Clinical pyelonephritis and focal renal scarring. A selected review of pathogenesis, prevention, and prognosis

Urinary tract infections. Old and new concepts

The recommendations for evaluation and management of pediatric patients with UTIs are summarized in Table 5. These recommendations were designed to minimize the risk of kidney damage in children with UTIs based on current perceptions of the pathogenesis of renal injury. The children at greatest risk for kidney damage are the infants and young children with febrile UTIs in whom effective treatment is delayed, those with gross VUR, and those with anatomic or neurogenic urinary tract obstruction. These recommendations likely will be modified as more is learned about the pathogenesis of renal injury associated with UTIs, as new therapeutic approaches are developed, and as imaging technology improves.

The intravenous urogram in the detection and evaluation of renal damage following urinary tract infection

Intravenous urography (IVU) still provides the most comprehensive structural assessment of the urinary tract. In particular, the radiological renal appearances approximate closely to the morphology of the renal scarring of reflux nephropathy or chronic atrophic pyelonephritis. It also provides reproducible renal measurements for follow-up assessment of renal growth and scarring. It is now less often used for first-line investigation of the acute urinary tract infection (UTI) because the swelling accompanying acute renal involvement is less easily recognised than the areas of defective function demonstrated on 99mtechnetium-dimercaptosuccinic acid (DMSA) studies. Also IVU contributes a higher radiation dose when calculated for full IVU (dependent on the number of films exposed) and there is a slight risk of side effects from injected contrast media, reduced by using non-ionic compounds. Because of its value in confirming such a serious diagnosis as renal scarring, suspected on ultrasonography or DMSA scintigraphy, modification of the technique of IVU with adequate preparation and the use of a reduced number of films, or single films localised to the renal areas, should be considered. Expertise in the interpretation of IVU must also be maintained because of the ancillary information regarding bowel and bladder function, the spine and evidence of stones, pertinent to the management of children with UTI and renal scarring. IVU and DMSA study remain complementary investigations.

Diagnostic imaging in children with urinary tract infection: the role of intravenous urography

Ninety children referred to hospital with urinary tract infection (UTI) were investigated by iv urography (IVU), ultrasonography (US) and 99mTc dimercaptosuccinic acid scan (DMSA). Fifty-eight children also underwent micturating cystourethrography (MCUG). In 36 (40%) of the children, at least one result was abnormal. Abnormal findings were found in 29 children with IVU, in 10 with US and in 16 with DMSA. Six of the 58 children had vesicoureteric reflux (VUR) in 8 kidneys. In 16 children, IVU was the only examination with an abnormal result, and in 10 of these the findings were considered important for treatment or prognosis. IVU is an important supplement to US and DMSA in investigation programs for children with UTI. IVU should be performed in cases of renal scars, dilatations or in children with recurrent infections.

The selective use of dimercaptosuccinic acid renal scans in children with vesicoureteral reflux

Dimercaptosuccinic acid (DMSA) renal scans were performed on 75 children (115 refluxing renal units) to determine the efficacy of routine scanning in patients with various grades of vesicoureteral reflux. Cystourethrography demonstrated grades I and II reflux in 75 renal units and grades III to V in 40. Of the patients 51 presented with febrile urinary tract infection and 24 were asymptomatic (patients presenting with nonfebrile urinary tract infections or those undergoing sibling screening). Renal ultrasounds were performed in 60 patients. All patients were initially managed with medical therapy and 19 (25%) ultimately underwent antireflux surgery. DMSA scans demonstrated scarring in 17 of 40 renal units (43%) of patients with high grade vesicoureteral reflux and 6 of 75 renal units (8%) of those with low grade reflux. Renal ultrasounds that were interpreted as normal always correlated to a normal DMSA scan in asymptomatic patients. In patients presenting with febrile urinary tract infections the correlation between ultrasound and DMSA scan was inconsistent. We advocate a tailored approach in the evaluation of patients with vesicoureteral reflux. Renal sonography may be sufficient in the assessment of renal scarring in asymptomatic patients with reflux and those with low grade reflux. Conversely, in patients with high grade vesicoureteral reflux, a history of febrile urinary tract infections and abnormal renal ultrasound DMSA renal scans appear to be most useful.

Urine testing in young febrile children: a risk-benefit analysis

OBJECTIVE

To assess the relative risks and benefits of 10 potential urine testing strategies (compared with no testing) involving urinalysis and urine culture for children aged 3 to 24 months with fever but no focus of bacterial infection.

DESIGN

Decision analysis based on the literature. The 10 testing strategies consist of five pairs; within each pair of strategies, one calls for urinalysis and urine culture of a clean-voided (bag) specimen, and urine culture, and in the other, the urine specimen is sent for culture only if the result of the urinalysis is abnormal. The five pairs differ in selectivity for testing: all children, girls only, temperature > or = 39 degrees C only, fever only (no respiratory or gastrointestinal symptoms), or temperature > or = 40 degrees C only. The results of the decision analysis are expressed as the preventive fraction (the proportion of cases prevented) for end-stage renal disease (ESRD) and hypertension, and as two risk/benefit (RB) ratios: the number of children tested per case of ESRD prevented (RB1), and the number of children with false-positive diagnosis and treatment of urinary tract infection per case of ESRD prevented (RB2).

RESULTS

On the basis of the available evidence, none of the testing strategies succeeds in preventing the majority of cases of ESRD and hypertension (preventive fraction = 0.10 to 0.50), and all are associated with high ratios of children tested (RB1 = 4167 to 12,500) and false-positive diagnosis and treatment (RB2 = 563 to 1800) per case of ESRD prevented. A strategy of combined urinalysis and urine culture in children with temperature > or = 39 degrees C is associated with the most favorable RB profile: preventive fraction = 0.45, RB1 = 5556; RB2 = 776. Sensitivity analyses indicate that the relative ranking of the strategies is relatively robust in regard to alterations in the estimates of the sensitivity or specificity of the urinalysis, the relative risk of renal scarring associated with delayed diagnosis and treatment, and the risk of scarring-induced hypertension or ESRD.

CONCLUSIONS

Up to 50% of the long-term sequelae of occult urinary tract infections in young febrile children appear preventable by urine testing, but even the most favorable strategies require testing of thousands of children, and unnecessarily treating hundreds, for every case prevented. Our analysis reveals those strategies with more favorable RB profiles and emphasizes the need for rapid and convenient urine tests with much higher sensitivity and specificity or the need for less aggressive management strategies for febrile infants and young children with urinary tract infection.

Retrospective study of children with renal scarring associated with reflux and urinary infection

OBJECTIVE

To review the histories of children with bilateral renal scarring and severe vesicoureteric reflux to determine whether an improvement in early management might reduce the risk of scarring.

