Updated Guidelines for Screening for Asymptomatic Bacteriuria.

Abstract

In this issue of JAMA, the US Preventive Services Task Force (USPSTF) has published updated guidelines for screening for asymptomatic bacteriuria in adults1 along with an updated evidence report and systematic review.2 These recommendations are not substantively changed from the previous recommendations, published in 2008.3 Screening for bacteriuria or antimicrobial treatment for asymptomatic bacteriuria is not recommended for healthy n o n p re g n a nt wo m e n o r healthy men (D recommendation). Screening with a urine culture collected at 12 to 16 weeks of gestation or at the first prenatal visit is recommended for pregnant women, with antimicrobial treatment if asymptomatic bacteriuria is present (B recommendation). These recommendations are consistent with other recent guidelines that have addressed screening and treatment of asymptomatic bacteriuria for these populations.4,5 The USPSTF guidelines have been developed in the context of a changing medical and societal perspective toward antimicrobials, with current approaches favoring the limitation of antimicrobial use, whenever appropriate. This was initially in response to an appreciation that excessive antimicrobial use has contributed to the evolution of antimicrobial resistance, potentially impairing future therapeutic options. More recently, increasing attention to the importance of the human microbiome, and the suggestion that antimicrobial therapy may have deleterious effects on the microbiome influencing both shortand long-term health status for both noninfectious and infectious diseases, has reinforced concerns about antimicrobial use.6 Inappropriate antimicrobial treatment of asymptomatic bacteriuria is well documented,4,7 and the implementation of programs to discourage treatment of asymptomatic bacteriuria is an important facet of antimicrobial stewardship initiatives.8 For this USPSTF update, there was no new evidence to inform the question of screening or treating asymptomatic bacteriuria for healthy, nonpregnant women. Healthy, young, sexually active women have a prevalence of asymptomatic bacteriuria of 1% to 5%.4 For most of these women asymptomatic bacteriuria is transient. In a prospective study of 796 women, only 12% had persistent bacteriuria with the same Escherichia coli strain 2 months after an initial positive urine culture.9 The prevalence of asymptomatic bacteriuria in women increases with age and is also increased in women with diabetes. For these women, asymptomatic bacteriuria with the same or different bacterial strains may persist for months or years.10 Symptomatic urinary tract infection occurs more frequently in women with asymptomatic bacteriuria, but asymptomatic bacteriuria does not cause symptomatic infection, and there is no evidence for other harms with asymptomatic bacteriuria. In fact, there is some suggestion that asymptomatic bacteriuria may protect a woman from symptomatic episodes of urinary tract infection.4 For men and nonpregnant women living in the community, nontreatment of bacteriuria should be straightforward—it is not necessary to obtain urine specimens for culture unless clinical signs and symptoms are consistent with symptomatic urinary tract infection that warrants antimicrobial treatment. A recommendation to screen for and treat asymptomatic bacteriuria in pregnant women is reaffirmed in the updated USPSTF guidelines. However, the certainty of evidence has been changed to moderate, from high certainty in the previous guideline. This change acknowledges a substantially lower risk of pyelonephritis for pregnant women with untreated asymptomatic bacteriuria reported in some reports11,12 and reconsiders the validity of the early clinical trials that were the basis for the previous recommendation. The systematic review, however, concluded that screening and treatment of asymptomatic bacteriuria in pregnant women was associated with substantially reduced risk of pyelonephritis (pooled relative risk [RR], 0.24 [95% CI, 0.14-0.40]) and also with reduced frequency of low birth weight in the infant (RR, 0.64 [95% CI, 0.46-0.90]).2 These outcomes are compelling but must be considered in context. Studies of treatment of asymptomatic bacteriuria in pregnant women published more than 30 to 40 years ago have been the basis for recommendations for screening and treatment of asymptomatic bacteriuria in all subsequent guidelines.5 These foundational studies were undertaken in the first decades of the antimicrobial era. Antimicrobials such as tetracycline, methenamine mandelate, early sulfonamides, cycloserine, and others not used today or now contraindicated in pregnancy were evaluated for treatment of asymptomatic bacteriuria in these previous trials. The use of the quantitative urine culture, which introduced the concept of asymptomatic bacteriuria, was only implemented in Related articles pages 1188, and 1195 and JAMA Patient Page page 1222