BERKELEY, CA (UroToday.com) - The study out of Germany in the November 2007 issue of Pediatric Nephrology focused on acute focal bacterial nephritis in children. The group gives the definition of acute focal bacterial nephritis formerly known as lobar nephronia as a rare form of interstitial bacterial nephritis. They state it is most often described in adults with diabetes and there is only a limited knowledge of this disease process in children. Typically it is found with ultrasonographic findings of hypoechogenic, hypoperfused parenchyma lesions that are usually misdiagnosed as a renal cell carcinoma abscess or other tumor.

Over and 11 year period the group found that 30 children at their institutions where diagnosed with acute focal bacterial nephritis. They were able to retrieve 25 charts for a retrospective analysis. The patients mean ages were 4.5 years with a range of 4 months to 17.5 years of age. They were followed up an average of 4.2 years, ranging between 6 months and 11 years. All the children had symptoms of fever and rapid deterioration. The primary suspected diagnosis upon admission were meningitis (four patients), urinary tract infections (five patients), renal tumor (three patients), pneumonia (two patients), appendicitis (one patient) and the remaining 10 patients with unspecific disorders and fevers of unknown origin. The disease process of acute focal bacterial nephritis was diagnosed by ultrasound on an average of 3 days after the onset of symptoms (range: 1-10 days). Almost 80% of the patients presented with pyuria and bacteria. Hematuria was found only in one patient. Interestingly, blood cultures were negative in all but one patient. Urinary tract abnormalities were found in 12 out of the 25 children. These included vesicotueral reflux in 8, megaureter in 1, urethral valves in another patient, and unilateral renal hypoplasia in another patient. There was one patient with a constellation of urologic issues including mega cystitis, megatureter, caudal dystopic left kidney combined with hypoplasia, and dysplasia of the right kidney. Antibiotic therapy was instituted and the lesions that were consistent with acute focal bacterial nephritis resolved completely within 12 weeks of the onset of symptoms. Interestingly, renal parenchymal cysts remained in 3 cases and focal scaring only in 2. In the follow up period both pressure and renal function was normal in almost all cases.

The group concludes that acute focal bacterial nephritis should be suspected in children with fever and rapid deterioration. They also state that residual lesions such as cysts or scaring of renal parenchyma could remain so patients who present with acute focal bacterial nephritis should have radiographic imaging follow up. Sequential DMSA scans as well as ultrasound are helpful, however, in my opinion MR urography may play even a more crucial role for follow up.

Seidel T, Kuwertz-Bröking E, Kaczmarek S, Kirschstein M, Frosch M, Bulla1 M, Harms M.

Pediatr Nephrol. 22(11): 1897-1901, November 2007
doi:10.1007/s00467-007-0589-9

PubMed Abstract
PMID: 17874139

Written by Pasquale Casale, MD, a Contributing Editor with UroToday.

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