What is asymptomatic bacteriuria?
Asymptomatic bacteriuria (ABU) is the abnormally high number of bacteria in the urine without any symptoms associated with an urinary tract infection. Normally urine is sterile, meaning that there are no microbes in it, until it reaches the distal urethra. Here bacteria attached to the urethral lining pass out with the urine. Overall this small number of bacteria is not significant and does not usually indicate a potential health risk. In asymptomatic bacteriuria, the number of bacteria in the urine exceeds 100,000 organisms (cfu ~ colony-forming units) per milliliter (mL).
Bacteria are the most common infectious agents of a urinary tract infection. The term urinary tract infection denotes a symptomatic state usually characterized by burning upon urination, frequent urination, strong smelling urine, urethral discharge and discoloration of the urine. Other symptoms such as a fever, lower abdominal and pelvic pain, and/or flank pain are also present to varying degrees but are non-specific for a UTI. With asymptomatic bacteriuria, these symptoms are absent despite the large number of bacteria in the urine. However, about 30% of such cases may become a symptomatic infection (urinary tract infection) usually within one year.