Andrea J. Zimmer

Background: Transplant Infectious Diseases (TID) is a growing, clinically complex subspecialty essential to transplant and oncology programs, yet the practice structure, compensation, and professional experience of TID physicians in the United States remain poorly characterized. Methods: The IDSA Immunocompromised Host Community of Practice Leadership Group conducted a cross-sectional survey of U.S.- based TID physicians. Results: A total of 184 physicians responded to the survey (86% adult, 13% pediatric; 94% academic). Adult TID physicians worked a median of 17 weeks (IQR 12–24) plus 8 (IQR 6-12)weekends per year on inpatient service, along with 1.5 half day clinics (IQR 1-2) outpatient. Physicians reported that a median of 67% of their non-clinical duties were not supported with FTE. Median base salary for adult TID physicians in an academic setting was $235,000 (IQR $205,000-$274,000), and $205,000 (IQR $183,000-$235,000) for pediatrics. Only 5% of junior faculty felt comfortable negotiating compensation. Forty-nine percent of respondents felt undercompensated, though 78.7% were satisfied or very satisfied with their job. Conclusions: This first national characterization of the TID workforce reveals substantial compensation inequity and unfunded non-clinical work alongside high job satisfaction and strong collegial value. Policy mandates, FTE protections, compensation transparency, and negotiation training are needed to sustain this workforce.

Toxoplasmosis has long been recognized as a serious complication in immunocompromised host, particularly those with advanced HIV/AIDS, hematopoietic stem‐cell transplantation (HSCT), solid‐organ transplant (SOT), and hematological malignancies. The rapid expansion of targeted immunomodulators, including chimeric antigen receptor T‐cell (CAR‐T) therapies, monoclonal antibodies, and small‐molecule inhibitors, is creating new at‐risk populations beyond traditional transplant settings. We present a 9‐year‐old boy with high‐risk B‐cell acute lymphoblastic leukemia (B‐ALL), who developed prolonged fever and macrophage activation syndrome (MAS). After an extensive unrevealing workup, disseminated acute toxoplasmosis was identified incidentally on bone marrow aspirate via morphologic identification of tachyzoites and confirmed by Toxoplasma gondii PCR. This case exemplifies the emerging threat of toxoplasmosis in non‐transplant immunomodulated hosts and supports three core mitigation strategies. First, baseline Toxoplasma IgG and IgM serology should be obtained in all patients initiating targeted immunotherapy, recognizing that B‐cell depletion or hypogammaglobulinemia may render IgG unreliable, and that IgM may be falsely negative, delayed, or persistently positive in immunocompromised individuals. Second, targeted PCR from clinically relevant compartments or metagenomic next‐generation sequencing when conventional diagnostics is unrevealing should be applied early. Third, prevention requires a bundled approach: baseline screening, patient education for seronegative individuals, and trimethoprim‐sulfamethoxazole prophylaxis with or without serial qPCR monitoring for seropositive patients. Toxoplasmosis is no longer a transplant‐exclusive concern. As targeted immunomodulators reshape practice across rheumatology, oncology, neurology, and autoimmune disease, infectious diseases specialists must lead efforts to raise cross‐specialty awareness, establish guidelines, and build registries to define the true burden of toxoplasmosis in these growing populations.

The population of iatrogenic immunocompromised individuals is steadily rising as we continue to improve in our ability to manage diseases, including cancer, autoimmune disease, and end‐organ dysfunction, with increasing access to novel agents and transplantation. Enhanced survivorship allows these patients to return to their home communities and lives, leading to an increased number of immunocompromised patients across all healthcare systems. However, expertise in immunocompromised host infectious diseases or transplant ID (TID) is concentrated in urban centers and often in academic settings. In this article, we review three cases to highlight common immunosuppressed groups that can be encountered in any health system: solid organ transplantation, hematologic malignancy, and autoimmune disease. The cases describe common illness scripts and key management considerations for the opportunistic pathogens highlighted. Finally, we outline high‐yield references that can support clinical care of these patients for those interested, whether they be community‐based general infectious diseases clinicians or infectious diseases fellows considering dedicated training in TID. The standards and expectations for immunocompromised infectious diseases training in both general infectious diseases fellowships and dedicated TID training are still being established. There are many societies and groups focused on addressing this need, and the importance of their collaboration and efforts is emphasized by our cases. Immunocompromising conditions are no longer niche, but rather an expected and substantial population of hospitalized patients everywhere. We will need the entire infectious diseases workforce, as well as further recruitment and retention of the next generation of physicians, to meet this ever‐increasing demand.

