Pyelonephritis: a study of bacteriological techniques. II. The identification and incidence of micro-organisms associated with pyelonephritis.
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Xanthogranulomatous pyelonephritis is an unusual variant of chronic pyelonephritis. Xanthogranulomatous pyelonephritis is associated with urinary calculi, urinary tract obstruction, and invasion of the renal parenchyma. Pathologically, xanthogranulomatous pyelonephritis consists of a yellow (xantho) colored infiltrate in renal tissue with granulomatous formation. Xanthogranulomatous pyelonephritis may be distinguished from chronic pyelonephritis by renal size. Typically, the kidneys are enlarged in xanthogranulomatous pyelonephritis and are small/shrunken with chronic pyelonephritis. The diagnosis of xanthogranulomatous pyelonephritis is made by abdominal computed tomography scanning showing the characteristic "bear paw" sign, or findings typical for xanthogranulomatous pyelonephritis, eg, multiple hypo dense areas with ring-enhancing lesions. The definitive treatment for xanthogranulomatous pyelonephritis is antimicrobial therapy and nephrectomy. We present a case of xanthogranulomatous pyelonephritis complicated by psoas abscess.
Xanthogranulomatous pyelonephritis usually occurs in women 50 to 60 years old, and has the distinct clinical presentation suggestive of a renal mass. Since 1963 an increasing number of children with xanthogranulomatous pyelonephritis have been reported in the literature, with data suggesting that the characteristics of the disease are different from those in adults. We compared our children with xanthogranulomatous pyelonephritis to adults who had been described in the literature and to our cases of chronic pyelonephritis to determine whether xanthogranulomatous pyelonephritis in children is an entity as clearly different from chronic pyelonephritis as it is in adults. Twenty-one cases were eliminated from the study because of incomplete charts. We found 39 cases in which nephrectomy had been done for an anatomical diagnosis of chronic or xanthogranulomatous (8) pyelonephritis. Average age at presentation, duration of clinical course and sex distribution were similar in both groups. The left kidney was involved more often in both groups. Severe malnutrition, urolithiasis, reno-cutaneous fistula and negative urine cultures were more frequent in cases of xanthogranulomatous pyelonephritis, while obstructive nonlithiasic uropathy occurred more often in cases of chronic pyelonephritis. Microorganisms were similar in both groups and Escherichia coli was isolated most frequently. All cases of xanthogranulomatous pyelonephritis were of the diffuse type with areas corresponding to all histological stages. Our study suggests that perhaps in children xanthogranulomatous pyelonephritis occurs the same as chronic pyelonephritis, and is determined possibly by an affected immune response secondary to malnutrition and by the presence of urolithiasis.
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)
PURPOSE: We investigate the efficacy of antibiotics combined with corticosteroid in diminishing post-pyelonephritic renal scarring compared to standard antibiotic therapy. MATERIALS AND METHODS: Bilateral vesicoureteral reflux was surgically created in 36 piglets (72 kidneys). A week later each bladder was inoculated by percutaneous injection with a standardized broth culture of Escherichia coli and molten paraffin. 99mTechnetium dimercapto-succinic acid (DMSA) scintigraphy was performed 3 days after introduction of urinary infection to detect the presence of acute pyelonephritis. Acute pyelonephritic lesions seen on DMSA scans were graded according to the percentage of renal zone involvement as grade 1--less than 33%, grade 2--33 to 66% and grade 3--greater than 66% involved. When pyelonephritis was present, piglets were randomized to receive either standard antibiotics or antibiotics and 2 mg./kg. prednisolone daily. 99mTechnetium-DMSA scintigraphy was repeated 2 months after completion of therapy, and the kidneys were harvested for gross and histopathological examination. Each kidney was divided into upper, middle and lower zones for correlation of pathological and imaging findings. Severity of renal scarring was then assessed using histopathological confirmation of gross anatomical findings as grade 1--less than 1, grade 2-1 to 2 and grade 3-greater than 2 cm. RESULTS: Acute pyelonephritis was induced in 136 of 216 renal zones. The sites of renal scarring corresponded anatomically to sites of acute pyelonephritis in all but 5 cases. Overall, the prevalence of post-pyelonephritic scarring was 56.6% (77 of 136) of renal zones. The severity of scarring in both groups correlated with the severity of the initial pyelonephritic lesion. Of the 31 zones that formed grade 3 renal scars the distribution of grades 1, 2 and 3 acute pyelonephritis on the initial DMSA scan was 3, 26 and 71%, respectively. Grade 3 acute pyelonephritis was more likely to result in severe (grade 3) renal scars in the control compared to the steroid treated group (59 versus 31%). Overall, acute pyelonephritis completely resolved in 40% of controls and 51% of steroid treated animals. However, only 9% of control animals with grade 3 acute pyelonephritis demonstrated complete resolution, as opposed to 28% of those receiving steroids. CONCLUSIONS: The risk of renal scarring is greatest after severe acute pyelonephritis involving greater than 66% of a renal zone. Adjunctive oral prednisolone appears to be effective in diminishing renal scarring in severely affected kidneys. In kidneys with mild and moderate acute pyelonephritis antibiotics alone appear to be equally effective in preventing scarring.
