In a man with fever and dysuria and an enlarged prostate, what is the most common causative organism of urinary tract infection?

In a man with fever and dysuria and an enlarged prostate, what is the most common causative organism of urinary tract infection?

• A. Staphylococcus aureus
• B. Pseudomonas aeruginosa
• C. Escherichia coli
• D. Klebsiella pneumoniae

Answer: (C)

Escherichia coli is the most common cause of urinary tract infections because it originates from the gut and has virulence factors that help it reach and cling to the urinary tract. It can ascend from the periurethral area into the bladder and, in men with an enlarged prostate, can contribute to prostatitis by ascending into the prostate. Its fimbriae enable attachment to uroepithelium, and other toxins facilitate invasion and inflammation, making it the leading pathogen in both uncomplicated UTIs and prostatitis. Other organisms like Staphylococcus aureus, Pseudomonas aeruginosa, or Klebsiella are less frequent causes in community-acquired UTIs; Pseudomonas is more common in hospital- or catheter-associated infections, and Staph aureus often indicates hematogenous spread or instrumentation.

Escherichia coli is the most common cause of urinary tract infections because it originates from the gut and has virulence factors that help it reach and cling to the urinary tract. It can ascend from the periurethral area into the bladder and, in men with an enlarged prostate, can contribute to prostatitis by ascending into the prostate. Its fimbriae enable attachment to uroepithelium, and other toxins facilitate invasion and inflammation, making it the leading pathogen in both uncomplicated UTIs and prostatitis. Other organisms like Staphylococcus aureus, Pseudomonas aeruginosa, or Klebsiella are less frequent causes in community-acquired UTIs; Pseudomonas is more common in hospital- or catheter-associated infections, and Staph aureus often indicates hematogenous spread or instrumentation.