Background: CD19 chimeric antigen receptor (CAR)‐T cell therapy has emerged as an effective treatment in those with refractory or relapsed lymphoma. CD19 CAR‐T cell therapy can cause direct and indirect toxic adverse effects and increased risk for infection. Infectious complications and optimal antimicrobial prophylaxis strategies are an ongoing area of investigation.Methods: A single‐center retrospective cohort study was conducted to review recipients of CD19 CAR‐T cell therapy between April 2018 and December 2020. Patient characteristics and clinical outcomes were extracted from the electronic health records.Results: Infectious complications were identified in 18/50 (36%) recipients with 31 episodes of infection. The median time to infection was 225 days (range 0–614). Bacterial infections were most common with bloodstream infection followed by sinusitis and skin and soft tissue infection. Eight viral infections were identified, most being respiratory viral illnesses. Two fungal infections were identified: Pneumocystis jirovecii pneumonia (PJP) and disseminated fusariosis. Seventeen infections (54.8%) were classified as severe: leading to death, requiring hospitalization, need for empiric intravenous antibiotics, or significant alteration in hospital course. No characteristics were found to be statistically significant risks for infection, although a trend toward significance was seen in prior autologous stem cell transplant recipients (p = .12) and those with recurrent neutropenia (p = .14). Three patients (6%) died from infection.Conclusion: Infections were common after CD19 CAR‐T cell therapy and occurred beyond the first year. Further multicenter studies are needed to define infectious risks and optimize antimicrobial prophylaxis recommendations in recipients of CD19 CAR‐T cell therapy. image

Allogeneic stem cell transplantation is a lifesaving treatment for many malignancies. Post-transplant patients may suffer from graft versus host disease in the acute and/or the chronic form(s). Post-transplantation immune deficiency due to a variety of factors is a major cause of morbidity and mortality. Furthermore, immunosuppression can lead to alterations in host factors that predisposes these patients to infections. Although patients who receive stem cell transplant are at an increased risk of opportunistic pathogens, which include fungi and viruses, bacterial infections remain the most common cause of morbidity. Here, we review bacterial pathogens that lead to pneumonias specifically in the chronic GVHD population.

Background: Rising antimicrobial resistance rates may impact the efficacy of empirical antibiotic treatment for febrile neutropenia in high-risk cancer patients. Lacking contemporary data about the epidemiology, antibiotic resistance patterns, and clinical outcomes from bloodstream infections (BSIs) in US cancer patients, it is unclear if current guidelines remain relevant. Methods: In a cross-sectional study, 14 US cancer centers prospectively identified BSIs in high-risk febrile neutropenic (FN) patients, including those receiving chemotherapy for hematologic malignancies or hematopoietic stem cell transplantation. Results: Among 389 organisms causing BSI in 343 patients, there was an equal distribution of gram-negative (GN) and gram-positive (GP) bacteria, with variability across centers. Cefepime and piperacillin-tazobactam were the most commonly prescribed empirical antibiotics for FN, at 62% and 23%, respectively; a GP-directed agent was empirically included in nearly half of all FN episodes within the first 24 hours. Susceptibility to fluoroquinolones, cefepime, piperacillin-tazobactam, and carbapenems was 49%, 84%, 88%, and 96%, respectively, among GN isolates. Critical illness (CrI), defined as a new requirement for mechanical ventilation, vasopressor, or death within 30 days, occurred in 15% and did not correlate with fluoroquinolone prophylaxis, organism type, initial antibiotics, or adequacy of coverage. Only severity of illness at presentation, signified by a Pitt bacteremia score ≥2, predicted for critical illness within 30 days. Mortality was 4% by day 7 and 10% overall. Conclusions: In accordance with US guidelines, cefepime or piperacillin-tazobactam remain effective agents or empirical treatment for high-risk cancer patients with FN who are stable at presentation, maintaining high GN pathogen susceptibility and yielding excellent outcomes.

Solid organ transplant recipients are at increased risk for infections due to chronic immunosuppression. Diarrhea is a commonly encountered problem post transplantation, with infectious causes of diarrhea being a frequent complication. Viral infections/enteritides in solid organ transplant recipients often result from frequently encountered pathogens in this population such as cytomegalovirus, adenovirus, and norovirus. However, several emerging viral pathogens are increasingly being recognized as more sensitive diagnostic techniques become available. Treatment is often limited to supportive care and reduction in immunosuppression, though antiviral therapies mayplay a role in the treatment in certain diseases. Viral enteritis is an important entity that contributes to morbidity and mortality in transplant recipients.

Febrile neutropenia (FN) is a common serious complication in patients undergoing hematopoietic stem cell transplantation (HSCT) requiring urgent evaluation and initiation of empiric broad spectrum antibiotics (BSA). The appropriate duration of BSA for FN in patients with negative cultures and no identifiable infection remains undefined. We retrospectively analyzed allogenic and autologous HSCT patients with FN and negative infectious work-up at our facility from 2012 to 2018. The early de-escalation group (EDG) included those who had BSA de-escalation to fluoroquinolone prophylaxis at least 24 h prior to absolute neutrophil count (ANC) recovery after the patient was fever-free for at least 48 h. Among 297 patients undergoing their first HSCT who experienced FN with negative infectious work-up, 83 patients were de-escalated early with the remaining 214 in the standard of care group (SCG) whose BSA were continued until ANC was > 500. Duration of broad-spectrum antibiotics was shorter in EDG compared to SCG (3.86 days vs. 4.62 days, p = 0.03). Rates of mortality, new infections, and clinical decompensation requiring intensive care unit transfer and/or pressor use within 30 days were all similar between the two groups (0% vs. 0.4% p = 1.00, 0% vs. 1.4% p = 0.56, 13.2% vs. 8.4% p = 0.27). This indicates that it is safe to de-escalate antibiotics prior to ANC recovery, leading to less BSA exposure.