Urine culture is a microbiological examination aimed at finding particular microorganisms in the urine; it therefore serves essentially a diagnostic purpose, but thanks to the possible antibiogram it can also be useful to choose the most suitable medicine for eradicating the pathogen.
Normally, urine culture does not show significant concentrations of bacteria, since the urine tends to be sterile; only a rather small bacterial microflora colonizes the terminal part of the male urethra, while it is generally absent in the female part.
Urine culture: the role of the patient
In the presence of urinary tract infections, urine culture represents a very useful diagnostic tool, but precisely because microorganisms are being sought it is essential that the sample is not contaminated with germs coming from outside. Let's see some simple rules to avoid this type of contamination.
- Suspend any antibiotic and antifungal therapies in the 48 hours prior to the examination, according to medical indications.
- In the morning, before urinating, thoroughly wash your hands and external genitals with soap and water, rinsing with water for a long time; do not use disinfectants. In the male the cleaning must take place after completely retracting the skin of the foreskin; the woman will instead have to clean - preferably with gauze soaked in physiological solution and with movements from the front to the back - the inner surface of the large and small lips, dividing these with the fingers before starting to urinate.
- The sample collection must take place the morning of the exam delivery day, collecting the urine at least two hours after the last urination.
- Start urinating by discarding the first jet. Hold the urine and open the sterile container previously received in the laboratory or pharmacy.
- Resume urinating in the sterile container, filling it for just under half. Try not to wet the edges of the container or contaminate them with your hands, hair, genitals or underwear. Even more important is to avoid touching the inside of the container.
- NOTES: never open the sterile container before use.
- Screw the lid back on immediately after urinating; make sure the operation has been carried out correctly in order not to spill urine during transport.
- If similar containers are used for urinalysis and urine culture, indicate which contains the first jet (valid for urine testing) and which is the next (valid for urine culture).
- Bring the urine sample to the laboratory as soon as possible or store it at 4 ° C (in the refrigerator) for up to 12 hours. Be careful not to turn it upside down during transport.
NOTE: the indications provided by the analysis center may vary slightly from those described. In pediatric age, for example, the urine culture sample is collected in a special sterile adhesive plastic bag.
Once the urine culture and antibiogram response is received, the doctor will choose the most suitable drug and advise the daily frequency and duration of therapy. If an antibiotic treatment is prescribed, this should not be interrupted at the first disappearance or attenuation of symptoms, but continued for the entire required period. This care limits the risk of recurrence and the spread of antibiotic - resistance.
Urine culture can also be performed in the asymptomatic patient, for example if a previous examination of the urine shows signs of an infection (alkaline pH, positive nitrites and leucocyturia, ie numerous white blood cells in the urinary sediment). Urine culture is often performed during pregnancy, a period in which the woman is particularly exposed to the risk of urinary tract infections (often asymptomatic); the gynecologist can then ask the pregnant woman to perform a urine culture every thirty days, prescribing the most appropriate treatment whenever it is positive.
