A consensus conference to define the utility of advanced infectious disease diagnostics in solid organ transplant recipients

Breaking Boundaries in Pneumonia Diagnostics: Transitioning from Tradition to Molecular Frontiers with Multiplex PCR

The advent of rapid molecular microbiology testing has revolutionized infectious disease diagnostics and is now impacting pneumonia diagnosis and management. Molecular platforms offer highly multiplexed assays for diverse viral and bacterial detection, alongside antimicrobial resistance markers, providing the potential to significantly shape patient care. Despite the superiority in sensitivity and speed, debates continue regarding the clinical role of multiplex molecular testing, notably in comparison to standard methods and distinguishing colonization from infection. Recent guidelines endorse molecular pneumonia panels for enhanced sensitivity and rapidity, but implementation requires addressing methodological differences and ensuring clinical relevance. Diagnostic stewardship should be leveraged to optimize pneumonia testing, emphasizing pre- and post-analytical strategies. Collaboration between clinical microbiologists and bedside providers is essential in developing implementation strategies to maximize the clinical utility of multiplex molecular diagnostics in pneumonia. This narrative review explores these multifaceted issues, examining the current evidence on the clinical performance of multiplex molecular assays in pneumonia, and reflects on lessons learned from previous microbiological advances. Additionally, given the complexity of pneumonia and the sensitivity of molecular diagnostics, diagnostic stewardship is discussed within the context of current literature, including implementation strategies that consider pre-analytical and post-analytical modifications to optimize the clinical utility of advanced technologies like multiplex PCR.

Cerebrospinal fluid metagenomics has greatest added value as a test for Powassan virus among patients in New England with suspected central nervous system infection

Cerebrospinal fluid (CSF) metagenomic next generation sequencing (mNGS) can detect diverse pathogens in patients with central nervous system infection. Due to its high cost and unclear clinical utility, it is typically reserved for patients with unrevealing routine workups. A multi-center retrospective analysis of real-world CSF mNGS was performed involving orders between 2017 and 2022 at a large New England healthcare system. CSF mNGS was performed 64 times with 17 positive results (27 %). In 11/17 positive samples (65 %), the infectious agent had not been previously detected using routine methods. Arboviruses (n = 8) were the most frequently detected agents, particularly Powassan virus (n = 6). Results changed therapy in 3/64 cases (5 %). Positive results were associated with immunodeficiency (p = 0.06), especially anti-B-cell therapy (p = 0.02), and earlier sample collection (p = 0.06). The association with compromised humoral immunity was stronger in the arbovirus and Powassan virus subgroups (p = 0.001), whose constituents were older than the overall cohort and had higher mortality rates.

QuantiFERON-CMV as a Predictor of CMV Events During Preemptive Therapy in CMV-seropositive Kidney Transplant Recipients

BACKGROUND

Prevention of cytomegalovirus (CMV) infection after kidney transplantation is costly and burdensome.

METHODS

Given its promising utility in risk stratification, we evaluated the use of QuantiFERON-CMV (QFCMV) and additional clinical variables in this prospective cohort study to predict the first clinically significant CMV infection (CS-CMV, ranging from asymptomatic viremia requiring treatment to CMV disease) in the first posttransplant year. A cost-effectiveness analysis for guided prevention was done.

RESULTS

One hundred adult kidney transplant recipients, CMV IgG + , were given basiliximab induction and maintained on steroid/mycophenolate/tacrolimus with weekly CMV monitoring. Thirty-nine patients developed CS-CMV infection (viral syndrome, n = 1; end-organ disease, n = 9; and asymptomatic viremia, n = 29). A nonreactive or indeterminate QFCMV result using the standard threshold around day 30 (but not before transplant) was associated with CS-CMV rates of 50% and 75%, respectively. A higher QFCMV threshold for reactivity (>1.0 IU interferon-γ/mL) outperformed the manufacturer's standard (>0.2 IU interferon-γ/mL) in predicting protection but still allowed a 16% incidence of CS-CMV. The combination of recipient age and type of donor, along with posttransplant QFCMV resulted in a prediction model that increased the negative predictive value from 84% (QFCMV alone) to 93%. QFCMV-guided preemptive therapy was of lower cost than preemptive therapy alone ( P  < 0.001, probabilistic sensitivity analysis) and was cost-effective (incremental net monetary benefit of 210 USD) assuming willingness-to-pay of 2000 USD to avoid 1 CMV disease.

