Antibiotic Treatment for Urinary Tract Infections
First-Line Antibiotics for Uncomplicated Lower UTI (Cystitis)
For uncomplicated cystitis in women, use nitrofurantoin, trimethoprim-sulfamethoxazole, or amoxicillin-clavulanate as first-line agents. 1
The WHO Expert Committee specifically recommends these three options based on maintained susceptibility patterns and feasibility considerations across different healthcare settings 1. While fosfomycin was proposed by the Working Group, it was not included in the final WHO recommendations 1.
Specific Dosing and Duration:
- Nitrofurantoin: 5-day course for uncomplicated cystitis 1, 2
- Trimethoprim-sulfamethoxazole (TMP-SMX): 160/800 mg twice daily for 10-14 days per FDA labeling 3, though shorter 3-5 day courses are used in practice for uncomplicated cystitis 2
- Amoxicillin-clavulanate: Added as an alternative option, particularly for young children 1
Critical Resistance Considerations:
Amoxicillin alone should NOT be used empirically - the WHO removed it from recommendations in 2021 after GLASS data showed 75% median resistance in E. coli urinary isolates globally 1. However, amoxicillin-clavulanate maintains generally high susceptibility 1.
Fluoroquinolones (ciprofloxacin, levofloxacin) are NOT recommended as first-line agents despite their efficacy, due to emergence of resistance and availability of sufficient alternatives 1. Local resistance rates should be <10% for pyelonephritis and <20% for lower UTI when selecting empiric antibiotics 1.
Treatment for Acute Pyelonephritis (Upper UTI)
For acute pyelonephritis in adults, use ceftriaxone or ciprofloxacin as first-line agents. 1
These recommendations come from the Infectious Diseases Society of America and European Society for Microbiology and Infectious Diseases 1. Ciprofloxacin 500 mg twice daily can be used for 7-14 days per FDA labeling 4.
UTI Treatment in Men
For men with UTI, use trimethoprim-sulfamethoxazole 160/800 mg twice daily for 7 days as first-line therapy. 5
Key Differences in Male UTI Management:
- Minimum 7-day treatment duration is required (never 3-5 days as in women) due to complicated nature and potential prostatic involvement 5
- Extend to 14 days when prostatitis cannot be excluded 5
- Always obtain urine culture before starting antibiotics to guide adjustments based on susceptibility 5
- Fluoroquinolones (ciprofloxacin 500 mg twice daily or levofloxacin 750 mg once daily for 7-14 days) are alternative options when TMP-SMX cannot be used or resistance is suspected 5
Common uropathogens in men include E. coli, Proteus, Klebsiella, Pseudomonas, and Enterococcus species 5.
Pediatric UTI Treatment
Newborns and Infants:
Use parenteral ampicillin plus an aminoglycoside OR a third-generation cephalosporin. 1
Children with Pyelonephritis:
- Age <6 months: Ceftazidime plus ampicillin, OR aminoglycoside plus ampicillin 1
- Age >6 months with uncomplicated pyelonephritis: Third-generation cephalosporin 1
- Complicated pyelonephritis (all ages): Ceftazidime plus ampicillin, OR aminoglycoside plus ampicillin 1
Empiric Treatment for Children 2-24 Months:
Amoxicillin-clavulanate or trimethoprim-sulfamethoxazole are recommended by the American Academy of Pediatrics 1. The recommended pediatric dose for TMP-SMX is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days 3.
Comparative Efficacy Data
Recent network meta-analysis (2024) provides ranking of antibiotics for uncomplicated UTI 6:
- Fosfomycin ranked highest for clinical cure (P-score 0.99) and microbiological cure (P-score 0.99) 6
- Ciprofloxacin ranked lowest for cure rates (P-scores 0.11 and 0.02) and had highest relapse rate and adverse events 6
- TMP-SMX had lowest relapse rate (P-score 0.07) 6
However, fosfomycin was not included in WHO final recommendations despite Working Group proposal 1, so nitrofurantoin, TMP-SMX, and amoxicillin-clavulanate remain the guideline-endorsed first-line options.
Common Pitfalls to Avoid
- Never use cefuroxime (second-generation cephalosporin) empirically for uncomplicated cystitis - it is not listed among WHO recommended options and should only be used with documented susceptibility or when first-line agents fail 7
- Do not use fluoroquinolones as first-line empiric therapy when other effective options are available, to preserve their utility and limit resistance 5, 8
- Avoid empiric antibiotics with local resistance rates >20% for lower UTI or >10% for pyelonephritis 1
- Never treat male UTIs for only 3-5 days - minimum 7 days required 5