Acute focal bacterial nephritis is associated with invasive diagnostic procedures - a cohort of 138 cases extracted through a systematic review

Acute Focal Bacterial Nephritis in a Patient with Solitary Kidney: Case Report

INTRODUCTION

Acute focal bacterial nephritis is an underdiagnosed condition. It clinically resembles acute pyelonephritis. If unrecognized and undertreated, it may progress into complications (kidney abscess and scars). Contrast-enhanced computed tomography (CT) reveals specific images of the disease and is considered the gold standard to make the diagnosis.

CASE REPORT

A 63-year-old male patient with solitary kidney presented with symptoms compatible with acute pyelonephritis. Kidney ultrasound was not conclusive. Because of persisting high-grade fever not resolving after 48 hours of antibiotics, a contrast-enhanced CT was then performed, and the diagnosis of acute focal bacterial nephritis was made. A repeat CT after three weeks of intravenous (IV) antibiotics showed marked improvement of the intrarenal lesions, and a fourth week of IV antibiotics was dispensed.

CONCLUSION

Diagnosing acute focal bacterial nephritis is important (particularly in a patient with solitary kidney). This will dictate the therapy duration. Unlike acute pyelonephritis, acute focal bacterial nephritis requires at least three weeks duration of antibiotics to avoid progress into further complications.

Structured diagnostic scheme clinical experience sharing: a prospective study of 320 cases of fever of unknown origin in a tertiary hospital in North China

BACKGROUND

There has been little research on the long-term clinical outcomes of patients discharged due to undiagnosed fevers of unknown origin (FUO). The purpose of this study was to determine how fever of unknown origin (FUO) evolves over time and to determine the prognosis of patients in order to guide clinical diagnosis and treatment decisions.

METHODS

Based on FUO structured diagnosis scheme, prospectively included 320 patients who hospitalized at the Department of Infectious Diseases of the Second Hospital of Hebei Medical University from March 15, 2016 to December 31,2019 with FUO, to analysis the cause of FUO, pathogenetic distribution and prognosis, and to compare the etiological distribution of FUO between different years, genders, ages, and duration of fever.

RESULTS

Among the 320 patients, 279 were finally diagnosed through various types of examination or diagnostic methods, and the diagnosis rate was 87.2%. Among all the causes of FUO, 69.3% were infectious diseases, of which Urinary tract infection 12.8% and lung infection 9.7% were the most common. The majority of pathogens are bacteria. Among contagious diseases, brucellosis is the most common. Non-infectious inflammatory diseases were responsible for 6.3% of cases, of which systemic lupus erythematosus(SLE) 1.9% was the most common; 5% were neoplastic diseases; 5.3% were other diseases; and in 12.8% of cases, the cause was unclear. In 2018-2019, the proportion of infectious diseases in FUO was higher than 2016-2017 (P < 0.05). The proportion of infectious diseases was higher in men and older FUO than in women and young and middle-aged (P < 0.05). According to follow-up, the mortality rate of FUO patients during hospitalization was low at 1.9%.

CONCLUSIONS

Infectious diseases are the principal cause of FUO. There are temporal differences in the etiological distribution of FUO, and the etiology of FUO is closely related to the prognosis. It is important to identify the etiology of patients with worsening or unrelieved disease.

Skin-to-Renal Pelvis Distance Predicts Costovertebral Angle Tenderness in Adult Patients with Acute Focal Bacterial Nephritis

OBJECTIVES

The aim of this study was to examine whether the distance between the skin and the renal pelvis affects the detection of costovertebral angle (CVA) tenderness in patients with acute focal bacterial nephritis (AFBN).

METHODS

We retrospectively reviewed the charts of our patients between April 2013 and June 2019 who were diagnosed as having AFBN. Diagnosis was based on ultrasound or computed tomography with contrast, revealing at least one wedge-shaped area of decreased vascularity and confirmation of fever not attributable to another condition.

