Solid organ transplantation (SOT) recipients receive immunosuppressive therapy to avoid rejection of the transplanted organ. Immunosuppressive therapy increases the risk of infections. However, no existing marker reliably reveals the status of the immune function in SOT recipients. Torque-Teno virus or Transfusion-transmitted virus (TTV) has gained attention as a possible endogenous marker of the immune function. TTV is a non-enveloped, circular single strand DNA virus, and it may be considered a part of the human virome. In a bidirectional relationship, the immune system detects TTV and TTV may also modulate the activity of immune system. These characteristics have made the virus a possible candidate indicator of immune function. In this systematic review, we describe the role and potential function of TTV viral load as an endogenous marker of the immune function and consequently the level of immune suppression in SOT recipients.

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has been associated with a high risk of adverse outcomes in solid organ transplant (SOT) recipients in the pre-vaccination era. In this retrospective cohort study, we examined the incidence and severity of COVID-19 in kidney and liver transplant recipients in Denmark in the post-vaccination era, from December 27, 2020, to December 27, 2021. We included 1428 SOT recipients with 143 cases of first-positive SARS-CoV-2 PCR test. The cumulative incidence of first-positive SARS-CoV-2 PCR test 1 year after initiation of vaccination was 10.4% (95% CI: 8.8–12.0), and the incidence was higher in kidney than in liver transplant recipients (11.6% [95% CI: 9.4–13.8] vs. 7.4% [95% CI: 5.1–9.8], p = .009). After the first-positive SARS-CoV-2 PCR test, the hospitalization rate was 31.5% (95% CI: 23.9–39.1), and 30-day all-cause mortality was 3.7% (95% CI: 0.5–6.8). Hospitalization was lower in vaccinated than in unvaccinated SOT recipients (26.4% [95% CI: 18.1–34.6] vs. 48.5% [95% CI: 31.4–65.5], p = .011), as was mortality (1.8% [95% CI: 0.0–4.3] vs. 9.1% [95% CI: 0.0–18.9], p = .047). In conclusion, SOT recipients remain at high risk of adverse outcomes after SARS-CoV-2 infections, with a lower risk observed in vaccinated than in unvaccinated SOT recipients.

Delftia acidovorans ( D. acidovorans ) is a Gram-negative bacteria that can cause infection in immunocompetent and immunocompromised individuals. The current knowledge comes mainly from case reports and case series.

Respiratory syncytial virus (RSV) and influenza cause significant health challenges, particularly for individuals with comorbid conditions and older adults. However, information on the clinical manifestations and outcomes of adults hospitalized with RSV in Europe remains limited. This multicenter observational cohort study of adults hospitalized with RSV or influenza A or B from March 2016 to April 2020 investigated the clinical manifestations, mortality risk factors, and association with 90-day mortality rates by logistic regression analysis after adjustment for covariates. Of 988 patients hospitalized with either virus, 353 had RSV, 347 had influenza A, and 288 had influenza B infection. Patients with RSV, compared with those with influenza A or B, were more likely to have comorbid conditions (83% for RSV vs 72% for influenza A [P = .03] and 74% for influenza B [P = .001]) or pneumonia (41% vs 29% [P = .03] and 24% [P < .001], respectively). After adjustment for covariates, RSV infection was associated with an increased all-cause mortality rate within 90 days compared with influenza B (odds ratio, 2.16 [95% confidence interval, 1.20–3.87]; P = .01) but not influenza A (1.38 [.84–2.29]; P = .21). Increasing age and present pneumonia were identified as independent mortality risk factors in patients with RSV. Older adults hospitalized with RSV infections are at a higher risk of dying within 90 days of hospitalization than patients admitted with influenza B but at a similar risk as those admitted with influenza A, emphasizing the detrimental effects and severity of older patients being infected with RSV. Our findings underscore the need for strategic testing and vaccination approaches to mitigate the impact of RSV among older adults.

Background: Bacterial and fungal bloodstream infections (BSI) are common after pediatric liver and kidney transplantations and associated with morbidity and mortality. However, knowledge about incidence rates, pathogen composition, and resistance patterns is limited. We aimed to describe the pattern of bacterial and fungal BSI in a cohort of pediatric liver and kidney transplant recipients. Methods: A prospective study of 85 pediatric liver and kidney transplant recipients transplanted from 2010 to 2017 with a total of 390 person-years of follow-up. Clinical characteristics and BSI were retrieved from national registries assuring nationwide follow-up for at least 1 year. BSI incidence rates and pathogen composition were investigated and stratified by the time post-transplantation and type of transplanted organ. Results: A total of 29 BSI were observed within the first 5 years post-transplantation with 16 different pathogens. The overall incidence rate of first BSI was 1.91 per 100 recipients per month (95% CI, 1.1–3.1) in the first year post-transplantation. The most common pathogens were Enterococcus faecium, Candida albicans, Escherichia coli, and Klebsiella pneumoniae. The pathogen composition depended on the transplanted organ with a higher proportion of BSI with Enterobacterales in kidney transplant recipients than in liver transplant recipients (67% vs. 20%, p = 0.03), while multiple pathogens were detected in the liver transplant recipients. Conclusions: BSI were common in pediatric liver and kidney transplant recipients and the pathogen composition differed between liver and kidney transplant recipients. Guidelines for empiric antibiotic therapy should consider the type of transplanted organ as well as the local resistance patterns.