Communicable & Infectious Disease · Topic 23 of 23
Chlamydia, Gonorrhea & Syphilis
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Chlamydia, Gonorrhea & Syphilis
Three reportable bacterial STIs. The danger is silent infection: untreated chlamydia or gonorrhea scars the tubes, and syphilis in pregnancy needs penicillin.
Why it matters
Often silent — and untreated infection climbs to the pelvis
What you'll see
Syphilis starts with a painless chancre
Latent syphilis has no symptoms and is found only by blood test. Tertiary syphilis causes gummas, aortitis and neurosyphilis.
Labs & diagnostics
NAAT for chlamydia and gonorrhea · RPR or VDRL for syphilis
NAAT = nucleic acid amplification test. FTA-ABS is a treponemal test. A meaningful RPR change is fourfold — two dilutions, such as 1:16 to 1:4; a fourfold fall shows response to treatment.
Red flags
Fever, headache and muscle aches within 24 hours of starting syphilis treatment is the Jarisch-Herxheimer reaction — expected, not a penicillin allergy. Disseminated gonococcal infection can also cause tenosynovitis.
Treatment
Ceftriaxone 500 mg IM once (1 g if 150 kg or more)
Chlamydia not ruled out? Add doxycyclineDoxycycline 100 mg PO twice a day for 7 days
Pregnant: azithromycin 1 g once insteadBenzathine penicillin G IM — the only treatment in pregnancy
Allergic and pregnant → desensitizeReport every case to the public health department
Even if the patient objectsNotify, test and treat recent sex partners
Doses, partners and follow-up
Nursing priorities
Chlamydia, gonorrhea or syphilis?
Chlamydia and gonorrhea share a NAAT · syphilis is a blood test
| Chlamydia | Gonorrhea | Syphilis | |
|---|---|---|---|
| Symptoms | Usually silent, especially in women | Purulent discharge, dysuria — many have none | Moves in stages |
| Key sign | Often none — screen women under 25 yearly | Thick purulent discharge | Painless chancre, then palm-and-sole rash |
| Test | NAAT on urine or a swab | NAAT on urine or a swab | RPR or VDRL blood test |
| Treatment | Doxycycline 100 mg PO twice a day, 7 days | Ceftriaxone 500 mg IM once | Benzathine penicillin G IM |
| Untreated | PID, ectopic pregnancy, infertility | PID, ectopic pregnancy, infertility | Tertiary: gummas, aortitis, neurosyphilis |
Teach your patient
Chlamydia is usually silent, gonorrhea often brings chlamydia along, and syphilis is treated with penicillin G — the only option in pregnancy. Painless chancre = syphilis; painful blisters = herpes.
Sources · STI Treatment Guidelines 2021 — Chlamydial Infections (CDC) · STI Treatment Guidelines — Gonococcal Infections (CDC) · STI Treatment Guidelines — Syphilis (CDC) · STI Treatment Guidelines — History of Penicillin Allergy (CDC) · STI Treatment Guidelines — Pelvic Inflammatory Disease (CDC) · Fundamentals of Nursing 16.3 Legal Dimensions of Care (OpenStax) · Microbiology 23.3 Bacterial Infections of the Reproductive System (OpenStax) · Doxycycline hyclate label (DailyMed) · Isolation Precautions Appendix A (CDC) · Follow your facility's protocol for STI treatment and reporting.
Chlamydia, Gonorrhea & Syphilis
The most common reportable STI in the United States is also the most silent — most people who have it will never know unless someone screens them.
Chlamydia (Chlamydia trachomatis) is the most commonly reported STI in the US. It is frequently asymptomatic, especially in women, making routine screening essential. Screen all sexually active women under 25 annually and older women with risk factors. Untreated chlamydia causes PID, ectopic pregnancy, and infertility. Treatment: doxycycline 100 mg twice daily for 7 days (preferred) or azithromycin 1 g single dose. Gonorrhea (Neisseria gonorrhoeae) often co-infects with chlamydia. Presents with purulent urethral or cervical discharge, dysuria, and can cause pharyngeal and rectal infections. Treatment: ceftriaxone 500 mg IM single dose (1 g if ≥150 kg). Treat for chlamydia concurrently if chlamydia has not been excluded. Disseminated gonococcal infection causes septic arthritis and dermatitis-arthritis syndrome. Syphilis (Treponema pallidum) progresses through stages. Primary: painless chancre at inoculation site (highly infectious, heals spontaneously in 3–6 weeks). Secondary: diffuse maculopapular rash including palms and soles (pathognomonic distribution), condylomata lata (moist flat wart-like lesions in skin folds), fever, lymphadenopathy. Latent: asymptomatic, detected only by serology. Tertiary: gummas (granulomatous lesions), cardiovascular syphilis (aortitis), neurosyphilis (tabes dorsalis, Argyll Robertson pupils). Diagnosis: RPR or VDRL for screening (quantitative, used to monitor treatment response), FTA-ABS for confirmation (stays positive for life). Treatment: benzathine penicillin G IM — the ONLY acceptable treatment during pregnancy. Jarisch-Herxheimer reaction may occur within 24 hours of treatment. ALL three STIs are reportable diseases. Nurses educate, facilitate partner notification per policy and public health requirements, and support expedited partner therapy where legally authorized and protocolized. Screen for HIV with any new STI diagnosis.
Key Distinctions
Painless chancre is primary syphilis — do not confuse with painful vesicular lesions (herpes). A rash on the palms and soles should trigger syphilis evaluation. Students confuse RPR/VDRL (screening, titers drop with treatment) with FTA-ABS (confirmatory, stays positive for life). Benzathine penicillin G is the ONLY treatment for syphilis in pregnancy — penicillin allergy in a pregnant patient with syphilis requires desensitization, not an alternative antibiotic. Doxycycline is contraindicated in pregnancy — if treating chlamydia in a pregnant patient, use azithromycin.
Clinical Pearl
Palms and soles rash — it's syphilis until proven otherwise. Painless sore — also syphilis. This disease is the great imitator.
Knowledge Check
3 quick questions on the must-knows for this topic.
Is the primary syphilis chancre painful or painless?
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