What does nitrates in urine mean

Symptoms may arise during a transitional phase when the urethra is the primary site of colonization and inflammation. According to this concept bacteria may enter the bladder transiently, but—as a result of urodynamic and other host defence mechanisms—they are not able to grow sufficiently to achieve the high densities that are observed in well-established UTI.

Several theories have been proposed to explain the phenomenon of low-count bacteriuria. Second, a low number of bacteria in the urine may be the result of increased urine output due to high fluid intake.

Third, low-count bacteriuria may be produced by slow growth of some uropathogens such as S. Thus, one major common error in the diagnosis of UTI is to underestimate the significance of low-count bacteriuria. Particularly in men, low bacterial counts with uropathogens may be clinically meaningful, because contamination is uncommon in males. Asymptomatic bacteriuria is frequently detected in routine investigations. For infections with S. Asymptomatic bacteriuria is extremely rare in the early childhood period except in the presence of anatomical abnormalities prevalence in males 0.

In elderly males the percentage is even higher, if there is retention of urine due to hyperplasia of the prostate. Asymptomatic bacteriuria and leukocyturia are found in up to one-third of haemodialysis patients [ 5 ]. The decrease of urine output and lack of adequate rinsing allow the bacteria to grow. A further common error in the diagnosis and treatment of UTI is the misinterpretation of asymptomatic bacteriuria.

Additional clinical information is required to decide who should be treated and who should only be monitored. Asymptomatic bacteriuria should not be treated except in pregnancy when dilatation of the urinary tract during pregnancy allows bacteria to ascend. Acute pyelonephritis during pregnancy is associated with a high frequency of abortion.

Patients with asymptomatic bacteriuria such as haemodialysis patients evaluated for kidney transplantation should be given prophylactic treatment with antibiotics at the time when they undergo invasive urological diagnostic procedures to prevent septic complications. Currently there is a debate whether diabetic or immunosuppressed patients with asymptomatic bacteriuria should be given antibiotics.

In our clinic we do not treat diabetic patients or patients with asymptomatic bacteriuria after kidney transplantation routinely.

We monitor these patients carefully at short intervals, however. Contamination is sometimes unavoidable and remains a pitfall in the diagnosis of UTI. Contamination is likely if only small numbers of bacteria or several bacterial species grow in urinary cultures. Lactobacilli, Corynebacteria species, Gardnerella, alpha-haemolytic streptococci, and aerobes are considered urethral and vaginal contaminants.

The presence of true infection can be confirmed by urethral catheterization or better by suprapubic aspiration. True polymicrobic infection is rare, except in patients with ileal conduit, neurogenic bladder, or vesicocolic fistula, and in patients with UTI complicated by stones, chronic renal abscesses, or long-term indwelling urinary catheters.

The isolation of more than one organism from a single specimen of urine must always be interpreted with caution and considering i whether one organism is dominant, ii which type of the specimen was examined chronic catheterization vs midstream specimen , iii whether features are present which suggest true infection presence of white blood cells or contamination presence of vaginal epithelial cells , and iv whether clinical signs, symptoms and history point to the presence of UTI.

Thus the presence of squamous cells in urine samples of women is not a good pointer to the presence of bacterial contamination [ 6 ]. A proposed strategy to diagnose UTI is shown in Figures 1 and 2. The interpretation of urine analysis and culture tests is entirely dependent on the quality of the urine samples submitted for examination and the conditions of transport to the laboratory.

Diagnostic algorithm for asymptomatic UTI. Diagnostic algorithm for symptomatic UTI. Because many cases of UTI present acutely there is a need for a rapid diagnostic procedure. The biochemical reagent strip test dipstick test is the generally accepted screening test for UTI.

Chemical test strips usually operate by detection of a leukocyte esterase and a nitrate reductase activity. A negative dipstick test is usually sufficient to exclude true infection. Pyuria is a characteristic feature of inflammation and is easily detected by a positive test for leukocyte esterase activity. Consequently, false-negative results by microscopy are more frequent than false-positive results by dipstick.

The presence of leukocyturia does not always correlate with bacteriuria. The leukocytes may originate from sites of inflammation other than the urinary tract, particularly the female genital tract. Moreover, leukocyturia may continue even if bacteriuria has cleared spontaneously or after treatment. The nitrite test depends on the detection of nitrite in the urine which is formed from nitrate by many uropathogens.

The presence of nitrite is highly specific for bacteria, but several uropathogens do not reduce nitrate to nitrite, and therefore its utility is restricted to Enterobacteriaceae which give a positive test result.

In general, patients with symptoms suggesting UTI should have a clean-catch specimen sent for urine analysis and culture test. Since the bacterial count of early morning specimens is usually greater than that of specimens obtained at other times, it has become common practice to collect the first urine of the day. This sample is the most concentrated and bacteria in the bladder have had time to multiply overnight.

