Syphilis MCQs With Answer

Syphilis MCQs With Answer provides B. Pharm students a focused, exam-oriented review of syphilis epidemiology, pathogenesis, clinical stages, diagnostic tests (VDRL, RPR, FTA‑ABS, TPPA, dark-field, PCR), and therapeutic principles including benzathine penicillin dosing, neurosyphilis management, and alternatives for penicillin allergy. This resource emphasizes lab interpretation, monitoring with non‑treponemal titers, prozone phenomenon, and public health measures such as partner notification and antenatal screening. It is tailored to strengthen clinical reasoning and pharmaceutical care skills for pharmacists involved in infectious disease control. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the causative organism of syphilis?

• Spirochete Treponema pallidum
• Gram-negative diplococcus Neisseria gonorrhoeae
• Acid-fast bacillus Mycobacterium tuberculosis
• Gram-positive coccus Streptococcus pyogenes

Correct Answer: Spirochete Treponema pallidum

Q2. Which is the primary route of transmission for syphilis in adults?

• Sexual contact with mucocutaneous exposure
• Airborne droplets
• Vector-borne transmission (ticks)
• Fecal-oral contamination

Correct Answer: Sexual contact with mucocutaneous exposure

Q3. The typical lesion of primary syphilis is characterized by:

• Painless indurated genital chancre
• Severely painful vesicular rash
• Pruritic excoriated papules
• Pustular lesions with purulent discharge

Correct Answer: Painless indurated genital chancre

Q4. The most useful direct method to visualize Treponema pallidum from a primary chancre is:

• Dark-field microscopy of lesion exudate
• Gram stain of exudate
• Standard bacterial culture on blood agar
• KOH preparation

Correct Answer: Dark-field microscopy of lesion exudate

Q5. Which test is a non-treponemal assay commonly used for screening and monitoring therapy?

• VDRL (Venereal Disease Research Laboratory) test
• FTA-ABS (Fluorescent treponemal antibody-absorption)
• TPPA (Treponema pallidum particle agglutination)
• Blood culture for spirochetes

Correct Answer: VDRL (Venereal Disease Research Laboratory) test

Q6. Which serologic test is treponemal and typically remains positive for life?

• FTA-ABS (Fluorescent treponemal antibody-absorption)
• RPR (Rapid plasma reagin)
• Non-treponemal cardiolipin test
• Culture on specialized media

Correct Answer: FTA-ABS (Fluorescent treponemal antibody-absorption)

Q7. The prozone phenomenon in syphilis testing results from:

• Excess antibody causing false-negative non-treponemal test
• Insufficient antibody leading to false-positive test
• Antigen degradation during storage
• Interference by hemolysis only

Correct Answer: Excess antibody causing false-negative non-treponemal test

Q8. Which reaction can occur within 24 hours after starting effective syphilis therapy?

• Jarisch-Herxheimer reaction (acute inflammatory response)
• Anaphylactic shock due to treponemal lysis
• Serum sickness from benzathine salt
• Stevens-Johnson syndrome

Correct Answer: Jarisch-Herxheimer reaction (acute inflammatory response)

Q9. First-line treatment for early (primary, secondary, early latent) syphilis in adults is:

• Single IM dose of benzathine penicillin G 2.4 million units
• Oral azithromycin single 1 g dose
• Oral amoxicillin for 7 days
• Intravenous vancomycin for 14 days

Correct Answer: Single IM dose of benzathine penicillin G 2.4 million units

Q10. The recommended treatment for neurosyphilis is:

• Aqueous crystalline penicillin G IV for 10–14 days
• Benzathine penicillin IM single dose
• Doxycycline orally for 7 days
• Oral azithromycin weekly for 3 weeks

Correct Answer: Aqueous crystalline penicillin G IV for 10–14 days

Q11. In a pregnant patient with penicillin allergy, the recommended management is:

• Cease allergy list and perform penicillin desensitization then treat with penicillin
• Use doxycycline instead of penicillin
• Use erythromycin orally as equivalent therapy
• No treatment necessary during pregnancy

Correct Answer: Cease allergy list and perform penicillin desensitization then treat with penicillin

Q12. For non-pregnant patients allergic to penicillin, an alternative regimen for early syphilis is:

• Doxycycline 100 mg orally twice daily for 14 days
• Amoxicillin 500 mg orally three times daily for 3 days
• Single IM ceftriaxone 250 mg dose
• Trimethoprim-sulfamethoxazole single dose

Correct Answer: Doxycycline 100 mg orally twice daily for 14 days

Q13. Early latent syphilis is defined as infection acquired within:

• One year of diagnosis
• Five years of diagnosis
• Ten years of diagnosis
• Two months of diagnosis

Correct Answer: One year of diagnosis

Q14. Tertiary syphilis may present with which of the following clinical features?

