From the Guidelines
The workup for a urinary tract infection (UTI) should include a urinalysis and urine culture, as recommended by the AUA/SUFU guideline 1. Here's a concise approach:
- Obtain a clean-catch midstream urine sample.
- Perform a urine dipstick test, looking for:
- Leukocyte esterase (indicates white blood cells)
- Nitrites (suggests presence of bacteria)
- Send the urine sample for culture and sensitivity testing.
- If symptoms are severe or there's suspicion of upper UTI (pyelonephritis), consider blood tests:
- Complete blood count (CBC)
- Basic metabolic panel (BMP)
- For recurrent or complicated UTIs, imaging may be necessary:
- Ultrasound of kidneys and bladder
- CT scan if structural abnormalities are suspected
- In elderly patients or those with risk factors, consider post-void residual urine measurement. While awaiting culture results, empiric antibiotic treatment can be started based on local resistance patterns, with common choices including:
- Nitrofurantoin 100mg twice daily for 5 days
- Trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days
- Fosfomycin 3g single dose, as recommended by the American College of Physicians 1. Adjust treatment based on culture results and patient response, and encourage increased fluid intake and frequent urination during treatment. This approach is supported by the most recent guidelines, including the ACR Appropriateness Criteria for acute pyelonephritis 1, which emphasizes the importance of prompt diagnosis and treatment to prevent complications. Additionally, the American College of Physicians recommends short-course antibiotics for uncomplicated UTIs, with the goal of reducing antibiotic resistance and improving patient outcomes 1. Overall, a thorough workup and appropriate treatment can help reduce morbidity, mortality, and improve quality of life for patients with UTIs.
From the FDA Drug Label
For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris It is recommended that initial episodes of uncomplicated urinary tract infections be treated with a single effective antibacterial agent rather than the combination When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to empiric selection of therapy
The workup for a Urinary Tract Infection (UTI) includes:
- Considering culture and susceptibility information when available
- Using local epidemiology and susceptibility patterns to guide empiric selection of therapy when culture and susceptibility information are not available
- Identifying the causative organism, such as Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris The FDA drug label does not provide a comprehensive workup for UTI, but it suggests considering culture and susceptibility information and local epidemiology to guide treatment decisions 2.
From the Research
Diagnostic Approach
The workup for a Urinary Tract Infection (UTI) involves a combination of symptoms, physical examination, and laboratory tests. The most diagnostic symptoms of UTIs include:
- Change in frequency
- Dysuria
- Urgency
- Presence or absence of vaginal discharge 3 In women, a self-diagnosis of a UTI with the presence of typical symptoms is accurate enough to diagnose an uncomplicated UTI without further testing 4.
Laboratory Tests
Laboratory tests used to diagnose UTIs include:
- Dipstick urinalysis: popular for its availability and usefulness, but results must be interpreted in context of the patient's pretest probability based on symptoms and characteristics 3
- Microscopic urinalysis: likely comparable to dipstick urinalysis as a screening test 3
- Urine culture: the gold standard for detection of UTI, particularly in cases where the probability of UTI is moderate or unclear 3, 4
- Bacteriuria: more specific and sensitive than pyuria for detecting UTI, even in older women and during pregnancy 3
Special Considerations
In certain populations, such as:
- Older women: asymptomatic bacteriuria is common and should not be treated with antibiotics 3
- Pregnant women: urine culture is the test of choice, and beta-lactams, nitrofurantoin, fosfomycin, and trimethoprim-sulfamethoxazole can be appropriate treatments 3, 4
- Men: always receive antibiotics, with urine culture and susceptibility results guiding the antibiotic choice 4
- Nonfrail women and men 65 years and older: urine culture with susceptibility testing is recommended to adjust the antibiotic choice after initial empiric treatment 4