DESIGN

Retrospective study of medical records and discussion with parents.

SETTING

Outpatient departments of two teaching hospitals.

PATIENTS

52 children aged 1-12 years participating in a randomised comparison of medical and surgical management. All had a history of symptomatic urinary tract infection. Two thirds presented with fever and two with hypertension or renal failure. In only one out of 32 children examined by antenatal ultrasonography was an abnormality suspected.

RESULTS

There was delay in diagnosis or appropriate imaging or effective treatment of urinary infection in 50 of the 52 children. In 41 there was delay in diagnosis; there was delay in treating a confirmed infection in 45; no antibacterial prophylaxis was prescribed before imaging in 28; and investigation of the urinary tract was delayed in 33. The severity of scarring was significantly related to delay in diagnosis (chi 2 for trend 7.43, P = 0.01). Four children of mothers known to have reflux nephropathy were not investigated until they developed urinary tract infection.

CONCLUSIONS

Efforts to reduce the incidence and severity of renal scarring should be directed towards rapid diagnosis and effective early management of urinary tract infection in infancy and childhood. Siblings and offspring of known patients with severe reflux nephropathy should be investigated for reflux.

Congenital renal damage associated with primary vesicoureteral reflux detected prenatally in male infants

To assess the course of vesicoureteral reflux, we performed cystography, renal scintigraphy, and urography in all neonates with the prenatal diagnosis of renal pelvic dilation and revealed the presence of primary reflux (grades I to V) in 27 cases. Higher grades of reflux were associated with congenital renal damage, as shown by reduced tracer uptake during scintigraphy. Reflux was diagnosed more frequently in male infants (male/female ratio, 6:1), in many of whom bladder abnormalities were found by cystography. In another group of seven infants, in whom the reflux was associated with other urologic abnormalities, there was no sex prevalence. We conclude that severe primary reflux associated with hydronephrosis usually affects male infants and may be due to abnormal embryologic development of the male urethra, and that the kidney damage is primary and not the result of urinary tract infections. This pattern differs from that of vesicoureteric reflux diagnosed at an older age, which is observed most commonly in female patients.

Pyuria and bacteriuria in urine specimens obtained by catheter from young children with fever

Results of urinalysis and culture of 2181 urine specimens obtained by catheter from febrile children aged less than 24 months were analyzed to determine the following: (1) an optimal cutoff point in considering a bacterial colony count clinically "significant," (2) the accuracy of leukocyte esterase and nitrite tests in identification of pyuria and bacteriuria, and (3) the utility of pyuria (defined as > or = 10 leukocytes/mm3) in the discrimination of urinary tract infection from asymptomatic bacteriuria. Among 110 urine cultures with > or = 10,000 colony-forming units per milliliter, 92 (84%) had > or = 100,000 CFU/ml, 10 (9%) had 50,000 to 99,000 CFU/CFU/ml and 8 (7%) had 10,000 to 49,000 CFU/ml. Urine specimens with 1000 to 49,000 CFU/ml were more likely than specimens with > or = 50,000 CFU/ml to yield Gram-positive or mixed organisms (36/60 vs 7/109; p < 0.001). A count of < 10 leukocytes/mm3 was almost invariably associated with a sterile culture; a count of > or = 10 leukocytes/mm3 was found in 93 of 102 patients with > or = 50,000 CFU/ml. The dipstick leukocyte esterase test had sensitivities of 52.9% and 66.7% in detecting > or = 10 leukocytes/mm3 and > or = 20 leukocytes/mm3, respectively. The dipstick nitrite test had a sensitivity of 31.4% in detecting bacteriuria (> or = 50,000 CFU/ml). Acute pyelonephritis was diagnosed by a renal scan with dimercaptosuccinic acid labeled with technetium 99m in 50 (77%) of 65 patients with > or = 10 leukocytes/mm3 but in none of five patients with < 10 leukocytes/mm3 (p < 0.01). The findings in these five patients were consistent with colonization of the urinary tract rather than infection. For urine specimens obtained by catheter, we believe that urinary tract infection is best defined by both a leukocyte count > or 10/mm3 and a CFU count > or = 50,000/ml. This definition almost always discriminates among true urinary tract infection, bacteriuria resulting from contamination of the urine specimen, and asymptomatic bacteriuria.

Renal scarring after acute pyelonephritis

Seventy six children, 18 boys and 58 girls, aged 0-15.9 (median 1.0) years, with acute pyelonephritis were prospectively studied with a technetium-99m dimercaptosuccinic acid (DMSA) scan during infection and two months later. Fifty nine of these children were also studied two years after the infection. Seventeen children with a normal DMSA scan during infection or at two months after infection, or both, were not investigated by a DMSA scan at two years after acute pyelonephritis. A micturition cystourethrogram was performed in all the children after two months. Changes on the DMSA scan were found in 65 (86%) children during acute pyelonephritis, in 45 (59%) children at two months, and in 28 (37%) children at two years after infection. Vesicoureteric reflux (VUR) was found in 19 (25%) children at two months. Renal scarring was significantly correlated with the presence of gross VUR and recurrent pyelonephritis, but 62% of the scarred kidneys were drained by non-refluxing ureters. Children with scars were older at the time of acute pyelonephritis than those without scars but no difference was found between the groups with regard to duration of illness, levels of C reactive protein and maximum white cell count, glomerular filtration rate, nor renal concentration capacity at the time of infection. It is concluded that renal scarring after acute pyelonephritis in children is more common than has been previously thought. Although children with gross VUR and recurrent pyelonephritis are at the greatest risk, renal scarring is more often seen without these risk factors.

Prevalence of urinary tract infection in febrile infants

Urinary tract infection (UTI), a relatively common cause of fever in infancy, usually consists of pyelonephritis and may cause permanent renal damage. This study assessed (1) the prevalence of UTI in febrile infants (temperature > or = 38.3 degrees C) with differing demographic and clinical characteristics and (2) the usefulness of urinalysis in diagnosing UTI. We diagnosed UTI in 50 (5.3%) of 945 febrile infants if we found > or = 10,000 colony-forming units of a single pathogen per milliliter in a urine specimen obtained by catheterization. Prevalences were similar in (1) infants aged < or = 2 months undergoing examination for sepsis (4.6%), (2) infants aged > 2 months in whom UTI was suspected, usually because no source of fever was apparent (5.9%), and (3) infants with no suspected UTI, most of whom had other illnesses (5.1%). Female and white infants had significantly more UTIs, respectively, than male and black infants. In all, 17% of white female infants with temperature > or = 39 degrees C had UTI, significantly more (p < 0.05) than any other grouping of infants by sex, race, and temperature. Febrile infants with no apparent source of fever were twice as likely to have UTI (7.5%) as those with a possible source of fever such as otitis media (3.5%) (p = 0.02). Only 1 (1.6%) of 62 subjects with an unequivocal source of fever, such as meningitis, had UTI. As indicators of UTI, pyuria and bacteriuria had sensitivities of 54% and 86% and specificities of 96% and 63%, respectively. In infants with fever, clinicians should consider UTI a potential source and consider a urine culture as part of the diagnostic evaluation.

