Test and treat three important sexually transmitted infections with site-specific diagnostics, resistance-aware regimens, pregnancy modifications, partner care and accurate follow-up advice.
Chlamydia trachomatis and Neisseria gonorrhoeae infect columnar epithelium of the cervix, urethra and exposed extragenital sites; Trichomonas vaginalis is a flagellated protozoan causing vaginal and urethral infection. All may be asymptomatic, so a normal examination does not exclude infection. Symptoms overlap: altered discharge, dysuria, postcoital or intermenstrual bleeding, lower abdominal pain and dyspareunia. Trichomoniasis more often produces vulvovaginal inflammation and malodour, while chlamydia and gonorrhoea can present with a friable mucopurulent cervix.
Take a confidential, inclusive history of sites and timing of exposure, barrier use, partners, pregnancy possibility, contraception, symptoms and prior antimicrobials. Ask about pelvic pain, fever and bleeding to identify PID or pregnancy complications. Explain specimen options and self-sampling. Vulvovaginal NAAT is the most sensitive genital sample for most women; take rectal and pharyngeal tests according to exposure, while also offering a pharyngeal test to everyone with urogenital gonorrhoea and every gonorrhoea contact regardless of reported pharyngeal exposure. Testing very soon after an exposure can miss infection, so the 2026 chlamydia guideline advises repeat NAAT at two weeks after exposure when the initial test was within that window.
C. trachomatis spreads through mucosal sexual contact and can establish clinically silent cervical, urethral, rectal or pharyngeal infection.
N. gonorrhoeae infects exposed mucosa and rapidly evolves antimicrobial resistance, making culture and susceptibility central to stewardship.
T. vaginalis is transmitted through genital sexual contact and persists in the vagina or urethra until effective nitroimidazole treatment.
Chlamydia alternates between infectious elementary bodies and replicating reticulate bodies, provoking cervicitis that may ascend despite few symptoms.
Gonococcal attachment and invasion stimulate purulent mucosal inflammation, while bloodstream spread can seed skin, tendons and joints.
Motile protozoa adhere to urogenital epithelium, disturb the microbial environment and cause variable inflammation, discharge and punctate haemorrhage.
Limited symptoms allow continued transmission and delayed upper-tract complications, making exposure-based screening more reliable than symptom-led detection alone.
Often asymptomatic, but mucopurulent cervical discharge, postcoital bleeding, dysuria or pelvic discomfort with a positive site-specific NAAT supports diagnosis.
Purulent cervicitis or urethritis may occur, but asymptomatic genital and pharyngeal infection is common; culture is essential for susceptibility information.
Malodorous yellow-green discharge, vulvovaginal soreness, raised pH and punctate cervical erythema can occur, though organism testing is required because signs are insensitive.
Pelvic pain, deep dyspareunia, abnormal bleeding and cervical or adnexal tenderness indicate possible PID regardless of lower-tract test status.
Fever with migratory joint pain, tenosynovitis, sparse pustules or septic arthritis requires blood, joint and mucosal cultures plus urgent specialist treatment.
Thin malodorous discharge and raised pH overlap with trichomoniasis, but BV usually causes little inflammation and has different partner management.
Intense itch, acidic pH and yeast-associated vulvitis differ from cervical chlamydia or gonorrhoea and from raised-pH trichomoniasis.
Persistent cervicitis or PID after standard management can involve M. genitalium, requiring validated testing and resistance-aware specialist therapy.
Ectropion, polyps, trauma, chemical irritation and malignancy can cause discharge or contact bleeding with negative infection tests.
Ascending infection produces lower abdominal pain and pelvic tenderness and is treated clinically without requiring a positive cervical organism test.
Ascending chlamydial or gonococcal infection can lead to tubal infertility, ectopic pregnancy, chronic pelvic pain and tubo-ovarian abscess.
Gonococcal bacteraemia may cause dermatitis, tenosynovitis and septic arthritis, requiring urgent cultures and parenteral specialist care.
Untreated maternal infection can affect pregnancy and expose a neonate to conjunctival or respiratory infection during birth.
Untreated partners drive reinfection, while inappropriate antibiotic choice and absent gonococcal cultures weaken detection and control of resistance.
