What is the first-line antibiotic for a complicated urinary tract infection (UTI) in women?

First-Line Antibiotic Treatment for Complicated UTI in Women

The first-line antibiotic treatment for complicated urinary tract infections (cUTIs) in women should be nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin, with the specific choice dependent on local antibiogram patterns. 1, 2

Definition of Complicated UTI

• Complicated UTIs occur when an individual has host-related factors or specific anatomic/functional abnormalities in the urinary tract that make the infection more challenging to eradicate 1
• Common factors associated with complicated UTIs include obstruction at any site in the urinary tract, foreign bodies, incomplete voiding, vesicoureteral reflux, recent instrumentation, ESBL-producing organisms, and immunosuppression 1

First-Line Treatment Options

Recommended First-Line Agents:

• Nitrofurantoin (100 mg twice daily for 5-7 days) - Effective against common uropathogens including E. coli with lower risk of promoting antimicrobial resistance 1, 2
• Trimethoprim-sulfamethoxazole (160/800 mg twice daily) - Effective for susceptible strains of E. coli, Klebsiella, Enterobacter, and Proteus species 1, 2
• Fosfomycin (3 g single dose) - Convenient and effective option for uncomplicated cystitis, may be used in complicated cases based on susceptibility 1, 2

Treatment Duration:

• For complicated UTIs, treatment should generally be given for 7 days 1
• Treatment may need to be extended to 10-14 days for patients with a delayed response 1

Diagnostic Approach

• Obtain urinalysis and urine culture with sensitivity testing before initiating treatment to confirm diagnosis and guide therapy 1, 2
• Culture results are essential for complicated UTIs due to the wider spectrum of potential pathogens and higher likelihood of resistance 1

Alternative Treatment Options

• If first-line agents cannot be used due to resistance or other factors, consider:
  • Fluoroquinolones (e.g., ciprofloxacin 500 mg twice daily or levofloxacin 750 mg once daily) 1, 3
  • Extended-spectrum cephalosporins 1
  • In severe cases with suspected multidrug-resistant organisms, parenteral therapy may be required 1

Special Considerations

• Local resistance patterns should always be considered when selecting antibiotics 1, 2
• For patients with ESBL-producing organisms, treatment options include nitrofurantoin, fosfomycin, or carbapenems depending on susceptibility 4
• If the patient has a catheter that has been in place for ≥2 weeks, it should be replaced to hasten resolution of symptoms 1

Important Caveats

• Avoid treating asymptomatic bacteriuria, which is common in older adults 2
• Fluoroquinolones should be reserved for cases where other options cannot be used due to concerns about resistance and adverse effects 2
• Moxifloxacin should be avoided for UTI treatment due to uncertainty regarding effective urine concentrations 1
• For postmenopausal women with recurrent UTIs, consider vaginal estrogen replacement as preventive therapy 1, 2

Follow-up

• If symptoms do not resolve by the end of treatment or recur within 2 weeks, obtain a urine culture and antimicrobial susceptibility testing 1
• For recurrent complicated UTIs, a urological evaluation may be necessary to identify and address underlying anatomical or functional abnormalities 1