Scintigraphic evaluation of pediatric urinary tract infection

Scintigraphic evaluation of urinary tract infection, pyelonephritis, and renal scarring represents a significant portion of a clinical pediatric nuclear medicine practice. Renal scarring from recurring infection remains an important cause of end-stage renal disease and hypertension in the pediatric population. However, the clinical presentation in infants and young children is often elusive, and clinical diagnosis of upper tract involvement is frequently unreliable. As a result, diagnostic imaging has a critical role to play in the localization of infection to the lower or upper urinary tract. Radionuclide cystography and renal cortical imaging have become mainstays of this evaluation. Direct radionuclide cystography is the preferred cystographic screening technique, because it has lower radiation exposure and greater sensitivity for the detection of vesicoureteral reflux than either indirect radionuclide cystography or fluoroscopic contrast cystography. Renal cortical scintigraphy has become the standard for the detection of pyelonephritis and renal scarring. Correlation with histopathology has demonstrated a high degree of diagnostic accuracy. Acute pyelonephritis has been shown to be the necessary etiologic factor for the development of subsequent renal scarring, and the mechanism of renal injury in pyelonephritis has been extensively studied in experimental models. The ability of prompt and appropriate antibiotic therapy to dramatically reduce the incidence of subsequent scarring also has been conclusively demonstrated both clinically and in the experimental model. Vesicoureteral reflux was once thought to be a necessary prerequisite for the development of renal scarring. Although it is clear that the intrarenal reflux of infected urine will create pyelonephritis in the experimental model, the high incidence of pyelonephritis and subsequent scarring in the absence of demonstrable vesicoureteral reflux leaves the role of reflux in question. Although the role of vesicoureteral reflux is incompletely understood, its detection nevertheless remains a standard part of the patient's evaluation.

Rational use of CT in acute pyelonephritis: findings and relationships with reflux

Enhanced renal CT scanners were performed in 38 children (82% girls) to rule out acute pyelonephritis. Patients were divided in 2 groups on the basis of clinical presentation and bacteriology data. In patients of group A (n = 16, preliminary study), upper urinary tract infection (UTI) was certain. CT confirmed the diagnosis in all but 3 patients (a 2-year-old child and 2 patients with UTI developed on prior obstruction). In subsequently studied patients of group B (n = 22), clinical findings or bacteriology data were negative or questionable. CT made the diagnosis of acute pyelonephritis in 11 patients. As well as DMSA scintigraphy, CT scanner can help to diagnose or to rule out upper UTIs in difficult cases. In all boys of both groups, ipsilateral vesico-ureteric reflux (VUR) was found by subsequent voiding cystourethrography (VCUG) on the side of pyelonephritis. In girls, this correlation was shown in only 7 of the 25 kidneys with pyelonephritis. This result supports the hypothesis of a gender-dependent contamination. We believe that absence of radiologic reflux cannot exclude the possibility of bacterial crossings of ureteric meatus capable to lead to genuine upper UTIs.

Diagnostic significance of 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy in urinary tract infection

A total of 106 children with symptomatic urinary tract infection (73 girls and 33 boys, 0-15.9 years of age) were studied by means of a dimercaptosuccinic acid (DMSA) scan, renal ultrasound, and a desmopressin test during infection and at follow up approximately two months later. At follow up they were also investigated by means of intravenous urography (IVU) and micturition cystourethrography (MCU). During infection 23 children had a normal DMSA scan while 83 children had an abnormal one. The median C reactive protein and SD score for renal concentration capacity in the former group were 15 (range < 10-178) mg/l and -1.0 SD score (range -2.4 to 1.8), respectively, and in the latter group 98 (range < 10-320) mg/l and -3.1 SD score (range -5.7 to 1.1), respectively. In the former group there was no significant finding in any child on ultrasound or IVU and only one had significant vesicoureteric reflux (VUR) (grade 3). At follow up 51 children had a normal DMSA scan while 55 children showed persistent changes. The median SD score for renal concentration capacity in the former group was -0.9 SD score (range -3.2 to 1.4) and in the latter group -1.6 SD score (range -4.6 to 2.5). No significant changes were found in the former group on ultrasound or IVU and only two children had significant VUR (grade 3). In the latter group 20 children showed changes on ultrasound, 15 showed changes on IVU, and 23 had VUR. These results suggest that a normal DMSA scan during or approximately two months after urinary tract infection in children indicates a low risk of finding significant pathology of the urinary tract.

Commentary: management of children with severe vesicoureteral reflux

The main findings of the IRSC after 5 years of observation are summarized. Of the 434 children entered 128 were from centers in America and 306 from Europe. They were randomly allocated and stratified to a medical or surgical regimen. Of the children 50% had scarred kidneys at entry evenly distributed between the groups. After 5 years of observation there was no difference in outcome between the 2 treatment groups in terms of renal size and growth, the development of new radiological renal scars or areas of parenchymal thinning, or of progression of established scarring. In Europe infection recurred in equal numbers of children but pyelonephritic symptoms were more common in the medical group. Nevertheless, new scars developed in 19 of 155 children treated medically and 20 of 151 children treated surgically, including 5 and 7, respectively, with previously normal kidneys. Factors influencing the choice of treatment include patient age, availability of expert surgical care and experienced medical supervision, parental choice and compliance. Followup studies indicate that renal scarring rather than persistence of reflux determines the prognosis and, therefore, emphasis should be placed on the prevention of scarring.

