T. James Beattie

Quantitative viral load monitoring and cidofovir therapy for the management of BK virus-associated nephropathy in children and adults.

Background. BK virus (BKV)-associated nephropathy (BKVAN) has been increasingly recognized as an important cause of renal transplant dysfunction. We report the role of quantitative viral load monitoring in the management of BKVAN. Methods. We developed a real-time quantitative polymerase chain reaction (PCR) assay for BKV detection in urine and plasma. Four renal allograft recipients, including two children, with BKVAN were treated with low-dose cidofovir and followed prospectively. Results. The PCR assay showed a detection limit of 10 viral copies with an intra-assay coefficient of variation of 19%. All four patients with BKVAN demonstrated intranuclear inclusions on allograft biopsy and a progressive rise in serum creatinine; three patients underwent multiple biopsies before the diagnosis of BKVAN was made. Three of the patients experienced a “viral syndrome” before the onset of renal dysfunction. One child also demonstrated an echogenic renal mass. All of the patients demonstrated strongly positive urinary PCR values (>100,000 copies/&mgr;L). BKV DNA was also detected in the plasma of three patients. All the patients were treated with intravenous low-dose cidofovir (0.25–1 mg/kg per dose, every 2–3 weeks, without probenecid). BK viruria resolved within 4 to 12 weeks (after 1–4 doses) of the cidofovir therapy, and all patients remain with stable renal function 6 to 26 months posttherapy. Conclusions. Quantitative PCR for BKV is a sensitive and reliable method for following the course of the infection in renal transplant patients. In addition, cidofovir therapy may be useful in the treatment of some of these patients, and its role needs to be investigated further.

Renal venous thrombosis in infancy: long-term follow-up.

Sixteen children (11 male, 5 female) who developed renal venous thrombosis in the neonatal period or early infancy have been followed for periods varying from 29 months to 16 years (median 12 years) after initial diagnosis. Twelve patients presented with a hyperosmolar state, and in 4 the ilness was preceded by severe birth asphyxia. The diagnosis was based on the findings of clinical and/or radiological renal enlargement (15 cases), haematuria (16 cases) and elevation in plasma urea (16 cases). Thrombocytopenia (13 cases), red cell fragmentation (13 cases) and oliguria (13 cases) were frequent associated findings. All 16 patients survived the acute illness, 1 patient died 3 years later from an unrelated event. On follow-up evaluation, 11 patients have normal renal function (glomerular filtration rate >80 ml/min per 1.73 m2), 5 developed hypertension, 2 of whom responded to unilateral nephrectomy. Urinary concentrating capacity was subnormal (<800 mosmol/kg) in 7 of the 15 cases studied. Follow-up renal imaging studies were undertaken in 14 patients, and the imaging procedure was normal in only 2 of these. Of the remainder, 8 showed unilateral abnormality and 4 bilateral abnormality. Intellectual development was normal in 12 patients, mildly impaired in 1, and severely impaired in 3.

Early Volume Expansion During Diarrhea and Relative Nephroprotection During Subsequent Hemolytic Uremic Syndrome

OBJECTIVES To determine if interventions during the pre-hemolytic uremic syndrome (HUS) diarrhea phase are associated with maintenance of urine output during HUS. DESIGN Prospective observational cohort study. SETTINGS Eleven pediatric hospitals in the United States and Scotland. PARTICIPANTS Children younger than 18 years with diarrhea-associated HUS (hematocrit level <30% with smear evidence of intravascular erythrocyte destruction), thrombocytopenia (platelet count <150 × 10³/mm³), and impaired renal function (serum creatinine concentration > upper limit of reference range for age). INTERVENTIONS Intravenous fluid was given within the first 4 days of the onset of diarrhea. OUTCOME MEASURE Presence or absence of oligoanuria (urine output ≤ 0.5 mL/kg/h for >1 day). RESULTS The overall oligoanuric rate of the 50 participants was 68%, but was 84% among those who received no intravenous fluids in the first 4 days of illness. The relative risk of oligoanuria when fluids were not given in this interval was 1.6 (95% confidence interval, 1.1-2.4; P = .02). Children with oligoanuric HUS were given less total intravenous fluid (r = -0.32; P = .02) and sodium (r = -0.27; P = .05) in the first 4 days of illness than those without oligoanuria. In multivariable analysis, the most significant covariate was volume infused, but volume and sodium strongly covaried. CONCLUSIONS Intravenous volume expansion is an underused intervention that could decrease the frequency of oligoanuric renal failure in patients at risk of HUS.

A prospective study of children with first acute symptomatic E. coli urinary tract infection. Early 99mtechnetium dimercaptosuccinic acid scan appearances.

