuss various animal models which have been developed to evaluate P. aeruginosa pathogenesis and assess therapeutics against this pathogen. Next, we review current treatments (antibiotics and vaccines) and provide an overview of their efficacies and their limitations. Finally, we highlight exciting literature on novel antibiotic-free strategies to control P. aeruginosa infections.

Immunopathology of Renal Tissue in Fatal Cases of Dengue in Children

Dengue virus (DENV) infection represents a worldwide public health concern and can cause damage to multiple organs, including the kidney. In this work, we investigated the histopathological changes caused by dengue virus infection along with the detection of inflammatory mediators, cytokines, and cell expression patterns in the renal tissue of three fatal cases in children. Hematoxylin and Eosin staining was performed to analyze these histopathological changes. Immunohistochemistry allowed for the detection of immunological inflammatory markers in renal tissues that were quantified and further analyzed. Vascular congestion, edema and glomerular infiltrate were observed in the three cases, in addition to the thickening of the matrix area around the glomerular capillaries and mononuclear infiltrate associated with vascular congestion in the medullary region. The renal tissues exhibited collagen deposition and high expression of CD68⁺ Mø, CD8⁺ T, CD56⁺ cells and MMP-9, and the cytokine profile was mainly characterized by the expression of IFN-γ and TNF-α. Additionally, the expression of RANTES, VEGFR-2 and VCAM-1 were observed. The replication of DENV was evidenced by the detection of the NS3 protein. These results contributed to clarifying the main factors that may be involved in changes in the renal tissue of fatal cases of dengue in children.

Infective endocarditis of a native aortic valve due to Pseudomonas aeruginosa complicated by progressive multi-drug resistance

BACKGROUND

Treatment of infective endocarditis secondary to Pseudomonas aeruginosa can be challenging because of this organism's ability to acquire antimicrobial resistance over time.

METHODS

We describe a patient with native aortic valve infective endocarditis due to P. aeruginosa who developed progressive multi-drug resistance while on therapy. The resistance mechanisms were characterized using whole-genome sequencing.

RESULTS

We identified two mutations in subsequent isolates (dacB and OprD) that conferred resistance to anti-pseudomonal penicillins, cephalosporins, and carbapenems. The patient was treated with combination high-dose continuous infusion meropenem and ciprofloxacin therapy, in addition to bioprosthetic aortic valve replacement and repair of ventricular septal wall defect. Antibiotics were continued for 6 weeks post-cardiac surgery and the patient remains infection free 18 months post-completion of antibiotic therapy.

CONCLUSION

Clinicians should be aware of the ability of P. aeruginosa to acquire resistance mechanisms in response to selective antibiotic pressures in high-inoculum infections such as infective endocarditis. The mutations identified in this case report correlated well with the evolving antimicrobial resistance profile observed.

Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens

Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.

Echocardiography and FDG-PET/CT scan in Gram-negative bacteremia and cardiovascular infections

PURPOSE OF REVIEW

Current evidence on cardiovascular infections in Gram-negative blood stream infections (GNBSI) with focus on the use of transesophageal echocardiography (TEE) and 18F-Fluorodeoxyglucose - positron emission tomography/Computed tomography (FDG-PET/CT) in the diagnostic workup.

RECENT FINDINGS

Most evidence focuses on characteristics of diagnosed cardiovascular infections and the proportion caused by GNBSI. These proportions are low (1-5%) when it comes to native and prosthetic valve endocarditis as well as cardiac implantable electronic device (CIED) infections whereas the proportion of vascular graft infections caused by GNBSI seems substantially higher (30-40%). Information on the prevalence of cardiovascular infection in patients with GNBSI is limited to a few studies finding around 3% endocarditis in patients with GNBSI and a prosthetic heart valve and 4-16% device-related infection in patients with CIED and GNBSI.

SUMMARY

Patients with GNBSI and native or prosthetic valves should only undergo work-up for endocarditis (TEE and FDG-PET/CT) if they present GNBSI relapse or signs suggestive of endocarditis. CIED patients with GNBSI with Pseudomonas or Serratia spp. should undergo TEE and PET/CT because of the high prevalence of device-related infection. In other GNBs without IE suggestive signs, normal BSI treatment is reasonable and only cases with relapse need work-up. GNBSI in patients with vascular grafts should lead to consideration of PET/CT.

Gram-negative endocarditis: disease presentation, diagnosis and treatment

PURPOSE OF REVIEW

Gram-negative bacilli (GNB) cause between 1% and 10% of infective endocarditis (IE). Most episodes are caused by microorganisms of the Haemophilus spp., Aggregatibacter spp. Cardiobacterium spp., Eikenella spp., and Kingella spp (HACEK) group. The frequency of IE caused by non-HACEK (GNB-IE) has increased in recent years. Uncertainties persist regarding its best medical treatment and the appropriateness and timing of surgical treatment. In addition, there are new drugs with activity against multiresistant microorganisms, of which there is little experience in this disease. We review this topic by answering the most frequently asked questions that arise among our colleagues.

