- The use of any existing antibiotics will reduce bacterial growth leading to no evidence of infection on dip
- Drinking too much liquid before providing a sample thus diluting it.
- The dipsticks are calibrated to detect white blood cells counts of >10 5 (100,000) bacteria per millilitre of urine or greater. For someone with a bacterial infections lower than this cut off range, the dipstick will report a false negative.
- Bacteria require a minimum of four hours to reduce the nitrate in urine to nitrites. Not all bacteria responsible for UTIs contain nitrite reductase, the enzyme responsible for this conversion. Examples of Nitrite reducing bacteria including E-coli, Proteus and Klebsiella. But if your infection is caused by Enterococcus or Pseudomonas, this enzyme conversion will not occur.
- Various chemicals can also interfere with urine dipstick analysis. Some chemicals that may cause false-negative results include ascorbic acid (such as vitamin C) and oxalic acid (an organic compound found in many plants such as leafy greens, vegetables, fruits, cocoa, nuts and seeds).
- Biofilm or embedded bladder wall infections mean that the bacteria are embedded and hidden away from the urine, not floating in it. When you urinate, the bacteria will not transfer into the sample pot resulting in lack of detection on a dipstick.