ABSTRACT. Between 1985 and 1987102 children, age 0–14 years, presented with a first acute symptomatic E. coliurinary tract infection. Investigations included early 99mtechnetium dimercaptosuccinic acid (DMSA) scan (which was performed at a median of 27 days), ultrasonography, micturating cysto‐urethrography and indirect voiding radionuclide cystography using 99mTc DTPA. Follow‐up DMSA scan was carried out after 6 months. Twenty‐one of 102 of initial DMSA studies showed diminished uptake of radionuclide and 12 showed cortical scarring. Twenty‐nine patients had significant vesicoureteral reflux (VUR). The finding of diminished uptake on the initial scan was significantly associated with fever, systemic upset, length of symptoms and a peripheral blood leucocytosis, (p<0.05). In addition the finding was associated with fever and loin pain in the older child. Both diminished uptake and scarring were more common in refluxing kidney units. We propose that, in children with UTI, diminished uptake on early DMSA scan localises infection in the renal parenchyma.

Accuracy of clean-catch urine collection in infancy

OBJECTIVE To compare the accuracy of cultures of urine obtained by clean-catch urine (CCU) collection and suprapubic aspiration (SPA) in infants. DESIGN Prospective case series undertaken in a pediatric teaching hospital and associated neonatal unit. Fifty-eight paired urine cultures (CCU collection and SPA) were obtained from 49 infants with suspected urinary tract infection. The primary outcome measure was the presence or absence of significant bacteriuria on both CCU collection and SPA; secondary outcome measures were the success of SPA with ultrasound guidance compared with aspiration without ultrasound guidance. Statistical analysis was done by using a chi(2) test. RESULTS A false-positive rate of 5% and a false-negative rate of 12% were recorded. Sensitivity was 88.9% (95% CI 65.3-98.6), and specificity was 95.0% (95 CI% 83.1-99. 4). Ultrasound-assisted SPA was successful in 26 of 28 patients (93%) and in 13 of 21 patients (62%) when SPA was performed without ultrasound (chi(2) = 7.08, P =.008). CONCLUSIONS We conclude that there is a good association in results of culture of urine obtained by CCU collection and SPA and would encourage the use of the CCU technique.

Complement activation in Henoch-Schönlein purpura.

Abstract. The pathogenetic mechanism underlying Henoch-Schönlein purpura (HSP) is poorly understood. Complement activation has been thought to have a role, but despite the demonstration of complement components in skin and renal biopsy material, serological evidence of complement activation is not convincing. We have assessed complement activation in 64 children with acute HSP. We used an enzyme-linked immunosorbent assay to measure plasma levels of three multimolecular complement activation protein (CAP) complexes: C1r: C1s: C1-inhibitor, C3bP and C5b-9. We found no significant difference between the levels of CAPs in children with acute HSP and a control group of children. This study does not support a role for complement activation in the pathogenesis of HSP.

Sorbitol-fermenting Escherichia coli O157, Scotland.

