Treatment of Asymptomatic Bacteriuria in Pregnancy
Yes, asymptomatic bacteriuria should always be treated in pregnancy due to the 20-30 fold increased risk of developing pyelonephritis and associated adverse pregnancy outcomes. 1, 2
Rationale for Treatment
- Pregnant women with untreated asymptomatic bacteriuria have a significantly higher risk (20-35%) of developing pyelonephritis compared to those who receive treatment (1-4%) 1
- Untreated asymptomatic bacteriuria is associated with increased risk of preterm delivery and low birth weight infants 1, 2
- Treatment of asymptomatic bacteriuria reduces the risk of preterm birth from approximately 53 per 1000 to 14 per 1000 1
- Antimicrobial therapy reduces the risk of very low birth weight from approximately 137 per 1000 to 88 per 1000 1
- The consistency and robustness of evidence has made screening for and treatment of asymptomatic bacteriuria during pregnancy a standard of care in developed countries 1
Screening Recommendations
- Urine culture should be collected at one of the initial prenatal visits early in pregnancy 1
- Urine culture is the gold standard for diagnosing asymptomatic bacteriuria 3
- Dipslide culture is a promising alternative screening test when urine culture is not readily available 3
- Asymptomatic bacteriuria occurs in 2-7% of pregnant women 1, 4
Treatment Approach
- For pregnant women with asymptomatic bacteriuria, a 4-7 day course of antimicrobial treatment is recommended 1, 5
- Nitrofurantoin is often the preferred antibiotic due to its safety profile in pregnancy and effectiveness against common pathogens 5
- Beta-lactam antibiotics such as ampicillin or cephalexin are safe alternatives during pregnancy 5
- The choice of antibiotics should be guided by antimicrobial susceptibility testing whenever possible 3
- Single-dose regimens have shown lower rates of bacteriuria clearance compared to short-course regimens and are not recommended 5
Common Pathogens and Antibiotic Resistance
- Escherichia coli is the most common pathogen isolated in asymptomatic bacteriuria during pregnancy 4, 6
- Other common pathogens include Klebsiella pneumoniae, Enterococcus faecalis, and Staphylococcus aureus 4
- Increasing antibiotic resistance is a concern, with high resistance rates to commonly used antibiotics like ampicillin and sulfonamides 4, 6
- Avoid tetracyclines and fluoroquinolones during pregnancy due to potential adverse effects on fetal development 2, 5
Potential Controversies and Caveats
- A 2015 Dutch study suggested that the absolute risk of pyelonephritis in untreated asymptomatic bacteriuria may be lower (2.4%) than previously reported 1, 7
- However, this study had limitations including enrollment of low-risk women and identification of bacteriuria with only a single urine culture 1
- The IDSA guidelines committee concluded that further evaluation in other populations is necessary before changing the recommendation to screen and treat all pregnant women 1
- There is insufficient evidence to recommend for or against repeat screening during pregnancy following an initial negative culture or after treatment of an initial episode 1
Follow-up Recommendations
- After completing antibiotic treatment, a follow-up urine culture is recommended to confirm clearance of the infection 5
- Some experts recommend continued screening throughout pregnancy after treatment of bacteriuria 2
- Recurrence is common and may require re-treatment 5
Despite some emerging evidence questioning universal screening and treatment, the current standard of care based on established guidelines remains clear: screen for and treat asymptomatic bacteriuria in all pregnant women to prevent serious complications.