Renal Epithelial Cells in Urinary Tract Infection
The presence of renal epithelial cells in the urine of this 4-year-old with fever, urinary symptoms, and E. coli bacteriuria indicates upper urinary tract involvement (pyelonephritis) with shedding of tubular epithelial cells from the renal parenchyma, though this finding is not considered sensitive or specific enough to be included as a diagnostic criterion for UTI. 1
Clinical Significance of Renal Epithelial Cells
The detection of renal epithelial cells in urine represents exfoliation of cells from the renal tubules, which occurs during active infection and inflammation of the kidney parenchyma. 1 However, the American Academy of Pediatrics guidelines explicitly state that renal epithelial cells are not considered sensitive or specific enough to be included as a diagnostic criterion for UTI in children. 1
What This Finding Means in Context
- Pyuria (white blood cells) is the hallmark of true UTI and helps distinguish UTI from asymptomatic bacteriuria, as it is the host's inflammatory response that results in scarring. 1
- The diagnosis of UTI requires both urinalysis results suggesting infection (pyuria and/or bacteriuria) AND at least 50,000 CFU/mL of a uropathogen from a properly collected specimen. 1
- In this case with confirmed E. coli growth and fever, the child meets criteria for febrile UTI (pyelonephritis), regardless of the renal epithelial cell finding. 1
Pathophysiology Context
Research demonstrates that uropathogenic E. coli can invade urothelial cells and form intracellular bacterial communities, leading to cell damage and exfoliation. 2 Additionally, E. coli produces alpha-hemolysin, which is directly cytotoxic to renal tubular epithelial cells, causing cell death and shedding into the urine. 3, 4
Key Clinical Implications
- Children younger than 1 year with febrile UTI have a lower risk (49%) of renal parenchymal involvement compared to children 1-4 years (73%) and 5-14 years (81%). 5
- Renal scarring occurs in approximately 15% of children after their first UTI episode, representing the most severe long-term sequela. 6
- Prompt treatment within 48 hours is crucial to limit renal damage, as delays increase the risk of renal scarring. 6
Management Priorities for This Patient
Immediate treatment should be initiated based on the confirmed diagnosis of febrile UTI with E. coli bacteriuria and pyuria, not based on the presence of renal epithelial cells. 1
Treatment Approach
- Duration: 7-14 days of antimicrobial therapy is recommended for febrile UTI in children. 1
- Route: Oral or parenteral administration is equally effective, with the choice based on practical considerations such as whether the child appears toxic or can retain oral intake. 1, 6
- Agent selection: Base initial choice on local antimicrobial sensitivity patterns and adjust according to sensitivity testing of the isolated uropathogen. 1
Required Follow-Up
- Renal and bladder ultrasound should be performed after the first febrile UTI to detect anatomic abnormalities. 6
- Parents should seek prompt medical evaluation for future febrile illnesses, with urine specimen obtained at the onset of subsequent fevers. 6
Common Pitfall to Avoid
Do not over-interpret the presence of renal epithelial cells as a specific diagnostic criterion or as requiring different management. The American Academy of Pediatrics explicitly excluded this finding from diagnostic criteria due to lack of sensitivity and specificity. 1 Focus instead on the confirmed presence of pyuria, bacteriuria, and positive culture with appropriate colony counts, which definitively establish the diagnosis of pyelonephritis in this febrile child. 1