Long-term followup of renal morphology and function in children with recurrent pyelonephritis

Renal morphology and function were evaluated in 161 children with recurrent pyelonephritis with or without vesicoureteral reflux and with or without scarred or small kidneys. The patients were followed for 1 to 21 years. Renal function was determined by glomerular filtration rate and effective renal plasma flow by clearances of inulin and paraaminohippuric acid. Of 105 children with normal kidneys originally small or scarred kidneys developed in 37, of whom 22 had grade III or greater vesicoureteral reflux, while small kidneys developed in 13 of 29 children with renal scarring originally. Of the 37 children with normal kidneys originally renal parenchymal scarring developed in 14 after the age of 4 to 5 years. Glomerular filtration rate was already < -2 standard deviations of that of controls in 51% of the patients at the first and in 53% at the last investigation of renal function. Of these patients with a glomerular filtration rate of < -2 standard deviations 69% had small or parenchymally reduced kidneys most of whom had the first pyelonephritis episode before age 3 years. Patients with small kidneys had a lower glomerular filtration rate than those with normal sized kidneys, whether scarred or not. The low glomerular filtration rate and its subsequent further reduction were related to kidney size and not to the presence or degree of vesicoureteral reflux. However, in individual patients the rate of functional deterioration could not be predicted from the radiological findings. Patients with bilateral small kidneys seemed to show the greatest decrease in glomerular filtration rate during followup as did those with grade III or greater reflux undergoing surgery bilaterally and those patients also had a lower glomerular filtration rate at the last investigation compared to patients not undergoing surgery. In conclusion, renal functional damage seems to occur early in the course of the disease and seems to be related to kidney size but there is a further slow progression with reduction in renal function which occurs, although this is difficult to predict from the radiological changes in individual patients. Therefore, patients with recurrent pyelonephritis should be followed regularly by glomerular filtration rate determination using an accurate method.

Medical management of mild and moderate vesicoureteral reflux: followup studies of infants and young children. A preliminary report of the Southwest Pediatric Nephrology Study Group

Mild and moderate vesicoureteral reflux is expected to resolve spontaneously in most children treated medically; however, maximum benefit or minimum risk of such therapy has not been defined. A prospective 5-year followup study of infants and children younger than 5 years at entry with primary vesicoureteral reflux (grades I to III/V) and radiographically normal kidneys after the first recognized urinary tract infection was initiated in 1984. A total of 113 patients was entered from 5 centers and 61% of the patients were less than 2 years old. Vesicoureteral reflux was unilateral in 65 cases (58%) and bilateral in 48 (42%). Of the 226 renal units reflux was grade IV in 4 (2%), III in 51 (22%), II in 81 (36%) and I in 25 (11%), and 65 (29%) had no vesicoureteral reflux. Data on 59 patients who have completed the protocol were analyzed for this report. Breakthrough urinary tract infection occurred in 20 patients. Of the 84 ureters with vesicoureteral reflux at diagnosis reflux resolved in 67%, and it was of lower grade in 22%, same grade in 8% and higher grade in 2%. Grade I vesicoureteral reflux resolved in 82%, grade II in 80% and grade III in 46% of the ureters. Resolution was better when vesicoureteral reflux was unilateral left (74%) than unilateral right (46%) or bilateral (60%). Renal scarring occurred, on average, in 10% of the kidneys without known vesicoureteral reflux or exposed only to nondilating (grades I and II) reflux and in 28% of those with dilating (grade III) reflux. Thirteen cases had breakthrough urinary tract infection but only after the scar was noted in 5. We conclude that under good medical management during 5 years of followup, even mild and moderate vesicoureteral reflux can be associated with renal injury.

Vesicoureteral reflux in children with and without a history of urinary tract infection: a comparative analysis

Eighty-eight children who were discovered to have vesicoureteral reflux were prospectively studied over a two-year period. Two groups were compared: 49 who presented with a urinary tract infection and 39 who were identified through prospective screening. Based on the distribution of grade and the presence of parenchymal scarring, the severity of vesicoureteral reflux was comparable in the two groups. Of note, more males with reflux were identified in the noninfected group, whereas sex distribution was almost equal in the infected group. Ultrasound alone was found to be highly inaccurate in identifying reflux or parenchymal changes. In conclusion, screening of at-risk groups of children without a history of urinary tract infection may identify patients with clinically significant vesicoureteral reflux.

The sensitivity of renal scintigraphy and sonography in detecting nonobstructive acute pyelonephritis

Recently it has been demonstrated that any child with proved acute pyelonephritis may be at risk for parenchymal scarring, whether or not reflux is present. Since cortical renal scintigraphy has been shown to detect accurately renal inflammation, we compared cortical scintigraphy with renal sonography in 46 children with documented acute pyelonephritis to determine which modality is best to detect patients at risk for renal injury. Cortical scintigraphy was abnormal in 36 children (78%) and renal ultrasonography was abnormal in 5 (11%). Reflux was demonstrated in only 20 cases (43%). We conclude that cortical scintigraphy is the preferred imaging technique for diagnosing renal inflammation, and it should be used routinely in every child with suspected acute pyelonephritis. A new imaging protocol is proposed.

The role of fosfomycin trometamol in the management of urinary tract infections in pediatrics

Single-dose therapy has been documented in defined groups of adults. For children, this type of treatment requires further investigation. Children to be studied should have uncomplicated UTI and the drugs should optimally have a broad antibacterial spectrum, a low tendency to select for resistant bacteria, and pharmacokinetic properties allowing maintenance of inhibitory antibiotic levels in urine for at least two to three days. Fosfomycin trometamol, trimethoprim and co-trimoxazole are oral antibacterials that may prove effective for single-dose therapy in children, as has been suggested in some studies.

Involvement of the renal parenchyma in acute urinary tract infection: the contribution of 99mTc dimercaptosuccinic acid scan

We performed 99mTc dimercaptosuccinic acid (DMSA) scan and ultrasonography in 146 children during the acute phase of a proven urinary tract infection (UTI). In 99 a micturating cysto-urethrography and in 83 an intravenous urography was also done. The occurrence of fever and increased WBC count, CRP and ESR were also studied. It appeared from this retrospective study that 47% of the kidneys had a cortical or patchy pattern of decreased uptake of 99mTc DMSA, as compared to 23% with abnormal findings on US. Vesico-ureteral reflux was present in 38% of the kidneys with parenchymal involvement on 99mTc DMSA scan. Although fever, leucocytosis and elevated CRP and ESR were significantly correlated with abnormal 99mTc DMSA scan, they were also observed in children without renal parenchymal involvement. Our results suggest that 99mTc DMSA scan is a sensitive method for the detection of parenchymal involvement during acute UTI. The exact nature of these lesions and their relation with scars need, however, to be defined.

