Asymptomatic Bacteriuria and Bacterial Interference

Asymptomatic bacteriuria is very common. In healthy women, asymptomatic bacteriuria increases with age, from <1% in newborns to 10% to 20% of women age 80 years, but is uncommon in men until after age 50 years. Individuals with underlying genitourinary abnormalities, including indwelling devices, may also have a high frequency of asymptomatic bacteriuria, irrespective of age or gender. The prevalence is very high in residents of long-term-care facilities, from 25% to 50% of women and 15% to 40% of men. Escherichia coli is the most frequent organism isolated, but a wide variety of other organisms may occur. Bacteriuria may be transient or persist for a prolonged period. Pregnant women with asymptomatic bacteriuria identified in early pregnancy and who are untreated have a risk of pyelonephritis later in pregnancy of 20% to 30%. Bacteremia is frequent in bacteriuric subjects following mucosal trauma with bleeding, with 5% to 10% of patients developing severe sepsis or septic shock. These two groups with clear evidence of negative outcomes should be screened for bacteriuria and appropriately treated. Asymptomatic bacteriuria in other populations is benign and screening and treatment are not indicated. Antimicrobial treatment has no benefits but is associated with negative outcomes including reinfection with antimicrobial resistant organisms and a short-term increased frequency of symptomatic infection post-treatment. The observation of increased symptomatic infection post-treatment, however, has led to active investigation of bacterial interference as a strategy to prevent symptomatic episodes in selected high risk patients.