At the time samples are obtained in the office more dilute urine and bacterial washout due to multiple voids yield markedly lower colony counts.

Because the first urine portion flushes out urethral contaminants, collection of midstream specimens is the standard procedure. In women, collection of midstream specimens requires far greater care and co-operation than in men.

It is necessary to spread the labiae and the introitus vaginae should be cleaned with water- or saline-soaked swabs. Soaps or antiseptics should not be used because they are bactericidal and result in misleadingly low bacterial counts. Obviously, a suitable sterile container for urine collection is mandatory. In uncircumcised men, the foreskin should be pulled back to avoid contamination resulting from potential colonization of the preputial sac.

Problems occur in the interpretation of urine analysis particularly in the elderly because of technical difficulties of sample collection. High false-positive test rates are found in elderly females [ 7 ]; if they are incapable of providing midstream clean-catch urine specimens, the procedure should be assisted by a nurse. Urine collected by suprapubic aspiration is generally considered as the diagnostic gold standard since contamination is thus reliably ruled out.

However, it is obvious that suprapubic aspiration is not a tool for routine diagnosis. It may be valuable, however, for young children from whom a clean specimen cannot be obtained. Urethral catheterization, frequently performed by urologists to obtain uncontaminated bladder urine, is not the method of choice unless there are strong clinical arguments for this procedure. It is likely to introduce pathogenic organisms into the bladder and is potentially more harmful than the diagnostic benefit it yields.

UTI can readily be diagnosed by microscopical examination of urine. Centrifugation always leads to loss of particles and may produce inaccurate results in quantitative terms.

On the other hand, in unspun samples a number of relevant elements can be missed. Thus, the results after centrifugation with a standardized procedure are more sensitive and specific. When compared with bright-field microscopy, the phase-contrast technique allows better detection of most elements, especially of bacteria.

The counts are usually given per low-power field or high-power field. Results can be also given per unit volume of urine. Bacteria will continue to multiply in the warm medium of freshly voided urine.

It is therefore mandatory that urinalysis and culture tests should be performed without delay. The average time of replication of E. Dip-slide culture or a similar semiquantitative method of culture is generally preferable. These methods offer the advantage of reflecting the true approximate concentration of bacteria at the time the sample is taken so that storage at low temperature is unnecessary. Occasionally, unusual or fastidious bacteria may induce UTI. These bacteria are difficult to detect without examination of the urine using Gram stain [ 8 ].

For example, Haemophilus influenzae and Haemophilus parainfluenza do not grow well in culture media commonly used for enteric bacteria and as a result may go undetected. Other unusual organisms include Pneumococcus, Campylobacter, Legionella pneumophila, Salmonella, Shigella, Corynebacterium group D2, acid-fast bacilli including Mycobacterium tuberculosis and atypical mycobacteria , and fungi such as Blastomyces and Coccidioides.

Gram and acid-fast stains should be performed for patients with urinary symptoms and pyuria when routine cultures are reported to be negative.

The clinical presentation of a patient with UTI ranges from asymptomatic bacteriuria to acute pyelonephritis bacterial interstitial nephritis or urosepsis. The most likely cause of nitrites in urine is a UTIs. Most UTIs, especially those in the bladder and urethra, are easy to treat and will clear up within a week of taking antibiotics.

If left untreated, a UTI in the lower tract can spread to the kidneys and cause more severe complications. In this article, we take a closer look at how safe and effective baking soda is for treating urinary tract infections, otherwise known as UTIs. Learn about nine ways to make yourself pee when you are unable to go. We also look at when someone might need to induce urination, and when to seek…. A kidney infection, or renal infection, happens when bacteria infecting the bladder or urethra spread to at least one of the kidneys.

In most cases…. Learn all about urinary tract infections in men, which are less frequent but can be more serious than UTIs in women. We look at symptoms and…. What does having nitrites in urine mean? Medically reviewed by Carissa Stephens, R. What are nitrites? What causes nitrites in urine? This mechanism might explain why urinary acidification and vitamin C may be effective in the treatment of bacteriuria. Abstract Objectives: The bacteriostatic gas nitric oxide NO is formed when nitrite is acidified.

Substances Nitrites Nitric Oxide. Tests to detect nitrites and leukocyte esterase have become part of a routine urinalysis. Most species of bacteria that colonize in the urine cause nitrates, which are derived from dietary metabolites, to be converted to nitrites.

In healthy people, both the urinary nitrite test and the leukocyte esterase LE tests are negative. A negative nitrite test does not necessarily mean that the urine is free of all bacteria, particularly if there are clinical symptoms, because some bacteria do not produce nitrites.