Acute focal bacterial nephritis in a cohort of hospitalized adult patients with acute pyelonephritis. Assessment of risk factors and a predictive model

Oral quinolones versus intravenous β-lactam for the treatment of acute focal bacterial nephritis: a retrospective cohort study

BACKGROUND

Evidence regarding the best antibiotic regimen and the route of administration to treat acute focal bacterial nephritis (AFBN) is scarce. The aim of the present study was to compare the effectiveness of intravenous (IV) β-lactam antibiotics versus oral quinolones.

METHODS

This is a retrospective single centre study of patients diagnosed with AFBN between January 2017 and December 2018 in Hospital Universitari Vall d'Hebron, Barcelona (Spain). Patients were identified from the diagnostic codifications database. Patients treated with oral quinolones were compared with those treated with IV β-lactam antibiotics. Therapeutic failure was defined as death, relapse, or evolution to abscess within the first 30 days.

RESULTS

A total of 264 patients fulfilled the inclusion criteria. Of those, 103 patients (39%) received oral ciprofloxacin, and 70 (26.5%) IV β-lactam. The most common isolated microorganism was Escherichia coli (149, 73.8%) followed by Klebsiella pneumoniae (26, 12.9%). Mean duration of treatment was 21.3 days (SD 7.9). There were no statistical differences regarding therapeutic failure between oral quinolones and IV β-lactam treatment (6.6% vs. 8.7%, p = 0.6). Out of the 66 patients treated with intravenous antibiotics, 4 (6.1%) experienced an episode of phlebitis and 1 patient (1.5%) an episode of catheter-related bacteraemia.

CONCLUSIONS

When susceptible, treatment of AFBN with oral quinolones is as effective as IV β-lactam treatment with fewer adverse events.

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.

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.

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.

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.

Pathogenic Mechanisms of Acute Obstructive Pyelonephritis

Among urological diseases, the most relevant is infection of the urinary tract. Pyelonephritis is on the 5th place in kidney diseases, and obstructive pyelonephritis occurs in 84% of all pyelonephritis. In the world, among the adult population, 100 people per 100,000 of the population suffer from pyelonephritis. In addition, from year to year, there is an increase in purulent forms of acute pyelonephritis by 4–5 times. This pathology is a separated manifestation of such an important urological problem as complicated urinary tract infection, which accounts for 84–86% of all infections. In acute obstructive pyelonephritis, more severe complications such as bacteriotoxic shock and urosepsis may develop. The mortality rate from these dangerous complications reaches 70–90%. In addition, the number of patients with urosepsis and bacteriotoxic shock has increased 4–6 times in recent years. The review presents current literature data on acute obstructive pyelonephritis. The main causes and pathogenetic mechanisms of the disease development are presented.

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.

Pain intensity and imaging at the initial phase of acute pyelonephritis

OBJECTIVE

To identify predictive factors of urological complication on imaging findings in women with pyelonephritis aged 18 to 65 years.

METHODS

We performed an observational, retrospective, single-center study. The medical charts of women diagnosed with pyelonephritis at the emergency department from 2010 to 2015 were reviewed. Only patients who underwent an imaging study at the emergency department and with microbiologically confirmed pyelonephritis were included for analysis. The primary endpoint was the presence of urological complications on imaging findings. The secondary endpoint was treatment changes after imaging diagnosis.

RESULTS

Of the 193 women enrolled, 88 (45.6%) had urological complication(s) on imaging findings. The multivariate analysis revealed that history of urolithiasis (OR=2.41; P=0.01) and pain requiring morphine use (OR=5.29; P=0.009) were predictive of urological complications on imaging findings. Of the 120 women with uncomplicated pyelonephritis who underwent imaging studies, 45% had urological complication, resulting in a treatment change in 36.7% of patients. The multivariate analysis revealed that age>40 years (OR=4.58; P=0.02) and pain requiring morphine use (OR=3.78; P=0.02) were predictive of urological complication(s) on imaging findings and of treatment change based on imaging findings (OR=6.76; P=0.005 and OR=4.19; P=0.01 respectively) in this subgroup.

CONCLUSIONS

Pain requiring morphine use, age, and history of urolithiasis are independent predictors of urological complications on imaging findings in patients with acute pyelonephritis.