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Bacteria in urine (bacteriuria)
Healthy urine in the bladder is sterile. Bacteria in a test mean either infection or contamination during collection.
Other names: Bacteria, BACT, bacteriuriaSection: UrinalysisSpecialist: Primary care physician, urologist; in pregnancy — an obstetrician-gynecologistSample: UrinePart of: Urinalysis
Updated: September 17, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortNormally, correctly collected urine contains no bacteria. Their presence is bacteriuria: either a urinary tract infection (especially with leukocytes and symptoms) or contamination during collection. The decisive test is a urine culture: growth from 10⁵ CFU/ml counts as significant.
What this marker is
Urine in the bladder of a healthy person is sterile. Bacteria enter the test in two ways: from an infection focus in the urinary tract, or from skin and mucosa during poor collection — the most common cause of “bacteria in urine” in people without complaints.
The result is always read together with leukocytes, nitrites and symptoms. Bacteria plus leukocytes and burning urination is the typical picture of cystitis. Bacteria with nothing else usually mean a collection error, and the test is repeated.
Reference ranges
Group
Reference range
All groups
normally none found (or single cells)
Urine culture: significant bacteriuria
growth ≥ 10⁵ CFU/ml
Borderline culture
10³–10⁴ CFU/ml — retest
Asymptomatic bacteriuria
bacteria without complaints; treated in pregnancy and before urological surgery
Accuracy depends on collection: genital hygiene, midstream first morning urine, sterile container, delivery within 1–2 hours. Warm urine stored longer multiplies bacteria and distorts the result.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
An approximate comparison with a typical range, not a diagnosis. Ranges differ between laboratories — use the one on your report; a doctor interprets the result.
When it is high or appears: possible causes
CystitisBacteria with leukocytes, burning and frequency — the most common picture.
PyelonephritisKidney infection: bacteriuria, leukocyturia, fever and flank pain.
Urethritis, including STIsBacteria in the first portion of urine, burning during urination.
Asymptomatic bacteriuriaBacteria without symptoms — always treated in pregnancy.
Collection contaminationNo hygiene or a non-sterile container — the most common cause.
What can skew the result
These factors can shift the result without any disease — keep them in mind before a retest:
Collection without genital hygieneNon-sterile containerUrine stored over 2 hoursDischarge contamination
How to prepare
A sterile container, careful genital hygiene, a midstream portion and delivery within 2 hours — otherwise bacteria multiply in the jar. The same rules apply to a urine culture.
When a retest makes sense
“Bacteria without symptoms” means a retest with flawless collection within a few days. A culture after antibiotics makes sense no earlier than 5–7 days after the course.
Who usually reviews this result
An out-of-range result is usually reviewed by: Primary care physician, urologist; in pregnancy — an obstetrician-gynecologist. Bring your report and any previous results to the visit.
Names used on lab reports
Look for one of these names on your report: Bacteria in urineBacteriaBACTBacteriuriaNitrites (NIT)
Several markers on your report?
The app reads your whole report — this marker together with its neighbors, not one by one.
Depends. In most adults asymptomatic bacteriuria is only observed; in pregnancy and before urological procedures it is always treated. The doctor decides, often after a urine culture.
What is 10⁵ CFU/ml in a urine culture?
CFU means colony-forming units. Growth of 10⁵ or more CFU/ml proves bacteriuria: the lab identifies the pathogen and its antibiotic sensitivity. Lower values matter when symptoms are present — the doctor judges.
Positive nitrites — what is that?
Nitrites form when bacteria process urinary nitrates. A positive test indirectly confirms bacteriuria, but a negative one does not exclude it: not all bacteria produce nitrites.
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