Thursday, October 18, 2007

UTI's Part 2: UTI vs Positive Urine Cultures

Not all positive urine cultures indicate that the patient has a UTI. Positive urine cultures can result from improper, non-aseptic collection technique, improper specimen handling, or the presence of an indwelling urinary catheter, in addition to an actual infection.

Signs that the positive urine culture is actually a false positive one include:
  • multiple positive cultures, each one with a different bacterial species
  • cultures with multiple organisms
  • positive cultures in the face of a normal UA
  • positive cultures in the absence of symptoms
  • urine cultures that grow atypical organisms
  • positive cultures in patients with chronic indwelling catheters and no symptoms
  • cultures with low levels of bacterial growth
Any of the above should alert the physician to the fact that the culture may not be accurate. Use of antibiotics in these cases may not be indicated and can actually promote subsequent bacterial resistance.

Thanks for listening.

Dr S.