USPSTF Updates Recommendations for Asymptomatic Bacteriuria Screening

The US Preventive Services Task Force (USPSTF) has downgraded its recommendation regarding the screening of pregnant women for asymptomatic bacteriuria, based on reduced applicability of the previous evidence.

The new recommendations were published today in JAMA.

Among the general population, it is reported that women have the highest prevalence of asymptomatic bacteriuria, although rates increase with age in both men and women.

It is estimated that asymptomatic bacteriuria is present in an estimated 1% to 6% of women who are premenopausal and an estimated 2% to 10% of pregnant women. The presence of bacteria in the urine infection is also associated with pyelonephritis, which is one of the most common non-obstetric reasons for hospitalizations in pregnant women.

When pyelonephritis occurs in pregnant women, it can be associated with serious perinatal complications including septicemia, respiratory distress, low birth weight, and spontaneous preterm birth.

The last update to the USPSTF asymptomatic bacteriuria in adults recommendation was conducted in 2008. The Task Force commissioned a review of evidence on the potential benefits and harms of testing for and the treatment of asymptomatic bacteriuria in adults, including pregnant women, in order to update the recommendations.

Their recommendations apply to adults 18 years and older and pregnant persons of any age without any signs and symptoms of a urinary tract infection. The recommendations may not apply to individuals with chronic conditions or urinary tract conditions who are hospitalized or living in a facility such as a nursing home.

Based on a review of the available evidence, the USPSTF found “with moderate certainty” that screening for and treatment of asymptomatic bacteriuria in pregnant persons has moderate net benefit in reducing pregnancy-related complications.

“There is adequate evidence that pyelonephritis in pregnancy is associated with negative maternal outcomes and that treatment of screen-detected asymptomatic bacteriuria can reduce the incidence of pyelonephritis in pregnant persons,” the authors wrote.

However, in its review, the Task Force reports finding adequate evidence of harms associated with asymptomatic bacteriuria, such as adverse effects related to antibiotic treatment and alterations in the microbiome, to be at least small in magnitude.

Based on these findings, USPSTF has concluded that with “moderate certainty” that screening for and treatment of asymptomatic bacteriuria in non-pregnant adults has no net benefit. This conclusion was drawn based upon the discovery that the harms associated with the treatment can also include adverse effects of antibiotic use and changes to the microbiome. Based on these harms, the Task Force determined that the overall harms are at least small in this group.

The updated recommendations of the USPSTF on screening for asymptomatic bacteriuria include:

• Non-pregnant adults should not be screened for asymptomatic bacteriuria (D-grade recommendation)
• Pregnant individuals should be screened for asymptomatic bacteriuria using urine culture (B-grade recommendation)

The recommendation for pregnant individuals should be implemented by screening for asymptomatic bacteriuria at the first prenatal visit using a midstream, clean-catch urine culture. Treatment is indicated in the presence of a urine culture showing >100,000 colony-forming units (CFU)/mL of a single uropathogen or 10,000 CFU/mL if the pathogen is group B streptococcus.

These recommendations are consistent with the 2008 recommendation, but the grade of the recommendation has changed from A to B, based on reduced applicability of the previous evidence. According to the Task Force, this includes outdated antibiotic treatment regimens and that newer evidence shows a significantly lower risk of pyelonephritis than originally found in previous reviews. Additionally, concerns about resistance and adverse changes increasing the likelihood of potential harms contributed to the grade change.