Reported exposure guides routine anatomical sampling, but the 2025 gonorrhoea guideline also recommends pharyngeal testing for every urogenital diagnosis and every contact; assumptions based on identity or an incomplete exposure history miss clinically silent infection.
Gonorrhoea NAAT confirms infection but culture supplies susceptibility data needed for the individual and national resistance surveillance.
A test of cure asks whether treatment eradicated infection, whereas later retesting looks for reinfection after renewed exposure.
A chlamydia NAAT taken shortly after exposure may be negative before reliable detection, so timing and a repeat plan matter.
Chlamydia exposure timing, gonorrhoea susceptibility and trichomonas concurrent treatment create different decisions despite the shared STI label.
Using urine alone when a self-taken vulvovaginal swab or exposure-site sample offers better diagnostic yield.
Giving empirical ciprofloxacin for gonorrhoea without confirmed susceptibility and assessment of fluoroquinolone safety.
Using a 2 g single metronidazole dose as the routine preferred trichomonas regimen despite lower effectiveness than multidose treatment.
Performing chlamydia NAAT too soon after treatment and interpreting residual DNA as viable persistent infection.
Applying routine test of cure to every infection while omitting it for pharyngeal gonorrhoea, pregnancy or another defined indication.
Neglecting pelvic examination and empirical PID treatment because a lower-tract NAAT is pending or negative.
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A non-pregnant adult has uncomplicated cervical gonorrhoea confirmed by NAAT, with culture collected before treatment and no severe beta-lactam allergy. Which regimen is recommended?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
Gonorrhoea requires both molecular detection and resistance surveillance. Where possible, culture each NAAT-positive or clinically suspected site before ceftriaxone. Microscopy may rapidly support gonorrhoea in symptomatic patients but is much less sensitive for cervical infection. Trichomonas NAAT is more sensitive than wet-mount microscopy; a negative wet mount therefore does not reliably exclude it. Complete an HIV and syphilis risk assessment and test for co-infection. Obtain pregnancy testing when it affects urgency or antibiotic choice.
Doxycycline is the sole preferred BASHH regimen for uncomplicated chlamydial infection at genital, rectal and pharyngeal sites when it is safe. Pregnancy is managed with an azithromycin, erythromycin or amoxicillin regimen selected from the current guideline; doxycycline before 15 weeks is reserved for situations without a suitable alternative under specialist judgement. For gonorrhoea, ceftriaxone 1 g intramuscularly once is used across uncomplicated anogenital and pharyngeal infection. Do not substitute oral cefixime or ciprofloxacin empirically; ciprofloxacin is appropriate only when susceptibility is known and fluoroquinolone safety has been considered.
For trichomoniasis, a seven-day oral metronidazole course produces better cure rates than a 2 g single dose. Treat current partners and avoid sex for at least one week and until the patient and partner have completed treatment and any planned follow-up. Pregnancy is not a reason to withhold clinically indicated metronidazole under BASHH guidance. Persistent infection requires assessment of adherence, re-exposure, timing of repeat testing and possible resistance; avoid an early NAAT that merely detects residual nucleic acid.
After treatment, give precise follow-up instructions. Chlamydia test of cure is not routine outside pregnancy, poor adherence, persistent symptoms or other defined concerns and should not be performed too early because residual DNA may remain; people under 25 should be retested for reinfection between two and six months. Gonorrhoea test of cure is routinely recommended for pharyngeal infection, pregnancy, persistent symptoms, unknown susceptibility or treatment other than ceftriaxone. People treated for gonorrhoea should avoid sex until seven days after they and their partners have completed treatment. Trichomoniasis needs no routine test of cure after symptom resolution. Ensure partners are notified through an agreed confidential method and offer risk-reduction care without blame.
Avoid routine use in pregnancy; counsel about oesophageal irritation, photosensitivity, interacting antacids and completing the course before sex resumes.
Review QT risk, macrolide interactions and vomiting; single-dose azithromycin alone is less reliable where rectal infection or M. genitalium is relevant.
Check severe beta-lactam allergy, obtain cultures before administration when feasible, and arrange indicated test of cure and resistance follow-up.
Discuss nausea, metallic taste and relevant interactions, treat current partners simultaneously and reassess persistent infection before extending therapy.