Post Gonococcal Urethritis (PGU): Correct Definition

Post Gonococcal Urethritis (PGU) is a classic clinical entity describing urethritis that appears or persists in a man after his gonococcal urethritis has been successfully treated with a drug that is active only against Neisseria gonorrhoeae and has no activity against other urethritis-causing organisms (historically, a single dose of penicillin or a single-dose cephalosporin/quinolone regimen not covering Chlamydia).

The reason this happens is that gonococcal urethritis is very frequently a co-infection with Chlamydia trachomatis, Ureaplasma urealyticum, or Mycoplasma genitalium. When treatment targets only the gonococcus, these co-pathogens survive and go on to produce urethritis symptoms once the gonococcal infection has cleared — by definition, this residual disease is non-gonococcal urethritis (NGU) occurring after treatment of gonorrhea, i.e., PGU.

Analysis of Options

• Option A — "PGU refers to non-gonococcal urethritis in men treated earlier with single dose of penicillin": Correct. This is precisely the textbook definition of PGU — chlamydial/ureaplasmal urethritis unmasked after gonococcus-only therapy (classically single-dose penicillin) fails to cover the co-infecting organism.
• Option B — "Neisseria gonorrhoea is the most frequent cause of PGU in men": Incorrect. By definition, PGU is non-gonococcal; N. gonorrhoeae has already been eradicated by the preceding treatment. The most frequent causes of PGU are Chlamydia trachomatis and Ureaplasma urealyticum, not the gonococcus itself.
• Option C — "Combination therapy with azithromycin leads to resistance and should be avoided": Incorrect. Azithromycin-based combination regimens (e.g., ceftriaxone plus azithromycin, historically) are used precisely to cover the likely chlamydial/ureaplasmal co-infection and reduce the chance of PGU developing; they are not "avoided" for this reason.
• Option D — "PGU usually occurs within one week after treatment of non-gonococcal urethritis": Incorrect on two counts — PGU follows treatment of gonococcal (not non-gonococcal) urethritis, and symptoms typically emerge after a longer incubation period (roughly 2–6 weeks, reflecting the longer incubation of chlamydial/ureaplasmal infection), not within one week.

Key Takeaway

PGU is essentially chlamydial/ureaplasmal (non-gonococcal) urethritis unmasked by gonococcus-specific treatment, classically single-dose penicillin, that leaves the co-infecting organism untreated. This makes Option A the correct statement.