RESULTS

We extracted 23 cases, all Japanese (mean age 60.0 years old [range 45-81 years], 7 males, 16 females). CVA tenderness was present in 8 of these 23 patients. Receiver operating characteristic curves were drawn to evaluate the ability to differentiate skin-to-renal pelvis distance (SPD), body mass index, and age. Only SPD was a useful predictor of CVA tenderness, and 66 mm was determined as the optimal cutoff point (area under the receiver operating characteristic curve 0.858, 95% confidence interval 0.70-1.00). Logistic regression analysis was performed with CVA tenderness as a dependent variable, and SPD, body mass index, and age as explanatory variables. SPD was an independent predictive variable of CVA tenderness (P = 0.038, odds ratio 0.76, 95% confidence interval 0.590-0.986).

CONCLUSIONS

CVA tenderness showed low yield in the diagnosis of AFBN in patients with longer SPD. Its use for diagnosis in obese patients may therefore be limited.

A Case of Acute Focal Bacterial Nephritis With Negative Pyuria and Urine Culture Test Results

Acute focal bacterial nephritis (AFBN) is a radiologically diagnosed acute localized kidney infection that appears in the continuum between a perinephric abscess and renal abscess. We report an unusual case of AFBN presenting without pyuria or positive urine cultures. A 42-year-old woman with chronic lower back pain who regularly used nonsteroidal anti-inflammatory drugs was admitted to our hospital with right-sided abdominal distention, fever, chills, and pain extending from the right lower abdomen to the back since two days. The physical examination revealed no abdominal or costovertebral angle tenderness. Urinalysis was negative. Abdominal ultrasound was notable for an indistinct nodular shadow (32 × 25 mm) on the upper pole of the right kidney. Abdominal contrast-enhanced computed tomography revealed a wedge-shaped area with a minimal uptake of the contrast in the right kidney. The patient was admitted to the hospital, and antimicrobial therapy was started for AFBN. Antibiotics were administered intravenously for one week and orally for two weeks. No relapse of symptoms was observed during the four-month follow-up period. This case report suggests the importance of considering AFBN as a differential diagnosis for cases of idiopathic fever and lateral pain or back pain, even when pyuria and urine culture test results are negative.

Renal Leukemic Infiltration Overlapping Acute Focal Bacterial Nephritis during Myelodysplastic Syndrome: An Autopsy Case Report

Renal leukemic infiltration is uncommon in myeloid neoplasms, including myelodysplastic syndromes (MDS). A 76-year-old male patient was admitted to our hospital with complaints of fever and dyspnea. He was diagnosed with MDS with multilineage dysplasia and acute focal bacterial nephritis (AFBN) based on clinical, laboratory, and radiological investigations. Antibiotic treatment temporarily improved his condition, but the radiological image of AFBN remained. His condition gradually deteriorated into multiple organ failure, and he unfortunately died on the 31st day of hospitalization. Autopsy findings revealed significantly increased p53-positive blasts in the bone marrow and renal parenchyma overlapping AFBN, suggesting leukemic transformation and renal infiltration. This case emphasizes the need to review the diagnosis when antibiotic treatment is ineffective in MDS patients with AFBN.

Acute focal bacterial nephritis and prolonged fever

Acute focal bacterial nephritis (AFBN) is characterised by a complicated upper urinary tract infection ranging from acute pyelonephritis to renal abscess. Timely diagnosis of AFBN is important because antibiotic therapy of longer duration is required. A 10-year-old boy presented with fever for 5 days and bilateral flank pain. He was oriented and cooperative but appeared ill. Physical examination did not reveal any oedema or costovertebral angle tenderness. Acute phase reactants such as erythrocyte sedimentation rate and C-reactive protein were raised, serum creatinine was 1.25 mg/dL (0.31-0.88) and leucocyte esterase was positive in the urine. Ultrasonographic examination demonstrated bilaterally enlarged kidneys with increased echogenicity. Because of the high creatinine level, abdominal magnetic resonance imaging (MRI) was performed instead of computed tomography (CT) for further evaluation. The MRI showed an increase in the size of both kidneys, renal cortical heterogeneity and multiple cortical nodular lesions with diffusion restriction (constrained Brownian movement of water molecules) on diffusion-weighted MRI. A negative urine culture result in children presenting with fever and abdominal pain may mislead the clinicians, causing them to miss a nephro-urological diagnosis. It is therefore recommended that patients in whom the cause of fever cannot be determined be scanned by ultrasound and examined by CT or MRI so that undiagnosed and/or suspected cases of AFBN might be detected.

