From the Guidelines
In pregnancy, asymptomatic bacteriuria should be treated when bacterial counts reach ≥100,000 colony-forming units (CFU)/mL in a clean-catch urine specimen, while symptomatic UTIs require treatment regardless of bacterial count. This recommendation is based on the evidence from the US Preventive Services Task Force, which concludes that there is high certainty that the net benefit of screening for asymptomatic bacteriuria in pregnant women is substantial 1.
Key Considerations
- First-line antibiotics for treating UTIs in pregnancy include nitrofurantoin, amoxicillin-clavulanate, or cephalexin, with the specific choice depending on factors such as allergy history and local resistance patterns 1.
- It is essential to avoid certain antibiotics in pregnancy, such as trimethoprim-sulfamethoxazole in the first trimester and near term, and fluoroquinclones throughout pregnancy, due to potential harmful effects on the fetus 1.
- Follow-up urine cultures are recommended after treatment to confirm resolution of the infection, and some providers perform monthly urine cultures throughout pregnancy for women with a history of UTIs 1.
Rationale for Treatment Threshold
The threshold for treating UTIs in pregnancy is based on the presence of at least 10^5 colony-forming units per mL of urine, of a single uropathogen, in a midstream clean-catch specimen 1. This threshold is supported by evidence that detection and treatment of asymptomatic bacteriuria in pregnant women significantly reduces the incidence of symptomatic maternal urinary tract infections and low birthweight 1.
Clinical Implications
Pregnant women have an increased risk of UTIs due to hormonal changes that relax the urinary tract muscles and the physical pressure of the growing uterus on the bladder. Untreated UTIs in pregnancy can lead to serious complications, including pyelonephritis, preterm labor, and low birth weight. Therefore, prompt treatment of UTIs in pregnancy is crucial to prevent these complications and ensure the best possible outcomes for both mother and baby.
From the Research
Threshold for Treating Urinary Tract Infection (UTI) in Pregnancy
- The threshold for treating UTI in pregnancy is low, as all UTIs, including asymptomatic bacteriuria, require treatment to prevent serious maternal and fetal complications 2, 3.
- Untreated asymptomatic bacteriuria in pregnancy can lead to the development of acute pyelonephritis, which can have negative effects on the woman and the fetus, including low birth weight, low gestational age, and higher neonatal mortality rate 3.
- Screening for bacteriuria in pregnant women is necessary, and when the finding is positive, treatment should be initiated 3, 4.
- The selection of an appropriate antimicrobial agent to treat UTI in pregnancy is limited by the safety of the drug for the woman and the fetus, and should be guided by urine culture results 3, 5.
- First-line treatments for UTI in pregnancy include beta-lactams, nitrofurantoin, fosfomycin, and trimethoprim-sulfamethoxazole, which have minimal collateral damage and resistance 5.
Key Considerations
- Asymptomatic bacteriuria should be treated in pregnancy to prevent the development of acute pyelonephritis and other complications 2, 3, 4.
- The diagnosis of UTI in pregnancy should be based on symptoms, test results, and urine culture, and treatment should be initiated promptly to prevent adverse outcomes 5, 4.
- International guidelines agree on the importance of treating UTI in pregnancy, but there may be some discordance on specific aspects of treatment, such as antenatal screening for bacteriuria and the use of fluoroquinolones 6.