Criteria for the Diagnosis of UTI (colony count, probability of infection)

Suprapubic aspiration

• Gram-negative bacilli: any number: >99%
• Gram-positive cocci: more than a few thousand: >99%

Transurethral catheterization

• >10^5:    95%
• 10⁴-10^5: likely
• 10³-10^4: suspicious, repeat
• <10^3: unlikely

Clean void

• Boy, >104, likely
• Girl
  • 3 Specimens 10^5, 95%
  • 2 Specimens 10^5, 90%
  • 1 Specimen 10^5, 80%
  • 50,000  10^5, Suspicious, repeat
  • 10,000  50,000, Asymptomatic: infection unlikely
  • <10^4,   infection unlikely

PEDIATRICS Vol. 103 No. 4 April 1999, pp. 843-852
AMERICAN ACADEMY OF PEDIATRICS:
Practice Parameter: The Diagnosis, Treatment, and Evaluation of the Initial Urinary Tract Infection in Febrile Infants and Young Children, Committee on Quality Improvement, Subcommittee on Urinary Tract Infection