Treatment of UTI in Pregnant Females
Nitrofurantoin 100 mg orally four times daily for 5-7 days is the recommended first-line treatment for urinary tract infections in pregnant women, with cephalexin 500 mg orally four times daily for 7-14 days as an alternative option. 1
Diagnostic Requirements
- Obtain a urine culture before initiating treatment to guide antibiotic selection and confirm diagnosis 1
- Screening for asymptomatic bacteriuria should occur at least twice during pregnancy, as untreated bacteriuria significantly increases risk of pyelonephritis (up to 20-37% in untreated women versus 1-4% in treated women) and preterm labor 2
- A single screening culture at 12-16 weeks of gestation is considered optimal and cost-effective 2
First-Line Antibiotic Regimens
Nitrofurantoin (Preferred)
- Dosing: 100 mg orally four times daily for 5-7 days 1
- Nitrofurantoin maintains excellent safety profile with over 35 years of clinical use and lacks R-factor resistance development 3
- Achieves high bactericidal concentrations in the urinary tract with minimal effect on introital flora 4
Cephalexin (Alternative)
- Dosing: 500 mg orally four times daily for 7-14 days 1
- Particularly effective for postcoital prophylaxis in women with recurrent UTIs during pregnancy 4
Fosfomycin (Alternative for Uncomplicated Cystitis)
- Dosing: 3 g single dose 2
- Single-dose fosfomycin shows equivalent efficacy to nitrofurantoin for uncomplicated UTI and asymptomatic bacteriuria in pregnancy 5
- Recommended specifically for uncomplicated cystitis in women 2
Treatment Duration
- Minimum 4-7 days for symptomatic UTI and asymptomatic bacteriuria 1
- A 7-14 day total course ensures complete eradication, particularly with cephalosporins 1
- Single-dose therapy with amoxicillin achieves approximately 80% cure rates for asymptomatic bacteriuria, though 3-day courses may be more reliable for symptomatic infections 6
Post-Treatment Monitoring
- Repeat urine culture 1-2 weeks after completing treatment to confirm microbiological cure 1
- Women with negative initial screening have only 1-2% risk of developing pyelonephritis later in pregnancy, but continued surveillance is warranted 2
Special Clinical Scenarios
Acute Pyelonephritis
- Initial parenteral therapy is required for severe infections or pyelonephritis 1
- Hospitalization is typically necessary given the significant maternal and fetal risks
Group B Streptococcus
- Any concentration of GBS bacteriuria requires immediate treatment at time of diagnosis 1
- This differs from other organisms where colony count thresholds apply
Recurrent UTI Prevention
- Continuous prophylaxis with nitrofurantoin 50 mg daily or cephalexin 250 mg postcoitally effectively prevents recurrent infections during pregnancy 4
- One study showed reduction from 130 UTIs in 7 months pre-prophylaxis to only 1 UTI during pregnancy with prophylaxis 4
Antibiotics to Avoid
- Trimethoprim-sulfamethoxazole: Contraindicated in first trimester (neural tube defects) and last trimester (kernicterus risk) 2
- Fluoroquinolones: Should be avoided during pregnancy due to concerns about cartilage development 2
Common Pitfalls
- Do not rely on dipstick or urinalysis alone - urine culture is essential for diagnosis confirmation and antibiotic susceptibility testing 2
- Do not use single-dose therapy for symptomatic UTI - reserve for asymptomatic bacteriuria only 6
- Do not skip post-treatment culture - failure to confirm cure leads to missed persistent infections that increase pyelonephritis risk 1