99mTechnetium-dimercaptosuccinic acid scan in the diagnosis of acute pyelonephritis in children: relation to clinical and radiological findings

Seventy-two children, 59 girls and 13 boys, 0.1-15.9 (median 1.1) years of age, with acute pyelonephritis (APN) were investigated with the aid of a dimercaptosuccinic acid (DMSA) scan, renal ultrasonography (US) and a desmopressin test within 5 days of admission. Sixty-two children were reinvestigated approximately 2 months later when intravenous urography (IVU) and micturition cysto-urethrography were also performed. During infection, 92% of the children showed changes in the DMSA scan with 69% by US, and the two investigations agreed in 58% of the kidneys. At follow-up, 68% showed changes in the DMSA scan, 47% by US and 48% by IVU. The DMSA scan and IVU agreed in 60% of the kidneys. Twenty-nine percent of the children had vesico-ureteric reflux (VUR). The presence of grade greater than or equal to 3 VUR was associated with greater defects on the DMSA scan during infection, and at follow-up with a higher frequency of persistent changes compared with no VUR (P less than 0.02 and 0.01, respectively). During infection the size of the defect on the DMSA scan correlated with renal volume and C-reactive protein and inversely with the glomerular filtration rate, and at follow-up it correlated inversely with the renal concentration capacity. The DMSA scan is a sensitive method for diagnosing and localizing APN in children, and findings on DMSA scan show a weak but significant correlation with routine clinical and radiological parameters. It is suggested that persistent renal damage after APN in children without VUR may be more common than previously assumed.

Renal scarring following reflux and nonreflux pyelonephritis in children: evaluation with 99mtechnetium-dimercaptosuccinic acid scintigraphy

99mTechnetium dimercaptosuccinic acid (DMSA) scintigraphy is the imaging modality of choice for the detection of acute pyelonephritis and chronic renal scarring in children. Using the DMSA scan we prospectively evaluated renal scarring after reflux and nonreflux pyelonephritis in children. The study population consisted of 33 patients with acute pyelonephritis documented by a DMSA renal scan at infection. The children were evaluated for renal scarring with a followup DMSA scan 4 to 42 months (mean 10.7 months) after the acute infection. All new scarring on followup DMSA scans occurred at sites corresponding exactly to areas of acute inflammation on the initial DMSA scan. Therefore, only those kidneys with acute changes on the initial scan were subsequently analyzed. Of 38 kidneys new or progressive scarring developed in 16 (42%), including 6 of 15 (40%) with associated vesicoureteral reflux and 10 of 23 (43%) without demonstrable reflux. New renal scarring developed in 6 of the 7 kidneys (86%) associated with a neuropathic bladder or posterior urethral valves. In contrast, new scarring developed in only 10 of 31 kidneys (32%) associated with a normal bladder (p = 0.028). Excluding the kidneys associated with a neuropathic bladder or posterior urethral valves, new renal scarring developed in 3 of 12 (25%) with primary reflux, compared with 7 of 19 (37%) without vesicoureteral reflux. Except for the white blood count and the species of infecting bacteria, no other statistically significant differences could be found between those cases in which scars did or did not develop. We conclude that acquired renal scarring only occurs at sites corresponding to previous areas of acute pyelonephritis, the acute parenchymal inflammatory changes of acute pyelonephritis are reversible and do not lead to new renal scarring in the majority of cases, and once acute pyelonephritis has occurred ultimate renal scarring is independent of the presence or absence of vesicoureteral reflux.

Five-year study of medical or surgical treatment in children with severe reflux: radiological renal findings. The International Reflux Study in Children

The renal findings on intravenous urography (IVU) are reported in 306 children (73 boys, 233 girls) from eight European centres entered into an international study comparing medical and surgical management of children with urinary tract infection and severe vesico-ureteric reflux followed for 5 years. One hundred and fifty-five children were randomly allocated to medical and 151 to surgical treatment. Protocol and investigative techniques were standardised and randomisation, data collection and analysis were performed centrally in Essen, Germany. At entry 149 (49%) has established renal scarring (79 medical, 70 surgical). Children with normal kidneys (105), areas of thinned parenchyma (52) and grade of reflux were also evenly distributed. IVU was repeated at 6, 18 and 54 months and serial urine culture, 99mtechnetium-dimercaptosuccinic acid scans and plasma creatinine estimations were performed. Two hundred and seventy-two children (89%) completed this follow-up. In 174 children (57%), (90 medical, 84 surgical) there was renal growth without morphological change. New renal scars developed in 19 children treated medically and 20 surgically; 12 (5 medical, 7 surgical) developed in previously normal kidneys. Six followed post-operative obstruction. No significant difference in outcome was found between medical or surgical management in terms of the development of new renal lesions or the progression of established renal scars.

Vesicoureteric reflux and renal scars in asymptomatic siblings of children with reflux

The purpose of the study was to determine the incidence of vesicoureteric reflux (VUR), renal scars and hypertension in asymptomatic siblings of children with VUR. The study comprised 105 siblings of patients with VUR. Their age ranged from 4 months to 6.3 years. All had a direct radionuclide voiding cystography (DRVC) performed, and VUR was detected in 47 of 105 (45%). High grade VUR in the first year of life had an incidence of 50% compared with a 9% incidence in siblings older than 2 years, while only one of the 27 siblings with a low VUR grade was younger than 1 year. In 43 of 47 siblings with VUR, a technetium-99m dimercaptosuccinic acid (99mTc-DMSA) scan was performed and renal scars were found in 10, which presents 23% of siblings with VUR who were scanned and 10% of all siblings studied. One child had hypertension. Identifying VUR among asymptomatic siblings could possibly prevent renal damage and its consequences. Thus, the predictive value of positive family history alone in identifying VUR was 45% while 23% of siblings had renal scars. This incidence justifies the routine investigation of asymptomatic siblings, by using DRVC at an early stage.

Renal cortical scintigraphy in the diagnosis of acute pyelonephritis

Comparative clinical studies have shown renal cortical scintigraphy, using technetium-99m (99mTc)-labeled glucoheptonate or dimercaptosuccinic acid (DMSA), to be significantly more sensitive than either intravenous pyelography or renal sonography in the diagnosis of acute pyelonephritis. However, due to uncertainties about the diagnostic accuracy of the clinical and laboratory parameters used in these studies, true sensitivity of renal cortical scintigraphy was unknown. Therefore, we evaluated the accuracy of [99mTc]DMSA scintigraphy in the diagnosis of experimentally induced acute pyelonephritis in piglets using strict histopathologic criteria as the standard of reference. The sensitivity and specificity of the DMSA scan for the diagnosis of acute pyelonephritis were 91% and 99%, respectively, with an overall 97% agreement between the scintigraphic and histopathologic findings. Based on the results of this experimental study, we used the [99mTc]DMSA scan as the standard of reference for the diagnosis of acute pyelonephritis, and conducted a prospective clinical study of 94 children hospitalized with the diagnosis of acute febrile urinary tract infection (UTI). The aims of this study were (1) to determine the relationship among vesicoureteral reflux, P-fimbriated Escherichia coli, acute pyelonephritis, and renal scarring, and (2) to evaluate the diagnostic reliability of the clinical and laboratory parameters commonly used in the diagnosis of acute pyelonephritis. We documented acute pyelonephritis in 62 (66%) of 94 patients. Vesicoureteral reflux was demonstrated in 29 (31%) of the total group and in only 23 (37%) of 62 patients with acute pyelonephritis. The prevalence of P-fimbriae in the E coli isolates was 64% in the patients with acute pyelonephritis and 78% in those with a normal DMSA scan. Even in patients without reflux, P-fimbriae were found in 71% of isolates from the patients with acute pyelonephritis and in 75% of those with a normal renal scan. Follow-up DMSA scans were obtained in 33 patients with acute pyelonephritis in 38 kidneys. We found complete resolution of the acute inflammatory changes in 58% of the involved kidneys and renal scarring in the remaining 42%, including 40% of the kidneys associated with reflux and 43% of those without reflux.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of DMSA scintigraphy with intravenous urography for the detection of renal scarring and its correlation with vesicoureteric reflux

