Sexual Health Data Interpretation
How to Use
Case 1
Miss Clarke is a 19-year-old woman attending for a routine sexual health screen after starting a new relationship 6 weeks ago. She is asymptomatic — no discharge, no dysuria, no abdominal pain. She is on the COCP and uses condoms inconsistently. LMP 2 weeks ago. She has no previous STI history.
| Test | Sample | Result | Method |
|---|---|---|---|
| Chlamydia trachomatis | Vulvo-vaginal swab | DETECTED | NAAT |
| Neisseria gonorrhoeae | Vulvo-vaginal swab | NOT DETECTED | NAAT |
| Bacterial vaginosis | High vaginal swab | Negative | Microscopy |
| Trichomonas vaginalis | High vaginal swab | Not detected | NAAT |
| HIV antibody/antigen | Blood | Non-reactive | 4th gen ELISA |
| Syphilis (TPPA) | Blood | Negative | Serology |
| Pregnancy test | Urine | Negative | — |
Chlamydia NAAT is positive. Gonorrhoea, BV, Trichomonas, HIV and syphilis are all negative. This is an uncomplicated genital chlamydial infection. She is asymptomatic — this is typical, as up to 70–80% of women with chlamydia have no symptoms, which is why routine screening is important.
Treatment: Doxycycline 100 mg BD for 7 days (first-line per BASHH guidelines; superior cure rates to azithromycin 1g stat). If pregnant or doxycycline contraindicated: azithromycin 1g stat or erythromycin.
Advice:
- Avoid sexual contact until she and her partner(s) have completed treatment and are symptom-free (minimum 7 days after stat dose, or until end of 7-day course)
- Partner notification — her current partner must be tested and treated. Previous partners within the last 6 months should also be notified.
- Test of cure is not routinely required for uncomplicated genital chlamydia in non-pregnant women, but a repeat screen in 3 months is recommended (high reinfection rate)
- Discuss consistent condom use
- Pelvic inflammatory disease (PID) — ascending infection to uterus, fallopian tubes and ovaries → pelvic pain, fever, adnexal tenderness
- Tubal factor infertility — scarring of fallopian tubes after repeated PID episodes
- Ectopic pregnancy — tubal damage increases risk
- Chronic pelvic pain
- Perihepatitis (Fitz-Hugh–Curtis syndrome) — rare; RUQ pain from perihepatic inflammation
- Reactive arthritis (Reiter's syndrome) — arthritis, urethritis, conjunctivitis (more common in men)
- Vertical transmission — neonatal conjunctivitis and pneumonia if infection present at delivery
Case 2
Mr Wright is a 25-year-old man presenting with a 3-day history of profuse yellow-green urethral discharge and dysuria. He has a new male partner (MSM). He reports inconsistent condom use. He is on PrEP. His last HIV test (on PrEP monitoring) was negative 6 weeks ago.
Urethral Swab — Gram Stain Microscopy
Numerous polymorphonuclear leucocytes (PMNLs). Gram-negative intracellular diplococci (GNID) seen — consistent with Neisseria gonorrhoeae.
| Test | Sample | Result | Method |
|---|---|---|---|
| Neisseria gonorrhoeae | Urethral swab | DETECTED | NAAT |
| Gonorrhoea culture | Urethral swab | Positive | Culture |
| Sensitivity testing | Culture | Pending | MIC |
| Chlamydia trachomatis | Urine (FVU) | DETECTED | NAAT |
| HIV Ag/Ab | Blood | Non-reactive | 4th gen ELISA |
| Syphilis (TPPA) | Blood | Negative | Serology |
| Pharyngeal swab — GC | Throat swab | DETECTED | NAAT |
Gram-negative intracellular diplococci (GNID) on urethral Gram stain in a symptomatic man is highly specific for Neisseria gonorrhoeae (sensitivity ~95% in symptomatic male urethral infection). It allows presumptive diagnosis and immediate treatment in a symptomatic patient without waiting for NAAT.
Culture is essential because it allows antibiotic sensitivity testing (MIC) — critically important given rising global resistance to cephalosporins. NAAT alone cannot provide sensitivity data. Culture also confirms the diagnosis microbiologically.
Gonorrhoea: Ceftriaxone 1g IM stat (BASHH 2019 guidelines). Sensitivity results are pending but ceftriaxone is current first-line empirical treatment for all sites.
Chlamydia co-infection: Treat simultaneously — doxycycline 100 mg BD for 7 days.
