Asymptomatic Bacteriuria: Significance for Different Patient Population

Infections of the urinary tract (UTI) are one of the most common infections for which antibiotics are prescribed. Asymptomatic bacteriuria, or asymptomatic urinary infection, is a common condition (Nicolle, 2003). Based on the microbiological definition, urinary tract infections are characterized by the presence of ≥105 colony-forming units per ml (CFUs/mL) of a single bacterial species or multiple organisms in two consecutive urine specimens, properly collected from a person with symptoms or signs of a UTI (Rubin et al., 1992). However, the presence of a significant quantity of bacteria in the urine of an asymptomatic patient is known as asymptomatic bacteriuria. Quantitative criteria to establish the diagnosis of significant bacteriuria in an asymptomatic person are: 1. at least 105 CFUs/mL of urine in a voided midstream, so called clean-catch specimen; and 2. at least 100 CFUs per mL of urine obtained by bladder catheterization. Despite several decades of research, there is still a considerable amount of controversy about the adequate management of bacteriuria. A common dilemma in clinical medicine is whether or not to treat asymptomatic bacteriuria. It is now recognized that certain patient characteristics can led to the development of symptomatic infections based on an asymptomatic bacteriuria. For several clinical scenarios, the antibiotic treatment of asymptomatic bacteriuria has been shown to improve patient outcomes. Based on clinical trials conducted over the last few decades, better recommendations for the management of bacteriuria in different patient population could be established. The Infectious Diseases Society of America (IDSA) established guidelines for the screening and treatment of asymptomatic bacteriuria (Nicolle et al., 2005). The optimal management depends significantly on specific patient characteristics, co-morbidities, and risk factors. Recent studies could prove that for certain patient populations, screening and treatment is beneficial or may be beneficial. However, for other clinical scenarios, screening and treatment for asymptomatic bacteriuria has not proven to be beneficial and therefore is highly controversial. Importantly, overtreatment of asymptomatic bacteriuria is a quality, safety, and cost issue. Recent studies have revealed a substantial gap between clinical practice, published guidelines, and recommendations (need reference). Treating physicians need to be aware that because of an increasing antimicrobial resistance, it is important to treat patients only if there is clear evidence of potential benefits. Therefore, in this chapter we review the most recent literature and provide up-to-date information for treating physicians on how to diagnose and when to treat asymptomatic bacteriuria.