To the Editor: Verotoxin-producing Escherichia coli (VTEC) of serogroup O157 causes severe gastrointestinal and renal illness; clinical signs may be mild diarrhea, hemorrhagic colitis, or hemolytic uremic syndrome (HUS). Typically, 10%–15% of reported VTEC infections quickly progress to HUS (1). Sorbitol-fermenting (SF)–O157 strains have emerged in continental Europe (2,3). Some evidence suggests that SF-O157 is more frequently associated with HUS than are non-sorbitol–fermenting strains (3–6). SF-O157 shows increased adherence to colonic epithelial cells and may in turn cause a more potent inflammatory host response, resulting in a higher risk for HUS (4). The potentially greater virulence of SF-O157 requires urgent identification of its reservoir(s) and vehicle(s) of infection, as well as determination of genetic or other predisposing factors for infection with this strain. To understand whether the host pathophysiologic responses to SF-O157 and non–SF-O157 strains differ, we analyzed a cohort of children with HUS who were infected with E. coli O157. During April and May 2006, Health Protection Scotland (HPS) identified 18 cases of verotoxin-producing SF-O157 infection in Scotland, 13 of which were associated with a nursery. HUS developed in 8 of the 18 patients; those with thrombotic microangiopathy were admitted to the renal unit of a specialist pediatric hospital, which immediately reports cases of HUS to HPS as part of national surveillance (7). To test the hypothesis that SF-O157 was more virulent than non–SF-O157, we performed an age-matched, nested case–case study of HUS case-patients and analyzed host clinical markers, treatment, and outcomes from SF-O157 and non–SF-O157 cases in 2006. Clinical questionnaires, patient information sheets, and consent forms were completed by clinicians for each case-patient and returned to HPS; data were entered into a database in Epi Info version 6 (Centers for Disease Control and Prevention, Atlanta, GA, USA). Statistical analysis by t test showed that nadirs for serum albumin were significantly higher for children with SF-O157 HUS (p = 0.03; Table) than for children with non–SF-O157 HUS and that children with SF-O157 HUS had significantly more sessions of hemodialysis than did children with non–SF-O157 HUS (p = 0.01; Table). All case-patients were oligoanuric; the 2 groups did not differ with respect to this parameter. Initial signs and symptoms were similar for both sets of patients, i.e., classic VTEC symptoms of bloody diarrhea and abdominal pain. This finding is in acccordance with those of other studies of SF-O157 outbreaks, which also noted signs and symptoms compatible with VTEC-associated gastroenteritis (5,6). Table Characteristics of patients infected with non–SF-O157 versus SF-O157 Escherichia coli, Scotland, 2006* Our study highlights a number of lessons. Medical practitioners rarely have the opportunity to recognize patients at such an appreciable and predictable risk of progressing rapidly to anuric renal failure as they do when they see children with early O157 infection. Failure to appreciate the potential gravity of O157 infection and the possible development of HUS may result in avoidable illness and even death. Our investigation of the prehospital management of SF-O157 and non–SF-O157 in this cohort found no difference in pharmacologic intervention or duration of delay in admission to hospital. Our study has limitations. A number of patients in the cohort were prescribed antimicrobial drugs and/or antimotility drugs or were sent home from the local hospital without hospital admission or further monitoring; such actions potentially exacerbate clinical outcomes (1,8). We recognize that comparison of the SF-O157 outbreak strain with non–SF-O157 strains (some of which caused sporadic cases) may be a potential confounding factor in the analysis. However, recently published work has indicated no statistically significant differences in the verotoxin proteins encoded by SF-O157 or non–SF-O157 strains or in their level of toxicity (9). Other virulence factors may contribute to increased likelihood of HUS (4). Our data suggest that infection with SF-O157 results in less severe colitis than does the more common non–SF-O157 infection. Less severe colitis could result in a lower risk for renal disease because less verotoxin would be translocated into the bloodstream and bound to the kidneys. However, patients infected with SF-O157 had anuria for longer periods and consequently had longer sessions of peritoneal and hemodialysis. Although unknown bacterial or host inflammatory cytokines may contribute to enhanced disease progression, this observation is surprising and requires further investigation. Additional research is needed to learn more about the virulence of SF-O157 strains and establish other host factors that contribute to disease progression.

Highly Virulent Escherichia coli O26, Scotland

To the Editor: Hemolytic uremic syndrome (HUS) is a rare disorder characterized by microangiopathic hemolytic anemia, microthrombi, and multiorgan injury. HUS is one of the commonest causes of acute renal failure in children worldwide and is most frequently precipitated by infection with verotoxin-producing Escherichia coli (VTEC) such as E. coli O157 (1). However, non-O157 VTEC serotypes have been increasingly found in the development of HUS (2–4). Although previous surveillance of childhood HUS in Scotland identified E. coli O157 in >90% of cases, non-O157 serotypes have also been associated with HUS (5). In 2010, several particularly severe cases of HUS were reported to Health Protection Scotland by a consultant pediatric nephrologist. Subsequent tests identified the pathogen in these cases as E. coli O26. However, in a recent study of pediatric HUS cases in Europe, children infected with E. coli O26 did not exhibit different clinical signs and symptoms from patients infected with other VTEC serotypes (6). To establish whether the host pathophysiologic responses to E. coli O157 and E. coli O26 strains differed, we analyzed a cohort of children with HUS who were infected with these VTEC serotypes. In Scotland, most patients with pediatric thrombotic microangiopathy are referred to a specialist pediatric hospital, which immediately reports cases of HUS to Health Protection Scotland as part of national surveillance. To test the hypothesis that E. coli O26 was more virulent than E. coli O157, we performed an age-matched, nested case–case study of HUS patients and compared host clinical markers, treatment, and outcomes from pediatric cases in 2010. Data collection has been described elsewhere (5). The statistical significances of associations between categorical variables were investigated by using χ2, Fisher exact, Mann-Whitney, or t tests. All analyses were performed by using SPSS version 11 (SPSS Inc., Chicago, IL, USA) with a significance level of 5%. Although initial signs and symptoms were similar for both sets of cases, i.e., bloody diarrhea and abdominal pain, statistical analysis showed that children with O26-HUS were more likely to have neurologic complications and diabetes mellitus and require admission to the intensive care unit than O157-HUS patients (p = 0.02 for neurologic complications and diabetes and p = 0.04 for admission to an intensive treatment unit; Table). Table Characteristics of infection in children with Escherichia coli O157 versus E. coli O26, Scotland, 2010* All patients with HUS were oligoanuric, and the 2 groups did not differ with respect to this parameter. However, O26-HUS patients had significantly longer periods of anuria than O157-HUS patients (p = 0.04; Table) and were more likely to require treatment with hemofiltration than with peritoneal or hemodialysis (p = 0.001; Table). One patient with O26-HUS also experienced cardiomyopathy resulting in reduced left ventricular function. Our study illustrates the potential for increased severity of E. coli O26 infection in children. In Scotland, HUS is more commonly associated with E. coli O157 infection, and the outcome for children infected with this pathogen is much better than that reported in other studies (7,8). In this study, the clinical severity and outcomes for the children with O26-HUS were worse than for children requiring treatment for O157-HUS. We investigated the prehospital management of E. coli O157 and O26 patients in this cohort and found no difference in pharmacologic intervention or duration of delay in admission to hospital. In our cohort, vtx1 and vtx2 genes were detected in isolates from 2 of 3 patients. A diagnosis was made in the third patient by detection of E. coli O26 lipopolysaccharide–specific immunoglobulin M in serum; it was therefore not possible to confirm the presence of vtx genes. However, it is not unusual for VTEC to be undetectable in stool samples from patients with HUS, most likely because of intrahost bacteriophage lysis. Therefore, serodiagnosis of VTEC is considered a necessary adjunct to bacteriological confirmation of infection (9). A recent study suggests E. coli O26 exists as a highly dynamic group of organisms that can undergo verotoxin gene loss and be transferred during infection in humans, resulting in new pathogenic clones (10). Therefore, vtx2 gene acquisition by E. coli O26 may have contributed to increased virulence. Our study was limited by the small number of patients with pediatric O26-HUS. However, given the severity of the complications experienced by the children in this cohort, we believe it is necessary to communicate these findings promptly to the international community. We suggest that infection with E. coli O26 in children can result in more severe and complicated forms of HUS than those caused by E. coli O157. In contrast to the findings of Gerber et al., we found that there was a significant difference in neurologic complications between the 2 groups (2). Epidemiologic investigations found that 2 of the 3 children lived on farms and may have acquired infection while playing near their homes (the other was acquired through foreign travel). Risk communication of VTEC infection to parents of young children who live in farming communities remains problematic, perhaps because of the perception that immunity has been acquired. Although this suggestion may be true for adults, children are likely to be immunologically naive. Salient public health messages on simple precautionary behavior need to be regularly reinforced because prevention of VTEC infection prevents HUS.

