Which urinalysis finding combination most strongly suggests a bacterial urinary tract infection?

• A. Pyuria with bacteriuria; nitrites may be positive in Gram-negative infections.
• B. Hematuria with proteinuria only.
• C. Crystalluria with low urine concentration.
• D. Normal urinalysis.

Answer: (A)

Having both white blood cells in the urine (pyuria) and bacteria present in the urine (bacteriuria) is a strong signal of a bacterial urinary tract infection, because it shows that inflammation is occurring in the urinary tract and bacteria are actually present. The nitrite test adds further support because many common bacteria that cause UTIs, especially Gram-negative rods like E. coli, convert nitrates in urine to nitrites; a positive nitrite result increases the likelihood that the infection is bacterial.

In contrast, hematuria with proteinuria can occur with kidney disease, stones, or trauma and isn’t specific to infection. Crystalluria with low urine concentration points to crystal formation or concentration issues rather than infection. A normal urinalysis would not indicate an infection at all.