Progression and resolution of acute focal bacterial nephritis

It is crucial that nephrologists correctly identify acute focal bacterial nephritis, as timely and adequate treatment with appropriate antibiotics can prevent unnecessary investigations, invasive surgical procedures, and renal complications such as renal abscess or renal scar. An urgent kidney ultrasonography should be performed if there is a delayed response to appropriate antibiotic treatment in patients with urinary tract infection. Serial kidney ultrasonography plays a significant role in confirming the diagnosis and monitoring the progression of acute focal bacterial nephritis. We presented a patient with acute focal bacterial nephritis and showed that a serial kidney ultrasonography could prevent the use of invasive investigations and inappropriate surgical procedures.     

Contemporary imaging of renal inflammatory disease

In addition to plain films and conventional excretory urography, ultrasound, computed tomography, and radionuclide scanning may contribute to the assessment of a wide spectrum of renal inflammatory diseases. This article discusses the role of contemporary imaging modalities in the diagnosis and management of patients with renal inflammatory lesions, including acute focal and diffuse bacterial infections, intra- and extrarenal abscess collections, pyonephrosis, xanthogranulomatous pyelonephritis, fungal infection, tuberculosis, and malakoplakia of the upper urinary tract.     

Renal and perirenal abscesses

Our knowledge of the spectrum of renal abscesses has increased as a result of more sensitive radiologic techniques. The classification of intrarenal abscess now includes acute focal bacterial nephritis and acute multifocal bacterial nephritis, as well as the previously recognized renal cortical abscess, renal corticomedullary abscess, and xanthogranulomatous pyelonephritis. In general, the clinical presentation of these entities does not differentiate them; various radiographic studies can distinguish them, however. The intrarenal abscess is usually treated successfully with antibiotic therapy alone. Antistaphylococcal therapy is indicated for the renal cortical abscess, whereas therapy directed against the common gram-negative uropathogens is indicated for most of the other entities. The perinephric abscess is often an elusive diagnosis, has a more serious prognosis, and is more difficult to treat. Drainage of the abscess and sometimes partial or complete nephrectomy are required for resolution.     

A pediatric case of acute focal bacterial nephritis; comparison with the reports in Japanese child cases]

We report an 8-year-old boy with acute focal bacterial nephritis (AFBN). At the age of 3 months, he had a history of urinary tract infection and vesicoureteral reflux. He was admitted to our hospital because of high fever and costovertebral angle pain. Although acute pyelonephritis was suspected, neither pyuria nor cultures of blood and urine were positive. An initial ultrasonogram (US) of his kidneys was normal except for bilateral hydronephrosis. Two days later, however, a computed tomography (CT) revealed a poorly enhanced mass in the upper pole of the right kidney. Similar findings were also observed by US. Under the diagnosis of AFBN, he received antibiotics for 3 weeks. Voiding cystourethrogram showed both-sided vesicoureteral reflux and he underwent an operation. At present the mass of the kidney still remains, albeit its size tends to decrease. We suggest that an early examination of US or enhanced CT is necessary in cases with fever of unknown origin, considering the possibility of AFBN even if neither pyuria nor cultures of urine are positive.     

Urinary tract infections and chronic renal failure

The paper briefly summarizes issues related to urinary tract infections in adults: predispositions and risk factors, classification, assessment of pathogenicity of bacterial agents, the role of bacteriuria and leucocyturia, interpretation of findings, treatment principles and an association with chronic renal failure. Urinary tract infections are the second most frequent infectious disease in the population. They most often affect women of childbearing potential and then seniors of both sexes who have multiple risk factors. Escherichia coli and Staphylococcus saprophyticus are the most pathogenic towards urinary tract; they are responsible for 85% and 10-15% of cases of acute uncomplicated urinary infections, respectively. Chronic pyelonephritis, a chronic interstitial nephritis, is the fourth most frequent cause of chronic renal failure. Chronic renal failure is a risk factor for the development of urinary infections due to metabolic disorders resulting in secondary immunodeficiencywith a disorder of all components of immunity. In patients with chronic renal failure, urinary tract infections occur most frequently after kidney transplantation when graft pyelonephritis is a life-threatening complication. Therefore, urinary tract infection prevention with co-trimoxazole once daily over at least 6 months is recommended in renal allograft recipients.     