Clinical features of acute focal bacterial nephritis in adults

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidneys presenting as an inflammatory mass that can develop into renal abscess. The current reports on AFBN mostly are among children and rarely described in adults. This study was aimed to analyze the clinical features of AFBN in adults and make a review for the disease to give the clinicians some clues to suspect and recognize it in adults. From January 2014 to December 2019, AFBN was diagnosed by contrast-enhanced computed tomography (CT) in 238 adults at the Department of Nephrology, the Second Hospital of Hebei Medical University, Shijiazhuang, China. We reviewed the clinical records of these patients and asked them about their post-discharge status via telephone follow-up. Of all the patients, 195 were female and 43 were male, the median age were 46.87 years. 86.13% presented with fever, 55.89% presented with lower urinary tract symptoms and 97.9% presented with pyuria. In renal ultrasonography, abdominal findings were seen only 22.69% patients. E.coli accounted for 74.73% of the isolated pathogen. After 4 weeks of treatment, the patients had no recurrence of symptoms. We recommend that when a patient presents clinically with acute pyelonephritis, but the fever persist longer after antimicrobial treatment (≥ 4 days in our study), AFBN should be suspected. For the diagnosis, contrast-enhanced CT is the “gold standard”, magnetic resonance imaging (MRI) may be a good option, but the ultrasonography is probably not satisfied. 3–4 weeks of antibiotic therapy may be appropriate for AFBN in adults.

A case of acute focal bacterial nephritis with acute kidney injury presenting as acute abdomen

Acute focal bacterial nephritis (AFBN) refers to the bacterial infection of the renal parenchyma without abscess formation. Although AFBN has mainly been reported in pediatric patients, it may be underdiagnosed in adults as it resembles acute pyelonephritis in its clinical presentation. However, the symptoms suggesting acute abdomen is an important clue to diagnose AFBN, which requires additional imaging studies such as contrast-enhanced computed tomography (CECT). Here, we present the case of a 49-year-old female presenting to our emergency room with acute abdomen as well as acute kidney injury (AKI). CECT was performed to rule out critical etiologies of severe abdominal pain and the results revealed multifocal wedge-shaped shadows in the right kidney and diffuse enlargement of bilateral kidneys. We diagnosed the patient with AFBN and treated her through temporal hemodialysis (two sessions) and antibiotics for 23 days. Although AKI associated with AFBN has rarely been reported, her renal dysfunction and other symptoms were completely improved. In conclusion, clinicians should be aware of AFBN and be cautious to avoid the unnecessary invasive interventions.

Increased cytokines/chemokines and hyponatremia as a possible cause of clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with acute focal bacterial nephritis

OBJECTIVE

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), the second most common encephalopathy syndrome in Japan, is most often associated with viral infection. Bacterial MERS has been rarely reported but is mostly associated with acute focal bacterial nephritis (AFBN) for an unknown reason. We examined cytokines and chemokines in four MERS patients with AFBN to determine if they play an important role in the pathogenesis.

METHODS

We examined the clinical charts and MRI results in four MERS patients with AFBN, and measured 10 cytokines and chemokines in serum and cerebrospinal fluid in the acute phase. These were analyzed using the Mann-Whitney U test, compared with the control group (cases with a non-inflammatory neurological disease). Longitudinal changes in the serum cytokine and chemokine levels were evaluated in two patients.

