Lesson
Follow a Systemic Infection Through Time
T. pallidum changes its visible phenotype while dissemination and organ invasion continue. Stage is a clinical and temporal model that determines treatment and follow-up.
- Spirochete
- Chancre
- Dissemination
- Latency
- Tertiary disease
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Start at inoculation
T. pallidum crosses skin or mucosa and classically causes a painless chancre, but primary lesions can be multiple, painful, or atypical.
Recognize dissemination
Secondary disease can cause diffuse rash including palms and soles, mucous patches, condyloma lata, lymphadenopathy, fever, liver or kidney findings, and neurologic, ocular, or auditory disease.
Define latency carefully
Latent syphilis has reactive serology without clinical primary, secondary, or tertiary findings. A complete examination is required before using the label.
Keep late injury visible
Untreated disease can later produce cardiovascular syphilis, gummatous lesions, tabes dorsalis, general paresis, or other neurologic injury.
Quick check
Lesson
Make Two Serologic Test Families Tell One Story
No single reactive serologic result distinguishes untreated infection, treated infection, early seroconversion, or false positivity. Algorithms combine complementary biology.
- RPR
- VDRL
- EIA or CIA
- TPPA
- Endpoint titer
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Use the traditional sequence
A reactive RPR or VDRL is quantified and confirmed with a treponemal test. Nontreponemal assays can have biologic false positives and a prozone effect.
Use the reverse sequence
A reactive treponemal EIA or CIA is followed by quantitative RPR or VDRL. If nonreactive, adjudicate with a second treponemal test, preferably TPPA.
Track with one assay type
RPR and VDRL titers are not interchangeable. Follow the same nontreponemal method and report the endpoint titer.
Do not monitor with treponemal tests
Treponemal antibodies usually persist for life. They establish exposure but generally do not demonstrate cure.
Quick check
Lesson
Treat Infectious Early Disease With One Correct Dose
Primary, secondary, and early latent disease share a stage-appropriate long-acting penicillin regimen, but organ involvement and pregnancy create separate pathways.
- Primary
- Secondary
- Early latent
- Benzathine penicillin
- HIV
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Use the recommended adult regimen
Give benzathine penicillin G 2.4 million units IM once for uncomplicated primary, secondary, or early latent syphilis.
Do not add routine doses
Additional benzathine penicillin doses do not improve uncomplicated early-syphilis efficacy in nonpregnant adults, including people with HIV.
Use alternatives narrowly
For a nonpregnant patient with a true allergy and reliable follow-up, doxycycline 100 mg orally twice daily for 14 days can be used. Azithromycin should not be used because of resistance and failures.
Close the visit
Test for HIV, offer PrEP when appropriate, examine for organ involvement, report to public health, manage partners, counsel about the Jarisch-Herxheimer reaction, and schedule titers.
Quick check
Lesson
Prove Recency or Treat the Unknown Duration
Early latency requires evidence of acquisition within the previous year. Titer magnitude alone cannot prove it.
- Seroconversion
- Fourfold rise
- Recent symptoms
- Documented partner
- Unknown duration
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Define early latent evidence
Use documented seroconversion, a sustained fourfold titer rise, unequivocal primary or secondary symptoms, a partner with documented early syphilis, or an exposure window confined to the prior 12 months.
Do not stage from titer alone
Nontreponemal titers tend to be higher early but overlap widely. A high titer cannot prove early latent disease.
Treat late or unknown duration
Give benzathine penicillin G 2.4 million units IM weekly for three doses, totaling 7.2 million units.
Manage intervals
For nonpregnant adults, 7 to 9 days is preferred and 10 to 14 days may be acceptable before restarting. Pregnancy has a stricter rule and requires restart when delay exceeds 9 days.
Quick check
Lesson
Protect Brain, Vision, and Hearing Before Damage Becomes Permanent
Neurologic, ocular, and auditory disease can occur at any syphilis stage. Evaluation follows the threatened organ, not the calendar.
- CSF
- Ophthalmology
- Otolaryngology
- IV penicillin
- Ten to fourteen days
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Use CSF for neurologic findings
Cognitive change, meningitis, stroke, cranial nerve dysfunction, or motor or sensory deficits warrant CSF examination before treatment.
Treat ocular disease urgently
Reactive serology with confirmed ocular abnormalities requires immediate ophthalmology collaboration and neurosyphilis therapy even if CSF is normal.
Do not delay otosyphilis for CSF
Isolated auditory symptoms with a normal neurologic examination rarely gain management value from CSF testing. Coordinate otolaryngology and treat as neurosyphilis.
Use the adult IV regimen
Give aqueous crystalline penicillin G 18 to 24 million units per day as 3 to 4 million units IV every 4 hours or continuous infusion for 10 to 14 days.
