Is Ancef (cefazolin) effective for treating urinary tract infections (UTIs)?

Cefazolin for Urinary Tract Infections

Cefazolin (Ancef) is not recommended as a first-line agent for treating urinary tract infections, as there are more appropriate antibiotics with better evidence for efficacy and safety in UTIs. 1, 2

Efficacy of Cefazolin for UTIs

While cefazolin is FDA-approved for urinary tract infections due to E. coli and P. mirabilis 2, it is not considered a preferred agent for several important reasons:

• Current guidelines from the American Urological Association (AUA) recommend nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), and fosfomycin as first-line therapies for uncomplicated UTIs 1
• These first-line agents are effective while producing less "collateral damage" to the gut microbiome than cephalosporins 1
• Beta-lactam antibiotics (including cefazolin) have been associated with more rapid recurrence of UTIs 1

Evidence on Cefazolin for UTIs

The research on cefazolin for UTIs shows:

• In a 2024 study, cefazolin showed 92.5% susceptibility against common uropathogens (E. coli, K. pneumoniae, P. mirabilis) for uncomplicated UTIs, which was slightly lower than ceftriaxone (97.0%) 3
• However, cefazolin was associated with significantly lower risk of hospital-onset Clostridioides difficile infection compared to ceftriaxone (0.15% vs 0.40%, adjusted odds ratio 2.44) 3
• A 2010 pediatric study found 91.3% efficacy for cefazolin in acute upper UTIs 4
• Older comparative studies showed similar efficacy between cefazolin and other cephalosporins for complicated UTIs 5, 6

Recommended Treatment Approach for UTIs

First-line options (preferred):

1. Nitrofurantoin
2. Trimethoprim-sulfamethoxazole (TMP-SMX)
3. Fosfomycin

When to consider cefazolin:

• When first-line agents cannot be used due to resistance patterns or allergies
• For complicated UTIs requiring parenteral therapy when susceptibility is confirmed
• When treating UTIs in hospitalized patients where reducing C. difficile risk is a priority

Important Considerations and Caveats

• Antimicrobial stewardship: Using first-line agents helps reduce resistance and collateral damage 1
• Treatment duration: Generally no longer than 7 days for acute cystitis episodes 1
• Resistance concerns: Beta-lactams may promote more rapid recurrence of UTIs 1
• Culture importance: Obtain urine cultures before initiating treatment in patients with recurrent UTIs 1
• Avoid fluoroquinolones: Despite historical use, fluoroquinolones are no longer recommended as first-line therapy due to unfavorable risk-benefit ratio 1

Special Situations

For carbapenem-resistant Enterobacterales (CRE) UTIs, newer agents are recommended 1:

• Ceftazidime-avibactam
• Meropenem-vaborbactam
• Imipenem-cilastatin-relebactam
• Plazomicin

In summary, while cefazolin has activity against common uropathogens and is FDA-approved for UTIs, it should be reserved as an alternative agent when first-line therapies cannot be used due to resistance, allergies, or other patient-specific factors.