CLSI Susceptibility / Reference Standard: No significant growth (< 10,000 CFU/mL) | Diagnostic UTI Threshold: >= 100,000 (10^5) CFU/mL
Quantitative Urine Culture (LOINC 630-4) coupled with Antibiotic Susceptibility Testing (ABST / MIC profiling) remains the gold standard for diagnosing uncomplicated cystitis, acute pyelonephritis, and catheter-associated urinary tract infections (CAUTI).
1. Colony-Forming Unit (CFU/mL) Thresholds
In a clean-catch midstream urine specimen, growth of a single predominant uropathogen (most commonly uropathogenic Escherichia coli [UPEC] accounting for 75–85% of community-acquired cases) at ≥ 105 CFU/mL confirms true bacteriuria. See also our antimicrobial monographs on Septra (TMP-SMX), Ciprofloxacin, and Ampicillin.
Related Clinical Practice & Patient Interpretation Guidelines:
• Urine Culture & Sensitivity (ABST) Complete Lab Interpretation
• Urinary Tract Infection (UTI) Clinical Management Protocol
• Urine Culture & Sensitivity (ABST) Complete Lab Interpretation
• Urinary Tract Infection (UTI) Clinical Management Protocol