Xanthogranulomatous pyelonephritis complicated by psoas abscess

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.     

Acute bacterial nephritis: a clinicoradiologic correlation based on computed tomography.

PURPOSE: Acute bacterial nephritis (ABN) represents localized, nonliquefied renal infection, and the subsequent alteration of tissue densities can be readily detected by computed tomography (CT). In recent literature, a variety of renal parenchymal alterations observed on CT were reported. However, previous reports on the clinical course of ABN were inconsistent and lacked correlation with radiologic findings. In this investigation, we attempt to correlate the severity of clinical manifestations with CT findings in ABN and draw some conclusions regarding the natural history, pathophysiology, and clinical management of this disease. PATIENTS AND METHODS: From July 1988 to June 1991, 30 cases of ABN were evaluated at our institute. On the basis of postcontrast-enhanced CT findings, 28 cases were grouped into (1) Group I (7 cases), wedge-shaped lesions (focal or diffuse); (2) Group II (12 cases), focal mass-like lesions; and (3) Group III (9 cases), diffuse (multifocal) mass-like lesions. The clinical features and outcomes of the three groups were compared. The positive detecting rates and clinical usefulness of ultrasonographic (US) and urographic examinations were also studied in each group. RESULTS: An excellent correlation can be demonstrated between the clinical parameters (including underlying diseases, maximum temperature and leukocyte count, duration of fever, flank pain, leukocytosis, and pyuria; the incidence of septic shock, diabetic ketoacidosis, and acute renal failure; and outcome) and the pattern of renal parenchymal abnormalities detected on CT. The clinical features in Group I patients displayed many similarities with those in uncomplicated acute pyelonephritis (APN) reported previously, and responded to antibiotic therapy promptly. Most patients in Group II were successfully treated with antibiotics but had a protracted clinical course with a slower clinical improvement than Group I. Only one case with a Group II lesion was noted to progress to renal abscess formation and extrarenal involvement. In comparison, 33% of the patients in Group III died despite antibiotic therapy. Our data also show that US examination is sensitive in detecting Group II ABN lesions (62% positive rate), and revealed marked renal enlargement in most Group III lesions (89%). It is therefore a useful initial imaging modality in providing information vital to clinical decision making. CONCLUSION: Our experiences suggest that renal bacterial infection may show the continuum of severity from uncomplicated APN to ABN, demonstrated on postcontrast CT scan as wedge-shaped lesions to mass-like lesions, and possibly, finally to frank abscess formation. We classify ABN into three subgroups according to CT findings, and good correlation with clinical severity is demonstrated. These findings deliver valuable concepts regarding the pathophysiology and clinical management of this disease.     

Histopathologic-microbiologic correlates of invasiveness in a mouse model of ascending unobstructed urinary tract infection.

To clarify the usefulness of histopathology in evaluating invasiveness during acute cystitis and pyelonephritis in a mouse model of urinary tract infection, findings from bladder and kidney sections of mice inoculated transurethrally with Escherichia coli were compared with results of bladder, kidney, spleen, and blood cultures and with changes in peripheral blood leukocyte counts. All of the 14 bladder histopathologic abnormalities evaluated were significantly associated with a positive bladder culture, and 7 were associated with splenic infection. Histopathologic features of cystitis were present in some culture-negative bladders. Eleven of 12 renal histopathologic abnormalities evaluated were significantly associated both with a positive kidney culture and with splenic infection, and two correlated with the development of peripheral leukocytosis. Histopathologic features of pyelitis and nephritis permitted culture-positive kidneys to be categorized as exhibiting colonization only, pyelitis only, or pyelitis plus frank nephritis and demonstrated that some culture-negative kidneys exhibit signs of pyelitis and nephritis. These findings suggest that detailed, semiquantitative histopathologic evaluation can add to quantitative cultures in the assessment of bacterial urovirulence in the mouse model of ascending urinary tract infection.     

