Bacterial Skin Infections Practice Questions

Q: Leprosy affects all the following except:

Ovaries. ***Ovaries*** - The **ovaries** are generally spared in leprosy due to their internal location and higher temperature, which is not conducive to the growth of *Mycobacterium leprae*. - *M. leprae* prefers cooler body temperatures (around 27-33°C), leading to its predilection for superficial tissues. *Testes* - The **testes** are frequently affected in leprosy, particularly in lepromatous forms, due to their cooler temperature. - Involvement can lead to **orchitis**, **atrophy**, and **infertility** in males [1]. *Eyes* - The **eyes** are commonly affected in leprosy, especially the anterior segment (cornea, iris, ciliary body) [1]. - Complications can include **keratitis**, **iritis**, glaucoma, and vision loss due to nerve damage and direct *M. leprae* invasion [1]. *Nerves* - **Nerves**, particularly peripheral nerves, are a hallmark of leprosy, as *M. leprae* has a strong tropism for Schwann cells [1]. - This leads to **nerve thickening**, loss of sensation, and motor weakness, which are crucial diagnostic features [1].

Q: Jarish-Herxheimer reaction is seen in early cases of what?

Syphilis. ***Syphilis*** - The **Jarisch-Herxheimer reaction** is an acute, self-limiting febrile reaction that occurs within a few hours of treatment initiation for spirochetal infections, most notably **syphilis** [1]. - It results from the release of **endotoxins** from dying spirochetes, leading to systemic inflammatory symptoms such as fever, chills, myalgia, headache, and exacerbation of existing skin lesions [1]. *Gonorrhea* - **Gonorrhea** is caused by the bacterium *Neisseria gonorrhoeae*, which is not a spirochete and does not typically trigger a Jarisch-Herxheimer reaction upon treatment. - Treatment for gonorrhea, usually with antibiotics like ceftriaxone, does not result in the rapid release of toxins associated with this specific immunologic response. *Lymphogranuloma venereum* - **Lymphogranuloma venereum (LGV)** is caused by specific serovars of *Chlamydia trachomatis* and is characterized by genital ulcers and prominent lymphadenopathy. - As it is not a spirochetal infection, treatment with antibiotics like doxycycline does not induce a Jarisch-Herxheimer reaction. *Granuloma inguinale* - **Granuloma inguinale**, also known as donovanosis, is caused by *Klebsiella granulomatis*. - This bacterial infection, characterized by progressive ulcerative lesions, is not a spirochetal disease, and thus, treatment does not lead to a Jarisch-Herxheimer reaction.

Q: Which of the following statements is true regarding the primary chancre of syphilis?

All of the options.. ***All of the options*** - This is the correct answer because **all three statements accurately describe the primary chancre of syphilis**. - The primary chancre is characteristically a **painless, indurated ulcer** with a clean base, appearing at the site of *Treponema pallidum* inoculation (typically 10-90 days after exposure). - It is accompanied by **painless, bilateral regional lymphadenopathy** developing 1-2 weeks after the chancre appears - the nodes are firm, discrete, and non-tender. - The chancre may have a **serous exudate** on its surface and is highly infectious, containing numerous spirochetes. - The combination of all these features is pathognomonic for **primary syphilis** and helps differentiate it from other genital ulcers (e.g., painful ulcers in herpes, tender adenopathy in chancroid). **Why not the individual options?** - While each statement is medically accurate, selecting only one option would be incomplete. - The question asks which statement is "true" - since all three are true, the most complete answer is "All of the options." - In clinical practice, recognizing the full constellation of features (painless ulcer + painless adenopathy + potential exudate) is essential for accurate diagnosis.

Q: A 35-year-old woman presents with hypopigmented and anesthetic patches on her arms, and a positive skin smear for acid-fast bacilli. What is the most likely diagnosis?

Leprosy. ***Leprosy*** - The presence of **hypopigmented and anesthetic patches** is pathognomonic for leprosy, indicating nerve involvement - A **positive skin smear for acid-fast bacilli** directly confirms the presence of *Mycobacterium leprae*, the causative agent - This combination of anesthesia with skin lesions and AFB positivity is diagnostic *Psoriasis* - Psoriasis presents with **red, scaly plaques** with well-demarcated borders, typically on extensor surfaces - Does not cause **anesthesia** and is not associated with acid-fast bacilli - Auspitz sign may be present (pinpoint bleeding on scale removal) *Vitiligo* - Causes **complete depigmentation (white patches)** due to melanocyte destruction, not hypopigmentation - Patches are **not anesthetic** - sensation remains intact - An **autoimmune condition** with no involvement of acid-fast bacilli *Pityriasis versicolor* - A **superficial fungal infection** (Malassezia species) causing hypo- or hyperpigmented patches with fine scaling - Patches are **not anesthetic** and maintain normal sensation - **Skin smear shows yeast and hyphae** ("spaghetti and meatballs" appearance), not acid-fast bacilli

Question 1

Leprosy affects all the following except:

Accepted Answer

Ovaries

Answer

Eyes

Answer

Nerves

Answer

Testes

Question 2

Jarish-Herxheimer reaction is seen in early cases of what?

Accepted Answer

Syphilis

Answer

Gonorrhea

Answer

Lymphogranuloma venereum

Answer

Granuloma inguinale

Question 3

Which of the following statements is true regarding the primary chancre of syphilis?

Accepted Answer

All of the options.

Answer

It is a painless ulcer.

Answer

It is associated with painless lymphadenopathy.

Answer

It may be covered with exudate.

Question 4

A 35-year-old woman presents with hypopigmented and anesthetic patches on her arms, and a positive skin smear for acid-fast bacilli. What is the most likely diagnosis?

Accepted Answer

Leprosy

Answer

Psoriasis

Answer

Vitiligo

Answer

Pityriasis versicolor

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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