Which urinalysis findings are most suggestive of a urinary tract infection?

• A. Negative nitrites
• B. Positive leukocyte esterase only
• C. Pyuria alone
• D. Positive nitrites, positive leukocyte esterase, pyuria, and bacteria on culture

Answer: (D)

UTI diagnosis by urinalysis relies on several clues that together create the strongest evidence of infection. A positive nitrite result happens when nitrate-reducing bacteria are present in the urine, which is typical of many UTI pathogens, though not all organisms produce nitrites. Leukocyte esterase is an enzyme from neutrophils, so a positive test indicates white blood cells in the urine and an inflammatory process. Pyuria, the presence of white blood cells in the urine, further supports inflammation within the urinary tract. Finally, actually seeing bacteria on culture confirms a bacterial infection and helps identify the culprit to guide treatment. When all of these findings occur together—nitrites, leukocyte esterase, pyuria, and bacteria on culture—the likelihood of a urinary tract infection is strongest.