Which organism is a common cause of urinary tract infections in hospitalized patients, and what are the associated risk factors?

• A. Staphylococcus aureus; risk factors include wound contamination
• B. Pseudomonas aeruginosa; risk factors include skin breaks
• C. Klebsiella pneumoniae; risk factors include antibiotic use
• D. Escherichia coli; risk factors include catheterization and urinary retention

Answer: (D)

The main idea is that urinary tract infections acquired in hospitals most commonly come from gut bacteria that ascend into the urinary tract, with Escherichia coli being the usual offender. E. coli has adhesins that help it attach to the lining of the bladder and urinary tract, allowing it to establish infection. In hospitalized patients, two major risk factors drive these infections: catheterization and urinary retention. An indwelling urinary catheter provides a direct route for bacteria to enter the bladder and often permits biofilm formation on the catheter, making infection more likely and tougher to treat. Urinary retention creates stagnant urine, which supplies a growth medium for bacteria and increases the chance of colonization and invasion. While other organisms can cause UTIs in hospital settings, the combination of E. coli being the most common cause and catheterization with urinary retention as key risk factors makes this the best-fitting answer.