Question
Read the following clinical history and answer the following: A 25 years old man came to STD OPD with history of white pus discharging through urethra for the past two days. He gave history of exposure about five days back. On examination signs of urethritis were seen.
- (a) Mention the probable diagnosis and the causative agent. 2 mark(s)
- (b) List the specimens to be collected and how it is transported to the laboratory 2 mark(s)
- (c) Briefly describe the laboratory diagnosis 3 mark(s)
- (d) What are the complications 1 mark(s)
- (e) How it is treated and add a note on its prevention 2 mark(s)
Answer
a) Probable diagnosis and causative agent Gonococcal urethritis (gonorrhoea) — profuse purulent urethral discharge with a short incubation period (2–7 days, consistent with the 5-day exposure history here) is classical. Causative agent: Neisseria gonorrhoeae (Gram-negative diplococcus).
b) Specimen collection and transport Urethral discharge/swab collected using a sterile cotton or calcium alginate swab, inserted 2–3 cm into the urethra; a first-void urine sample can be used for NAAT/PCR testing. Since N. gonorrhoeae is fastidious and rapidly loses viability outside the host, the swab must be plated directly at the bedside wherever possible, or transported promptly in Amies/Stuart’s transport medium with charcoal, kept at room temperature (not refrigerated) and processed without delay; for longer transport, Transgrow or JEMBEC systems (self-contained CO2-generating transport/culture systems) can be used.
c) Laboratory diagnosis
- Gram stain of urethral discharge — shows numerous pus cells with intracellular Gram-negative diplococci (kidney/coffee-bean-shaped, arranged in pairs with flattened adjacent surfaces) — highly sensitive and specific in symptomatic males, allowing rapid presumptive diagnosis.
- Culture — on selective Modified Thayer-Martin medium (chocolate agar base with added antibiotics — vancomycin, colistin, nystatin, trimethoprim — to suppress commensal/contaminating flora), incubated at 35–37°C in a 5–10% CO2-enriched, humid atmosphere; confirmed by oxidase test (positive) and sugar fermentation (glucose only, not maltose/sucrose/lactose) or other biochemical/molecular identification.
- Nucleic acid amplification test (NAAT/PCR) — highly sensitive, now widely used, including on first-void urine, and also detects concurrent chlamydial infection.
d) Complications In men: epididymitis, prostatitis, urethral stricture. In women (often via ascending spread): pelvic inflammatory disease, tubal infertility, ectopic pregnancy. Disseminated gonococcal infection (bacteraemia, arthritis, skin lesions) in a minority; ophthalmia neonatorum in babies born to infected mothers.
e) Treatment and prevention Treatment: a single dose of injectable ceftriaxone (current first-line, given rising resistance to older agents like penicillin and fluoroquinolones), often combined with azithromycin to cover possible co-infection with Chlamydia trachomatis. Prevention: safe sexual practices (condom use), prompt treatment of cases and sexual partners, screening of high-risk populations, and prophylactic instillation of silver nitrate/erythromycin/tetracycline eye ointment in newborns to prevent gonococcal ophthalmia neonatorum.