What Is the First-Line Antibiotic for UTI?

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First-line antibiotics for UTIs include fosfomycin, nitrofurantoin and trimethoprim

First-line antibiotics for acute, uncomplicated urinary tract infections (UTIs) typically include:

• Fosfomycin
• Nitrofurantoin
• Trimethoprim or sulfamethoxazole (Bactrim)

Drug (Brand) Dosage Cost of generic (Cost of brand) First

Fosfomycin (Monurol)
3 grams single dose
NA ($51)

Nitrofurantoin macrocrystals (Macrodantin)
100 mg twice daily for 5 days
$55 ($64)

Pivmecillinam
400 mg orally 2-3 times daily for 3-7 days
NA in the U.S.

Trimethoprim/sulfamethoxazole (Bactrim DS, Septra DS)
160/800 mg twice daily for 3 days
$17 ($34)

Second

Ciprofloxacin (Cipro)
250 mg twice daily for 3 days
$26 ($30)

Ciprofloxacin, extended release (Cipro XR)
500 mg daily for 3 days
$57 ($76)

Levofloxacin (Levaquin)
250 mg daily for 3 days
NA ($86)

Ofloxacin

200 mg daily for 3 days or
400 mg single dose

$14 (NA)
$10 (NA)

Third

Amoxicillin/clavulanate (Augmentin)
500/125 mg twice daily for 7 days
$32 ($98)

Cefdinir (Omnicef)
300 mg twice daily for 10 days
$40 ($119)

Cefpodoxime
100 mg twice daily for 7 days
$71 (NA)

Since there is a lower chance of antibiotic resistance with nitrofurantoin and fosfomycin as compared to other classes of antibiotics, they are often used as first-line antibiotics for the treatment of UTI.

However, for severe UTI with complications, fosfomycin or nitrofurantoin may not be effective.

How do doctors choose which antibiotics to treat UTI?

Your doctor chooses which antibiotic to use for treating UTI based on the:

• Effectiveness of the antibiotic on the bacteria causing the infection
• Severity of the infection
• Age group of the infected person
• Potential for antibiotic resistance

What other antibiotics are used to treat UTI?

Other antibiotics used to treat UTI include:

• Beta-lactams, including penicillins and cephalosporins (amoxicillin, Augmentin, Keflex, Duricef, Ceftin, Lorabid, Rocephin, Cephalexin, Suprax and others). Many organisms have shown resistance to some of these drugs.
• Trimethoprim-sulfamethoxazole combination antibiotic (Bactrim DS and Septra DS).  Many organisms have shown resistance to some of these drugs.
• Fluoroquinolones (Cipro, Levaquin and Floxin). The risk of antibiotic resistance to this is developing. These should not be given to pregnant women or children. 
• Tetracyclines (Sumycin, Vibramycin or Minocin) are used for Mycoplasma or Chlamydia infections. These should not be given to pregnant women or children. 
• Aminoglycosides (gentamicin, amikacin and tobramycin) are usually used in combination with other antibiotics to treat severe UTIs.
• Macrolides (clarithromycin, azithromycin and erythromycin) are often used to treat urinary problems caused by sexually transmitted diseases.
• Fosfomycin (Monurol) is a synthetic phosphonic acid derivative and used for acute cystitis but not for more complicated UTIs.

Severe UTI (high fever, chills, hypotension, etc.)

Agent
What to consider

First

Ceftriaxone
Can be used safely in patients with a mild penicillin allergy (i.e., rash); cross-reactivity is very low

Second

Gentamicin
Use with caution if there is a concern of kidney toxicity or ear toxicity

Cystitis/lower UTI (complicated or uncomplicated)

Agent
What to consider

First

Nitrofurantoin
Most active agent against E coli

Trimethoprim/sulfamethoxazole
Potassium levels need to be monitored if using alongside spironolactone, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs)

Second

Cephalexin
Active against E coli, Proteus and Klebsiella pneumoniae

Pyelonephritis/upper UTI

Agents
What to consider

First

Trimethoprim/sulfamethoxazole
One dose of intravenous/intramuscular injection ceftriaxone should be administered before starting oral therapy

Second

Ciprofloxacin
If patients are unable to tolerate trimethoprim/sulfamethoxazole