Pharyngeal gonorrhoea: This is important for two reasons:
- Pharyngeal gonorrhoea is harder to eradicate than urogenital infection and requires test of cure (TOC) — repeat swab 2 weeks after treatment to confirm clearance
- The pharynx is a reservoir for antimicrobial resistance — recombination can occur between gonococci from different sources, generating resistant strains
Advise no sexual contact until he and partner(s) complete treatment and TOC is confirmed.
No change — ceftriaxone 1g IM was already given and remains appropriate as the isolate is sensitive. Fluoroquinolone resistance (ciprofloxacin) is now extremely common in gonorrhoea (>50% of UK isolates) and ciprofloxacin is no longer used empirically. The fact that this isolate remains ceftriaxone-sensitive is reassuring. Continue to monitor for treatment response. If symptoms persist after 72 hours, repeat culture and NAAT to check for treatment failure; consider ID/GUM specialist advice if resistance to cephalosporins is found.
Case 3
Mr Okonkwo is a 32-year-old man referred by his GP after syphilis serology was unexpectedly positive on a health check blood panel. He reports no symptoms. He has a regular male partner and has not noticed any genital sores, rashes or lymphadenopathy. He is HIV negative on PrEP. He does not recall any previous syphilis testing or diagnosis.
| Test | Result | Interpretation |
|---|---|---|
| TPPA (Treponema pallidum particle agglutination) | Reactive | Treponemal antibody present |
| TPHA (T. pallidum haemagglutination) | Reactive | Treponemal antibody present |
| RPR (Rapid Plasma Reagin) | Reactive · Titre 1:32 | Non-treponemal, reflects disease activity |
| VDRL (Venereal Disease Research Laboratory) | Reactive · Titre 1:16 | Non-treponemal, reflects disease activity |
| HIV Ag/Ab | Non-reactive | HIV negative |
| Hepatitis B sAg | Negative | — |
| Test type | Examples | What it detects | Stays positive after treatment? | Use |
|---|---|---|---|---|
| Treponemal | TPPA, TPHA, FTA-ABS, EIA | Antibodies to Treponema pallidum antigens | Yes — usually lifelong (serofast) | Screening; confirms past or present infection |
| Non-treponemal | RPR, VDRL | Antibodies to cardiolipin-lecithin-cholesterol (a non-specific antigen released by damaged cells) | No — titres fall with treatment; used to monitor response | Assessing disease activity; monitoring treatment |
Positive TPPA = syphilis (past or present). Positive RPR with titre = active disease. Together: confirms current syphilis infection.
| Stage | Timing | Features | RPR titre |
|---|---|---|---|
| Primary | 9–90 days post exposure | Painless genital ulcer (chancre); regional lymphadenopathy; heals spontaneously | Low or negative early |
| Secondary | 4–10 weeks post chancre | Maculopapular rash (including palms & soles), condylomata lata, mucous patches, systemic symptoms (fever, malaise, lymphadenopathy) | High (1:16–1:128) |
| Early latent | <2 years post infection | Asymptomatic — diagnosed serologically; acquired within last 2 years | Moderate-high |
| Late latent | >2 years or unknown duration | Asymptomatic; not infectious (except vertical transmission) | Low or undetectable |
| Tertiary | Years–decades later | Gummas, cardiovascular syphilis (aortitis), neurosyphilis | Variable |
In Mr Okonkwo: no symptoms + no history of syphilis = likely early or late latent syphilis. RPR titre 1:32 suggests reasonably active disease — early latent is more likely than late latent (which tends to have lower titres). Refer to GUM for full assessment including neurological examination and LP if neurosyphilis suspected.
Early latent syphilis: Benzathine penicillin G 2.4 MU IM single dose (or doxycycline 100 mg BD for 14 days if penicillin-allergic).
Late latent / unknown duration: Benzathine penicillin G 2.4 MU IM once weekly × 3 doses (or doxycycline 100 mg BD for 28 days).
Monitoring response: Repeat RPR titre at 3, 6 and 12 months. A 4-fold (2-dilution) fall in RPR titre (e.g. 1:32 → 1:8) indicates adequate treatment response. Treponemal tests (TPPA) remain positive for life and cannot be used to monitor treatment.
Jarisch–Herxheimer reaction — warn the patient; occurs within 24 hours of first penicillin dose (fever, rigors, headache, flushing); caused by cytokine release from dying treponemes; manage with paracetamol; not an allergy.
Partner notification: All partners in the last 2 years (early latent) or last 4 years (late latent / unknown) should be contacted and tested.