A 52-year-old woman with recurrent UTIs has a high urine pH. Which organism is most likely responsible for her condition?

• A. Escherichia coli
• B. Mycobacterium tuberculosis
• C. Proteus vulgaris
• D. Pseudomonas aeruginosa

Answer: (C)

The high urine pH in this patient suggests an alkaline environment, which is often associated with certain urinary tract infections (UTIs) caused by specific organisms. Among the options given, Proteus vulgaris is the most recognized organism that produces urease, an enzyme that catalyzes the conversion of urea to ammonia. This process increases the urine pH, leading to alkaline urine.

Chronic infections with Proteus vulgaris can result in persistent UTIs, often presenting with elevated urine pH, which contributes to the formation of struvite stones due to the ammonia produced. This characteristic sets Proteus vulgaris apart from other organisms typically linked to UTIs, such as Escherichia coli, which generally causes acidic urine.

While other organisms like Pseudomonas aeruginosa and Mycobacterium tuberculosis can be involved in urinary infections, they are less commonly associated with high urine pH compared to Proteus vulgaris. Therefore, the presence of recurrent UTIs along with high urine pH strongly suggests that Proteus vulgaris is the most likely pathogen in this case.