Radiologic evaluation of patients with renal infections

Although renal imaging is not indicated routinely in cases of uncomplicated renal infection, CT is a highly sensitive modality to diagnose and guide the management of patients with acute renal infection. CT is particularly useful in identifying complications of renal infection. Intravenous urography and US are limited to screening for urinary obstruction, renal calculi, and underlying anomalies. CT is also of value in establishing the diagnosis in equivocal cases, in evaluating high-risk patients, and in determining the nature and extent of disease. CT urography is increasingly performed as a comprehensive urinary tract imaging study. MRI may be performed when patients have contraindications to iodinated contrast material. Cortical scintigraphy is the preferred imaging study for the evaluation of children with acute pyelonephritis, although power Doppler US can be considered as a possible alternative. Recent limited studies using gadolinium-enhanced MRI have been shown to be valuable in the depiction of changes of acute pyelonephritis.     

Urinalysis and urine culture in women with dysuria

In caring for women with acute dysuria, clinicians traditionally have relied on clinical findings to distinguish between acute pyelonephritis and "cystitis"; they have ordered urinalysis and urine culture regularly for patients with suspected acute pyelonephritis and ordered these tests inconsistently for patients with suspected "cystitis." Recent evidence indicates that "cystitis" may actually be any of six different clinical conditions, each of which is managed differently; subclinical pyelonephritis, lower urinary tract bacterial infection, chlamydial urethritis, other forms of urethritis, vaginitis, or dysuria without any urinary tract or vaginal infection. The distinction between these entities is made primarily from clinical findings. Urinalysis is also of great value in symptomatic patients; the presence of pyuria (and possibly indirect quantitation of pyuria by the leukocyte esterase test) is a reliable indicator of treatable infection, and its absence indicates infection is not present. In contrast, urine culture is of clear value only in patients with acute pyelonephritis or subclinical pyelonephritis.     

Psoas abscess and bacterial peritonitis caused by urinary tract infection in a patient of liver cirrhosis and diabetes mellitus

Prognosis of patients with diabetes mellitus or liver cirrhosis can be worsened by the development of a variety of infectious diseases. We describe a case of psoas abscess and bacterial peritonitis in a 58-year-old woman with type C liver cirrhosis and diabetes mellitus hospitalized after having an elevated temperature caused by urinary tract infection for 2 months. The cirrhosis had not been treated and daily self-administration of insulin had been discontinued for the previous 5 months. On day 2 of hospitalization, vomiting and decreased blood pressure developed. Abdominal computed tomography scan revealed ascites, pneumoperitoneum, and psoas abscess. Laparotomy revealed psoas abscess and bacterial peritonitis without gastrointestinal perforation and psoas abscess perforation. Surgical drainage of the abscess and peritoneal cavity was performed. Immediately after the operation, upper gastrointestinal bleeding, shock, hypoglycemia, and metabolic acidosis developed, followed by hepatic failure, renal insufficiency, and cerebral dysfunction. Death occurred on postoperative day 19. Upon autopsy, bacterial peritonitis residue of psoas abscess, and urinary tract infection were confirmed. We surmise that untreated liver cirrhosis and diabetes mellitus is a risk for urinary tract infection that may spread in iliopsoas and free peritoneal space.     

