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Prostatic Antibiotic Penetration — SCE Infectious Diseases MCQ

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ModerateAntimicrobial StewardshipProstatic Antibiotic PenetrationSCE Infectious Diseases

A 55-year-old man develops acute bacterial prostatitis with E. coli bacteraemia. He is septic. After IV antibiotics (Ceftriaxone), he improves. What oral step-down agent achieves the best prostatic tissue penetration?

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Correct answer: C — Ciprofloxacin 500 mg BD — fluoroquinolones achieve excellent prostatic penetration (prostatic concentration exceeding serum); Trimethoprim is an alternative

The prostate has a unique pharmacological barrier (blood-prostate barrier) that limits penetration of many antibiotics. Fluoroquinolones (Ciprofloxacin, Levofloxacin) achieve excellent prostatic tissue concentrations (often exceeding serum levels) and are the preferred oral step-down for prostatitis. Trimethoprim also achieves good prostatic levels. Beta-lactams (Amoxicillin, Cefalexin) and Nitrofurantoin have poor prostatic penetration. Total treatment duration for acute bacterial prostatitis: 2-4 weeks.

Reference: NICE NG109 2018 – UTI; EAU 2024 – Prostatitis; BNF 2024