• Gummatous lesions and cardiovascular aortitis
• Primary painless chancre only
• Superficial mucocutaneous patches limited to secondary stage
• Acute bacterial meningitis caused by Gram-negative rods

Correct Answer: Gummatous lesions and cardiovascular aortitis

Q15. Congenital syphilis results from:

• Transplacental transmission of Treponema pallidum
• Breastfeeding transmission only
• Perinatal airborne exposure
• Postnatal skin contact with infected lesions only

Correct Answer: Transplacental transmission of Treponema pallidum

Q16. The recommended initial screening test for syphilis in many antenatal programs is:

• Non-treponemal test (RPR or VDRL)
• CSF VDRL
• Dark-field microscopy of maternal blood
• Treponemal EIA without non-treponemal screening

Correct Answer: Non-treponemal test (RPR or VDRL)

Q17. A fourfold decline in non-treponemal titer (e.g., 1:32 to 1:8) after therapy usually indicates:

• Adequate therapeutic response and serologic cure trend
• Treatment failure requiring immediate re-treatment
• Laboratory error and test should be repeated
• Conversion to false-positive status

Correct Answer: Adequate therapeutic response and serologic cure trend

Q18. The term “serofast” refers to:

• Persistent low-level non-treponemal titers despite adequate therapy
• Immediate seroreversion to negative after treatment
• False-positive treponemal test due to other infections
• High-titer relapse indicating neurosyphilis

Correct Answer: Persistent low-level non-treponemal titers despite adequate therapy

Q19. The best specimen for dark-field examination is:

• Exudate from an undisturbed chancre or lesion
• Blood sample drawn in EDTA
• Urine specimen collected midstream
• Throat swab placed in viral transport medium

Correct Answer: Exudate from an undisturbed chancre or lesion

Q20. For serologic testing, how should serum specimens be stored if testing is delayed?

• Refrigerate at 2–8°C and avoid repeated freeze-thaw cycles
• Keep at room temperature for several days
• Store at 37°C to preserve antibody activity
• Freeze and thaw repeatedly to concentrate antibodies

Correct Answer: Refrigerate at 2–8°C and avoid repeated freeze-thaw cycles

Q21. The primary mechanism of action of penicillin against Treponema pallidum is:

• Inhibition of bacterial cell wall synthesis via penicillin-binding proteins
• Inhibition of 30S ribosomal subunit protein synthesis
• Disruption of DNA gyrase activity
• Blocking folate synthesis by dihydropteroate synthase inhibition

Correct Answer: Inhibition of bacterial cell wall synthesis via penicillin-binding proteins

Q22. Benzathine penicillin G is formulated to provide which pharmacokinetic property?

• Prolonged low serum concentrations after IM depot injection
• Rapid high peak levels after oral administration
• Exclusive cerebrospinal fluid penetration when given IM
• Short half-life requiring continuous IV infusion

Correct Answer: Prolonged low serum concentrations after IM depot injection

Q23. The recommended regimen for late latent syphilis (without neurosyphilis) is:

• Three weekly IM injections of benzathine penicillin G 2.4 million units
• Single IM benzathine penicillin G dose only
• Doxycycline for 7 days
• Oral azithromycin weekly for 2 weeks

Correct Answer: Three weekly IM injections of benzathine penicillin G 2.4 million units

Q24. Which statement about treponemal tests is correct?

• They are highly specific and often remain positive for life
• They are useful for quantitative monitoring of treatment response
• They frequently revert to negative within months after treatment
• They detect non-specific reagin antibodies

Correct Answer: They are highly specific and often remain positive for life

Q25. RPR titers are most useful clinically for:

• Monitoring treatment response by quantitative changes over time
• Definitive lifetime confirmation of past infection
• Detecting T. pallidum DNA in lesions
• Identifying specific treponemal antigens

Correct Answer: Monitoring treatment response by quantitative changes over time

Q26. Which condition commonly produces a biological false-positive non-treponemal test?

