Urine culture
Also known as: midstream urine, urine microscopy, culture and sensitivity
A urine sample is spread on culture plates and incubated for 24-48 hours to grow any bacteria, identify them and test which antibiotics kill them. It turns a dipstick suspicion into a proven infection with a targeted treatment.
- Abbreviations
- MSU, MC&S
- Kind
- Microbiology test
- Categories
- Infectious disease & microbiology, Kidney & urinary
- Specimen
- Midstream urine
- Method
- Culture, Antimicrobial susceptibility testing, Microscopy
- Terminology
- LOINC 630-4
What it measures
| Measure | What it tells you |
|---|---|
| Colony count | 100,000 or more colony-forming units per mL of a single organism is significant; lower counts count in symptomatic patients and catheter samples. |
| Organism | E. coli causes most infections; Proteus suggests stones; Staphylococcus saprophyticus in young women; mixed growth usually means contamination. |
| Sensitivities | Which antibiotics the organism is sensitive or resistant to. |
Why it is ordered
- Infection in men, children, pregnancy and anyone with a catheter or kidney disease
- Infections that keep coming back or fail treatment
- Suspected kidney infection or sepsis from a urinary source
- Before urological surgery
How it is done
Midstream sample in a sterile pot (or from a fresh catheter); refrigerate if it cannot reach the lab within hours.
Preparation. Collect before starting antibiotics whenever possible.
Reading the result
| Finding | Usual meaning |
|---|---|
| Pure growth of E. coli, sensitive to nitrofurantoin | Confirmed infection; treat with the narrowest effective antibiotic |
| Mixed growth | Probably contaminated; repeat with careful collection |
| Growth without symptoms | Asymptomatic bacteriuria: treat only in pregnancy or before urological procedures |
Reference ranges vary by laboratory, method, age, sex and clinical context; a result is read against the person, not a table.
Limitations
Results take two days, so treatment often starts empirically. Antibiotics taken beforehand can sterilise the sample.
Medicines monitored with this test
Each medicine page cites the official document that names this test in its monitoring plan.