Infective endocarditis following heart transplantation: A systematic review

Bacterial infections in solid organ transplant recipients

PURPOSE OF REVIEW

Bacteria are the leading cause of infections in solid organ transplant (SOT) recipients, significantly impacting patient outcome. Recently detailed and comprehensive epidemiological data have been published.

RECENT FINDING

This literature review aims to provide an overview of bacterial infections affecting different types of SOT recipients, emphasizing underlying risk factors and pathophysiological mechanisms.

SUMMARY

Lung transplantation connects two microbiotas: one derived from the donor's lower respiratory tract with one from the recipient's upper respiratory tract. Similarly, liver transplantation involves a connection to the digestive tract and its microbiota through the bile ducts. For heart transplant recipients, specific factors are related to the management strategies for end-stage heart failure based with different circulatory support tools. Kidney and kidney-pancreas transplant recipients commonly experience asymptomatic bacteriuria, but recent studies have suggested the absence of benefice of routine treatment. Bloodstream infections (BSI) are frequent and affect all SOT recipients. Nonorgan-related risk factors as age, comorbidity index score, and leukopenia contribute to BSI development. Bacterial opportunistic infections have become rare in the presence of efficient prophylaxis. Understanding the epidemiology, risk factors, and pathophysiology of bacterial infections in SOT recipients is crucial for effective management and improved patient outcomes.

Outcomes of tricuspid valve prostheses after heart transplantation: a systematic review

Tricuspid regurgitation (TR) is the most common valvular pathology after heart transplantation (HTx) and endomyocardial biopsy (EMB) remains responsible for the majority of cases due to the high probability of structural valve damage. The aim of the present review was to describe the results of surgical management of severe tricuspid regurgitation through tricuspid valve replacement (TVR) after a previous HTx. A systematic review was conducted by searching Pubmed, ScienceDirect, SciELO, DOAJ, and Cochrane databases until June 2023 for publications reporting patients undergoing TVR surgery after a previous HTx. If no right heart valve surgery was undertaken, or a heterotopic heart transplant was performed, or if the concomitant procedure was performed during the transplant itself, the paper was excluded. Twenty articles met our inclusion criteria out of 1532 potentially eligible studies, with a total of 300 patients. Mean age was 55.1 ± 9.6 years, and 85.1% were male. The mean number of EMB per patient was 31.1 ± 5.5 with a mean time between HTx and TVR of 7.64 ± 3.31 years. Bioprostheses were used in 83.3% of cases and 75.0% of patients with a bioprosthesis were reported as alive at last follow-up. Tricuspid valve repair is a valuable option, but these patients will be susceptible to recurrent TR after EMB. TVR with a bioprosthesis may provide the optimal solution for this subset of patients, as EMB is not feasible with a mechanical valve.

Management of Bilateral Synchronous Knee Prosthetic Joint Infection in a Patient with Infected Heart Transplant: A Case Report

CASE

A 74-year-old man presented with septic shock with infection of his heart transplant and bilateral prosthetic knee joints simultaneously. He underwent bilateral knee resection arthroplasties with placement of articulating spacers. At 3-year follow-up, the patient was alive and ambulating independently.

CONCLUSION

This case represents the first report of bilateral hematogenous prosthetic knee infections associated with concomitant enterococcal endocarditis of a heart transplant treated successfully and definitively with radical debridement and placement of articulating spacer with regular implants.

Immune Regulator Retinoic Acid-Inducible Gene I (RIG-I) in the Pathogenesis of Cardiovascular Disease

Retinoic acid-inducible gene I (RIG-I) is a cytosolic pattern recognition receptor that contains two CARD domains, an RNA helicase domain, and a C-terminal domain. RIG-I initiates antiviral innate immunity by recognizing exogenous viral RNAs/DNAs. However, some studies have reported that RIG-I activation leads to damage in various organs and tissues in diverse circumstances. Recent studies have shown that RIG-I is involved in cancer, lupus nephritis, immunoglobulin A nephropathy, Crohn’s disease, and atherosclerosis. These reports indicate that RIG-I not only participates in antiviral signaling pathways but also exerts an influence on non-viral infectious diseases. RIG-I is widely expressed in immune and non-immune cells including smooth muscle cells, endothelial cells, and cardiomyocytes. A succinct overview of RIG-I and its signaling pathways, with respect to the cardiovascular system, will aid in the development of novel therapeutics for cardiovascular diseases. In this review, we summarize the structure, activation, signaling pathways, and role of RIG-I in cardiovascular diseases.

Exebacase: A Novel Approach to the Treatment of Staphylococcal Infections

Lysins are bacteriophage-derived enzymes that degrade essential components of bacteria. Exebacase (Lysin CF-301) is an attractive antimicrobial agent because it demonstrates rapid bacteriolytic activity against staphylococcal species, including Staphylococcus aureus, has a low resistance profile, eradicates biofilms, and acts synergistically with other antibiotics. Combinations including exebacase and standard of care antibiotics represent an alternative to antibiotic monotherapies currently used to treat invasive staphylococcal infections. This manuscript reviews what is known about exebacase and explores how this novel agent may be used in the future to treat human bacterial pathogens.