Pyelonephritis and acute renal failure

Bacterial invasion of the renal parenchyma, pyelonephritis, is rarely considered as a primary cause of acute renal failure, particularly in adults. We report two cases of acute renal failure occurring in absence of hypotension, urinary tract obstruction, or nephrotoxic medications that are likely the direct consequence of pyelonephritis. The first case involved a 48-year-old HIV-positive woman who presented with 3 days of nonspecific symptoms and was noted to have acute renal failure. Due to unremitting renal dysfunction, a renal biopsy was performed confirming the diagnosis of bacterial pyelonephritis. The second case, a 33-year-old man with HIV disease, presented with fever and was found to have pyelonephritis by urine culture and ultrasonography. These cases represented initial diagnostic dilemmas for the admitting physicians and demonstrate the varied clinical presentations of acute renal failure as a direct consequence of bacterial infiltration of the renal parenchyma.     

Antibody-coated bacteria as an indicator of the site of urinary tract infection in renal transplant recipients receiving immunosuppressive agents.

Distinguishing an infection in the upper urinary tract from one in the lower urinary tract is especially important in renal transplant patients. Although the presence of antibody-coated bacteria in the urine has been shown by others to be a reliable indication of an infection in the upper urinary tract, it was not known whether sufficient antibody to coat the bacteria would be produced in a renal transplant recipient undergoing immunosuppression. We used a fluorescent test for detecting antibody-coated bacteria in the urine to follow 80 renal transplant patients prospectively for six months. Antibody-coated bacteria were detected in specimens from four patients with a clinical picture compatible with, or histopathologic evidence of, pyelonephritis. The origin of bacteriuria in a fifth patient was indeterminate both clinically and by the fluorescent antibody test. Twenty-three other patients with bacteriuria without clinical or histopathologic evidence of pyelonephritis had negative tests for antibody-coated bacteria. One patient with pyelonephritis in her own end-stage kidney had persistent bacteriuria with a negative fluorescent antibody test. Her transplanted kidney, however, was not infected.     

Nifedipine-induced renal dysfunction. Alterations in renal hemodynamics

Nifedipine caused acute, reversible deterioration in renal function in four patients with chronic renal insufficiency. The absence of hypotension, clinical course, benign urinary sediments, and normal results of renal ultrasound examinations excluded acute tubular necrosis, pyelonephritis, interstitial nephritis, obstructive uropathy, and acute glomerulonephritis. It is postulated that this slow calcium channel blocker produced deleterious intrarenal hemodynamic alterations in the setting of moderate to severe renal functional impairment. Nifedipine may alter renal function by blocking calcium entry into renal vascular smooth muscle, thereby reducing the efficacy of vasoconstrictor hormones in regulation of renal blood flow and glomerular filtration rate. An alternative explanation is that nifedipine may inhibit the compensatory synthesis of vasodilatory prostaglandin E2 analogous to the clinical observation of acute deterioration in renal function by nonsteroidal anti-inflammatory drugs in patients with pre-existing renal insufficiency. These observations suggest that clinicians should monitor renal function closely and exercise caution when administering nifedipine to patients with underlying renal insufficiency.     

Bilateral renal cortical abscesses in a young woman with type 1 diabetes

Serious complications of urinary tract infection, such as papillary necrosis or perinephric abscess, occur more frequently in diabetic patients. However, severe bilateral renal parenchymal infection with multiple intrarenal abscesses is not well recognized. We described an 18-year-old insulin-dependent diabetic woman with such infection, in whom renal imaging showed progression to a major perinephric abscess, but only after 5 weeks of intensive antibiotic therapy. Complete recovery followed surgical drainage and no renal cortical scarring was present on computerized tomographic scan 18 months later.     

Urinary tract infection in patients with diabetes mellitus

Urinary tract infection is an important infection in patients with diabetes mellitus. Asymptomatic and symptomatic infections of urinary tract, and also some rarer serious complications of urinary tract infections (papillary necrosis, renal and perirenal abscess, emphysematous and xantogranulomatous pyelonephritis and s.o.). Incidence, outcome and treatment in patients with diabetes, which deserve special clinical attention, are commonly viewed by prism of personal opinion, and should be based on clinical studies, focused on this topic.     

