Diagnosing a common kidney infection of the elderly inpatient.

Initial antibiotic therapy should be based on Gram's stained urine. For the elderly patient with acute symptomatic bacterial pyelonephritis caused by gram-negative aerobic bacilli, an aminoglycoside is recommended, eg, gentamicin, tobramycin, or amikacin. Pathologic pyuria (greater than 10 WBC/high-power field) supports the clinical impression of acute symptomatic bacterial pyelonephritis. However, many factors can spuriously lower the number of bacteria in the urine: prior diuresis or antimicrobials; obstruction distal to the site of infection; and infection not directly accessible to the collecting system.