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

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          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.


          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.


          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.



          La pyélonéphrite aigüe focale (PNAF) a principalement été observée en pédiatrie. Il pourrait s’agir d’une affection sous-diagnostiquée chez les adultes puisque sa présentation clinique est similaire à la pyélonéphrite aigüe (PNA).

          Présentation des cas:

          Nous présentons les cas de deux jeunes femmes (âgées respectivement de 25 et de 27 ans) qui présentaient des troubles compatibles avec une PNA. Cependant, dans les deux cas, la fièvre était élevée et a persisté plusieurs jours malgré l’administration d’antibiotiques. On a également observé une augmentation des biomarqueurs de l’inflammation. Un examen par CECT a mené au diagnostic de PNAF dans les deux cas.


          La tomodensitométrie avec injection de contraste (CECT) révèle les images les plus sensibles et les plus spécifiques à la PNAF. Notamment les lésions cunéiformes avec intensification réduite pouvant être focale ou multifocale.

          Interventions (prévention et habitudes de vie):

          Un traitement antibiotique d’une durée de trois semaines.


          La PNAF s’est résorbée après un traitement aux antibiotiques de trois semaines.

          Enseignements tirés:

          Nos deux cas illustrent l’importance de recourir à l’imagerie par CECT pour confirmer le diagnostic de la PNAF. Le pronostic de l’infection bactérienne interstitielle est susceptible de s’assombrir si celle-ci n’est pas diagnostiquée rapidement et traitée efficacement. Contrairement à la PNA, la prise en charge de la PNAF exige un traitement antibiotique d’au moins trois semaines afin de prévenir la fibrose rénale et la formation d’abcès rénaux.

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          Most cited references 18

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          Acute focal bacterial nephritis (acute lobar nephronia).

          Acute lobar nephronia (ALN) refers to a renal mass caused by acute focal infection without liquefaction. The radiological findings in 12 patients with 13 episodes of ALN are described. A characteristic combination of uroradiological findings is (a) a relatively sonolucent mass which disrupts corticomedullary definition on ultrasonography; (b) a solid-appearing mass on other uroradiological studies; and (c) a positive gallium image in the region of the mass, which may be associated with increased activity elsewhere in the same or opposite kidney. The angiographic finding of significant venous narrowing within the mass associated with only minor arteriographic abnormalities is characteristic of ALN as well.
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            Effective duration of antimicrobial therapy for the treatment of acute lobar nephronia.

            Effective treatment of acute lobar nephronia (ALN) can prevent its progression to renal abscess. The goal of this prospective study was to compare the treatment efficacy for pediatric patients who had ALN with a 3- vs 2-week intravenous plus oral antimicrobial-therapy regimen. Patients who were suspected of having an upper urinary tract infection underwent a systematic scheme of ultrasonographic and computed tomographic (CT) evaluation for ALN diagnosis. Patients with positive CT findings were enrolled and randomly allocated with serial entry for either a total 2-week or a 3-week antibiotic treatment regimen. Antibiotics were changed from an intravenous form to an oral form 2 to 3 days after defervescence of fever. Follow-up clinical evaluations and urine-culture analyses were performed 3 to 7 days after cessation of antibiotic treatment. Patients with persistent infection or relapse were considered as treatment failures. A total of 80 patients with ALN were enrolled. Forty-one patients were treated with a 2-week antimicrobial protocol, and the other 39 patients were treated with a 3-week course. Seven treatment failures, 1 persistent infection, and 6 infection relapses were identified, all of which were in the 2-week treatment group. Prolonged fever before admission and positive Escherichia coli growth (>10(5) colony-forming units per mL) in urine culture were noted as risk factors for treatment failure. All treatment failures were managed successfully with an additional 10-day antibiotic course. A total of 3 weeks of intravenous and oral antibiotic therapy tailored to the pathogen noted in cultures should be the treatment of choice for pediatric patients with ALN.
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              Is acute lobar nephronia the midpoint in the spectrum of upper urinary tract infections between acute pyelonephritis and renal abscess?

              To examine acute lobar nephronia (ALN) in the spectrum of upper urinary tract infections between acute pyelonephritis (APN) and renal abscess. Medical records of 115 patients diagnosed with APN, ALN, or renal abscess with computed tomography (CT) were reviewed retrospectively. CT lesions and patterns of ALN were checked, and the volume of CT lesions was estimated in every patient. Then the correlation between clinical presentation and CT lesions was examined. The study included 21 patients with APN, 85 with ALN (63 simple ALN, 22 complicated ALN), and 9 with renal abscesses. The volume fraction of CT lesions correlated well with duration of fever before and after treatment in patients with APN or simple ALN, and only the correlation between fever duration after treatment and CT lesions was significant in patients with complicated ALN or renal abscess. We suggest that simple ALN be regarded clinically as the progression of APN. By contrast, complicated ALN is a distinct, more severe disease entity, and it may relate to or progress to renal abscess. ALN is probably not the midpoint in the traditional dynamic spectrum of upper urinary tract infections between APN and renal abscess.

                Author and article information

                Can J Kidney Health Dis
                Can J Kidney Health Dis
                Canadian Journal of Kidney Health and Disease
                SAGE Publications (Sage CA: Los Angeles, CA )
                25 October 2019
                : 6
                [1 ]University Hospital Sharjah, United Arab Emirates
                Author notes
                Adnane Guella, Consultant Nephrologist, University Hospital Sharjah, Sharjah PO Box 72772, United Arab Emirates. Email: adnane.guella@
                © The Author(s) 2019

                This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License ( which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (

                Educational Case Report
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                January-December 2019


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