Gonorrhoea and Chlamydia
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Direct answer
Gonorrhoea and chlamydia are the two commonest bacterial sexually transmitted infections, caused by Neisseria gonorrhoeae and Chlamydia trachomatis respectively, and they frequently coexist. Men typically present with urethral discharge, while women are often asymptomatic and present later with pelvic inflammatory disease or infertility. Nucleic acid amplification testing on urine or vaginal swabs is the preferred diagnostic method, and treatment combines an intramuscular cephalosporin with azithromycin or doxycycline to cover chlamydia.
What you must remember
- Organisms: Neisseria gonorrhoeae is a Gram-negative diplococcus seen within neutrophils; Chlamydia trachomatis is an obligate intracellular organism, with serovars D to K causing urogenital disease.
- Gonococcal presentation: Purulent urethral discharge in men; disseminated infection with tenosynovitis, pustular skin lesions and septic arthritis.
- Chlamydial complications: Pelvic inflammatory disease, tubal infertility, reactive arthritis, and neonatal conjunctivitis and pneumonia after vaginal delivery.
- Diagnosis: Nucleic acid amplification testing is the test of choice; culture with susceptibility testing is needed when treatment failure or resistance is suspected.
- Treatment: An intramuscular cephalosporin for gonorrhoea, together with azithromycin or doxycycline to cover chlamydia; doxycycline for chlamydia is given for seven days.
- Lymphogranuloma venereum: Serovars L1 to L3 cause a small painless ulcer, followed by tender inguinal lymphadenopathy that may show a groove sign; doxycycline is given for 21 days.
- Test of cure: Not routine in uncomplicated cases, but retesting at about three months is advised because reinfection is common.
- Pregnancy: Doxycycline is avoided, and azithromycin is used for chlamydia in pregnancy.
Worked scenario: two presentations in one couple
A 23-year-old man presents with urethral discharge, and his partner, a 21-year-old woman, attends separately with lower abdominal pain and a mucopurulent cervical discharge. The reasoning starts from the likelihood that the two presentations are the same infection at different sites.
- Test both partners: Nucleic acid amplification testing is sent on a urine sample from the man and a vaginal swab from the woman.
- Treat presumptively: Both are treated at the first visit with an intramuscular cephalosporin and azithromycin, since cover for gonorrhoea and chlamydia must be simultaneous.
- Assess the woman for PID: If she has cervical motion tenderness with adnexal pain, she receives a broader regimen for pelvic infection.
- Abstain and retest: Both partners abstain until treatment is complete, and the test is repeated at about three months.
- Record partner notification: Partner notification is recorded because treating only the index patient leaves the couple open to reinfection from each other.
The male presentation alerts the clinician to the silent female infection.
Where the examiner tests the coexistence
Coexistence and look-alike infections are the main sources of error here.
- Trap: assuming every urethritis is gonorrhoea. Correct: chlamydia causes a similar discharge with a longer incubation period, and the two frequently coexist, so treatment must cover both.
- Trap: using doxycycline for chlamydia in pregnancy. Correct: azithromycin is preferred, because doxycycline is avoided in pregnancy.
- Trap: confusing lymphogranuloma venereum with chancroid and donovanosis. Correct: lymphogranuloma venereum has a painless initial ulcer and deep inguinal buboes with the groove sign.
- Trap: reaching for culture first to diagnose chlamydia in women. Correct: nucleic acid amplification on a vaginal swab or urine is the expected test.
Frequently asked questions
Which test is preferred to diagnose chlamydia in women?
Nucleic acid amplification testing on a vaginal swab or first-catch urine is the preferred test for chlamydia in women. It is more sensitive than culture and can be done on non-invasive samples. Results guide treatment and are used for partner management.
Why is azithromycin combined with a cephalosporin for gonorrhoea?
Azithromycin is combined with a cephalosporin because gonorrhoea and chlamydia coexist frequently, and the combined regimen covers both organisms at the first visit. The intramuscular cephalosporin treats gonococcal infection, which carries resistance concerns. Current CDC guidance prefers doxycycline for the chlamydia component, so choice follows national and CDC guidance.
What is the treatment of lymphogranuloma venereum?
Lymphogranuloma venereum is treated with doxycycline for 21 days, which is the standard regimen for serovars L1 to L3 of Chlamydia trachomatis. Buboes may need aspiration or drainage to relieve pressure and pain. Partner notification and HIV testing are part of the management.
Which antibiotic is used for chlamydia in pregnancy?
Azithromycin is used for chlamydia in pregnancy because doxycycline is avoided in pregnant women. A single oral dose of azithromycin is the standard treatment, with test of cure advised. Untreated infection in pregnancy risks neonatal conjunctivitis and pneumonia.
Why do many women with gonorrhoea remain unrecognised?
Many women with gonorrhoea remain unrecognised because the infection is often asymptomatic or causes only mild vaginal discharge, and it can persist unnoticed until pelvic inflammatory disease or infertility develops. Screening in higher-risk women and partners of infected men is therefore important. Nucleic acid testing improves detection in women who are otherwise well.