What does a positive nitrite test on dipstick suggest?

• A. Bacteria that reduce nitrate to nitrite, usually gram-negative pathogens
• B. White blood cells
• C. Protein present
• D. Glucose present

Answer: (A)

A positive nitrite on a urine dipstick indicates bacteria in the urine that convert nitrates to nitrites. Many common urinary pathogens, especially gram-negative rods such as E. coli, have nitrate reductase and reduce nitrate to nitrite when they grow in urine. This makes the nitrite test a rapid clue for a bacterial urinary tract infection caused by nitrate-reducing organisms. It’s separate from other dipstick findings: leukocyte esterase points to white blood cells (pyuria), protein indicates proteinuria, and glucose reflects glycosuria. Keep in mind limitations: some bacteria don’t reduce nitrate, and nitrite may be negative if the bladder isn’t in contact with urine long enough, if nitrate intake is low, or if substances like high-dose vitamin C interfere.