Which statement about nitrite testing in urine is correct?

Which statement about nitrite testing in urine is correct?

• A. It detects nitrite in all bacterial infections
• B. It indicates nitrate-reducing bacteria, supporting UTI
• C. It is a test for leukocyte esterase
• D. It is not helpful in diagnosing UTIs

Answer: (B)

Nitrite testing in urine hinges on detecting nitrite produced when certain bacteria reduce nitrates present in urine to nitrites. Many common urinary pathogens possess nitrate reductase and convert nitrate to nitrite, so a positive nitrite result supports the presence of nitrate-reducing bacteria and, in the right clinical context, a urinary tract infection. This test is especially useful for infections caused by typical Gram-negative bacteria like E. coli. However, not all pathogens reduce nitrate, so some UTIs can be nitrite-negative, and a negative result does not rule out infection. Also, sufficient time in the bladder is needed for reduction to occur, so early infections or low bacterial load may yield a negative nitrite test. Clinically, this test is often interpreted alongside leukocyte esterase to provide a fuller picture of infection.

Nitrite testing in urine hinges on detecting nitrite produced when certain bacteria reduce nitrates present in urine to nitrites. Many common urinary pathogens possess nitrate reductase and convert nitrate to nitrite, so a positive nitrite result supports the presence of nitrate-reducing bacteria and, in the right clinical context, a urinary tract infection. This test is especially useful for infections caused by typical Gram-negative bacteria like E. coli. However, not all pathogens reduce nitrate, so some UTIs can be nitrite-negative, and a negative result does not rule out infection. Also, sufficient time in the bladder is needed for reduction to occur, so early infections or low bacterial load may yield a negative nitrite test. Clinically, this test is often interpreted alongside leukocyte esterase to provide a fuller picture of infection.