Urine culture and sensitivity

What it measures

Grows and counts bacteria in urine to confirm urinary tract infection and identify the organism and its antibiotic susceptibility.

Specimen and preparation

• Specimen: Clean-catch midstream urine or catheter sample
• Tube: Urine top
• Preparation: Collect before antibiotics; sterile container; culture within 2 hours or refrigerate (up to 24 h).

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• ≥ 10⁵ CFU/mL of a single uropathogen: significant bacteriuria
• Lower counts (10³–10⁴) may be significant in symptomatic women, men or catheter samples
• Mixed growth of 3+ organisms: likely contamination

Method

Calibrated-loop culture on CLED/chromogenic agar, identification and antimicrobial susceptibility testing

Good to know

E. coli causes most community UTIs; asymptomatic bacteriuria is treated mainly in pregnancy and before urological surgery.

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