Renal transplant biopsy specimen adequacy in a paediatric population

Updated guidelines on the diagnosis of acute allograft rejection including criteria for biopsy specimen adequacy were published in 1999. We sought to determine the adequacy of specimens in paediatric transplant patients and identify factors influencing adequacy. All renal transplant biopsies performed between 1998 and 2003 were classified as adequate (n =25), minimal (n =19) or inadequate (n =27) in accordance with the Banff 97 criteria, and the histological diagnoses were documented. The effect on specimen adequacy of grade of operator, method of sedation, age of child, needle gauge, number of cores and total core length was then investigated. Overall, a minimal or adequate specimen was obtained in 62% of cases. No histological diagnosis could be made in 30% of all specimens, just over half of which were inadequate. Higher rates of rejection were found in adequate (52%) than inadequate (33%) samples. The grade of operator (p =0.498), the age of the child at the time of biopsy (p =0.815) and type of sedation (p =0.188) did not affect adequacy. More than one core was obtained in 38 (54%) cases, and this was significantly associated with specimen adequacy (p <0.0005) as was longer total core length (p =0.002). Clinical features in isolation are not sufficient for the diagnosis of acute allograft rejection. Renal biopsy remains the gold standard and relies on adequate specimen collection. Our data shows that specimen adequacy according to the Banff 97 guidelines is achievable in children and that more than one core at the time of sampling significantly improves this achievement. Adequate sampling reduces the risk of an inconclusive histological diagnosis.

Use of rapamycin in a transplant patient who developed cyclosporin neurotoxicity

Abstract. We describe the case of a paediatric kidney transplant patient who developed cyclosporin neurotoxicity on day 7 post-transplant. Consequently, her cyclosporin was stopped and she was commenced on rapamycin. Over the next 3 weeks her creatinine remained elevated and she had several episodes of biopsy proven rejection, despite increasing the initial dose of rapamycin by tenfold. Her whole blood rapamycin levels also remained well below the target range of 10–20 ng/ml. On day 38 post-transplant, the decision was made to add tacrolimus to her immunosuppression. At the same time, phenytoin, which had been commenced during her episode of cyclosporin neurotoxicity, was withdrawn. After this point her rapamycin blood levels rapidly increased to within the therapeutic range and she improved clinically. We propose that phenytoin, as a p450 cytochrome enzyme inducer, increased the metabolism of rapamycin in this patient and hence decreased the initial therapeutic effectiveness of this drug.