[Acute pyelonephritis in adults]

Acute pyelonephritis (APN) is a frequent and possibly severe pathological condition responsible for more than 100,000 hospitalizations per year in the United States. Etiology is prevalently Escherichia coli, and risk factors include sexual activity, genetic predisposition, old age and infection via urological instrumentation. The exact correlation between APN and vesicoureteral reflux has not yet been defined. Diagnosis of APN may be clinical, but examination using computed tomography (CT) or nuclear magnetic resonance (NMR) spectroscopy allows a more precise definition and may provide evidence of abscesses. Severe cases should be treated with a fluoroquinolone or extended-spectrum cephalosporin associated or not with aminoglycoside. Treatment should be continued for at least 10 days. Long-term evolution of APN is still unknown, even if formation of cortical scars and possible development of macroalbuminuria or renal failure are described. Pregnancy, diabetes and renal transplantation represent situations in which APN may be particularly severe. Formation of renal abscesses is underestimated and must be evaluated by CT or NMR spectroscopy evaluation. Abscesses must be drained only if they are of great size.