Complicated Urinary Tract Infection

How to Cite This Chapter: Mertz D, Duława J, Drabczyk R. Complicated Urinary Tract Infection. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. Accessed May 28, 2024.
Last Updated: October 14, 2021
Last Reviewed: October 14, 2021
Chapter Information

Clinical Features And DiagnosisTop

The most frequently observed factors responsible for the diagnosis of complicated urinary tract infection (UTI) include male sex, diabetes mellitus, pregnancy, nephrolithiasis, and urinary obstruction.

Clinical features range from mild cystitis to urosepsis. In each case of a diagnosed or suspected complicated UTI, perform urinalysis, urine cultures, and blood biochemical tests to assess kidney function. Order blood cultures in all febrile hospitalized patients. Consider ultrasonography and abdominal radiographs in patients in whom it is necessary to exclude nephrolithiasis and urinary obstruction. Indications for additional imaging studies: suspected renal and perinephric complications of UTI (see Complications of Urinary Tract Infections), other coexisting pelvic or abdominal abnormalities, previously diagnosed urinary tract abnormalities that have contributed to the complicated UTI.


1. Depending on the intensity of symptoms and the presence of comorbidities, the patient may either be treated as an outpatient or be admitted to the hospital.

2. Urologic intervention is the mainstay of treatment in the setting of an underlying obstruction. The key objective is to correct potential abnormalities in the urinary tract; in such cases antimicrobial treatment is only an adjunctive therapy.

3. Empiric treatment of complicated UTI, including selection of oral antibiotics and duration of treatment, is the same as in uncomplicated acute pyelonephritis, with an aim to use an antibiotic with an expected resistance rate of <10%. If the empiric treatment is ineffective and microbiology results are unavailable, start a broad-spectrum antimicrobial agent active against Pseudomonas spp (eg, piperacillin + tazobactam, ceftazidime, or a carbapenem).

4. Treatment in young men with no additional risk factors for complicated UTI: The usual duration is 7 to 14 days, depending on how quickly symptoms resolve while on treatment.

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