What are the signs of a urinary tract infection (UTI) on urinalysis (UA)?

From the Guidelines

Urinary Tract Infection (UTI) signs on urinalysis (UA) include pyuria, which is the presence of white blood cells in the urine, indicating an inflammatory response. The diagnostic value of UA for UTI is limited, and the positive predictive value of pyuria for diagnosing infection is low, as it can also indicate noninfectious genitourinary inflammation 1. However, the absence of pyuria can help rule out infection in most patient populations.

• Key findings on UA may include:
  • Pyuria (presence of white blood cells)
  • Bacteriuria (presence of bacteria)
  • Hematuria (presence of blood in the urine)
  • Proteinuria (presence of protein in the urine)
  • Leukocyte esterase (a chemical test that detects the presence of white blood cells)
  • Nitrites (a chemical test that detects the presence of certain bacteria) A clean-catch or catheterized specimen for culture typically reveals >100,000 organisms per milliliter of urine, with Escherichia coli being the most common organism, causing approximately 75% of recurrent UTIs 1. Urine cultures are reasonable for complicated cases and/or recurrent UTIs, particularly in suspected pyelonephritis, to guide targeted therapy 1.

From the Research

Urinalysis (UA) Signs of Urinary Tract Infection (UTI)

• The signs of a urinary tract infection (UTI) on urinalysis (UA) include:
  • Leukocyte esterase positive result in first-void urine 2, 3
  • At least 10 white blood cells per high-power field in urine sediment 2, 3
  • Presence of polymorphonuclear leucocytes (PMNLs) in a stained smear 4
  • Presence of mononuclear leucocytes in the smear, which may indicate a viral etiology 4
• These signs are indicative of urethritis, which is characterized by inflammation of the urethra and can be caused by various pathogens, including Chlamydia trachomatis, Neisseria gonorrhoeae, and Mycoplasma genitalium 2, 4, 3, 5, 6

Diagnostic Criteria

• The diagnostic criteria for urethritis include:
  • Typical signs and symptoms, such as dysuria, mucopurulent urethral discharge, and urethral discomfort 2, 4, 3
  • History of exposure to a sexually transmitted infection (STI) 2
  • Positive result on a leukocyte esterase test in first-void urine or at least 10 white blood cells per high-power field in urine sediment 2, 3
  • Presence of PMNLs in a stained smear or positive nucleic acid amplification test (NAAT) result for a specific pathogen 4, 5, 6

Clinical Profile

• The clinical profile of urethritis in men includes:
  • Dysuria, which is the most common symptom 6
  • Urethral discharge, which can be purulent or transparent 6
  • Balanitis/meatitis, genital warts, and proctalgia, which can be observed in some cases 6
  • Co-infections, which are rare but can occur with multiple pathogens, including M. genitalium, C. trachomatis, and N. gonorrhoeae 6