Differnent reading from a urinalysis dipstick and a culture.


Q: I was diagnosed with a UTI from a dipstick urinalysis, from an urgect care facility, but the culture came back negative. Visited my PCP and she also confirmed a UTI (twice) with a dipstick urinalysis, NIT positive, but again the culture was negative. Meanwhile I have been treated with nitrofurant am now on Cipro. No back pain, no fever, blood tests showed no kidney concerns, just feeling of urgency.
I have tried Advil, Xanax and AZO Pain Relief.

Symptoms:  Urinary urgency

A:   Hello,
Thanks for the query to askthedoctor.com for an opinion.

Overall, the sensitivity of the urine dipstick test for nitrites in testing for a UTI has been found to be low (45-60% in most situations) with higher levels of specificity (85-98%). The test for nitrites has its highest accuracy in specific populations such as pregnant women, urology patients and elderly people. The test for nitrites may perform better in asymptomatic patients and in patients who are not on antibiotics.When testing for urinary tract infections, the sensitivity of the urine dipstick test for leukocyte esterase has been found to be, in general, slightly higher than for the dipstick test for nitrites (48-86%), while the specificity was slightly lower (17-93%). Generally, this results in a lower accuracy, compared to the test for nitrites, lower predictive values of positive test results and similar predictive values of negative test results.

The leukocyte esterase test has been found to have a much higher accuracy in urology patients. Sensitivity is highest in primary care, but requires further investigations because of the high rates of false positives. In primary care, negative results do not exclude the presence of infection.
Now if the urine dipstix test has been positive indicating either presence of nitrites or leucocyte esterase in urine indicating infection but the urine culture is negative, indicates that you may be suffering from UTI and have been rightly offered treatment for the same. Culture negativity can be explained by the start of treatment already with nitrofurantoin when the sample was taken making the culture results false negative and sterile for infection. Hence considering the dipstix results and urgency as a symptom, you should still follow a complete course of antibiotics as advised and increase your water intake to flush out the infection sooner.
I hope i have answered your query in detail,
Wishing you good health,

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