gonorrhoea, chlamydia, and other STIs
in review
5 min read
Updated 2026-09-29
gonorrhoea, chlamydia, and other STIs
Test by NAAT from every exposed site (genital, pharyngeal, rectal); culture before treating gonorrhoea when possible for susceptibility. Gonorrhoea: ceftriaxone 500 mg IM × 1 as monotherapy (PHAC 2024) + test of cure at every positive site. Chlamydia: doxycycline 100 mg BID × 7 days (azithromycin 1 g in pregnancy). PID: ceftriaxone + doxycycline + metronidazole × 14 days. Always screen for HIV and syphilis, notify partners (60 days), and retest at 3 months.
testing principles
- NAAT on first-void urine or vaginal swab + pharyngeal and rectal swabs by exposure
- gonorrhoea culture (for susceptibility) before treatment if symptomatic, PID, DGI, suspected treatment failure, or test of cure
- test all patients for HIV and syphilis; offer HBV/HAV vaccination and HIV PrEP
- reportable to public health; partner notification for contacts within 60 days
gonorrhoea (PHAC 2024)
| scenario | treatment |
|---|---|
| uncomplicated anogenital or pharyngeal (incl. pregnancy) | ceftriaxone 500 mg IM × 1 (monotherapy) |
| alternative — anogenital | cefixime 800 mg PO × 1 + azithromycin 1 g PO × 1 (or + doxycycline 100 mg BID × 7 days) |
| alternative — pharyngeal | cefixime 800 mg PO × 1 + azithromycin 1 g PO × 1 |
| cephalosporin anaphylaxis or severe non-IgE reaction | gentamicin 240 mg IM × 1 + azithromycin 2 g PO × 1 (not in pregnancy) |
| chlamydia not excluded | add doxycycline 100 mg BID × 7 days |
- test of cure at every positive site: culture ≥3 days after treatment and/or NAAT ≥3–4 weeks after
- ceftriaxone-resistant gonorrhoea has been reported in Canada — report failures; ID/public health input
chlamydia and LGV
| scenario | treatment |
|---|---|
| anogenital, pharyngeal — preferred | doxycycline 100 mg PO BID × 7 days (better for rectal infection) |
| adherence concern | azithromycin 1 g PO × 1 |
| pregnancy/breastfeeding | azithromycin 1 g × 1 or amoxicillin 500 mg TID × 7 days |
| LGV (L1–L3; proctitis, inguinal buboes, mostly GBMSM) | doxycycline 100 mg BID × 21 days |
- test of cure 3 weeks after treatment in pregnancy, non-preferred regimen, persistent symptoms, or doubtful adherence
- retest at 3 months (reinfection is common)
syndromes
| syndrome | empiric treatment | notes |
|---|---|---|
| urethritis / cervicitis | ceftriaxone 500 mg IM × 1 + doxycycline 100 mg BID × 7 days | persistent → test for M. genitalium and Trichomonas |
| PID (outpatient) | ceftriaxone 500 mg IM × 1 + doxycycline 100 mg BID × 14 days + metronidazole 500 mg BID × 14 days | admit if pregnancy, tubo-ovarian abscess or surgical emergency not excluded, severe illness, failure at 48–72 h, can’t take PO, immunocompromised; PID is not an indication to remove an IUD |
| epididymitis — STI likely | ceftriaxone 500 mg IM × 1 + doxycycline 100 mg BID × 10–14 days | exclude torsion |
| epididymitis — enteric likely (insertive anal sex, older, instrumentation) | ceftriaxone 500 mg IM × 1 + levofloxacin 500 mg daily × 10 days | — |
| proctitis | ceftriaxone 500 mg IM × 1 + doxycycline 100 mg BID × 7 days | extend doxycycline to 21 days if LGV suspected; test HSV, syphilis |
| M. genitalium | azithromycin 500 mg day 1 → 250 mg days 2–5 | macrolide resistance or failure → moxifloxacin 400 mg × 7 days (14 days if PID) |
disseminated gonococcal infection
- two patterns: arthritis–dermatitis syndrome (migratory polyarthralgia, tenosynovitis of wrists/hands, sparse pustules) or purulent monoarthritis (knee)
- blood cultures, synovial fluid culture/NAAT, and NAAT from all mucosal sites (mucosal sites are often the only positive specimens)
- ceftriaxone 1 g IV q24h; switch to oral per susceptibility after 24–48 h of improvement, ≥7 days total; meningitis/endocarditis → 2 g IV q12h for longer — ID consult
- test for complement deficiency if recurrent neisserial infection
vaginitis
| bacterial vaginosis | trichomoniasis | vulvovaginal candidiasis | |
|---|---|---|---|
| findings | thin grey discharge, pH >4.5, positive whiff, clue cells | frothy discharge, pH >4.5, motile trichomonads, “strawberry” cervix | thick white discharge, pH <4.5, pseudohyphae |
| treatment | metronidazole 500 mg PO BID × 7 days (or vaginal gel/clindamycin cream) | metronidazole 500 mg PO BID × 7 days or 2 g PO × 1 | fluconazole 150 mg PO × 1 (topical azole in pregnancy) |
| partners | not treated | treated | not treated |
| recurrence | common; suppressive regimens | retest at 3 months | ≥4/year → fluconazole 150 mg q72h × 3 then weekly × 6 months |
mpox
- painful, deep-seated, umbilicated vesiculopustular lesions (anogenital, oral), proctitis, lymphadenopathy, fever; lesions may be few
- lesion swab PCR; test for HIV, syphilis, gonorrhoea, chlamydia
- contact + droplet precautions with N95 in hospital; isolate until lesions crust and re-epithelialise
- prevention: Imvamune 2 doses for people at risk; post-exposure within 4 days (up to 14)
- tecovirimat showed no clinical benefit in randomised trials — reserve for severe disease or immunocompromise via ID/protocol
prevention
- doxycycline PEP 200 mg within 72 h — see syphilis
- HIV PrEP — see HIV: diagnosis, ART, and prevention
- HPV, HBV, HAV vaccination
traps
- ceftriaxone 250 mg or azithromycin co-treatment by default — outdated; 500 mg monotherapy unless chlamydia not excluded
- skipping pharyngeal/rectal swabs → missed infections and missed test of cure
- azithromycin single dose for rectal chlamydia — doxycycline is more effective
- no test of cure after gonorrhoea
- removing an IUD for PID
- DGI with negative joint culture — the mucosal NAAT is the diagnosis