Epidemiology and outcomes of pretransplant methicillin-resistant Staphylococcus Aureus screening in pediatric solid organ transplant candidates

Long-term outcomes and risk factors for early bacterial infection after pediatric liver transplantation: a prospective cohort study

BACKGROUND

Liver transplantation (LT) is the most efficient treatment for pediatric patients with end-stage liver diseases, while bacterial infection is the leading reason for post-transplant mortality. The present study is to explore the outcomes and risk factors of early bacterial infection (within 1 months) after pediatric LT.

METHODS

In this prospective cohort study, 1316 pediatric recipients [median (IQR) age: 9.1 (6.3-28.0) months; male: 48.0%; median (IQR) follow-up time: 40.6 (29.1-51.4) months] who received LT from September 2018 to April 2022 were included. Bacterial culture samples such as sputum, abdominal drainage, blood, and so on were collected when recipients were presented with infective symptoms. Kaplan-Meier analysis was applied to estimate the long-term survival rates and logistic regression was used to identify independent risk factors. To explore the role of pretransplant rectal swab culture (RSC) in reducing post-transplant bacterial infection rate, 188 infant LT recipients [median (IQR) age: 6.8 (5.5-8.1) months; male: 50.5%] from May 2022 to September 2023 were included. Log-binomial regression was used to measure the association of pretransplant RSC screening and post-transplant bacterial infection. The 'Expectation Maximization' algorithm was used to impute the missing data.

RESULTS

Bacterial infection was the primary cause for early (38.9%) and overall mortality (35.6%) after pediatric LT. Kaplan-Meier analysis revealed inferior 1-year and 5-year survival rates for recipients with post-transplant bacterial infection (92.6 vs. 97.1%, 91.8 vs. 96.4%, respectively; P <0.001). Among all detected bacteria, Staphylococcus spp. (34.3%) and methicillin-resistant coagulase-negative Staphylococci (43.2%) were the dominant species and multidrug resistant organisms, respectively. Multivariable analysis revealed that infant recipients [adjusted odds ratio (aOR) 1.49; 95% CI: 1.01-2.20], male recipients (aOR, 1.43; 95% CI: 1.08-1.89), high graft-to-recipient weight ratio (aOR, 1.64; 95% CI: 1.17-2.30), positive post-transplant RSC (aOR, 1.45; 95% CI: 1.04-2.02) and nasopharyngeal swab culture (aOR 2.46; 95% CI: 1.72-3.52) were independent risk factors for early bacterial infection. Furthermore, RSC screening and antibiotic prophylaxis before transplantation could result in a relatively lower post-transplant infection rate, albeit without statistical significance (adjusted RR, 0.53; 95% CI: 0.25-1.16).

CONCLUSION

In this cohort study, post-transplant bacterial infection resulted in an inferior long-term patient survival rate. The five identified independent risk factors for post-transplant bacterial infection could guide the prophylaxis strategy of post-transplant bacterial infection in the future. Additionally, pretransplant RSC might decrease post-transplant bacterial infection rate.

Challenges of Antimicrobial Resistance and Stewardship in Solid Organ Transplant Patients

Purpose of Review

Without effective antimicrobials, patients cannot undergo transplant surgery safely or sustain immunosuppressive therapy. This review examines the burden of antimicrobial resistance in solid organ transplant recipients and identifies opportunities for antimicrobial stewardship.

Recent Findings

Antimicrobial resistance has been identified to be the leading cause of death globally. Multidrug-resistant pathogens are associated with significant morbidity and mortality in transplant recipients. Methicillin-resistant S. aureus affects liver and lung recipients, causing bacteremia, pneumonia, and surgical site infections. Vancomycin-resistant enterococci is a nosocomial pathogen primarily causing bacteremia in liver recipients. Multidrug-resistant Gram-negative pathogens present urgent and serious threats to transplant recipients. Extended-spectrum beta-lactamase-producing E. coli and K. pneumoniae commonly cause bacteremia and intra-abdominal infections in liver and kidney recipients. Carbapenemase-producing Enterobacterales, mainly K. pneumoniae, are responsible for infections early-post transplant in liver, lung, kidney, and heart recipients. P. aeruginosa and A. baumannii continue to be critical threats. While there are new antimicrobial agents targeting resistant pathogens, judicious prescribing is crucial to minimize emerging resistance. The full implications of the COVID-19 global pandemic on antimicrobial resistance in transplant recipients remain to be understood. Currently, there are no established standards on the implementation of antimicrobial stewardship interventions, but strategies that leverage existing antimicrobial stewardship program structure while tailoring to the needs of transplant recipients may help to optimize antimicrobial use.

Summary

Clinicians caring for transplant recipients face unique challenges tackling emerging antimcirobial resistance. Coordinated antimicrobial stewardship interventions in collaboration with appropriate expertise in transplant and infectious diseases may mitigate against such threats.

Reduced pannexin 1-IL-33 axis function in donor livers increases risk of MRSA infection in liver transplant recipients

Liver transplantation patients are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) infection, but the molecular mechanism remains unclear. We found that genetic predisposition to low pannexin 1 (PANX1) expression in donor livers was associated with MRSA infection in human liver transplantation recipients. Using Panx1 and Il-33-knockout mice for liver transplantation models with MRSA tail vein injection, we demonstrated that Panx1 deficiency increased MRSA-induced liver injury and animal death. We found that decreased PANX1 expression in the liver led to reduced release of adenosine triphosphate (ATP) from hepatocytes, which further reduced the activation of P2X2, an ATP-activating P2X receptor. Reduced P2X2 function further decreased the NLRP3-mediated release of interleukin-33 (IL-33), reducing hepatic recruitment of macrophages and neutrophils. Administration of mouse IL-33 to Panx1^-/- mice significantly (P = 0.011) ameliorated MRSA infection and animal death. Reduced human hepatic IL-33 protein abundance also associated with increased predisposition to MRSA infection. Our findings reveal that genetic predisposition to reduced PANX1 function increases risk for MRSA infection after liver transplantation by decreasing hepatic host innate immune defense, which can be attenuated by IL-33 treatment.

Methicillin-resistant Staphylococcus aureus in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the epidemiology, diagnosis, prevention, and management of methicillin-resistant Staphylococcus aureus (MRSA) infections in solid organ transplantation. Despite an increasing armamentarium of antimicrobials active against MRSA, improved diagnostic tools, and overall declining rates of infection, MRSA infections remain a substantial cause of morbidity and mortality in solid organ transplant recipients. Pre- and post-transplant MRSA colonization is a significant risk factor for post-transplant MRSA infection. The preferred initial treatment of MRSA bacteremia remains vancomycin. Hand hygiene, chlorhexidine bathing in the ICU, central-line bundles that focus on reducing unnecessary catheter use, disinfection of patient equipment, and the environment along with antimicrobial stewardship are all aspects of an infection prevention approach to prevent MRSA transmission and decrease healthcare-associated infections.