Criteria for the diagnosis of urinary tract infection

Despite years of clinical experience with urinary tract infection, the criteria for the diagnosis of this common condition are controversial. Accumulating evidence confirms prior suggestions that criteria must be flexible and varied, depending on the clinical syndrome encountered. The combination of pyuria and bacteriuria, with a uropathogen present at a urine colony count level predictive of infection, offers the best way to distinguish infection from contamination of the collected urine specimen. The level of bacteriuria on quantitative urine culture that should be considered significant varies from 10(2) to 10(5) colonies or more per milliliter of urine, depending on the clinical setting.