multi class comparison
STI Comparison: Chlamydia vs Gonorrhea vs Syphilis ā Presentation, Diagnosis, Treatment
All three are bacterial, all are reportable, and all get antibiotics ā but the NCLEX expects you to match the right symptom to the right organism and pick the correct drug. Choosing azithromycin alone for gonorrhea misses ceftriaxone, and missing syphilis staging means missing neurosyphilis entirely.
Comparison
| Feature | Chlamydia | Gonorrhea | Syphilis |
|---|---|---|---|
| Causative organism | Chlamydia trachomatis (obligate intracellular) | Neisseria gonorrhoeae (gram-negative diplococcus) | Treponema pallidum (spirochete) |
| Incubation period | 1ā3 weeks | 2ā5 days (shorter than chlamydia) | 10ā90 days (primary chancre appears ~3 weeks) |
| Key presenting symptom | Often none ā the "silent" STI | Purulent, yellow-green urethral or cervical discharge | ā¢ Painless chancre (primary) ā¢ Rash on palms/soles (secondary) |
| Asymptomatic rate | Up to 70ā80% of women, ~50% of men | ~50% of women; men usually symptomatic | Primary chancre painless ā easily missed |
| Discharge characteristics | Thin, mucopurulent, or absent | Thick, purulent, yellow-green, copious | No discharge; lesion-based presentation |
| Pathognomonic finding | None ā diagnosed by screening | ā¢ Purulent discharge ā¢ Gram-negative intracellular diplococci on smear | ā¢ Primary: painless chancre ā¢ Secondary: symmetric rash incl. palms and soles |
| Diagnostic test | NAAT (nucleic acid amplification) ā urine or swab | NAAT preferred; culture for resistance testing | RPR or VDRL (screening) ā confirm with FTA-ABS |
| Treatment (first-line) | ā¢ Doxycycline 100 mg PO BID Ć 7 days ā¢ Preferred over azithromycin | ā¢ Ceftriaxone 500 mg IM Ć 1 dose ā¢ Add doxycycline if chlamydia not excluded | ā¢ Benzathine penicillin G 2.4 million units IM Ć 1 ā¢ 3 weekly doses for late latent |
| Partner treatment | ā¢ Yes ā treat all partners within 60 days ā¢ Expedited partner therapy allowed in many states | ā¢ Yes ā same 60-day window ā¢ Co-treat for chlamydia presumptively | ā¢ Yes ā partners evaluated and treated ā¢ Based on exposure timing and staging |
| Pregnancy concern | ā¢ Neonatal conjunctivitis ā¢ Pneumonia ā¢ Screen all pregnant clients | ā¢ Neonatal ophthalmia neonatorum ā¢ Erythromycin eye prophylaxis at birth | ā¢ Congenital syphilis ā crosses placenta ā¢ Screen at first prenatal visit and in third trimester |
| Reportable disease | Yes ā mandatory in all U.S. states | Yes ā mandatory in all U.S. states | Yes ā mandatory in all U.S. states |
| Complication untreated | ā¢ PID ā¢ Ectopic pregnancy ā¢ Infertility ā¢ Reactive arthritis | ā¢ PID ā¢ Disseminated gonococcal infection (septic arthritis) ā¢ Infertility | ā¢ Neurosyphilis ā¢ Cardiovascular syphilis ā¢ Gummas ā¢ Congenital syphilis in newborn |
Clinical Pearl
Silent = chlamydia; purulent = gonorrhea + ceftriaxone; painless chancre + palm rash = syphilis + penicillin.
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