NCHR Comments on the USPSTF Draft Research Plan for Asymptomatic Bacteriuria in Adults: Screening

Thank you for the opportunity to express our views on the USPSTF draft research plan regarding screening for asymptomatic bacteriuria (ASB) in adults. The National Center for Health Research is a nonprofit think tank that conducts, analyzes, and scrutinizes research, policies, and programs on a range of issues related to health and safety. We do not accept funding from companies that make products that are the subject of our work, so we have no conflicts of interest

According to the American College of Obstetricians and Gynecologists (ACOG), asymptomatic bacteriuria is found in 5% of young sexually active nonpregnant women, in less than 0.1% of men, and in 20-40% of women older than 651. Generally, the health effects of ASB are unknown. We know that bacteria found in the urine of pregnant women can lead to serious urinary infections in mothers and low birth weight in babies. Therefore, the USPSTF’s current recommendations to screen pregnant women between 12-16 weeks gestation has become a key component of routine prenatal care. However, the 2014 “D” ratings strongly recommend against screening in a broad population including, non-pregnant women and men.

We support the efforts of the USPSTF to draft a research plan to identify benefits and harms of screening in a broad screening population and in specific vulnerable populations, including pregnant women. We now know more about the microbiome (normal beneficial bacteria) and the association of the microbiome to chronic urinary symptoms, which are not due to an underlying urinary infection. Research2,3, has suggested that certain bacteria, or an imbalance of normal bacteria may play a role in causing chronic symptoms. Detection of bacteria on screened urine may lead to treatment with antibiotics, which could cause more harm than good.

We have several recommendations that would strengthen the USPSTF research plan:

  1. A key question to be answered is: What is the strength of the association between asymptomatic bacteriuria and lower urinary tract symptoms including overactive bladder, incontinence nighttime urination, and bladder pain?  It is unclear whether treatment of screen-detected ASB could provoke chronic urinary symptoms or alleviate them. We encourage the USPSTF to explore research on the urinary microbiome, and the potential benefits and harms of antibiotic treatment.
  2. We agree that a research review of the treatment benefits of screen-detected bacteriuria (KQ3) is necessary to establish appropriate screening recommendations in pregnant women. Given the update to the Cochrane review (the USPSTF last reviewed the 2007 update), we recommend that the USPSTF reassess the benefits in pregnant women.
    1. The 2015 Cochrane review4 showed that the body of evidence supports antibiotics as an effective treatment option in pregnant women, but the estimate of the effect remains uncertain due to the limitations of the studies. Notably, the reviewed studies were rated as “low” or “very low” in quality.
    2. Moreover, the Cochrane analysis found that rates of pyelonephritis in those not treated with antibiotics for ASB ranged from 2.5 to 36%. Given the wide range,  it seems likely that there are other risk factors independent from ASB alone that increase susceptibility of symptomatic urinary infections. Perhaps treating all ASB in screened pregnant women is not as beneficial as previously assumed. We encourage the USPSTF to assess whether treatments benefits may differ by sub-groups of pregnant women.
  3. Given the current “D” recommendations for all other adults excluding pregnant women, we agree that a research review is necessary to assess the harms and benefits of screening in a broad population of adults. The term “adults” is a very broad category that includes men, nonpregnant women, older persons, and persons with diabetes. We suggest the USPSTF specify a review of key at-risk populations, including persons with diabetes and older persons. Consider the following:
    a. A research review5 found that the prevalence of asymptomatic bacteriuria in persons with diabetes is 12% compared to 4.5% in the general population. Persons with diabetes are at increased risk of complications from urinary tract infections, including hospitalization. However, it is not clear how ASB may affect the health of persons with diabetes.

    b. Asymptomatic bacteriuria is more common in older adults. However, it is estimated that 40-75% of prescribed antibiotics are unnecessary6. It may also be difficult to differentiate an underlying urinary infection from ASB because older persons may not present with classic urinary symptoms. Even so, most professionals recommend against treating ASB in older persons. This begs the question: if it is not beneficial to treat asymptomatic bacteriuria, are there other benefits to be gained from screening? Given the burdens of bacteriuria and over-treatment, it would be helpful for older persons, caregivers, and providers to have evidence-based guidelines for screening and treatment of asymptomatic bacteriuria.

  4. We appreciate the USPSTF inclusion of quality of life indicators in the proposed key questions 1 and 3. We suggest that the USPSTF look at quality of life indicators in relation to chronic urinary symptoms. It is possible that unnecessary antibiotic treatment of screen-detected bacteriuria may provoke chronic urinary symptoms2,3 (by causing an imbalance of the urinary microbiome), and chronic urinary symptoms can diminish quality of life. These are harms which the USPSTF ought to thoroughly consider.
  5. As part of the proposed analysis, we suggest a review of comparative effectiveness research, which also includes watchful waiting as a treatment option. For example, the Patient-Centered Outcomes Research Institute (PCORI) 2016 document7 is entitled “Comparative effectiveness of treatments for asymptomatic bacteriuria including watchful waiting.”

In conclusion, we generally support the USPSTF’s draft research plan regarding screening for asymptomatic bacteriuria in adults, but recommend additional issues be addressed as noted above.

For questions or more information, please contact Diana Zuckerman, PhD, at


1. American College of Obstetricians and Gynecologists. Treatment of Urinary Tract Infections in Nonpregnant Women. ACOG Practice Bulletin Number 91. March 2008. Reaffirmed 2016.

2. Felice Sorrentino, et. al. Associations between individual lower urinary tract symptoms and bacteriuria in random urine samples in women.Neurourol Urodyn. 2015 Jun; 34(5): 429–433.

3. Karstens L, et al. Does the Urinary Microbiome Play a Role in Urgency Urinary Incontinence and Its Severity? Frontiers in Cellular and Infection Microbiology. 2016;6:78.

4. Smaill FM, Vazquez JC. Antibiotics for asymptomatic bacteriuria in pregnancy. Cochrane Database of Systematic Reviews 2015, Issue 8. Art. No.: CD000490.

5. Renko M, Tapanainen P, Tossavainen P, Pokka T, Uhari M. Meta-Analysis of the Significance of Asymptomatic Bacteriuria in Diabetes. Diabetes Care. 2011;34(1):230-235.

6. Rowe TA, Juthani-Mehta M. Urinary tract infection in older adults. Aging health. 2013;9(5):10.2217/ahe.13.38

7. Hutfless, Susan et al. Comparative effectiveness of treatments for asymptomatic bacteriuria including watchful waiting. PCORI Topic Brief. October 2016. Available online: