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Norwich-Eaton lectureship. Pathogenesis of nonobstructive urinary tract infections in children
1Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana.
Insights
Urinary tract infections in children often stem from bacterial colonization and adherence, leading to kidney damage. Escherichia coli
Area of Science:
- Pediatric Nephrology
- Infectious Diseases
- Urology
Background:
- Most urinary tract infections (UTIs) occur without obstruction or vesicoureteral reflux.
- Bacterial colonization, often from maternal flora, can lead to perineal or preputial adherence in children.
- Nephropathogenic bacteria utilize P-fimbriae of Escherichia coli for adherence to urothelial cells.
Purpose of the Study:
- To elucidate the pathogenic mechanisms of UTIs leading to pyelonephritis and renal damage.
- To describe the progression from bacterial colonization to acute and chronic pyelonephritis.
Main Methods:
- The study describes the pathogenic cascade of UTIs based on established microbiological and physiological principles.
- It details bacterial adherence, ascent, and the host's inflammatory response.
Main Results:
- Escherichia coli P-fimbriae facilitate bacterial adherence and ascent, causing intrarenal reflux and acute pyelonephritis.
- Complement activation and granulocyte respiratory burst lead to renal ischemia, nephron loss, and tubular damage.
- Untreated infection results in renal scarring, chronic pyelonephritis, and progressive loss of renal function.
Conclusions:
- Bacterial factors like E. coli P-fimbriae and host inflammatory responses are critical in UTI pathogenesis.
- Early recognition and management are crucial to prevent irreversible kidney damage and chronic pyelonephritis.
- The described mechanism highlights the pathway to reflux nephropathy and long-term renal dysfunction.
Abstract:
Most urinary tract infections occur without either obstruction or vesicoureteral reflux. Children become colonized by their mother's bacterial flora, that within the nursery or by siblings. Bacterial adherence may lead to colonization of the perineum in girls and of the prepuce in boys (if uncircumcised). Nephropathogenic bacteria ascend the urinary tract because of the P-fimbriae of Escherichia coli which adhere to a specific urothelial cell glycolipid. The endotoxin effect on ureteral peristalsis leads to intrarenal reflux, adherence in the kidney and acute pyelonephritis. Complement activation then causes granulocytic aggregation in capillaries with renal ischemia and activates granulocytes to produce the respiratory burst of phagocytosis, which releases superoxide into both phagosomes and the tubular lumen. Bacteria are thus killed as are renal tubules, leading to nephron loss. Untreated, the ischemia and respiratory burst lead to a loss of renal function and scar formation ending as chronic pyelonephritis (or reflux nephropathy).