What is the recommended treatment for urinary tract infections (UTI) in pregnancy?

Treatment of UTI in Pregnancy

Pregnant women with UTI should receive a 7-14 day course of antibiotics, with nitrofurantoin or cephalosporins (such as cephalexin) as first-line agents, avoiding trimethoprim in the first trimester and sulfonamides in the third trimester. 1, 2

Diagnostic Approach

• Always obtain a urine culture before initiating treatment in pregnant women with suspected UTI, as this is the appropriate screening test with optimal timing at 12-16 weeks gestation 1, 2
• Pyuria screening alone has only 50% sensitivity for identifying bacteriuria and is inadequate 2
• Pregnancy is the one clinical scenario where asymptomatic bacteriuria must always be treated, as untreated bacteriuria increases pyelonephritis risk 20-30 fold (from 1-4% with treatment to 20-35% without) 2

First-Line Antibiotic Selection by Trimester

First Trimester

• Nitrofurantoin (50-100 mg four times daily for 5 days OR 100 mg twice daily for 5 days) is the preferred first-line agent 1, 2
• Fosfomycin trometamol (3g single dose) is an acceptable alternative for uncomplicated cystitis 1, 2
• Cephalosporins (e.g., cephalexin 500 mg four times daily) are appropriate if local resistance patterns support their use 1, 2
• Avoid trimethoprim and trimethoprim-sulfamethoxazole in the first trimester due to potential teratogenic effects 1, 2

Second Trimester

• All first-line agents (nitrofurantoin, fosfomycin, cephalosporins) remain appropriate 1
• Trimethoprim-sulfamethoxazole may be used if necessary based on susceptibility patterns 1

Third Trimester

• Cephalexin (500 mg four times daily for 7-14 days) is the preferred first-line alternative 2
• Avoid trimethoprim-sulfamethoxazole in the last trimester of pregnancy 1
• Avoid nitrofurantoin near term due to theoretical risk of hemolytic anemia in the newborn 2
• Fosfomycin (3g single dose) can be considered for uncomplicated lower UTIs, though clinical data is more limited 2
• Amoxicillin-clavulanate (20-40 mg/kg per day in 3 doses) is appropriate if the pathogen is susceptible 2

Treatment Duration and Route

• 7-14 day courses are recommended for all pregnant women with UTI, despite insufficient evidence comparing shorter regimens 1, 2
• Oral therapy is appropriate for uncomplicated cystitis 1, 3
• Parenteral therapy is required for suspected pyelonephritis, toxic-appearing patients, or inability to retain oral medications 1, 2
• Agents that do not achieve therapeutic bloodstream concentrations (such as nitrofurantoin) should not be used for pyelonephritis 1, 2

Antibiotics to Avoid Throughout Pregnancy

• Fluoroquinolones (ciprofloxacin, levofloxacin) should be avoided throughout all trimesters due to potential adverse effects on fetal cartilage development 2, 4
• Despite being frequently prescribed in practice, fluoroquinolones are explicitly contraindicated by multiple guidelines 2, 4

Follow-Up and Monitoring

• Repeat urine culture 1-2 weeks after completing treatment to confirm cure 2
• For women whose symptoms do not resolve by end of treatment or recur within 2 weeks, obtain urine culture and antimicrobial susceptibility testing 1
• Assume the infecting organism is not susceptible to the originally used agent and retreat with a 7-day regimen using another agent 1

Special Considerations

Group B Streptococcus (GBS) Bacteriuria

• GBS bacteriuria in any concentration during pregnancy is a marker for heavy genital tract colonization and requires treatment at diagnosis plus intrapartum prophylaxis during labor 2

Recurrent UTIs During Pregnancy

• Consider prophylactic antibiotics (cephalexin or nitrofurantoin 50 mg postcoitally) for the remainder of pregnancy in women with history of recurrent UTIs 2, 5
• Postcoital prophylaxis with cephalexin 250 mg or nitrofurantoin macrocrystals 50 mg has been shown to reduce UTI recurrence from 130 infections to a single infection during pregnancy 5

Critical Clinical Context

• Treatment reduces premature delivery and low birth weight infants 2
• Implementation of screening programs decreased pyelonephritis rates from 1.8-2.1% to 0.5-0.6% 2
• The choice of antimicrobial should be guided by local resistance patterns and adjusted according to susceptibility testing of the isolated uropathogen 1