A Comprehensive Review of Infections in Older Kidney Transplant Recipients

Effect of increasing age and ureteral stent implantation on urinary tract infections after kidney transplantation - update of recent literature

PURPOSE OF REVIEW

This review aims to present the recent literature regarding effects of aging and ureteral stent implantation (UrS) on the risk of urinary tract infections (UTIs) in kidney transplant (KTX) recipients.

RECENT FINDINGS

UTIs in kidney transplant recipients remain a clinical challenge and represent a leading cause of morbidity, hospitalization rates, and mortality. Higher age was described as a significant risk factor for UTIs in several studies including a recent Brazilian analysis, indicating a 3.6%/years of age increase in UTI risk. Subsequently, a large meta-analysis, published in 2023, confirmed the correlation between older age and elevated UTI risk. The Swiss Transplant Cohort Study in 2022, largest of its kind, similarly confirmed a link between advanced age and heightened risk of recurrent UTIs in KTX. A recent prospective study highlighted UrS placement as a modifiable risk factor, emphasizing the need for careful consideration and antibiotic prophylaxis. Additionally, the type of stents played a crucial role, with external stents associated with a 1.69 times higher UTI risk. The challenge of determining optimal UrS removal timing further complicates posttransplant care, with insufficient evidence to guide practices.

SUMMARY

The aging population of KTX recipients requires a personalized approach to effectively reduce and manage UTIs as one of the most important complications following KTX. Prophylactic stent implantation is successful in lowering ureteral complications, however, is associated with an increased incidence of UTIs. To reduce the increased risk of UTIs, the length of stent insertion requires strict supervision and maintenance.

Induction immunosuppression and outcome in kidney transplant recipients with early COVID-19 after transplantation

COVID-19 in kidney transplants has a high risk of complications and mortality, especially in older recipients diagnosed during the early period after transplantation. Management of immunosuppression has been challenging during the pandemic. We investigated the impact of induction immunosuppression, either basiliximab or thymoglobulin, on the clinical evolution of kidney transplants developing COVID-19 during the early period after transplantation. Kidney transplant recipients with less than 6 months with a functioning graft diagnosed of COVID-19 from the initial pandemic outbreak (March 2020) until July 31st, 2021 from different Spanish centers participating in a nationwide registry. A total of 127 patients from 17 Spanish centers developed COVID-19 during the first 6 months after transplantation, 73 (57.5%) received basiliximab and 54 (42.5%) thymoglobulin. Demographics were not different between groups but patients receiving thymoglobulin were more sensitized (cPRA of 32.7±40.8% vs. 5.6±18.5%) and were more frequently re-transplants (30% vs. 4%). Recipients older than 65 years treated with thymoglobulin showed the highest rate of acute respiratory distress syndrome (64.7% vs. 37.1% for older recipients receiving thymoglobulin and basiliximab [p<0.05], and 23.7% and 18.9% for young recipients receiving basiliximab and thymoglobulin [p>0.05]) and the poorest survival (mortality rate of 64.7% and 42.9% for older recipients treated with thymoglobulin and basiliximab, respectively [p<0.05], and 8.1% and 10.5% for young recipients treated with thymoglobulin and basiliximab [p>0.05]). Older recipients treated with thymoglobulin showed the poorest survival in the Cox's regression model adjusted for comorbidities. Thus, thymoglobulin should be used with caution in older recipients during the present pandemic era.

Validation of a dried blood spot method to measure tacrolimus concentrations in small volumes of mouse blood

Background: The small blood volume of mice complicates tacrolimus pharmacokinetic studies in these animals. Here we explored dried blood spot (DBS) as a novel method to measure tacrolimus blood concentrations in mice. DBS samples were collected from three sampling sites (cheek, tail and heart) and compared with heart whole blood samples measured via LC-MS/MS. Results: Tacrolimus concentrations in the whole blood samples ranged from 2.56 to 27.64 μg/l. DBS of cheek vein blood was the most reliable sampling site, with a mean bias of 0.15 μg/l (95% CI: -4.20 to 4.50). Conclusion: The DBS cheek method can be used for serial monitoring of tacrolimus blood concentrations in mice, offering an animal-friendly method for tacrolimus pharmacokinetic studies in mice.