References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Bacterial STIs are caused by bacteria and can usually be cured with a course of antibiotics. The main bacterial STIs are chlamydia, gonorrhoea, syphilis and mycoplasma genitalium. Knowing about each helps you recognise symptoms, get tested and understand treatment options.
Here’s a concise guide.
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Main Bacterial STIs
| STI | Cause | Treatment |
|---|---|---|
| Chlamydia | Chlamydia trachomatis | Doxycycline 7 days |
| Gonorrhoea | Neisseria gonorrhoeae | Ceftriaxone injection |
| Syphilis | Treponema pallidum | Penicillin injection |
| Mycoplasma genitalium | Mycoplasma genitalium | Doxycycline + azithromycin or moxifloxacin |
| LGV | Specific chlamydia strains | Doxycycline 21 days |
| Non-specific urethritis | Various bacteria | Doxycycline |
Chlamydia
- Most commonly diagnosed bacterial STI in the UK
- Often silent, especially in women
- Can cause pelvic inflammatory disease if untreated
- Tested by urine or swab NAAT
- Easily cured with a 7-day course of doxycycline
Gonorrhoea
- Second most common bacterial STI
- Rising rates in the UK
- Antibiotic resistance is a growing concern
- Infects urethra, throat, rectum, eyes and cervix
- Treated with a ceftriaxone injection
Syphilis
- Progresses through four stages if untreated
- Rising rates in the UK
- Curable with penicillin, especially when caught early
- Can cause serious complications in late stages
- Routinely screened in antenatal care
Mycoplasma Genitalium
- Less well-known but increasingly recognised
- Can cause urethritis, cervicitis and PID
- Often resistant to macrolides
- Test of cure recommended
Symptoms of Bacterial STIs
Common symptoms (when present) include:
- Unusual discharge
- Pain or burning on urination
- Abnormal bleeding
- Pelvic or testicular pain
- Sore throat or rectal discomfort
Many people have no symptoms at all.
Testing for Bacterial STIs
- Urine or swab NAAT for chlamydia, gonorrhoea, mycoplasma
- Blood test for syphilis
- Home kits and clinic testing both available
- Throat and rectal swabs important for people with oral or anal sex
Prevention
- Condoms reduce transmission risk
- Regular testing catches silent infections
- Prompt treatment of partners prevents reinfection
- DoxyPEP (where available) reduces bacterial STI risk for MSM
Read more: What is chlamydia? | What is gonorrhoea? | Mycoplasma genitalium
Frequently Asked Questions
Can bacterial STIs be cured?
Yes. All major bacterial STIs respond to antibiotics when taken correctly.
Do I need to treat multiple STIs separately?
Yes. Different bacteria need different antibiotics.
Can I catch the same bacterial STI more than once?
Yes. Treatment doesn’t give immunity.
Related reading
- A to Z of Sex: Sexual Health Terms Explained
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
