Letter: Late urinary-tract infection after renal transplantation

In vivo analysis of onset and progression of retinal degeneration in the Nr2e3rd7/rd7 mouse model of enhanced S-cone sensitivity syndrome

The photoreceptor-specific nuclear receptor Nr2e3 is not expressed in Nr2e3rd7/rd7 mice, a mouse model of the recessively inherited retinal degeneration enhanced S-cone sensitivity syndrome (ESCS). We characterized in detail C57BL/6J Nr2e3rd7/rd7 mice in vivo by fundus photography, optical coherence tomography and fluorescein angiography and, post mortem, by histology and immunohistochemistry. White retinal spots and so-called 'rosettes' first appear at postnatal day (P) 12 in the dorsal retina and reach maximal expansion at P21. The highest density in 'rosettes' is observed within a region located between 100 and 350 µM from the optic nerve head. 'Rosettes' disappear between 9 to 12 months. Non-apoptotic cell death markers are detected during the slow photoreceptor degeneration, at a rate of an approximately 3% reduction of outer nuclear layer thickness per month, as observed from 7 to 31 months of age. In vivo analysis of Nr2e3rd7/rd7 Cx3cr1gfp/+ retinas identified microglial cells within 'rosettes' from P21 on. Subretinal macrophages were observed in vivo and by confocal microscopy earliest in 12-months-old Nr2e3rd7/rd7 retinas. At P21, S-opsin expression and the number of S-opsin expressing dorsal cones was increased. The dorso-ventral M-cone gradient was present in Nr2e3rd7/rd7 retinas, but M-opsin expression and M-opsin expressing cones were decreased. Retinal vasculature was normal.

Do urinary tract infections trigger chronic kidney transplant rejection in man?

PURPOSE

Urinary tract infections are frequent after kidney transplantation but little is known about the impact on long-term survival. As chronic rejection is the major cause of graft loss in the long term, we retrospectively analyzed the role of urinary tract infections in this process.

MATERIALS AND METHODS

We included in the study all adult patients who received kidney transplants at our unit between 1972 and 1991, which ensured followup of at least 5 years, and we focused on the relationship between urinary tract infections and the incidence of chronic rejection episodes. To analyze the influence of urinary tract infections on chronic rejection patients were separated into those in whom biopsy proved chronic rejection developed within the first 5 years after transplantation (chronic rejection group 225) and those without apparent signs of chronic rejection during that period (control group 351). The correlation between urinary tract infections per year and the incidence of chronic rejection was analyzed.

RESULTS

Patients with chronic rejection had more urinary tract infections per year than controls. In the first year after transplantation both groups had the highest incidence of urinary tract infections but thereafter the rate of urinary tract infections per year declined. However, the incidence consistently remained higher in the chronic rejection group. This difference reached significance by year 3 after transplantation. Furthermore, a high rate of urinary tract infections correlated with an early onset of chronic rejection.

CONCLUSIONS

Urinary tract infections are an important risk factor for the onset of chronic rejection, and early and intense treatment is critical.

Prevalence of urinary tract infection during outpatient follow-up after renal transplantation

Seven hundred and twenty-seven renal transplant patients are reviewed with respect to the occurrence of urinary tract infection (UTI) after renal transplantation. UTI was defined as the detection of both bacteriuria (10(5) CFU/ml) and pyuria (10 leukocytes/hpf). UTI developed in 11 of the inpatients (20.8%) and in 30 (4.2%) of the outpatients during a one-year period. Among outpatients, 12 had symptomatic infections, comprising seven with acute pyelonephritis and five with acute cystitis. Asymptomatic UTI was detected in 18 patients. In addition, asymptomatic bacteriuria without pyuria was observed in ten (1.4%) patients. UTI was more common in patients with diabetes, and underlying urinary tract complications were present in some patients. Administration of trimethoprim-sulfamethoxazole for about 4 months is suggested to reduce the frequency of UTI in the early period after renal transplantation.

Urinary tract infection in pediatric renal transplantation

Urinary tract infection is a frequent complication following renal transplantation and represents a potential focus for systemic infection in the immunosuppressed transplant recipient. The incidence, etiologic factors, temporal pattern, bacteriology, and prognostic significance of urinary tract infection were determined by analysis of 85 renal allografts in 69 patients. Significant bacteriuria occurred after 49 of 85 transplants (58 per cent). The incidence of infection was not related to success or source of the allograft, but was related to patient gender. Urinary tract infections developed in 68 per cent of females, while only 43 per cent of males became infected (p less than 0.05). Escherichia coli caused most first infections (30 per cent), while Pseudomonas aeruginosa and E. coli were equally responsible for recurrent infections (25 per cent each). Children with previous reconstructive urologic surgery had similar allograft success (63 per cent) and infection rates (53 per cent) as our other children (61 per cent and 58 per cent, respectively). No apparent correlation was noted between episodes of infection and graft rejection. Thorough preoperative assessment and preparation and prompt, specific treatment minimize the adverse influences of urinary tract infection.

Anaerobic bacteriuria in renal transplantation

Renal allograft recipients were studied prospectively utilizing improved culture techniques to investigate anaerobic bacteriuria. The study population was compared with a population of patients with chronic renal insufficiency and end stage renal disease. The over-all incidence of anaerobic urinary tract infection was 7.5 per cent while the over-all incidence of aerobic urinary tract infection was 23.5 per cent. Patients with cadaver renal transplants during the early postoperative period had the highest incidnece of both anaerobic (42.9 per cent) and aerobic (71.4 per cent) urinary tract infection of all groups. The potential association between significant anaerobic bacteriuria during the first postoperative month and poor prognosis for cadaver renal allografts merits further investigation.

One hundred kidney transplants in the Belfast city hospital

100 kidney transplants have been carried out on 91 patients (7 had 2 transplants and 2 had 3 transplants). 4 transplants were from living related donors and 96 from cadavers. 76 patients survive, all but one with functioning kidneys. The cumulative survival of patients was 82% at 2 years and 80-7% at 5 years. 8 patients died with functioning grafts, and 2 of the other deaths took place more than 3 months after removal of a rejected kidney and resumption of haemodialysis. There were no deaths from sepsis in the first 60 days after transplantation. The cumulative survival of all grafts was 82-1% at 2 and 5 years. The cumulative survival of first grafts was 82-5% at 2 and 5 years.

Urinary infection in kidney transplantation

Urinary tract infection is the most frequent complication following renal transplantation and is important in the etiology of post-transplantation sepsis. The 87 renal homografts done in 1974 at The New York Hospital-Cornell Medical Center were reviewed retrospectively, with at least one year follow-up, in all cases, with particular attention to factors relating urinary tract infection to ultimate success or failure of the renal graft. The over-all incidence of urinary tract infection was 61%. Early infection was associated with a particularly poor prognosis for graft survival. Most patients with urinary infections after successful transplantation experience a combination of both early and late infections. Anatomic factors constitute a remediable cause of urinary infections after transplantation and should be searched for in cases of multiple, recurrent infections, de novo hypertension, or deterioration of previously stable graft function. There were significant differences in the bacteriologic spectrum of urinary tract infections associated with successful transplants as opposed to unsuccessful transplants.