North American Registry of Midwives (NARM) Practice Exam

What urine bacterial count is indicative of a urinary tract infection (UTI)?

1. 10,000 bacteria per milliliter of urine

2. 25,000 bacteria per milliliter of urine

3. 50,000 bacteria of the same species per milliliter of urine

4. 100,000 bacteria of different species per milliliter of urine

The correct answer is: 50,000 bacteria of the same species per milliliter of urine

A urine bacterial count of 50,000 bacteria per milliliter of urine is widely accepted as a threshold indicative of a urinary tract infection (UTI). This standard is based on clinical studies and guidelines which have determined that this level of bacterial concentration is typically associated with an active infection rather than contamination or mild colonization. In practice, urinary tract infections are generally diagnosed when this concentration is observed alongside appropriate symptoms, such as dysuria, frequency, urgency, or flank pain. The reasoning behind setting the count at this level rather than lower counts is to avoid misdiagnosis and unnecessary treatment for conditions that do not warrant intervention. Lower counts, such as 10,000 or even 25,000 bacteria per milliliter, might not be clinically significant and could arise from various benign or non-infectious processes. Additionally, the presence of 100,000 bacteria of different species may suggest contamination or mixed flora rather than an infection by a specific pathogen, which further complicates diagnosis and proper treatment. Hence, the definitive count associated with a UTI diagnosis is 50,000 bacteria of the same species.