CHEMICAL EXAMINATION OF URINE (NITRITE)

(NITRITES) (Escherichia coli) (Klebsiella species) (Proteus species) () () ()

(______________)

● Together with leukocyte esterase, this aid the physician

in screening for Urinary tract infection (UTI)

○ If leukocyte esterase and nitrite both give a positive

result, this will give an input to the physician that the

patient is suffering from UTI, rather than

contamination.

● Bacteria involved in the reduction of nitrate to nitrite:

gram-negative bacilli

○ (____________)

○ (____________)

○ (____________)

(urinary tract infection (UTI) (Cystitis) (Pyelonephritis) (untreated cystitis) (Untreated cystitis) (nitrite test) (Subsequent antibiotic therapy) (nitrite test) () () () () () () () () () ()

CLINICAL SIGNIFICANCE

● Provides a rapid screening test for (___________),

together with a reagent strip test for leukocyte

esterase

○ The detection of nitrite is designed to detect cases

in which the need for culture may not be necessary.

● (______) is an initial bladder infection. the nitrite test is

valuable for this infection.

● (___________) is referred to as (________) which

is an inflammatory process of the kidney and adjacent

renal pelvis.

○ (______________) may lead to renal tissue damage,

impairment of the renal function, hypertension and

septicemia.

● Bacteriuria detection, through the use of the (________) in

the reagent strip method

● (______________________) can prevent the serious

complications of pyelonephritis, among others.

○ The (_________) can be used to evaluate the success

of antibiotic therapy

(60) (Griess Reaction) (para-arsanilic acid (or sulfanilamide)) (First Morning Void Urine) (Specimen collection after bladder retention of at least 4 hours) (4 HOURS) () () () () () () () () ()

REAGENT STRIP METHOD

Reading time:	(__) seconds
Principle:	● (___________) ● In the presence of nitrite in the reaction, it will combine with (_________________) ● In an acid medium, it will combine with diazonium salt and tetrahydrobenzoquinolin and produced a pink azodye ○ Any shade of color pink in the nitrite reagent strip pad is considered as a positive result
Best Specimen:	● (___________), or ● (___________________) ○ WHY (_________)? This is the time to take for the bacteria to convert nitrate to nitrite and will produce a positive result in the nitrite reagent strip pad

(100,000 organisms/mL) (bacteriuria) (pink) (negative or positive)

REAGENT STRIP METHOD

Sensitivity:	● Sensitivity for the test of nitrite is at least (___________) ● Reagent Strip Method for Nitrite does not measure the degree of (_______). Any shade of , is considered to represent a clinically significant amount of bacteria.
Reporting:	● Can only be reported as (________/_______)

(examined immediately (not fresh, not refrigerated) (not fresh) (not fresh) (beets

(beeturia), phenazopyridine) (beets

(beeturia),) (phenazopyridine) (ascorbic acid (vitamin C)) (diazonium salt) (diazotization) (diazonium salt) (diazotization reaction) (Diazonium salt)

(4 hours) (no Greiss

reaction) () () ()

REACTION INTERFERENCE

False-Positives ● Urine sample not (____________, (_________)- contaminant bacteria (if present) multiplies
○ Some contaminating bacteria can potentially reduce nitrate to nitrite. If these bacteria multiply in urine that is (_________), it could result in a positive reagent strip test for nitrite, even if there was no UTI-causing bacteria in the first place. ● Substances that give urine a pink or red color - (_____(________) (___________)
False-Negatives ● High levels of (__________) in urine ○ Directly reacts with the (________) (produced in the (__________)) to form a colorless end product ○ Consequently, the azo coupling reaction cannot occur and the reagent pad remains negative despite presence of adequate nitrite ○ (__________) is unavailable for the second part of the Greiss reaction. ● Urine sample retained in the bladder for less than 4 hours (inadequate time for conversion of nitrate to nitrite). ● Urine sample not examined immediately ○ Any nitrite present in the urine sample can be further reduced to nitrogen by the same bacteria when urine is left out in room temperature for too long. Nitrogen does not react with their agents in the reagent strip pad resulting in (________). ● A negative nitrite test does not rule out the possibility of UTI.

(p-arsanilic acid Tetrahydrobenzo(h)-quinolin-3-ol) (Sulfanilamide, hydroxytetrahy- dro benzoquinoline ) (0.06-0.1 mg/dL nitrite ion) (0.05 mg/dL nitrite ion) () ()

Nitrite Reagent Strip Summary

Reagents

Multistix: (__________________________)

Chemstrip: (____________, ___________________)

Sensitivity

Multistixc (________________)

Chemstrip: (_________________)

Sensitivity Interference False-negative: Nonreductase-containing bactenia Insufficient contact time between bacteria and urinary nitrate Lack of urinary nitrate Large quantities of bacteria converting nitrite to nitrogen Presence of antibiotics High concentrations of ascorbic acid High specific gravity

False-positive: Improperly preserved specimens Highly pigmented urine Correlations with other tests: Protein Leukocytes Microscopis