A series of 208 patients was prospectively assessed for reflux nephropathy by intravenous urography (IVU) and 99mTc-dimercaptosuccinate (DMSA) scintigraphy. All patients were studied at least 3 months after their most recent urinary tract infection and micturating cystourethrography (MCU) was performed prior to the scintigraphic studies. DMSA scintigraphy detected significantly more cortical abnormalities than did IVU. There was also a correlation between cortical abnormalities in the DMSA studies and the degree of reflux on MCU. The validity of DMSA as a cortical imaging agent is evaluated and the histological evidence for its efficacy derived from the animal model is reviewed, lending weight to its establishment as the "gold standard" for renal cortical scarring.

Circumcision: is the risk of urinary tract infection really the pivotal issue?

Recent information regarding the increased risk of urinary tract infections in the first year of life for uncircumcised boys has created confusion regarding the appropriate guidance to be given to parents confronting the circumcision issue. A decision model was built that addressed the question of whether or not to circumcise a newborn male considering the probability of a non-circumcised boy having a UTI in the first year of life (0.041), the probability of a circumcised boy having a UTI in the first year of life (0.002), and the likelihood of renal scarring from a UTI (0.075). After considering the morbidity associated with the procedure, all possible outcomes were ranked from worst to best (circumcised-renal pathology to uncircumcised-no infection) and given a value on a 0 to 1 scale. For the set of values assigned to the outcomes, the choice of no circumcision yielded the highest expected utility. For the set of assigned utilities, sensitivity analysis showed that unless the probability of a UTI in the first year of life for an uncircumcised male was greater than or equal to 0.29, then non-circumcision was still the preferred choice. The decision was most sensitive to the degree of aversion to the morbidity associated with the procedure (pain, bleeding, inflammation).

Blood group non-secretors have an increased inflammatory response to urinary tract infection

The aim of this study was to assess the possible relationship between secretor state and the inflammatory response to urinary tract infection (UTI). Girls with recurrent UTI were prospectively studied. They included 61 secretor and 23 non-secretor individuals with 604 episodes of recurrent UTI. The response to each UTI episode was measured as the levels of C-reactive protein, erythrocyte sedimentation rate and the body temperature as well as renal concentrating capacity and pyuria. The levels of C-reactive protein, erythrocyte sedimentation rate and the body temperature were significantly higher in non-secretors than in secretors (p less than 0.04). As a consequence, non-secretors had an increased probability of being assigned a diagnosis of acute pyelonephritis rather than asymptomatic bacteriuria (p less than 0.05). The higher inflammatory response in non-secretors was independent of the Gal alpha 1-4Gal beta adhesin expression of the infecting Escherichia coli strains. The increased inflammatory response to UTI in non-secretors might explain the accumulation of these individuals among patients with renal scarring.

Long-term prognosis of post-infectious renal scarring in relation to radiological findings in childhood--a 27-year follow-up

In a previous report the long-term prognosis of 30 patients with renal scarring after pyelonephritis in childhood was described. In this study, we have related the extent of renal scarring present in childhood to the conditions in early adulthood. A radiological progression of scarring from childhood to adulthood was seen in one-third of the kidneys. The 7 patients with bilateral scarring in childhood had a smaller renal area, lower glomerular filtration rate and higher plasma vasopressin at follow-up than 13 healthy controls. The 20 patients who had unilateral scarring in childhood had a smaller renal area, lower glomerular filtration rate, higher diastolic blood pressure and higher plasma renin at follow-up than controls; 4 had hypertension. The most important finding was that children with unilateral disease are at risk of serious long-term complications. Filtration fraction at follow-up was higher in patients with extensive renal scarring in childhood compared with those with a normal renal area or small scars in childhood (r = -0.43, P less than 0.05). This may indicate glomerular hyperfiltration by remnant glomeruli. This paper emphasizes t the potential seriousness of childhood urinary tract infections especially when early infantile infections are overlooked. A follow-up of more than 4 decades may be necessary before the ultimate prognosis can be established, especially in patients with unilateral renal disease. It is advised that most patients with post-infectious renal scars are followed as high-risk patients, and that treatment continuity is established between paediatricians, nephrologists and, when required, obstetricians.

Extracellular release of reactive oxygen species from human neutrophils upon interaction with Escherichia coli strains causing renal scarring

The production of reactive oxygen metabolites by neutrophils plays a key role in the host defense against invading microorganisms and in tissue damage resulting from infection. In the present study we measured the ability of different uropathogenic Escherichia coli strains to induce generation of oxygen metabolites upon interaction with human neutrophils. The strains were selected to represent two groups of patients with recurrent episodes of acute pyelonephritis: one with renal scars (12 strains) and one without renal scarring (11 strains). The majority of strains (from both groups) induced a pronounced neutrophil respiratory burst activity. When the intracellular and extracellular oxidative responses were measured separately, it was found that the response induced by nonscarring strains was primarily of intracellular (intraphagosomal) origin, whereas a proportionally larger fraction of the response induced by the scarring strains was extracellular. Since reactive oxygen products are toxic to the renal tissue, this release can be of importance in the development of renal scars.

