If there's a good end of the STI spectrum to be on, this is it. Chlamydia, gonorrhoea, and syphilis are all bacterial — which means they're fully eliminated by antibiotics. You take the treatment, you follow up, and the infection is gone. That's the headline.

The reason they need their own guide is that each one works a bit differently, has different treatment, and comes with a few specific things worth knowing before you walk out of the clinic.

🔩 Chlamydia

What it is: The most common bacterial STI. Caused by Chlamydia trachomatis.

Why it's so common: It's almost entirely silent. No discharge, no burning, no symptoms — especially in the throat and rectum, where the majority of infections in MSM actually sit. Most people have no idea they have it until a routine swab picks it up.

The treatment: Doxycycline, 100mg twice daily for 7 days. Don't shorten the course because you feel fine — you felt fine before you started. Finish it.

Test of cure: Recommended for rectal chlamydia — a follow-up swab 3–5 weeks after treatment confirms clearance. Your clinic may do this automatically; if not, ask.

Sex during treatment: Avoid sex (or use condoms for all acts) until you've finished the full course and had at least 7 days since your last dose. If a test of cure is required, wait for that result.

🔩 Gonorrhoea

What it is: Caused by Neisseria gonorrhoeae. Second most common bacterial STI and increasingly difficult to treat.

Why it matters more than chlamydia: Two reasons. First, it's developing resistance to antibiotics at a serious rate — standard oral antibiotics no longer work reliably in most countries. Second, throat gonorrhoea is particularly hard to clear and frequently recurs or persists.

The treatment: Ceftriaxone — a single intramuscular injection (500mg in most countries, 1g in some). This is first-line almost everywhere now because oral options can no longer be counted on. It's a quick injection, not a course of tablets — you don't need to worry about remembering pills.

Test of cure: Standard for gonorrhoea, especially throat infections. Throat gonorrhoea is stubborn — a follow-up swab at 2–3 weeks is important, and your doctor may want to retest regardless of whether you have symptoms.

The resistance problem: If this is a recurrent gonorrhoea diagnosis and it doesn't clear after treatment, go back to the clinic. Resistant strains are treated with alternative antibiotic combinations — this needs clinical management, not a second round of the same thing.

Sex during treatment: None (or condoms for all acts) for 7 days after the injection, plus until your partner(s) have been treated. Reinfection from an untreated partner is the most common reason gonorrhoea comes back.

🔩 Syphilis

What it is: Caused by Treponema pallidum. Rates among gay and bisexual men have surged significantly since 2010 and continue to rise in most countries.

Why syphilis is different: It progresses through stages — and the stage you're diagnosed at affects both the treatment and how you talk to partners.

The stages:

Primary: A painless sore (chancre) at the point of entry — could be on the penis, inside the rectum, in the mouth, or on the skin. It disappears on its own after a few weeks. Gone doesn't mean treated.
Secondary: Usually 4–10 weeks after the initial sore. Rash (often on palms and soles — an unusual location), flu-like symptoms, mouth sores, swollen lymph nodes. Also resolves on its own without treatment.
Latent: No symptoms. The infection goes quiet but is still present and doing systemic damage over time — including to the heart, blood vessels, and nervous system.
Tertiary: Rare now that testing and treatment are accessible, but serious. Cardiovascular and neurological damage.

The treatment: A single intramuscular injection of benzylpenicillin (Penicillin G). For later-stage syphilis, a course of three weekly injections is standard. If you're penicillin-allergic, doxycycline for 2–4 weeks depending on stage.

Follow-up blood tests: Syphilis is confirmed via blood test (RPR or VDRL titre). After treatment, these titres should fall — usually halving every 3 months. Your clinic will want follow-up blood tests at 3, 6, and 12 months after treatment to confirm the response. This is important — don't skip these.

The notification window: The notification window is longer than for chlamydia or gonorrhoea — often 3–12 months depending on the stage. Your doctor will advise you on the right window for your situation.

Sex during treatment: No sex (or condoms for all acts) for at least 2 weeks after the injection, and until partners have been treated. Primary and secondary syphilis are highly infectious via the sores and rash.

🛡️ The Testing Picture

Window periods:

Chlamydia and gonorrhoea: Detectable within 1–2 weeks of exposure. If you've had a specific exposure, test at 2 weeks for a reliable result.
Syphilis: The blood test can take 2–4 weeks after infection to turn positive. If you suspect a recent exposure — especially if you noticed a sore — tell the clinic so they can factor in timing.

What to ask for: A 3-site test — throat swab, rectal swab, and urine or urethral swab. A urine test alone misses the majority of chlamydia and gonorrhoea infections in MSM. This is worth repeating every time, because clinics don't always offer 3-site automatically.

⚠️ Partner Notification

Bacterial STIs require notification — the windows are defined and the treatment is straightforward, which means notifying partners is genuinely useful to them.

The typical windows:

Chlamydia and gonorrhoea: Partners from the last 3–6 months, or back to the last negative test if that was more recent.
Syphilis: Your doctor will specify based on stage — could be 3 months (primary), 6 months (secondary), or 12 months (latent).

The notification script in the Protocol: Positive Result guide applies directly here — keep it factual, keep it short, and frame it as a health advisory rather than an apology.

Anonymous notification services are available in most countries if direct contact isn't possible. Check the relevant country guide.

🟢 The Emotional Side

Bacterial STIs don't carry the same cultural weight as HIV or herpes — but some people still have a strong shame response, particularly to a syphilis diagnosis or a repeated gonorrhoea diagnosis.

Worth naming: having chlamydia or gonorrhoea is not evidence of being reckless. These infections are common precisely because they're silent — the only reliable way to find them is to test, which is exactly what you're doing. A positive result means your system is working.

Syphilis sometimes hits harder emotionally because of the historical connotations. The modern reality: it's a bacterial infection treated with a single injection. The history of syphilis as a devastating disease belongs to the era before antibiotics. That era ended.

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