Urine culture – laboratory test

Description

Why a urine culture is performed

A urine culture is a microbiological test that detects bacteria or fungi in urine and identifies their species and quantity. A healthy person’s urine is sterile, and the presence of significant numbers of microorganisms confirms a urinary tract infection. The most commonly detected bacterium is Escherichia coli. If the culture is positive, the results also include an antibiogram, which assesses the susceptibility of the cultured bacteria to antibiotics. This helps the doctor choose an effective medicine for the infection, reducing recurrence and the development of bacterial resistance.

When to consider this test

• if you have burning or pain when urinating, a frequent urge to urinate, lower abdominal or lower back pain, or fever,
• if you have recurrent urinary tract infections,
• if symptoms persist after treatment or return within a month of completing it,
• during pregnancy, as the infection may cause no symptoms,
• before a planned urological procedure,
• if you have diabetes, urinary stones, prostate disease or a weakened immune system.

How to prepare

• Collect the urine before starting antibiotics; if you are taking an antibiotic, tell the collection point staff and your doctor, as it may give a falsely low result.
• First morning urine is best, or urine collected at least 4 hours after you last urinated.
• Wash your genital area with soap and water, rinse and dry with a disposable towel. Women should separate the labia; men should pull back the foreskin.
• Pass the first part of the urine into the toilet, then, without stopping the flow, collect the midstream portion in a sterile container (do not touch its inside or rim), and pass the rest into the toilet.
• Close the container tightly, label it and deliver it within 2 hours; if this is not possible, keep it in the fridge (2–8°C) for up to 24 hours.

How to interpret the results

The threshold for significance depends on sex, age, symptoms, pregnancy and the collection method, so the results should be assessed by a doctor. A negative culture in someone with symptoms does not always rule out infection, for example after taking an antibiotic; refer to the interpretation on the laboratory report.

Tests to consider alongside this test

Urinalysis, CRP, Full blood count, Creatinine, Glucose. More information: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Urine culture (results turnaround time, antibiogram included in the results, collection method, interpretation of CFU/ml); MedlinePlus, Urine culture (indications, collection, effects of antibiotics on the results); Mayo Clinic, Urinalysis (midstream urine collection, storage in the fridge). This content is for information only and does not replace a medical consultation.