Relationship among vesicoureteral reflux, P-fimbriated Escherichia coli, and acute pyelonephritis in children with febrile urinary tract infection

Ninety-four children with febrile urinary tract infection were studied prospectively to determine the relationship between vesicoureteral reflux, P-fimbriated Escherichia coli, and acute pyelonephritis, and to evaluate the diagnostic reliability of commonly used clinical and laboratory observations. By using renal scan with dimercaptosuccinic acid labeled with technetium 99m as the standard of reference, we documented acute pyelonephritis in 62 (66%) of 94 patients. Vesicoureteral reflux was demonstrated in 29 (31%) of the total group and in only 23 (37%) of 62 patients with pyelonephritis. Of the 70 E. coli urinary isolates, 48 (69%) were P-fimbriated, including 30 (64%) of 47 isolates from patients with pyelonephritis and 18 (78%) of 23 isolates from patients with normal renal scans. The prevalence of P-fimbriated E. coli in patients with pyelonephritis and vesicoureteral reflux was 46%, compared with 71% in those with pyelonephritis who had no concurrent vesicoureteral reflux (p = 0.222). Multiple clinical and laboratory variables commonly used in the diagnosis of acute pyelonephritis did not adequately predict the presence or absence of parenchymal involvement. These data show the following: (1) Acute pyelonephritis in the absence of demonstrable vesicoureteral reflux is common. (2) Febrile urinary tract infections in children are commonly associated with P-fimbriated E. coli, both in the presence and absence of vesicoureteral reflux. (3) The presence of P fimbriae alone does not fully explain the pathophysiology of renal parenchymal invasion by bacteria in the absence of vesicoureteral reflux. (4) The diagnosis of acute pyelonephritis in children with febrile urinary tract infections on the basis of clinical and laboratory observations is unreliable.

Detecting vesico-ureteral reflux in asymptomatic siblings of children with reflux by direct radionuclide cystography

The incidence of vesicoureteral reflux (VUR) among asymptomatic siblings of children with VUR is much higher than the estimated incidence in the general population. It might be expected that identifying them and keeping them under close observation and/or either surgical or conservative treatment, might reduce the risk of renal scarring. Fifty-three asymptomatic children, all under 6 years of age and all siblings of children with proven VUR, were studied and direct radionuclide voiding cystography (DRVC). There were 31 (58%) boys, and 22 (42%) girls. Nine children (17%) were younger than 1 year, 13 (25%) were between 1 and 2 years of age, while 31 (58%) were older than 2 years. VUR was detected in 22 (42%) of the 53 siblings. The incidence of VUR varied considerably according to the age, and sex of the child, the highest being in boys younger than 1 year. Most of the severe reflux was seen in children under 2 years of age. Out of 11 patients with VUR, grade 2 and 3, there were 10 younger than 2 years, whereas, only 2 of the 11 siblings with VUR, grade 1 were younger than 2 years of age. The mean age of children with VUR grades 2 and 3 was 19 months, compared to the mean age of 50 months for those with VUR grade 1. DRVC, a highly sensitive method, exposes the patient to much less radiation than X-ray voiding cystography. We believe that the benefit of detecting VUR in asymptomatic siblings with DRVC outweights the invasiveness of the procedure. The predictive value of positive family history alone in identifying VUR in our study was 42%.(ABSTRACT TRUNCATED AT 250 WORDS)

Vesicoureteric reflux and renal injury

Renal injury associated with the intrarenal reflux (IRR) of urine that is either infected, under high pressure, or both, is a major cause of severe hypertension during childhood and adolescence and of chronic renal insufficiency in patients less than 30 years of age. Many, but not all, adolescent and adult patients with reflux nephropathy (RN) give a history of urinary tract infection (UTI) or unexplained fevers in infancy or early childhood, when the kidney is thought to be at greatest risk of injury. Although vesicoureteric reflux (VUR) is observed more commonly in infants than children with UTI, it is rare in uninfected patients at any age and should never be considered a normal finding during human development. Renal scarring may not be obvious in radiographic or radionuclear studies to medical management alone, no definite benefit of one over the other was observed, regardless of the grade of VUR. Moreover, progressive renal injury in scarred kidneys has been noted even after VUR had been corrected, when infection had been prevented, and while hypertension had been controlled satisfactorily. Focal glomerular sclerosis, a lesion found in patients with proteinuria and RN, has been identified not only in scarred kidneys, but also may be seen in contralateral, unscarred kidneys without VUR, which might suggest a humoral factor or, perhaps, a hyperfiltration phenomenon. RN is one of the most frequent causes of end-stage renal disease (ESRD) in children, adolescents, and young adults, which is potentially preventable. However, prevention will depend on early identification of patients at risk--infants and young children after the first UTI and siblings of patients with VUR--aggressive and effective treatment of UTI, minimizing intravesical pressure, and education of patients, parents, and physicians.

Management of urinary tract infections in children

Urinary tract infection is common in children. The presentation varies with age. Younger children exhibit protean signs. Diagnosis is dependent on the demonstration of significant bacteriuria in a properly collected and handled urine sample. The approach to treatment depends on the degree of illness at presentation, the presence of structural urinary tract abnormalities, and the age of the patient. Pathophysiology of urinary tract infection is dependent on interactive factors of the host and of the invading microorganism. Urinary tract abnormalities have significant impact on the management of children with urinary tract infections, both medically and surgically. Of particular importance is the observation that renal damage usually occurs within the first 5 years of life, and treatment delay in some young patients may have significant consequences. The overall prognosis in children with urinary tract infection is favorable.

Virulence factors in Escherichia coli urinary tract infection

Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans.

Six year follow up of infants with bacteriuria on screening

OBJECTIVE

To determine the value of screening for bacteriuria in infants with special emphasis on the natural course of untreated asymptomatic bacteriuria, renal growth, and renal damage.

DESIGN

Prospective six year follow up of infants with bacteriuria on screening in an unselected infant population.

SETTING

Paediatric outpatient clinic.

PATIENTS

50 Infants (14 girls, 36 boys) with bacteriuria on screening verified by suprapubic aspiration from an unselected population of 3581 infants in a defined area of Gothenburg.

INTERVENTIONS

Children with asymptomatic bacteriuria and normal findings on initial urography were untreated, although other infections were treated.

MAIN OUTCOME MEASURES

Culture of urine and determination of C reactive protein concentration every six weeks for the first six months after diagnosis, every three months from six months to two years, and every six months between two and three years; thereafter yearly urine culture. Evaluation of renal concentrating capacity with a desmopressin test; radiological examination, including first and follow up urography and micturition cystourethrography without antibiotic cover; and measurement of renal parenchymal thickness and renal surface area.

RESULTS

Of the original 50 infants, 37 (12 girls, 25 boys) were followed up for at least six years. Two infants developed pyelonephritis within two weeks after bacteriuria was diagnosed; the others remained free of symptoms. 45 Infants were untreated; the bacteriuria cleared spontaneously in 36 and in response to antibiotics given for infections in the respiratory tract in eight. Recurrences of bacteriuria were observed in 10 of the 50 children, of whom one had pyelonephritis. No child had more than one recurrence. At follow up urography in 36 of the 50 children (9 girls, 27 boys) after a median of 32 months no child had developed renal damage. First samples tested for renal concentrating capacity showed significantly higher values than those from a reference population (mean SD score 0.50, 95% confidence interval 0.21 to 0.79; p less than 0.001), but the last samples showed no significant difference (mean SD score 0.08, -0.24 to 0.40; p greater than 0.05).

