1524. Presentation of Acute Focal Bacterial Nephritis in Children

BACKGROUND: Ascending infections are thought as the main route of infection in acute pyelonephritis (APN). However, among patients diagnosed with APN, a subset has atypical presentation unexplainable by ascending routes of infections. This study aimed to review 8 cases initially diagnosed as APN, however presenting with no or minimal pyuria and presenting as acute focal bacterial nephritis (AFBN). METHODS: This was a retrospective cohort study of children <18 years old without underlying diseases, treated for their first episode of APN during 2006 and 2016. Those that fit the following inclusion criteria were diagnosed as AFBN: (1) characteristic CT findings compatible AFBS, (2) atypical presentation of APN including lack of urinary symptoms, and (3) no antibiotic administration prior to urine culture. Electronic medical records were analyzed, and radiologic images re-evaluated. RESULTS: During the 11-year period, of the total of 359 patients were diagnosed with the first episode of APN. Of these, 8 were re-diagnosed as AFBN. The mean age was 9.8 years old (1.9–17.4). Abdominal pain with nausea and vomiting were chief complaints (62.5%), and none had urinary symptoms including dysuria, incontinence, or increased frequency. Initial urinalysis in all the patients showed WBC <10–19 hpf, and were negative for nitrite. High initial WBC and CRP levels were observed (median 17.892 × 10(3)/mm(3) and 13.1 mg/dL, respectively). Cultures were positive for E. coli in 3 cases. CT findings showed nephromegaly with multifocal wedge-shaped heterogeneous enhancement defects corresponding to blood supply patterns of renal segmental arteries, no hydronephrosis, and no inflammation in the pelviureteric calyceal system. A mean duration of fever was 6.6 days, and time to defervescence after initiation of antibiotics was an average of 3 days. CONCLUSION: Lack of urinary symptoms, insignificant pyuria, and CT findings of AFBN support the possibility of an alternative route of infection, other than the ascending route. DISCLOSURES: All authors: No reported disclosures.