Diagnosis: Escherichia coli–Associated Pyelonephritis
• UTIs include cystitis (infection of the bladder) and pyelonephritis (infection of the kidney). Most episodes of cystitis and pyelonephritis are generally considered to be uncomplicated in otherwise healthy nonpregnant adults.
• A complicated UTI, whether localized to the lower or the upper tract, is associated with an underlying condition that increases the risk of failing therapy. Underlying conditions include diabetes, pregnancy, and history of acute pyelonephritis in the past year as well as other conditions.
• Underlying urinary tract anatomic or functional abnormalities (e.g., obstruction or neurogenic bladder) should be evaluated and treated in consultation with a urologist. If such an abnormality is present, antibiotics alone may be unsuccessful unless the underlying condition is corrected.
• An infection of the renal parenchyma (tubulointerstitial compartment) occurs secondary to either an ascending infection that has gained access to the kidney via the ureters, renal pelvis, and calyces (most common route) or a hematogenous infection.
• The major morphologic findings are patchy interstitial inflammation by neutrophils and acute tubular injury. The glomeruli and blood vessels are not involved by pyelonephritis.
