From the Research
Yes, a urine culture showing less than 100,000 colony-forming units (CFU) of Proteus in a catheterized patient likely represents colonization rather than a true urinary tract infection (UTI). This is based on the most recent and highest quality study available, which suggests that catheterized patients commonly develop bacterial colonization of the urinary tract without clinical infection 1. For catheterized patients, the diagnostic threshold for a UTI is typically higher, with many experts suggesting that counts of 100,000 CFU/mL or greater, along with symptoms, are needed to diagnose a catheter-associated UTI.
Some key points to consider in this context include:
- The ability of Proteus species to form biofilms on catheter surfaces, which can lead to colonization without infection 2
- The importance of minimizing the incidence and duration of urinary catheterization to prevent infection 3
- The need for hospitalists to be aware of and engage in processes that reduce the rate of CAUTIs, given the significant financial and patient outcome implications 1
- The high resistance rates of Proteus isolates to empiric antibiotics, which highlights the need for careful consideration of treatment options 4
Without accompanying symptoms such as fever, suprapubic tenderness, altered mental status, or other signs of infection, treatment is generally not recommended as it may lead to unnecessary antibiotic use and promote antimicrobial resistance. If the patient is asymptomatic, continued monitoring rather than antibiotic treatment is appropriate. However, if the patient develops symptoms consistent with UTI, reassessment and potential treatment would be warranted.