Urine culture
A test that tries to grow bacteria from a urine sample to confirm a urinary tract infection and identify exactly which bacterium is responsible. It also tests which antibiotics will work (sensitivity), so treatment can be targeted rather than guessed.
What it measures
A urine culture is not a chemistry number but a microbiology test performed on a urine sample (usually a clean-catch midstream sample). The urine is placed on a growth medium, and if bacteria are present they multiply into visible colonies over a day or two. The result reports the type of bacterium and how many there are — a bacterial count, given in colony-forming units per millilitre (CFU/mL). A high count of a single organism, in a person with urinary symptoms, confirms a urinary tract infection and identifies the culprit — most commonly E. coli. Crucially, the laboratory then tests the grown bacteria against a panel of antibiotics (the 'sensitivity' or 'susceptibility' test) to show which will kill it and which it resists, so the right antibiotic can be chosen. A urine culture is the definitive test for a urinary infection, used especially when the infection is complicated, recurrent, in pregnancy, in men, in children, or has not cleared with first-line treatment. A negative culture (no significant growth) argues against a bacterial infection and prompts a look for other causes of the symptoms.
What a high value can mean
- A confirmed urinary tract infection — a high count of a single organism with symptoms.
- Identification of the bacterium — most often E. coli, guiding treatment.
- A complicated, recurrent or resistant infection — the sensitivity report shows which antibiotics still work.
- Asymptomatic bacteriuria — bacteria present without symptoms; usually only treated in pregnancy or before certain procedures.
What a low value can mean
- No significant growth (a negative culture) — argues against a bacterial urinary infection; symptoms may have another cause.
- Contamination — mixed low-count growth of several organisms usually reflects a poorly collected sample, not a true infection.
When to discuss with a doctor
A urine culture is used to confirm a urinary tract infection and, importantly, to choose the right antibiotic. It is especially valuable when an infection is recurrent, has not responded to first treatment, or occurs in situations that need extra care — pregnancy, men, children, or people with kidney problems or a catheter. If you have symptoms such as burning on passing urine, needing to go often and urgently, cloudy or bloody urine, or fever and back pain (which can mean the kidney is involved), the culture directs targeted treatment. A negative culture is useful too, pointing away from infection. Mediora.AI shows urine culture results alongside the urinalysis so the infection picture is read together; the interpretation and antibiotic choice belong with your doctor, guided by the sensitivity report.