CONCLUSIONS

Guided CMV prevention by the prediction model with QFCMV is cost-effective and would spare from CMV surveillance in 42% of patients with low risk for CS-CMV.

What's New: Updates on Cytomegalovirus in Solid Organ Transplantation

Cytomegalovirus (CMV) is one of the most common infections occurring after solid organ transplantation. This high burden of disease, which incurs sizeable morbidity, may be worsening with the proportion of high-risk D+/R- solid organ transplantation recipients increasing in some regions globally. Cohort studies continue to support either universal prophylaxis or preemptive therapy as effective prevention strategies. Letermovir prophylaxis was noninferior to valganciclovir in adult high-risk D+/R- kidney transplant recipients with fewer drug-related adverse events in a recent clinical trial and has now been approved for such use in some regions. Maribavir preemptive therapy failed to demonstrate noninferiority when compared with valganciclovir in hematopoietic stem cell transplant recipients but looked promising for safety. Donor matching could be useful in prevention CMV disease with a survival advantage demonstrated in seronegative recipients waiting up to 30 mo for a seronegative kidney. Immune-guided prophylaxis resulted in fewer CMV infection episodes in lung transplant recipients when compared with fixed-duration prophylaxis in a recent clinical trial. For treatment of refractory or resistant CMV infection, maribavir was more efficacious and better tolerated when compared with investigator-initiated therapy in its registration trial for this condition. Further research regarding best treatment and prophylaxis of resistant or refractory CMV infection is needed to reflect best clinical practice choices. Optimal use of immune globulin or CMV-specific T cells for prevention or treatment of CMV disease remains undefined. Standardized definitions for the design of CMV clinical trials have been developed. In this review, we highlight recent updates in the field from data published since 2018.

A Diagnostic Approach to Fungal Pneumonia: An Infectious Diseases Perspective

Although bacteria significantly exceed fungi as the most common cause of lower respiratory tract infection, the incidence of fungal pneumonia is increasing because of a growing at-risk population of immunocompromised individuals as well as anthropogenic global heating and environmental disruption. When a patient presents with a clinical syndrome of pneumonia, a constellation of factors must be considered to determine the probability of a fungal pneumonia, including host factors, epidemiologic exposures, suggestive radiographic patterns, and the presence of a non-resolving pneumonia. In addition, knowledge of clinically important fungal pathogens, their epidemiology, and associated clinical syndromes are key in guiding appropriate diagnostic testing and result interpretation, and ultimately rendering a correct diagnosis of a fungal pneumonia. This article aims to provide a framework for the evaluation and appropriate diagnostic testing of patients with suspected fungal pneumonia.

Current Landscape and Future Directions of Pediatric Transplant Infectious Diseases

As the field of pediatric transplant infectious diseases continues to grow, new challenges are constantly arising. Advances in immunosuppressive drugs, antimicrobial development, and novel diagnostic tests add new wrinkles to the care of pediatric transplant recipients. This progress in clinical care serves as a call to direct energy toward pediatric transplant infectious diseases research, to better understand how to use these interventions in pediatric practice.

Pre-Transplantation Strategies for Infectious Disease Mitigation and Prevention

Pediatric Infectious Disease (ID) clinicians play a critical role in helping prevent and mitigate infectious risks in children peri- and post-transplantation. Prevention starts during the pre-transplant evaluation and persists throughout the solid organ transplant and hematopoietic cell transplant continuum. The pre-transplant evaluation is an opportunity to screen for latent infections, plan preventative strategies, optimize immunizations, and discuss risk mitigation practices. An ideal pre-transplant evaluation establishes a relationship with the family that further promotes post-transplant infectious risk reduction. This manuscript builds on shared pediatric ID prevention strategies, introduces updated ID testing recommendations for transplant donors/candidates, highlights emerging data, and identifies ongoing knowledge gaps that are potential areas of research.

Cytomegalovirus Cell-mediated Immunity Assays in Pediatric Transplantation

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in pediatric transplantation. However, currently utilized CMV prevention paradigms have limitations, leading to research aimed at novel strategies for mitigation of CMV infection. Cell-mediated immunity (CMI) is crucial in controlling CMV infection and the use of CMV-specific CMI assays to guide prevention and treatment of CMV infection in both solid organ transplant and hematopoietic cell transplant recipients shows great promise. In this article, we review the immune response to CMV infection to highlight the rationale for CMI assays, describe available commercial assays and strategies for their use, and summarize relevant literature regarding the use of CMI assays in transplant recipients.

