Urine Diagnostics / Urine Test Strips / Portfolio Urine Test Strips / Nitrite


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Test principle 
 
Sensitivity
Bacteria free urine does not contain nitrite.Detection limit: 0.05 mg/dl (11 µmol/l)
Specifity
Nitrite detection is specific for detecting bacteriuria. Each pink coloration is deemed to be positive and indicates ≥105 bacteria per ml urine.Negative results do not exclude significant bacteriuria (urine dwell time in the bladder too short, infection due to bacteria without nitrate reductase).
To ensure reliable results
  • Normal rich vegetable diet during the day before the day of the investigation to make sufficient reducible nitrate available,
  • Repeated examination of the morning urine is recommended,
  • Exclusion of antibacterial therapy (no antibiotics, no sulphonamides),
  • Stop taking antibiotics and chemotherapies at least 3 days beforehand.
Sources of errors
 False-negative results:
  • Urine dwell time in the bladder is too short (severe diuresis with frequent mictions).
  • Urinary tract infection caused by bacteria without nitrate reductase.
  • Inadequate quantity of substrate, nitrate deficiency (no nitrate - no nitrite), as in- vegetable diet feed,
    - parenteral nutrition,
    - hunger conditions (fasting).
  • Urine should not contain antibiotics or sulphonamides.
  • Expiered urine (possibility of reduction to nitrogene or ammonia)
False-positive results:
  • Bacterial contamination using expiered urine (longer than 4 hours).
  • Taking medicines containing phenazopyridine.
  • Eating beetroots
Clinical significance
Besides respiratory tract infections, urinary tract infections are one of the most frequently occurring bacterial diseases in humans. Most pathogenic bacteria (Escherichia coli as the most frequent pathogen and other pathogenic bacteria such as Klebsiella, Proteus, Aerobacter, Citrobacter, Salmonella, Staphylococcus, Enterococcus and several species of Pseudomonas) reduce the nitrate in urine to nitrite. The nitrite and thus the nitrite forming bacteria can be detected using the nitrite test pad of the urine test strips. Most cases of bacterial infections of the urinary tracts are the cause of pyelonephritis. Women are especially affected by urinary tract infections. Searching for urinary tract infections is indispensable during pregnancy. The formation of nitrite requires a long urine dwell time in the bladder, therefore morning urine should preferably be used for the examination. The urine of healthy persons does not contain nitrite.
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