Host and Bacterial Markers that Differ in Children with Cystitis and Pyelonephritis

Objective To determine whether treatment for urinary tract infections in children could be individualized using biomarkers for acute pyelonephritis. Study design We enrolled 61 children with febrile urinary tract infections, collected blood and urine samples, and performed a renal scan within 2 weeks of diagnosis to identify those with pyelonephritis. Renal scans were interpreted centrally by 2 experts. We measured inflammatory proteins in blood and urine using LUMINEX or an enzyme-linked immunosorbent assay. We evaluated serum RNA expression using RNA sequencing in a subset of children. Finally, for children with Escherichia colt isolated from urine cultures, we performed a polymerase chain reaction for 4 previously identified virulence genes. Results Urinary markers that best differentiated pyelonephritis from cystitis included chemokine (C-X-C motif) ligand (CXCL)1, CXCL9, CXCL12, C-C motif chemokine ligand 2, INF gamma, and IL-15. Serum procalcitonin was the best serum marker for pyelonephritis. Genes in the interferon-gamma pathway were upregulated in serum of children with pyelonephritis. The presence of E coli virulence genes did not correlate with pyelonephritis. Conclusions Immune response to pyelonephritis and cystitis differs quantitatively and qualitatively; this may be useful in differentiating these 2 conditions.