RECENT FINDINGS

HACEK microorganisms cause 1.5-2% of IE with only a 2% mortality. In contrast, non-HACEK GNB-IE accounts for 2.5-3% of all IE cases and is associated with nosocomial acquisition, advanced age, solid organ transplantation and 20-30% mortality. Drug addiction is important in areas with epidemic opioid abuse.

SUMMARY

The frequency of IE caused by GNB has been modified in recent years. HACEK episodes are no longer treated with ampicillin and aminoglycosides. In non-HACEK GNB-IE, combination therapy with a beta-lactam and a quinolone or aminoglycoside is recommended. The surgical indication and its value are evident in many patients. Management should rely on a collaborative group with experience in this disease.

Hematology and Culture Assessment of Cranially Implanted Rhesus Macaques (Macaca mulatta)

The use of percutaneous cranial implants in rhesus macaques (Macaca mulatta) has long been a valuable tool for neuroscience research. However, when treating and assessing these animals, veterinarians are required to make assumptions about diagnostic results due to a lack of research into how these implants affect physiology. Microbial cultures of cranial implant sites show an abundance of colonizing bacteria, but whether these microbes affect animal health and wellbeing is poorly understood. In addition, microbial antibiotic resistance can present significant health concerns for both the animals and the researchers. To help elucidate the relationship between percutaneous cranial implants and blood parameters, complete blood cell counts and serum chemistry results were assessed on 57 nonhuman primates at our institution from September 2001 to March 2017. Generalized estimating equations were used to compare the results before and after an animal's first implant surgery. This modelling showed that cranial implants were a significant predictor of alterations in the number of neutrophils, lymphocytes, and red blood cells, and in the concentration of hemoglobin, alkaline phosphatase, creatinine, calcium, phos- phorus, total protein, albumin, and globulin. Anaerobic and aerobic bacterial cultures were performed to identify bacteria associated with cranial implants. Staphylococcus spp., Streptococcus spp., and Corynebacterium spp. comprised the majority of the aerobic bacterial isolates, while Fusobacterium spp., Peptostreptococcus spp. and Bacterioides fragilis comprised the majority of anaerobic bacterial isolates. Using a Pearson r correlation for statistical analysis, we assessed whether any of these bacterial isolates developed antibiotic resistances over time. Cefazolin, the most frequently used antibiotic in monkeys in this study, was the only antimicrobial out of 41 agents tested to which bacteria developed resistance over time. These results indicate that percutaneous implants are associated with a generalized inflammatory state, multiple bacterial species are present at the implant site, and these bacteria may contribute to the inflammatory response.

Infective Endocarditis After Transcatheter Aortic Valve Replacement

BACKGROUND

Infective endocarditis may affect patients after transcatheter aortic valve replacement (TAVR).

OBJECTIVES

The purpose of this study was to provide detailed information on incidence rates, types of microorganisms, and outcomes of infective endocarditis after TAVR.

METHODS

Between February 2011 and July 2018, consecutive patients from the SwissTAVI Registry were eligible. Infective endocarditis was classified into early (peri-procedural [<100 days] and delayed-early [100 days to 1 year]) and late (>1 year) endocarditis. Clinical events were adjudicated according to the Valve Academic Research Consortium-2 endpoint definitions.

RESULTS

During the observational period, 7,203 patients underwent TAVR at 15 hospitals in Switzerland. During follow-up of 14,832 patient-years, endocarditis occurred in 149 patients. The incidence for peri-procedural, delayed-early, and late endocarditis after TAVR was 2.59, 0.71, and 0.40 events per 100 person-years, respectively. Among patients with early endocarditis, Enterococcus species were the most frequently isolated microorganisms (30.1%). Among those with peri-procedural endocarditis, 47.9% of patients had a pathogen that was not susceptible to the peri-procedural antibiotic prophylaxis. Younger age (subhazard ratio [SHR]: 0.969; 95% confidence interval [CI]: 0.944 to 0.994), male sex (SHR: 1.989; 95% CI: 1.403 to 2.818), lack of pre-dilatation (SHR: 1.485; 95% CI: 1.065 to 2.069), and treatment in a catheterization laboratory as opposed to hybrid operating room (SHR: 1.648; 95% CI: 1.187 to 2.287) were independently associated with endocarditis. In a case-control matched analysis, patients with endocarditis were at increased risk of mortality (hazard ratio: 6.55; 95% CI: 4.44 to 9.67) and stroke (hazard ratio: 4.03; 95% CI: 1.54 to 10.52).

CONCLUSIONS

Infective endocarditis after TAVR most frequently occurs during the early period, is commonly caused by Enterococcus species, and results in considerable risks of mortality and stroke. (NCT01368250).

Expect the Unexpected: A Rare Case of Pseudomonas aeruginosa Endocarditis

Infective endocarditis (IE) caused by Pseudomonas aeruginosa is extremely uncommon. Reported cases have usually been associated with intravenous drug use, prosthetic heart valves, and/or implanted cardiac devices. Traditionally, successful treatment has necessitated a combination of antimicrobial(s) and valve replacement. Yet, P. aeruginosa IE remains difficult to manage, especially in cases where valve replacement may not be an immediate option. We present such a case of P. aeruginosa IE, highlighting that medical management with 2 antipseudomonal synergistic agents may be an alternative to surgery in particularly complicated cases.