RESULTS

Hyponatremia was observed in all four patients with MERS associated with AFBN (128-134 mEq/L). CSF analysis revealed increased cytokines/chemokines associated with Th1 (CXCL10, TNF-α, IFN-γ), T reg (IL-10), Th17 (IL-6), and neutrophil (IL-8 and CXCL1). In serum, upregulation was observed in those associated with Th1 (CXCL10, TNF-α, IFN-γ), Th17 (IL-6), and inflammasome (IL-1ß). The increased serum cytokines/chemokines in the acute stage normalized within 2 weeks in patients 1 and 2, so examined, in accordance with their clinical improvement.

CONCLUSION

Increased cytokines/chemokines and hyponatremia may be factors that explain why AFBN is likely to cause MERS.

Renal Mass Biopsy

Kidney cancer accounts for 2% of cancer related deaths. Historically, a patient with a solid renal mass would undergo surgery without biopsy given the previously low diagnostic yield of biopsy and the fear of tumor seeding. This led to a high rate of resection for benign masses. With the rising incidence of renal masses discovered on imaging, improvements in biopsy technique and advancements in pathologic evaluation of biopsy samples of renal masses, renal mass biopsy now plays an important role in selected patients with renal masses. Coaxial core needle biopsy is the preferred technique with a low rate of complications and a high diagnostic yield. This article will discuss indications, methods, utility, limitations and complications of renal mass biopsy.

Acute lobar nephronia: Pitfalls and insights of an underdiagnosed urologic condition

Background:

Acute lobar nephronia (ALN) is an underdiagnosed urological condition which has scarce publications available. It is described as an acute inflammatory and bacterial infection of the kidney without liquefaction, and in fact likely represents a mid-point between acute pyelonephritis and renal abscess. Patients usually present with fevers, septic shock, and occasionally abdominal and flank pain. To date there is no consensus on its optimal management.

Objective:

The aim of this study was to describe the presentation, evaluation, multidisciplinary involvement and management, and follow-up of ALN.

Method:

An observational study was performed utilising four patients from our single centre urology department. Data collected included basic demographics and diagnosis and management. All four patients are presented below. Observations and comparisons were made between all patients to aid in understanding the commonality between their presentations and managements.

Conclusion:

ALN is an underdiagnosed condition. Its diagnosis and management is difficult and requires a multidisciplinary approach. Many patients require prolonged inpatient management and close follow-up. An underlying renal mass is always an important differential diagnosis to be considered. Level of evidence: Not applicable for this multicentre audit.

Thinking of Draining a Renal Abscess? Wait! - Could Be Acute Lobar Nephronia

Acute Lobar Nephronia (ALN) is a rare infective condition of the kidney currently described only in case reports and small case series. The diagnosis of ALN is made by characteristic clinico-radiological findings. Differentiation from acute pyelonephritis, renal abscess and renal tumor is crucial for proper management and to avoid unnecessary diagnostic interventions. Herein, we report a 58-year-old woman with an uncontrolled diabetes mellitus, who was diagnosed clinically as acute pyelonephritis and treated with standard duration of antibiotics but had recurrence of symptoms. On evaluation, she was found to have ALN which was treated successfully with prolonged antibiotic course.

Literature review of allograft adenovirus nephritis and a case presenting as mass lesions in a transplanted kidney without symptoms of urinary tract infection or acute kidney injury

Adenovirus (AdV) infection is a common complication in bone marrow/hematopoietic stem cell transplant and solid organ transplant recipients. AdV infection usually presents as hemorrhagic cystitis, but sometimes it can progress to acute kidney injury showing AdV nephritis (AdVN). We present the case of a 52-year-old Japanese female who had received a living kidney transplantation (KT) from her husband. At 21 months post-KT, the patient presented with a fever, but no renal dysfunction and no abnormal urine findings. A contrast-enhanced computed tomography (CT) scan revealed a few mass lesions with hypoperfusion in the transplanted kidney. An enhanced CT-guided biopsy targeting one of these lesions revealed a necrotizing tubulointerstitial nephritis suggesting AdVN. The polymerase chain reaction tests for ADV were negative in a urine sample but positive in the sera and the frozen kidney biopsy samples. AdVN can manifest as an unusual pattern of acute lobar nephritis/acute focal bacterial nephritis-like localization without symptoms of acute kidney injury or urinary tract infection. Enhanced CT can provide clues for clinical diagnosis.