PURPOSE: The diagnosis of pyelonephritis is primarily clinical. However, the history and physical findings can be confusing in children, leading to adjunctive nuclear renal cortical scintigraphic studies (99mtechnetium dimercapto-succinic acid [DMSA]) to confirm the diagnosis. Nonetheless, ambiguity occurs when differentiating between acute pyelonephritis and chronic scarring. We report our initial experience with gadolinium enhanced inversion recovery magnetic resonance imaging (MRI) to diagnose acute pyelonephritis. MATERIALS AND METHODS: Nine patients 7 months to 18 years old (mean age 81 months) underwent MRI to confirm radiographically a clinical suspicion of acute pyelonephritis. All patients had at least 1 prior episode of clinical pyelonephritis. Data were collected to determine whether acute pyelonephritic changes could be differentiated from chronic pyelonephritis on the basis of MRI characteristics. RESULTS: Of the 9 patients 4 were identified as having acute pyelonephritis on MRI (persistently high signal intensity after gadolinium), 2 demonstrated evidence of postpyelonephritic scar (parenchymal loss without change in signal intensity), 1 had evidence of acute pyelonephritis and chronic changes, and 2 had a completely normal examination (decreased signal intensity after gadolinium). At our institution the billable cost of MRI to the patient is $1,329, while the billable cost of 99mtechnetium DMSA is $1,459. All patients younger than 6 years required intravenous sedation for MRI, whereas 70% of those younger than 6 years require intravenous sedation for DMSA scanning at our institution. MRI provided greater anatomical detail regarding the renal architecture without radiation exposure, and allowed the unambiguous diagnosis of acute versus chronic pyelonephritis scar in a 1-time (versus often multipart for DMSA) imaging study. CONCLUSIONS: In cases where adjunctive imaging studies are useful to make a diagnosis gadolinium enhanced inversion recovery magnetic resonance imaging allows the detection of acute pyelonephritis rapidly, cost-effectively and safely in the pediatric population.
OBJECTIVE: Focal areas of decreased perfusion may be shown by power Doppler sonography in children with acute pyelonephritis. The purposes of this study were to assess the ability of power Doppler sonography to reveal acute pyelonephritis and to compare the sonographic images with enhanced CT images. SUBJECTS AND METHODS: We performed B-mode sonography, power Doppler sonography, and enhanced CT (reference method) of the kidneys of 30 children with symptoms suggesting upper urinary tract infection. All imaging studies were obtained within 24 hr of admission of each child to our hospital. Power Doppler sonography was performed with the same equipment and the same settings for all children. Imaging studies were performed before the results of urine cultures were obtained. Triangular areas of decreased perfusion visible on both longitudinal and axial scans were considered indicative of acute pyelonephritis on power Doppler sonographic images. On CT images, areas of decreased attenuation of the renal parenchyma visible immediately after IV injection of iodinated contrast agent or areas of increased attenuation on delayed scans were considered indicative of acute pyelonephritis. Power Doppler sonography and CT were compared for each renal pole (n = 120). RESULTS: For 17 (89%) of the 19 patients with CT-proven acute pyelonephritis, power Doppler sonography diagnosed this condition on the correct side. Seventeen (77%) of the 22 poles showing acute pyelonephritis on CT scans were also revealed by power Doppler sonography. The two patients in whom acute pyelonephritis was not revealed by power Doppler sonography were an obese 15-year-old girl and a 7-year-old boy with right upper pole pyelonephritis. This boy was one of the first patients to be included in the study. Also, in an obese 11-year-old girl, a false-positive indication of pyelonephritis was given by power Doppler sonography. CONCLUSION: Power Doppler sonography seems to be significantly more sensitive than conventional sonography for the detection of acute pyelonephritis in children. This noninvasive technique should be able to replace CT or dimercaptosuccinic acid scintigraphy in many children with urinary tract infections.
This study aims to define the effects of pyelonephritis on intrarenal resistive indices and to determine the role of Doppler sonography in the diagnosis of pyelonephritis in pregnant patients. Twenty pregnant women with pyelonephritis underwent renal Doppler sonography with calculation of intrarenal resistive indices. The resistive index was calculated for the upper, lower, and interpolar areas of each kidney in the patients with pyelonephritis (40 kidneys) and was compared to the resistive indices for a control group of 153 normal asymptomatic pregnant women (306 kidneys). Doppler findings were correlated with the location (sidedness) of flank pain in the pyelonephritis group. The mean resistive index values of patients with pyelonephritis were 0.04 higher than in the controls, and this difference was statistically significant (P < 0.001). Four patients with pyelonephritis had a mean resistive index > or = 0.70, whereas the remaining 16 patients had resistive indices within the normal range of < or = 0.70. In patients with confirmed pyelonephritis and unilateral pain, the average resistive index in the kidney on the side of pain was 0.03 greater than that on the asymptomatic side (P = < 0.01). The mean renal resistive index is significantly greater in pregnant patients with pyelonephritis than in pregnant women without pyelonephritis. Even so, the magnitude of the differences in resistive index is too small and the overlap between the groups too large for this parameter to be of discriminating clinical value.