Diagnosis and treatment of acute pyelonephritis in women

Acute pyelonephritis is a common bacterial infection of the renal pelvis and kidney most often seen in young adult women. History and physical examination are the most useful tools for diagnosis. Most patients have fever, although it may be absent early in the illness. Flank pain is nearly universal, and its absence should raise suspicion of an alternative diagnosis. A positive urinalysis confirms the diagnosis in patients with a compatible history and physical examination. Urine culture should be obtained in all patients to guide antibiotic therapy if the patient does not respond to initial empiric antibiotic regimens. Escherichia coli is the most common pathogen in acute pyelonephritis, and in the past decade, there has been an increasing rate of E. coli resistance to extended-spectrum beta-lactam antibiotics. Imaging, usually with contrast-enhanced computed tomography, is not necessary unless there is no improvement in the patient's symptoms or if there is symptom recurrence after initial improvement. Outpatient treatment is appropriate for most patients. Inpatient therapy is recommended for patients who have severe illness or in whom a complication is suspected. Practice guidelines recommend oral fluoroquinolones as initial outpatient therapy if the rate of fluoroquinolone resistance in the community is 10 percent or less. If the resistance rate exceeds 10 percent, an initial intravenous dose of ceftriaxone or gentamicin should be given, followed by an oral fluoroquinolone regimen. Oral beta-lactam antibiotics and trimethoprim/sulfamethoxazole are generally inappropriate for outpatient therapy because of high resistance rates. Several antibiotic regimens can be used for inpatient treatment, including fluoroquinolones, aminoglycosides, and cephalosporins.