Quick check
Lesson
Use Penicillin to Treat the Pregnant Patient and the Fetus
Maternal stage, treatment timing, partner treatment, and dose completion determine congenital risk. No nonpenicillin regimen reliably substitutes.
- First prenatal screen
- Third-trimester retesting
- Stage therapy
- Fetal evaluation
- Delivery documentation
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Screen at the right moments
Screen at the first prenatal visit. Repeat at 28 weeks and delivery for increased geographic or personal risk, and document maternal status before discharge.
Use penicillin only
Treat the maternal stage with penicillin G. If allergy is reported, evaluate and desensitize as needed. Doxycycline and azithromycin do not reliably treat fetal infection.
Add pregnancy-specific safeguards
A second benzathine dose one week after the initial dose can be considered for primary, secondary, or early latent disease. Fetal ultrasound in the second half of pregnancy should not delay treatment.
Protect the weekly sequence
Use an optimal 7-day interval for late latent therapy. If more than 9 days elapse between doses, restart the entire three-dose course.
Quick check
Lesson
Prevent Product, Route, and Allergy Errors
Syphilis therapy is vulnerable to look-alike products, viscous injection challenges, catastrophic route errors, dose-interval loss, and unverified allergy labels.
- Bicillin L-A
- Not Bicillin C-R
- Deep IM
- Never IV
- Allergy evaluation
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Select the exact product
Use benzathine penicillin G, commonly Bicillin L-A in the United States. Never substitute Bicillin C-R, which combines benzathine and procaine penicillin and does not provide the recommended exposure.
Protect the route
Benzathine penicillin is deep IM only and must never be injected IV. Use an appropriate needle, site, divided injections when needed, and trained technique.
Clarify allergy
Obtain the reaction phenotype and consider skin testing or graded challenge when appropriate. Pregnancy or unreliable alternative follow-up can require desensitization.
Plan for supply constraints
Verify current FDA and public-health product guidance when standard supply is limited, and document the exact product and regulatory pathway used.
Quick check
Lesson
Anticipate the Inflammatory Response Without Calling It Allergy
Spirochete killing can produce fever, chills, myalgia, headache, and transient symptom worsening within 24 hours. It must be separated from anaphylaxis.
- Timing
- Fever
- Inflammation
- Anaphylaxis differential
- Pregnancy warning
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Recognize Jarisch-Herxheimer
A cytokine-mediated febrile reaction can begin within hours after treatment, especially in early disease. It is not an IgE-mediated penicillin allergy.
Separate anaphylaxis
Hives, wheeze, angioedema, hypotension, or rapid airway symptoms require emergency anaphylaxis treatment rather than routine supportive care.
Treat supportively
Use fluids and antipyretic or analgesic support as clinically appropriate while monitoring for alternate diagnoses and severe physiology.
Protect pregnancy
After treatment in the second half of pregnancy, fever, contractions, or decreased fetal movement requires urgent obstetric attention. Concern about the reaction must not delay necessary therapy.
Quick check
Lesson
Read Quantitative Change, Not Persistent Positivity
Response monitoring uses the same nontreponemal assay and treatment-day titer. Treponemal tests often remain reactive after cure.
- Same assay
- Fourfold change
- Six months
- Twelve months
- Twenty-four months
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Calculate fourfold change
A fourfold change equals two dilution steps, such as 1:32 to 1:8. A change from 1:32 to 1:16 is only twofold.
Follow early disease
Primary and secondary syphilis require clinical and serologic evaluation at 6 and 12 months, compared with the titer at treatment.
Follow latent disease
Repeat quantitative nontreponemal testing at 6, 12, and 24 months.
Investigate concerning trends
Persistent or recurrent symptoms or a sustained fourfold rise for more than two weeks suggests reinfection or failure. Reassess exposure, neurologic findings, HIV, treatment, and CSF indications.
Quick check
Lesson
Close Exposure, HIV Risk, and Public Health Together
A successful injection can still leave untreated partners, reinfection, missed HIV prevention, and congenital risk in the community.
- Ninety-day exposure
- Partner services
- HIV test
- PrEP
- Reporting
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Connect stage, serology, organ involvement, pregnancy, treatment history, and exposure.
Treat recent exposure presumptively
A partner exposed to primary, secondary, or early latent syphilis within 90 days should receive presumptive early-syphilis treatment even when serology is negative.
Use longer windows for notification
Notify partners from three months plus symptom duration for primary disease, six months plus symptom duration for secondary disease, and one year for early latent disease.
Integrate HIV prevention
Test every patient for HIV. Offer PrEP to appropriate HIV-negative patients and repeat HIV testing when the exposure window or local prevalence supports it.
Remove barriers to closure
Coordinate reporting, partner services, transport, product access, language, housing, privacy, follow-up titers, and abstinence guidance until treatment is complete and partners receive care.
Quick check
Module test
Check the connections.
Each attempt draws 10 questions from the complete 130 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.