• Systemic lupus erythematosus (autoimmune disease)
• Untreated hypothyroidism only
• Recent vaccination exclusively
• Hypercholesterolemia

Correct Answer: Systemic lupus erythematosus (autoimmune disease)

Q27. A practical limitation of dark-field microscopy is:

• Requirement for fresh lesion material and skilled microscopist
• High sensitivity in late latent lesions
• Ability to detect antibodies in serum
• Usefulness on fixed, stored specimens

Correct Answer: Requirement for fresh lesion material and skilled microscopist

Q28. PCR testing for Treponema pallidum is most useful when:

• Detecting treponemal DNA from lesion swabs in early infection
• Used as the sole test for serologic monitoring after treatment
• Preferred for routine screening of blood donors only
• Substituting for CSF VDRL in neurosyphilis confirmation

Correct Answer: Detecting treponemal DNA from lesion swabs in early infection

Q29. Typical cerebrospinal fluid (CSF) findings in neurosyphilis include:

• Lymphocytic pleocytosis, elevated protein, and reactive CSF VDRL
• Neutrophilic pleocytosis with low protein
• Normal cell count with decreased glucose only
• Yeast cells on Gram stain

Correct Answer: Lymphocytic pleocytosis, elevated protein, and reactive CSF VDRL

Q30. Ocular syphilis commonly presents as which ophthalmic condition?

• Uveitis (inflammation of the uveal tract)
• Primary open-angle glaucoma exclusively
• Retinal detachment without inflammation
• Isolated conjunctivitis only

Correct Answer: Uveitis (inflammation of the uveal tract)

Q31. Cardiovascular involvement in tertiary syphilis most characteristically affects:

• Ascending aorta (aortitis and aneurysm formation)
• Coronary arteries only causing acute MI
• Pulmonary arteries causing emboli
• Peripheral veins causing phlebitis

Correct Answer: Ascending aorta (aortitis and aneurysm formation)

Q32. Which statement about antimicrobial resistance in Treponema pallidum is correct?

• No clinically significant penicillin resistance has been documented
• Widespread high-level penicillin resistance mandates alternative therapy
• T. pallidum is intrinsically resistant to all beta-lactams
• Resistance to penicillin is common and requires combination therapy

Correct Answer: No clinically significant penicillin resistance has been documented

Q33. The Jarisch-Herxheimer reaction typically occurs within what timeframe after initiating therapy?

• Within 24 hours of starting effective antibiotic treatment
• Two weeks after completing therapy
• Only in untreated latent infection
• After months due to chronic immune response

Correct Answer: Within 24 hours of starting effective antibiotic treatment

Q34. In many countries, syphilis diagnosis is legally categorized as:

• A notifiable disease requiring public health reporting
• A non-reportable private laboratory result only
• Reportable only if neurosyphilis is present
• Confidential with no partner notification requirements

Correct Answer: A notifiable disease requiring public health reporting

Q35. Currently, there is a vaccine available to prevent syphilis:

• No, there is no licensed vaccine for syphilis
• Yes, a WHO-approved killed whole-cell vaccine
• Yes, a recombinant protein vaccine used in pregnancy
• Yes, a live-attenuated Treponema vaccine

Correct Answer: No, there is no licensed vaccine for syphilis

Q36. The average incubation period from exposure to primary chancre is approximately:

• Three weeks (about 21 days)
• Six hours to two days
• One year on average
• Three to six months routinely

Correct Answer: Three weeks (about 21 days)

Q37. Which clinical sign is most characteristic of secondary syphilis?

• Generalized maculopapular rash often involving palms and soles
• Localized pustular acneiform lesions only on face
• Severe necrotizing fasciitis at inoculation site
• Isolated deep abscess formation

Correct Answer: Generalized maculopapular rash often involving palms and soles

Q38. Neurosyphilis may occur during which stage(s) of infection?

