The Question is from neet-zoology reproductive-health sexually-transmitted-diseases, and it was created by the author K SUNKANNA

Question

A patient presents with painless genital ulcers, followed weeks later by painful swollen lymph nodes (buboes).  Serological testing confirms a bacterial infection. Which of the following is the MOST likely causative agent considering the characteristic latency period between primary and secondary symptoms?

K SUNKANNA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**:  Stages of sexually transmitted infections (STIs)
 **Related Topics**: Syphilis, Chancroid, Lymphogranuloma venereum, Gonorrhea
 **Prerequisites**: Understanding of the clinical presentations of various bacterial STIs.
## SOLUTION PATHWAY
**Given Information**:
  Painless genital ulcers (primary syphilis)
  Painful swollen lymph nodes (buboes) weeks later (secondary syphilis)
  Bacterial infection confirmed by serological testing
**Method & Steps**:
 1. Identify the characteristic features:
  Reasoning: The description points towards a two-stage infection with a distinct latency period between the primary lesion (painless ulcer) and secondary manifestation (lymphadenopathy).
  Formula/Rule:  None directly applicable; this is a diagnostic reasoning problem.
 2. Match the features to known bacterial STIs:
  Working: Let's analyze each option:
  * **Treponema pallidum pallidum (Syphilis):**  Causes painless chancre (primary stage) followed by secondary symptoms such as lymphadenopathy (buboes) weeks to months later. This matches the patient presentation.
  * **Haemophilus ducreyi (Chancroid):**  Causes painful genital ulcers (chancroids) with tender inguinal lymphadenopathy, but the onset of lymphadenopathy is often simultaneous with or shortly after the ulceration, not weeks later.
  * **Chlamydia trachomatis (Lymphogranuloma venereum):** Can cause painless ulcers initially, but progresses to painful inguinal lymphadenopathy, however, the primary lesion is often unnoticed or heals quickly, making the later lymphadenopathy the more prominent feature. The time frame might be consistent but less typical than syphilis.
  * **Neisseria gonorrhoeae (Gonorrhea):** Usually presents with purulent discharge and may cause painful urination, but not typically with painless ulcers followed by a delayed lymphadenopathy.
 3. Determine the most likely causative agent:
  Result: Treponema pallidum pallidum is the most likely causative agent due to the characteristic latency period between painless primary lesions and the later development of painful secondary lymphadenopathy.
  Verification: The clinical presentation and the latency period strongly support the diagnosis of syphilis.
 ## OPTION ANALYSIS
A ✓: Treponema pallidum pallidum – This is the correct answer because syphilis presents with painless genital ulcers (primary stage) followed by systemic symptoms including painful lymphadenopathy (secondary stage) weeks or months later.
B :x: Haemophilus ducreyi – Chancroid typically presents with painful ulcers and often simultaneous or rapidly developing painful lymphadenopathy, not weeks later.
C :x: Chlamydia trachomatis – While lymphogranuloma venereum can present with lymphadenopathy, the primary lesion is often less noticeable, and the timing might not perfectly match the description.
D :x: Neisseria gonorrhoeae – Gonorrhea usually presents with purulent discharge and dysuria, not painless ulcers and delayed lymphadenopathy.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the clinical presentations of different STIs:  Careful attention to the details of the primary and secondary stages is crucial.
  2.Overlooking the latency period: The time interval between the primary and secondary symptoms is a key diagnostic feature.
 **Quick Tips**:
  1.Remember the classic presentation of syphilis: painless chancre followed by weeks to months of latency before secondary symptoms.
  2.Use a mnemonic device to remember the key features of different STIs.

K SUNKANNA · Answer

The correct Option is "Treponema pallidum pallidum"

K SUNKANNA · Answer

Haemophilus ducreyi

K SUNKANNA · Answer

Chlamydia trachomatis

K SUNKANNA · Answer

Neisseria gonorrhoeae

NEET Zoology Reproductive Health Sexually Transmitted Diseases (Stds) MCQs

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