Stanovení dusitanů v moči
Nitrite is determined in the urine as an indirect sign of bacteriuria . Normal urine does not contain them in measurable concentrations. Some primarily gram -negative bacteria , such as Escherichia coli , Proteus , Klebsiella , staphylococci and others, have the ability to reduce the nitrates present in the urine to nitrite. Diagnostic strips for indirect detection of bacteriuria use nitrite in the so-called Griess reaction . Its essence is the diazotization of sulfanilamide with nitrite in the sample to form the diazonium salt. This is followed by azocoupling of the resulting salt with a coupling agent, developing a pink to purple color.
The nitrite urine test should be performed in the first morning urine, as in this case a sufficiently long time is guaranteed for the bacterial reduction of nitrates to nitrite in the bladder. Another recommendation is to consume enough vegetables (contains nitrates) the day before the examination. A positive urinary nitrite test confirms bacteriuria, while a negative one does not excrete it.
Indirect evidence of bacteriuria is indicative and does not replace microbiological examination.