How I approach: the transplant recipient with fever and pulmonary infiltrates

Recipients of hematopoietic stem cell transplants and solid organ transplants frequently develop pulmonary infiltrates from both infectious and non-infectious etiologies. Differentiation and further characterization of microbiologic etiologies-viral, bacterial, and fungal-can be exceedingly challenging. Pediatric patients face unique challenges as confirmatory evaluations with bronchoscopy or lung biopsy may be limited. A generalizable approach to diagnosing and managing these conditions has not been well established. This paper aims to summarize our initial clinical approach while discussing the relative evidence informing our practices. A pediatric patient with characteristic infiltrates who has undergone HSCT is presented to facilitate the discussion. Generalizable approaches to similar patients are highlighted as appropriate while highlighting considerations based on clinical course and key risk factors.

Natural history and prognostic factors of candidemia in kidney transplant recipients: A retrospective, multinational study

BACKGROUND

The natural history of candidemia in kidney transplant recipients (KTR) remains poorly understood. This study aimed to evaluate mortality, prognostic factors and overall graft loss after candidemia in KTRs.

METHODS

This is a retrospective multicentre study enrolling all KTRs ≥15 years old with candidemia diagnosed at hospitals in Brazil, Spain and Italy from 2010 to 2020. Primary endpoints were mortality rates at 14 and 30 days. Secondary endpoints were prognostic factors of 14-day mortality and overall graft loss.

RESULTS

We enrolled 93 KTRs of which 75 were from Brazil. The mean time interval from transplantation to the onset of candidemia was 45.2 ± 61.5 months. 42% of all patients were on haemodialysis, 31.3% had an episode of sepsis and 39% underwent surgery within 30 days before fungemia. European patients were more likely to receive echinocandin (32 vs. 72%, p < .001). 22.7% of Brazilian patients did not receive any antifungal before death. All-cause mortality at 14 days was higher in Brazil (41.3 vs. 11.1%, p = .016). Candida colonisation (OR 6.91 [95% CI: 1.08-44.3], p = .042) and hypotension (OR 4.87 [95% CI: 1.62-14.66], p = .005) were associated with 14-day mortality. Echinocandin treatment had a protective effect (OR 0.19 [95% CI: 0.05-0.73], p = .015). Graft loss at 90 days occurred in 48% of patients (70.7 in Brazil vs. 22.2% in Europe, p < .01).

CONCLUSIONS

Candidemia in KTR is usually documented late after engraftment in patients requiring HD, surgical procedures and dysbiosis secondary to antibiotic use. Mortality was higher in Brazil. Echinocandin therapy was associated with improved survival.

A review of transplant infectious diseases and pediatric transplant infectious diseases curriculum

PURPOSE OF REVIEW

As the volume and complexity of solid organ and hematopoietic stem cell transplantation continue to see rapid growth, the training of a specialized transplant infectious diseases physician workforce is of increasing interest and importance. This review provides an overview of the evolution of transplant infectious diseases training programs, essential elements of training, as well as future needs.

RECENT FINDINGS

Despite the first publication of a transplant infectious diseases curriculum in 2010, more recent surveys of infectious diseases trainees have identified gaps in didactic curriculum, donor and recipient assessment, and safe living practices.

SUMMARY

This review of transplant infectious diseases training summarizes growth through the decades, the current landscape of recommend training elements, suggested areas for continued development and expansion in training as well as novel methodologies to reach a modern trainee audience.

Reliability of QuantiFERON®-CMV in predicting CMV recurrence in heart transplant recipients: A single-center retrospective study

BACKGROUND

Recurrence after Cytomegalovirus (CMV) infection in heart transplant recipients is difficult to predict, in spite of its high incidence. Secondary prophylaxis could reduce this burden; however, its duration remains unestablished. We evaluated the QuantiFERON®-CMV test to see if it could predict CMV recurrence and help optimize the duration of secondary prophylaxis.

METHODS

This observational retrospective single center study included all heart transplant recipients who developed CMV infection between 2019 and 2021, with the CD8+ T-cell-mediated CMV immunity QuantiFERON®-CMV test assessed at the time of (val)ganciclovir curative treatment completion. The main outcomes were CMV recurrence and duration of secondary prophylaxis. Secondary outcomes included immunosuppressive regimen, rejection, lymphocyte count, CMV viral load, infection type, and duration as possible confounding factors for recurrence.

RESULTS

Among the 15 patients included, five (33%) experienced recurrence, of whom three (60%) had a positive QuantiFERON®-CMV test. The duration of secondary prophylaxis was similar regardless of QF-CMV positivity. No confounding factor was significantly associated with CMV recurrence; however, it occurred in only 1/7 (14%) of the patients receiving an everolimus-containing immunosuppressive regimen.

