A urine culture is the gold standard test for diagnosing a urinary tract infection. A urine sample is placed on culture media and incubated to identify any bacteria or fungi present, quantify their numbers, and test antibiotic sensitivity. The result guides appropriate antibiotic selection for treatment.
A positive culture shows which organism is growing (e.g. E. coli, Klebsiella), at what level (significant bacteriuria is typically above 100,000 colony-forming units per mL from a midstream clean-catch sample), and which antibiotics it is sensitive or resistant to (antibiogram). This information prevents unnecessary broad-spectrum antibiotic use and manages antibiotic resistance.
FAQs
How do I collect a urine culture correctly?
Collect midstream clean-catch urine: clean the genital area, start urinating into the toilet, then collect mid-stream into a sterile container without stopping. Deliver to the lab within 2 hours or refrigerate. Correct technique significantly reduces contamination.
What does 'mixed growth' mean?
Mixed growth indicates contamination with multiple organisms from skin or perineum rather than a true UTI. The sample should be repeated with improved collection technique.
Can I still be treated without a culture?
Yes, for uncomplicated lower UTI in non-pregnant women, empirical treatment based on dipstick and symptoms is acceptable. Culture is most valuable when treatment fails, the patient is at high risk, or antibiotic resistance is a concern.
How long does a urine culture take?
Preliminary results may be available within 24 hours; complete antibiogram results typically take 48-72 hours. Sensitivity testing is crucial for resistant organisms.
