What causes acute pyelonephritis?

In recent years, it has become clear that carriers of specific uroepithelial receptors and individuals who do not secrete the protective enzyme fucosyltransferase are more prone to developing pyelonephritis. The enzyme fucosyltransferase blocks bacterial adhesion to uroepithelial receptors.

Factors predisposing to pyelonephritis:

• Presence of kidney disease in the family, especially in the mother.
• Toxicosis of pregnancy.
• Infectious diseases of the mother during pregnancy, especially acute pyelonephritis or exacerbation of chronic.
• Intrauterine fetal infections.
• Congenital fetal malnutrition, intrauterine growth restriction and ischemic-hypoxic conditions of the central nervous system and kidneys.
• Immunodeficiency states.
• Frequent acute respiratory viral infections.
• Diseases of the gastrointestinal tract, both acute and chronic.
• Habitual constipation.
• Dystrophy and rickets.
• Atopic dermatitis.
• Diseases of the external genitalia.
• Worm infestations.
• Chronic foci of infection.
• Diabetes mellitus.
• Environmental factors.
• Genetic factors.

Pyelonephritis develops when three conditions are present:

1. Infection.
2. Impaired urodynamics predisposing to infection.
3. Decreased resistance of the body and decreased local protective renal factors.

Factors predisposing to urodynamic disorders:

1. Anomalies in the development of the urinary tract and kidneys.
2. Vesicoureteral reflux.
3. Obstruction of the ureter - compression by an additional renal vessel.
4. Kinking of the ureter due to disruption of the normal position of the kidney (nephroptosis or rotation, dystopia).
5. Neurogenic bladder dysfunction.
6. Functional disorders of the ureter (spasms, hypotension).
7. Renal dysplasia.
8. Dysmetabolic disorders of purine metabolism with excessive formation of uric acid, oxaluria, hypercalciuria.
9. Formation of combined pathology of the urinary system and spine (spina bifida, scoliosis).

In recent years, the role of E. coli in urodynamic disorders has been established. The endotoxin component of E. coli, lipid A, enhances the attachment of bacteria to the receptors of the urinary tract epithelium and, through the prostaglandin system, affects smooth muscles, causing functional obstruction and increased pressure in the urinary tract. In this case, the pressure in the urinary tract can reach 35 mm Hg, which is comparable to the pressure in vesicoureteral reflux.

The most common causative agents of pyelonephritis are uropathogenic strains of E. coli (70%). The second most common etiology in children is Proteus (3%), especially in young children and with intestinal dysbiocenosis. Proteus is considered a stone-forming microbe. With the help of urease, it breaks down urea into ammonia, which results in an increase in urine pH, increased damage to epithelial cells, and precipitation of calcium and magnesium salts. In the presence of simultaneous inflammation and in the bladder, enterobacter is cultured. In recent years, the role of mycoplasmas in the etiology of pyelonephritis has become more frequent (up to 17%), especially in children with intrauterine infections and during childbirth, as well as often in microbial pyelonephritis and persistent long-term relapses. The role of chlamydia in infection of newborns in the birth canal and persistence of chlamydia in children in the first year of life with microbial pyelonephritis and long-term relapses of the disease has increased somewhat. The frequency of isolation of Klebsiella has increased (12%). Less frequently, streptococcus, staphylococcus (3%), enterobacter (5%), as well as persistent latent enterovirus infection in intrauterine infection and in pyelonephritis in early childhood are important in the etiology of pyelonephritis.

The route of infection spread in newborns and infants is often hematogenous in the presence of foci of infection. They may also have a lymphogenous route - in acute gastrointestinal infections, habitual constipation, and intestinal dysbiocenoses. In children of other age periods, the urinogenous route of infection spread predominates.