CONCLUSION

In the population of heart transplant recipients, most of whom received ATG-based induction, the QuantiFERON®-CMV assay may not accurately predict CMV recurrence and would have not helped refining the duration of secondary prophylaxis in our patients. Other cell-mediated immunity tests and strategies in this specific population, including everolimus-containing regimens, may help predict and manage CMV recurrence.

Rapid antimicrobial resistance detection methods for bloodstream infection in solid organ transplantation: Proposed clinical guidance, unmet needs, and future directions

Recent advances in antimicrobial resistance detection have spurred the development of multiple assays that can accurately detect the presence of bacterial resistance from positive blood cultures, resulting in faster institution of effective antimicrobial therapy. Despite these advances, there are limited data regarding the use of these assays in solid organ transplant (SOT) recipients and there is little guidance on how to select, implement, and interpret them in clinical practice. We describe a practical approach to the implementation and interpretation of these assays in SOT recipients using the best available data and expert opinion. These findings were part of a consensus conference sponsored by the American Society of Transplantation held on December 7, 2021 and represent the collaboration between experts in transplant infectious diseases, pharmacy, antimicrobial and diagnostic stewardship, and clinical microbiology. Areas of unmet need and recommendations for future investigation are also presented.

Oral antiviral drugs for treatment of cytomegalovirus in transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is an opportunistic pathogen responsible for substantial morbidity after solid organ transplantation and haematopoietic stem cell transplantation. Treatment of CMV disease involves a two-pronged approach with antiviral drug treatment coupled with strategies to minimize the intensity of immune suppression.

OBJECTIVES

This narrative review examines the evidence for the current treatment of CMV disease in transplant recipients, including the use of oral antiviral drugs.

SOURCES

Literature search was performed on PubMed with keywords cytomegalovirus, transplantation, ganciclovir, valganciclovir, maribavir, letermovir, cidofovir, and foscarnet.

CONTENT

Intravenous and oral valganciclovir are the standard first-line treatment of cytomegalovirus disease after transplantation. Oral maribavir has demonstrated superior efficacy and safety over CMV DNA polymerase inhibitors for the treatment of refractory or resistant CMV infection. Transplant patients with severe and life-threatening CMV disease, those with very high viral load, and patients with impaired gastrointestinal absorption should still be treated initially with intravenous antiviral drugs, including ganciclovir and foscarnet. Criteria for the safe transition from intravenous therapies to oral antiviral drugs include achieving clinical improvement and satisfactory decline in viral load. Recurrence of CMV viremia and disease is common, particularly among transplant patients who are lymphopenic and have impaired CMV-specific immunity.

IMPLICATIONS

Oral antiviral drugs for the treatment of CMV infection and disease in transplant recipients have improved the CMV landscape, because they reduce the cost and mitigate the inconvenience and risks related to prolonged hospitalization and the need for long-term intravascular access. However, their antiviral efficacy should be complemented by an intentional strategy of reducing the degree of immune suppression to allow for immunologic recovery that ensures durable control of CMV infection.

Emerging Diagnostics and Therapeutics for Invasive Fungal Infections

Recently, there have been significant advances in the diagnosis and management of invasive fungal infections. Compared with traditional fungal diagnostics, molecular assays promise improved sensitivity and specificity, the ability to test a range of samples (including noninvasive samples, ie, blood), the detection of genetic mutations associated with antifungal resistance, and the potential for a faster turnaround time. Antifungals in late-stage clinical development include agents with novel mechanisms of action (olorofim and fosmanogepix) and new members of existing classes with distinct advantages over existing antifungals in toxicity, drug-drug interactions, and dosing convenience (oteseconazole, opelconazole, rezafungin, ibrexafungerp, encochleated amphotericin B).

Updates in Molecular Diagnostics in Solid Organ Transplantation Recipients

Advances in molecular diagnostics have the potential to improve patient care among solid organ transplant recipients by reducing time to pathogen identification and informing directed therapy. Although cultures remain the cornerstone of traditional microbiology, advanced molecular diagnostics, such as metagenomic next-generation sequencing (mNGS), may increase detection of pathogens. This is particularly true in the settings of prior antibiotic exposure, and when causative organisms are fastidious. mNGS also offers a hypothesis-free diagnostic method of testing. This is useful in situations whereby the differential is broad or when the infectious agent is unlikely to be detected by routine methods.