Unit V – Problem 11 – Pathology: Pyelonephritis and End-Stage Renal Disease (ESRD) - Urinary Tract Infection (UTI): presence of bacteria and leukocytes (pyuria) in the urine. - What are the causative organisms of (UTI) and pyelonephritis? E. coli. Species of Klebsiella, Enterobacter, Proteus and Pseudomonas. In immunocompromised patient (especially those with transplanted organs): polyomavirus, cytomegalovirus and adenovirus. - Pyelonephritis: Definition: it is a renal disorder affecting tubules, interstitium and renal pelvis. Routes of infection: Hematogenous: It is less common. From distant foci: septicemia or infective endocarditis. From the lower urinary tract (ascending infection): Colonization of dsital urethra and then: Spread to urinary bladder: in females it is due to short urethra or catheterization Multiplication in urinary bladder. Spread to ureters and renal pelvis via vesicoureteral reflux. Spread to renal parenchyma: intrarenal reflux. Acute pyelonehpritis: Morphology: Gross (image-1): discrete focal abscesses in one or both kidneys which can extend to large wedge-shaped areas; hyperemia. Histologic features (image-2): patchy interstitial supparative inflammation; intratubular aggregates of neutrophils and tubular necrosis. 1 2 Complications of acute pyelonephritis: Pyonephrosis: ureter, calyces and renal pelvis filled with pus. Perinephric abscess. Papillary necrosis (image-3): it is seen also in analgesic abuse, sickle- cell disease, obstruction and diabetes. 3 Natural course of acute pyelonephritis: Healing. Irregular scars: cortical surface with fibrous depressions. Pelonephritic scar: deformation of the underlying calyx and pelvis. Urinalysis in acute pyelonephritis: Pyuria. Bacteruria. WBC casts. Chronic pyelonephritis: Definition: It is a chronic tubule-interstitial inflammation + renal scarring + pathologic involvement of the calyces and pelvis. It is an important cause of End-Stage Renal Disease (ESRD). It can be divided into two forms: Chronic reflux-associated: A more common form of chronic pyelonephritic scarring. Early in childhood → urinary infection on congenital vesicoureteral reflux and intrarenal reflux. Reflux may be unilateral or bilateral: scarring and atrophy of one kidney or involving both kidneys, leading to chronic renal insufficiency. Chronic obstructive: Obstruction predisposes the kidney to infection. Recurrent infections superimposed on obstructive lesions → recurrent bouts of renal inflammation and scarring → chronic pyelonephritis → parenchymal atrophy. Morphology: Gross (image-4): irregular scared asymmetric contracted kidney with blunted, deformed calyces. The scars vary from one to several in one or both kidneys. Histologic features (image-5): chronic tubulointerstitial nephritis + thyroidization ± periglomerular fibrosis 4 5 - End-Stage Renal Disease (ESRD): Causes: Diabetic glomerulosclerosis. Glomerulonephritis. Chronic pyelonephritis. Obstructive uropathy. Hypertensive nephrosclerosis. Polycystic kidneys. Drugs and toxins. Morphology: Gross (image-6): shrunk kidneys; diffusely granular cortical surfaces. Histologic features (image-7): Tubules are atrophic with casts. Sclerotic glomeruli. Thick-walled arteries. Chronic inflammation and fibrosis. 6 7 .