CONCLUSIONS

Mass screening for bacteriuria in infancy results primarily in detection of innocent bacteriuric episodes and is not recommended.

The influence of artificial colonization with E. coli strain O83 on the intestinal flora in infants

Dominant bacterial strains present in stool (with particular emphasis on E. coli strains) were examined in 4 groups of healthy infants: breast-fed and bottle-fed, colonized with E. coli O83, and control (non-colonized) breast-fed and bottle-fed newborns. The presence of fimbriae was examined by hemagglutination, the P-fimbriae-bearing strains were tested by the PPA latex test. In addition, adherence to cell line HT-29 and serotyping was performed in selected strains. The E. coli strain O83 was found to possess type 1 fimbriae. Fewer bacterial strains possessing type 1 fimbriae were found in E. coli O83-colonized infants (except the O83 serotype) than in control infants. The E. coli O83 strain colonized significantly better the breast-fed than the bottle-fed infants; its higher adherence activity was demonstrated even in cell line HT-29. Finally, colonization with E. coli O83 influenced the character of microbial intestinal flora: the frequency of positive E. coli isolates was significantly higher in colonized (both breast- and bottle-fed) than noncolonized infants.

Relation of urinary tract infection and vesicoureteral reflux to scars: follow-up of thirty-eight patients

A prospective study compared the outcome of vesicoureteral reflux and recurrent urinary tract infections in children (3 boys, 62 girls) who received medical prophylaxis or underwent surgical correction of reflux. Thirty-eight children returned for reevaluation 6 to 13 years (average 9.5 years) after entry. There was a marked decrease in prevalence and severity of reflux. At entry, 13 had significant scarring that had progressed at follow-up. New scars were documented by dimercaptosuccinic acid scan at follow-up in eight children on the medical regimen and two who were initially treated with surgical correction of reflux. Four patients with high-grade sterile reflux were followed for 6 to 10 years without the development of cortical scars. Our data support the role of urinary tract infection and vesicoureteral reflux, but not sterile reflux, in the pathogenesis of chronic pyelonephritis and reflux nephropathy.

Bacterial attachment as a predictor of renal abnormalities in boys with urinary tract infection

The development of renal scarring was analyzed prospectively in 241 boys with their first known episode of symptomatic urinary tract infection (140 acute pyelonephritis, 61 acute cystitis, and 40 nonspecific). Of 197 boys undergoing urography, 22 (11%) had scars; 20 were in the pyelonephritis group. Vesicoureteral reflux occurred in 81% of those with scarring, compared with 20% of those without scarring. The bacteria causing the first episode of urinary tract infection in each patient were saved, and Escherichia coli organisms were characterized for the expression of both galactose-alpha (1----4)galactose-beta (Gal-Gal)-specific adhesins and pap homologous DNA. Scarring occurred in 41% and other renal abnormalities in 11% of boys infected with bacteria that did not bind Gal-Gal (Gal-Gal negative), compared with 5% and 1%, respectively, in those infected with Gal-Gal-binding strains (Gal-Gal-positive) (relative risk 8.3; 95% confidence limits 3.3 to 20.4; p less than 0.001). That boys infected with Gal-Gal-negative strains more often had reflux did not explain the increased risk for renal scarring in this group. The possibility that the phenotypically negative strains could be induced to express Gal-Gal adhesions in vivo was excluded by dot blot analysis, which showed the absence of pap homologous DNA in all but one of the Gal-Gal-negative strains. The results suggest that the absence of Gal-Gal-specific adhesins in E. coli can be used as an indicator of risk for renal scarring and the need for radiologic examination.

Bacterial adherence in urinary tract infections: preliminary studies in a primate model

Escherichia coli with both P and type 1 fimbriae caused vaginal colonization in the female green monkey, while only the P-fimbriated bacteria frequently caused ascending bladder infection. Bladder inoculation caused only short-lived bladder infection from type 1 fimbriated E. coli, but those with P-fimbriae caused acute pyelonephritis even in the absence of vesicoureteral reflux. Thus, type 1 fimbriae of E. coli, while causing vaginal colonization, did not often cause ascending infection in the non-compromised host as did P-fimbriated bacteria.

P-fimbriae vaccines. II. Cross reactive protection against pyelonephritis

Protection against acute pyelonephritis was induced by immunization of baboons with purified P-fimbriae of Escherichia coli as vaccines. To test for cross-protective capacity of two different P-fimbriae vaccines we vaccinated baboons with P-fimbriae purified from either E. coli strain ER2 or strain JR1 and subsequently challenged the animals with E. coli strain JR1. All vaccinated animals showed elevated antibody titers to P-fimbriae from both of the E. coli strains used. Both vaccines tended to reduce the time of bacteriuria. They partially prevented pyelonephritis and protected against loss of renal function.

Secretor state and renal scarring in girls with recurrent pyelonephritis

The non-secretor phenotype was significantly associated with the occurrence of renal scarring among patients with recurrent pyelonephritis. Girls (n = 77) with recurrent pyelonephritis were followed from the first known episode of infection for up to twelve years with repeated radiological investigations. They were divided into two categories: those with renal scars (n = 35) and those who did not develop scars (n = 42). There was a significant over-representation of non-secretors among the patients with scarring, (14/35, 40%) compared to the healthy controls (21.8%, P less than 0.05). The frequency of non-secretors among the girls who did not develop scars in spite of repeated episodes of acute pyelonephritis was not significantly different from the healthy controls (9/42, 21% n.s.). This study provides a basis for analysis of the influence of secretor state on host-parasite interaction in the urinary tract.

The prepuce: a mistake of nature?

Retrospective studies suggest that circumcision of newborn boys will reduce the frequency of male early infantile urinary tract infection (UTI) by about 90%. If they are correct, this will be the first known instance of a common potentially lethal disease being preventable by extirpation of a piece of normal tissue. To reconcile the phenomenon with existing views of evolution and biology, it is suggested that the effects of one unphysiological intervention are counterbalancing those of another--ie, colonisation of the baby's gastrointestinal tract and genitals in maternity units by Escherichia coli strains of non-maternal origin, to which the baby has no passive immunity. As an alternative to circumcision to prevent early infantile male UTI, more natural colonisation could be promoted by strict rooming-in of mother and baby or by active colonisation of the baby with his mother's anaerobic gut flora.