What is what does it mean when a urine culture showed mixed flora?

A urine culture showing mixed flora indicates that multiple types of bacteria were identified in the urine sample. This often means the sample is contaminated, usually during collection.

Here's a breakdown:

• What does it mean? A "normal" or "clean" urine sample should ideally have little to no bacteria present. When a culture shows mixed flora, it suggests that bacteria from sources other than the urinary tract (like skin, vaginal area, or the environment) have likely contaminated the sample.

• Common causes: The most frequent cause is improper collection technique. Bacteria from the skin surrounding the urethra can contaminate the sample as it's being collected. This is why a "clean-catch" method is important, involving cleaning the area before urinating into the sterile cup.

• Implications: A result of mixed flora makes it difficult to determine if a true urinary tract infection (UTI) is present. The identified bacteria may not be the cause of any symptoms, and treating them could lead to unnecessary antibiotic use.

• What happens next? Usually, the doctor will repeat the urine culture. The patient is instructed on proper urine collection techniques to minimize contamination. If the repeat culture is still contaminated, but the patient has symptoms of a UTI, the doctor might consider a "true" UTI based on clinical judgment. If a repeat culture is negative, it confirms that the initial mixed flora result was likely due to contamination.

• Important Considerations:

  • The interpretation of mixed flora can vary depending on the patient's circumstances, symptoms, and medical history.

  • If the patient has a catheter, mixed flora in the urine can be more concerning, as it might indicate a catheter-associated UTI.

  • The laboratory's report may indicate the types and amounts of bacteria present. This information can sometimes help the doctor assess the likelihood of a genuine infection versus contamination.

Here are the links: urinary tract infection urine collection catheter