Virulence-associated traits in Escherichia coli causing first and recurrent episodes of urinary tract infection in children with or without vesicoureteral reflux

Virulence-associated properties of 606 urinary isolates from 174 children with urinary tract infections were related to severity of infection and factors increasing host susceptibility, e.g., vesicoureteral reflux (grade II or higher) and P1 blood group phenotype. A high proportion of strains of Escherichia coli causing first or recurrent episodes of acute pyelonephritis in children without reflux expressed the previously noted high frequency of certain O antigens, resistance to serum killing, hemolysin production, and adhesive capacity. A significantly lower frequency of these traits and a higher frequency of non-E. coli were seen among isolates from children with pyelonephritis and reflux, cystitis, and asymptomatic bacteriuria. Reflux was thus found to be a determinant of the level of infection and of the bacterial properties required to produce pyelonephritis. Efforts aimed at preventing or treating urinary tract infection by interfering with "virulent" bacteria may be of less value in patients with recurrent pyelonephritis and reflux, who are most likely to develop renal scars.     

Renal dysfunction in HIV-1-infected patients

Improved therapy directed against opportunistic infection and HIV-1 itself has resulted in greatly enhanced patient survival in the past decade among patients infected with HIV-1. Since patients are living longer, HIV-1 infection is associated with a rising burden of kidney disease. Approximately 14% of black patients and 6% of white patients dying with HIV-1 infection in 1999 in the United States had renal disease. Overall, 10% of patients dying with HIV-1 infection had renal failure. The most common glomerular diseases are focal segmental glomerulosclerosis and immune complex glomerulonephritis. Appropriate therapy for focal segmental glomerulosclerosis includes effective antiretroviral therapy and angiotensin antagonist medication. Drug toxicity is also common, often manifesting as electrolyte abnormalities, acute renal failure, interstitial nephritis, or nephrolithiasis. In particular, indinavir is associated with crystalluria, nephrolithiasis, interstitial nephritis, and lower urinary tract inflammation. Appropriate screening for renal disease and appropriate intervention will likely reduce the morbidity and mortality associated with progressive renal disease.     

Acute multifocal bacterial nephritis complicated with acute renal failure and thrombocytopenia

A 50-year-old woman was transferred to our hospital because of acute renal failure and thrombocytopenia. Due to rapid enlargement of the kidney, we first suspected that she had diffuse renal invasion of anaplastic carcinoma or lymphoma of the kidney. Anti-bacterial treatment for complicated urinary tract infection and hemodialysis treatment resulted in recovery of both renal function and thrombocytopenia. Serial CT study demonstrated disappearance of kidney swelling and multiple masses within the kidney. We finally made a diagnosis of acute multifocal bacterial nephritis. Timely initiation of dialysis therapy and appropriate anti-bacterial treatment was essential to rescue this case.     

Renal ultrasonographic correlates of acute pyelonephritis.

To determine the frequency and clinical significance of ultrasonographically detectable alterations in renal volume and anatomy that are associated with acute pyelonephritis, 25 women underwent renal ultrasonography during the acute phase of their illness, and 21 of these patients underwent the procedure after receiving antimicrobial therapy. One patient had a predisposing anatomic abnormality (4%; 95% confidence interval, 0-12%), and one patient each (8%; 95% confidence interval, 0-19%) experienced focal complications (an intrarenal mass and perinephric fluid collection). The kidneys of the 21 evaluable patients were acutely swollen (mean, 20%; P = .0001); one or both kidneys were enlarged by greater than or equal to 15% in 17 (81%). Acute renal enlargement was associated with protracted pretherapy symptoms (P less than .01), leukocytosis (P less than .01), focal infectious complications (P less than .01), and prolonged hospitalization (P less than .05). Thus, ultrasonographically demonstrable renal swelling characteristically occurs in women with acute pyelonephritis but is usually apparent only in retrospect. The degree of swelling correlates with selected clinical parameters, and the frequency of underlying anatomic abnormalities and focal infectious complications is low.