• At any stage (early or late) of syphilis
• Only during primary syphilis
• Only during tertiary syphilis after 10 years
• Only in congenital syphilis

Correct Answer: At any stage (early or late) of syphilis

Q39. A critical public health step after diagnosis of syphilis is:

• Partner notification and treatment to prevent reinfection and spread
• Isolating the patient in a negative pressure room
• Vaccinating all household contacts immediately
• Only advising abstinence without partner evaluation

Correct Answer: Partner notification and treatment to prevent reinfection and spread

Q40. Regarding blood transfusion safety, syphilis is of concern because:

• Window period infected donations may transmit infection if screened inadequately
• Syphilis is routinely transmitted by airborne exposure in transfusion centers
• All donors are vaccinated so screening is unnecessary
• Treponema pallidum multiplies in stored blood products leading to outbreaks

Correct Answer: Window period infected donations may transmit infection if screened inadequately

Q41. The main contraindication to administering benzathine penicillin is:

• History of immediate-type (anaphylactic) penicillin allergy
• Mild nausea from prior oral penicillin only
• Concurrent use of antacids
• Age above 60 years without allergy

Correct Answer: History of immediate-type (anaphylactic) penicillin allergy

Q42. Ceftriaxone can be used as an alternative regimen in which scenario?

• Some penicillin-allergic adults for early syphilis when desensitization is not possible
• Preferred treatment for neurosyphilis over IV penicillin in pregnancy
• As a single-dose oral therapy for congenital syphilis
• Never appropriate due to universal resistance

Correct Answer: Some penicillin-allergic adults for early syphilis when desensitization is not possible

Q43. Doxycycline is contraindicated in which patient group for syphilis treatment?

• Pregnant women and children under 8 years of age
• Healthy non-pregnant adults only
• Adults with renal impairment exclusively
• Adults with previous rash to penicillin but no systemic allergy

Correct Answer: Pregnant women and children under 8 years of age

Q44. A persistently positive treponemal test after successful therapy indicates:

• Past treated infection or lifelong seropositivity, not necessarily active disease
• Definitive ongoing active infection requiring retreatment
• Laboratory contamination in all cases
• Autoimmune cross-reaction only

Correct Answer: Past treated infection or lifelong seropositivity, not necessarily active disease

Q45. After a reactive non-treponemal screening test, the confirmatory test typically used is:

• Treponemal-specific test such as FTA-ABS or TPPA
• Repeat non-treponemal test only
• Complete blood count as confirmatory assay
• Urine culture for Treponema pallidum

Correct Answer: Treponemal-specific test such as FTA-ABS or TPPA

Q46. Proper intramuscular administration of benzathine penicillin requires:

• Deep IM injection into the upper outer gluteal quadrant to form a depot
• Slow IV infusion to achieve depot effect
• Subcutaneous injection into the abdomen only
• Oral ingestion after mixing with water

Correct Answer: Deep IM injection into the upper outer gluteal quadrant to form a depot

Q47. Common adverse effects of benzathine penicillin include:

• Local injection pain, allergic reactions, and Jarisch-Herxheimer reaction
• Nephrotoxicity and ototoxicity similar to aminoglycosides
• Severe bone marrow suppression in all patients
• Photosensitivity and tendon rupture as primary risks

Correct Answer: Local injection pain, allergic reactions, and Jarisch-Herxheimer reaction

Q48. If a high suspicion of syphilis yields a non-reactive VDRL, the laboratory should:

• Repeat the test on diluted serum to detect the prozone effect
• Report as negative without further action
• Only perform a urine antigen test next
• Assume immunodeficiency and ignore serology

Correct Answer: Repeat the test on diluted serum to detect the prozone effect

Q49. The CSF VDRL test for neurosyphilis is best described as:

• Highly specific but less sensitive for neurosyphilis diagnosis
• Highly sensitive and always positive in neurosyphilis
• Unreliable and not used in clinical practice
• Useful for screening pregnant women only

Correct Answer: Highly specific but less sensitive for neurosyphilis diagnosis

Q50. The RPR (rapid plasma reagin) test detects which type of antibodies?

• Non-treponemal reagin antibodies against cardiolipin-lecithin-cholesterol antigen
• Treponemal-specific IgG against T. pallidum proteins
• Antibodies to HIV co-infection only
• Antibodies against encapsulated bacteria polysaccharides

Correct Answer: Non-treponemal reagin antibodies against cardiolipin-lecithin-cholesterol antigen

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