Clinical Characteristics of Pediatric Pyelonephritis Without Pyuria or Bacteriuria

BACKGROUND

The gold standard for the diagnosis of acute pyelonephritis (APN) in children is the finding of both pyuria (P) and bacteriuria (B); however, some APN patients have neither of these findings [APN(P(-);B(-))].

METHODS

In this study, we investigated APN patients who visited our hospital over 14 years to identify specific clinical characteristics of APN(P(-);B(-)).

RESULTS

A total of 171 APN patients were included in the study, and of these 29 were APN(P(-);B(-)). Of the APN(P(-);B(-)) patients, 25.9% had vesicoureteral reflux (VUR), the same percentage as the APN(P(+);B(+)) patients, and 69.0% of APN(P(-);B(-)) patients had already taken antibiotics before diagnosis. APN(P(-);B(-)) patients were older and had a longer duration between onset of fever and diagnosis than the patients with pyuria and/or bacteriuria. In addition, they showed higher C-reactive protein levels. APN(P(-);B(-)) patients had high levels of urinary α-1 microglobulin and urinary β-2 microglobulin.

CONCLUSIONS

APN is difficult to diagnose in febrile patients who display neither pyuria nor bacteriuria, but as these patients have the same risk for VUR as APN patients with pyuria and bacteriuria, a detailed history establishing the clinical course as well as urinary chemistry investigations, may assist in diagnosis.

Imaging findings of infectious and inflammatory diseases of the urinary system mimicking neoplastic diseases

Neoplastic diseases affecting the urinary organs are common, and diagnosis by imaging is usually straightforward. However, infectious/inflammatory processes also commonly affect these organs and can be mistaken for a neoplasm. Familiarity with these potential mimickers and awareness of their imaging presentations are key for correct diagnosis. We present the imaging findings of non-neoplastic infectious/inflammatory diseases that can mimic a neoplastic process.

Comparison of mild encephalopathy with reversible splenial lesion with and without acute focal bacterial nephritis

OBJECTIVE

Clinically mild encephalitis/encephalopathy with a reversible lesion (MERS) is characterized by reversible lesions with transiently-reduced diffusion in the splenium of the corpus callosum on magnetic resonance imaging. Recently, cases of MERS with accompanying acute focal bacterial nephritis (AFBN) have been reported in children. This study aimed to clarify the clinical features of MERS with AFBN.

METHODS

A retrospective study of patients with MERS was conducted at Nagano Children's Hospital, Japan, from April 2013 to March 2018. The clinical signs and laboratory findings of MERS patients with AFBN (AFBN group) and without AFBN (non-AFBN group) were measured and compared.

RESULTS

Of 12 patients diagnosed as having MERS, 3 were also found to have AFBN. Seven of the 9 patients without AFBN were associated with infectious agents, including rotavirus and influenza viruses. No patient received steroids or intravenous immunoglobulin therapy, and none displayed neurological sequelae. Serum C-reactive protein (CRP) levels were significantly higher in the AFBN group than in the non-AFBN group (14.7 mg/dL versus 0.8 mg/dL, P = 0.009). AFBN group patients were also significantly older (97 months versus 27 months, P = 0.018) and experienced significantly less frequent seizures (33% versus 100%, P = 0.045). The mean duration of neurological symptoms was significantly longer in the AFBN group than in the non-AFBN group (4 days versus 1.7 days, P = 0.013).

CONCLUSIONS

Pediatric patients with AFBN often present with non-specific findings, such as fever and abdominal pain. Pediatricians should be aware of the possibility of AFBN in the clinical setting of MERS, particularly when the patient exhibits inexplicably high CRP.

Acute Focal Bacterial Nephritis: Two Cases and Review of the Literature

Rationale:

Acute focal bacterial nephritis (AFBN) has mainly been reported in pediatrics. It may be an underdiagnosed condition in adults because it resembles acute pyelonephritis (APN) in its clinical presentation.

Presenting concerns of the patients:

Two young women (25 and 27 years old, respectively) presented with complaints compatible with a diagnosis of APN. However in both, fever was of high grade, persistent for several days in spite of antibiotic administration, and there was demonstrated worsening of the inflammatory biomarkers. A contrast-enhanced computed tomography (CECT) led to the diagnosis in both cases.

Diagnoses:

Contrast-enhanced computed tomography reveals the most sensitive and specific images of AFBN. This includes wedge-shaped lesions with decreased enhancement, which may be focal or multifocal.

Interventions (including prevention and lifestyle):

Antibiotic therapy for at least 3 weeks.

Outcomes:

Resolution of AFBN was obtained after 3 weeks of antibiotics.

Lessons learned:

Our 2 cases illustrate the importance of CECT imaging to confirm the diagnosis of AFBN. Interstitial bacterial inflammation may have a worse prognosis if not diagnosed early and efficiently treated. Unlike APN, the management of AFBN requires at least 3 weeks of antibiotics to prevent the development of renal scarring and renal abscess.

Ureteral dilatation detected in magnetic resonance imaging predicts vesicoureteral reflux in children with urinary tract infection

Objective

Urinary tract infection (UTI), one of the most common bacterial infections occurring during infancy and early childhood, is frequently associated with vesicoureteral reflux (VUR). Although several guidelines recommend performing ultrasonography as a screening test, its utility is not adequate and appropriate screening tests are strongly desirable. In this study, we evaluate the use of magnetic resonance imaging (MRI) as a screening test for VUR in children with UTI.

Methods

We prospectively studied 108 patients with suspected UTI between April 2014 and March 2016. UTI was diagnosed on the basis of diffusion-weighted MRI (DW-MRI) and urine culture findings. We measured ureteral dilatation using MRI in 96 patients with UTI and assessed the relationship between ureteral dilatation in MRI and VUR in 46 patients who underwent voiding cystourethrography (VCUG).

Results

Among 108 patients, 88 and 8 were diagnosed with upper and lower UTI, respectively. Among 46 patients who underwent VCUG, 23 had VUR (14 low grade and 9 high grade). Patients with ureteral dilatation detected on MRI had VUR more frequently than those without ureteral dilatation (any grades VUR, 71% vs. 32%; P = 0.02; high-grade VUR, 38% vs. 2%, P = 0.007). Overall, ureteral dilatation findings on MRI achieved sensitivity 65.2% and specificity 73.9% as a screening test for VUR. In addition, DW-MRI achieved sensitivity 100% and specificity 81.8% in the diagnosis of upper UTI.

Conclusion

These findings suggested that MRI is a valuable tool for screening of VUR as well as diagnosis of upper UTI.

Acute focal bacterial nephritis characterized by acute encephalopathy with biphasic seizures and late reduced diffusion

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidney presenting as an inflammatory mass, and some patients show deterioration of clinical condition with neurological symptoms. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a syndrome that is characterized by biphasic seizures and impaired consciousness with reduced diffusion in the subcortical white matter on magnetic resonance imaging, typically observed between days 3 and 9 after clinical onset. Although AFBN sometimes causes neurological symptoms, no cases of AFBN with AESD have been reported, and no studies have presented the cytokine profiles of patients with a severe form of acute encephalopathy with AFBN. We report here a very rare case involving a 6-month-old boy who developed AFBN due to Enterococcus faecalis with both the clinical and radiological features of AESD. In our patient, serum interleukin (IL)-6, IL-10, and interferon (IFN)-γ levels markedly increased on admission, and on day 4, only IL-6 levels significantly increased in the cerebrospinal fluid (CSF). These results suggest that high serum cytokines are produced locally in response to AFBN and elevated IL-6 levels in CSF may have neuroprotective roles.