Bacterial Skin Infections Practice Questions

Q: Which of the following drugs controls lepra reactions in leprosy?

Clofazimine. ***Clofazimine*** - **Clofazimine** is an anti-leprosy drug known for its **anti-inflammatory** and **immunomodulatory properties**, which help control **lepromin reactions** (specifically ENL or Type 2 lepra reactions) [1, 2]. - It stabilizes **mast cell membranes** and inhibits lymphocyte proliferation, thereby reducing the inflammatory response seen in lepromin reactions. *Dapsone* - **Dapsone** is a primary anti-leprosy drug that works by inhibiting **folate synthesis** in *Mycobacterium leprae* [2]. - While effective against the bacteria, it does not directly control the **immunological reactions** associated with leprosy, such as the lepromin reaction [1]. *Streptomycin* - **Streptomycin** is an antibiotic primarily used for **tuberculosis** and other bacterial infections, belonging to the **aminoglycoside** class. - It is **not a first-line drug** for leprosy and has no established role in controlling lepromin reactions. *Ethambutol* - **Ethambutol** is an anti-tuberculosis drug that inhibits **mycolic acid synthesis**, leading to impaired cell wall formation in mycobacteria. - It is **not used for treating leprosy** and therefore has no function in managing lepromin reactions.

Q: Apple jelly nodules are characteristic of which condition?

Lupus vulgaris. ***Correct: Lupus vulgaris*** **Apple-jelly nodules** are the pathognomonic sign of lupus vulgaris, a form of cutaneous tuberculosis. This characteristic appearance is revealed when suspected lesions are compressed with a **diascope (glass slide)**, demonstrating the underlying **granulomatous inflammation** with tuberculoid histology. *Incorrect: Cutaneous anaphylaxis* Cutaneous anaphylaxis presents with **rapid-onset urticaria (hives)** and angioedema, often with systemic symptoms like bronchospasm and hypotension. It does not produce slow-growing, persistent nodules or demonstrate the apple-jelly phenomenon on diascopy. *Incorrect: Erythroderma* Erythroderma is characterized by **diffuse erythema and scaling** affecting more than 90% of the body surface area. This widespread inflammatory condition does not form localized nodular lesions or exhibit the apple-jelly sign on diascopy. *Incorrect: Erythema nodosum* Erythema nodosum presents as **tender, erythematous, subcutaneous nodules**, typically on the lower extremities, representing panniculitis (inflammation of subcutaneous fat). These nodules are deep, painful, and do not blanch to reveal an apple-jelly appearance on diascopy.

Q: A 40-year-old female presented with numerous, non-itchy, erythematous, scaly papules (lesions) on the trunk, with a few oral white mucosal plaques and erosive lesions in the perianal area. The probable diagnosis is

Secondary syphilis. ***Secondary syphilis*** - **Erythematous, scaly papules** on the trunk (syphilitic roseola or papulosquamous lesions), **oral white mucosal plaques** (mucous patches), and **erosive lesions in the perianal area** (condylomata lata) are classic manifestations of secondary syphilis [1]. - The lesions are typically **non-itchy** and can appear widespread [1]. *Psoriasis* - Psoriasis typically presents with well-demarcated, **erythematous plaques covered with silvery scales**, often on extensor surfaces, and is usually itchy. - While psoriasis can affect mucous membranes, the specific combination of oral white plaques and perianal erosions is less characteristic than in secondary syphilis. *Lichen planus* - Lichen planus typically presents with **pruritic, purple, polygonal, planar papules** and often involves flexural surfaces. - Oral lichen planus can manifest as white reticular patterns (Wickham's striae) or erosions, but the widespread scaly papules on the trunk and perianal erosions observed here are not typical. *Disseminated candidiasis* - Disseminated candidiasis usually occurs in **immunocompromised individuals** and presents with widespread skin lesions, fever, and systemic symptoms. - The skin lesions are typically **macular, papular, or nodular and can be pustular**, but the description of scaly papules, oral white plaques, and perianal erosions is not characteristic of candidiasis.

Q: Which is the most common type of cutaneous tuberculosis?

Lupus vulgaris. ***Lupus vulgaris*** - This is the most common and persistent form of **cutaneous tuberculosis** in developed countries. - It often presents as **reddish-brown plaques** that expand peripherally, commonly affecting the head and neck. *Scrofuloderma* - This form typically arises from direct extension of tuberculosis from an underlying **lymph node** or bone abscess to the skin. - It presents as **cold abscesses** or ulcers with undermined edges and draining sinuses. *T.B. verruca cutis* - This is a **hyperkeratotic, warty lesion** that results from exogenous inoculation of *Mycobacterium tuberculosis* into the skin of an individual with high immunity. - It is often seen in pathologists or veterinarians who come into contact with infected tissues. *Erythema induratum* - Also known as **Bazin's disease**, it presents as recurrent, tender, **subcutaneous nodules** and plaques, typically on the calves. - It is usually associated with a systemic tuberculous focus and is considered a form of **panniculitis**.

Q: Which of the following conditions is associated with pseudo-buboes?

Granuloma inguinale. **Granuloma inguinale** - **Pseudo-buboes** are characteristic of granuloma inguinale and are subcutaneous granulomas that mimic the appearance of true buboes. - They are typically formed by **granulomatous tissue** in the inguinal region, not by inflamed lymph nodes as seen in true buboes. *Chancroid* - Chancroid is associated with true **buboes**, which are enlarged, painful, and often suppurative inguinal lymph nodes. - These buboes result from localized **lymphadenitis** due to *Haemophilus ducreyi* infection. *LGV* - **Lymphogranuloma venereum (LGV)** is known for causing characteristic **groove sign**, which involves deep inguinal lymphadenopathy that can lead to coalesced, firm, and matted nodes (true buboes) that may suppurate. - The buboes in LGV are typically **unilateral** and painful, evolving from initial infection with *Chlamydia trachomatis* serovars L1, L2, or L3. *All of the options* - This option is incorrect because while chancroid and LGV cause true buboes, only **granuloma inguinale** causes pseudo-buboes. - The distinction lies in the **etiology**; pseudo-buboes are granulomas, whereas true buboes are inflamed or suppurative lymph nodes.

Q: In multibacillary leprosy, what is the recommended follow-up examination period after adequate treatment?

5 years. ***5 years*** - Follow-up for **multibacillary leprosy** after adequate treatment is recommended for **5 years** to monitor for relapse. - This extended period is crucial due to the higher bacterial load and potential for late recurrence in multibacillary forms. *3 years* - A 3-year follow-up period is typically recommended for **paucibacillary leprosy**, which has a lower risk of relapse compared to multibacillary forms. - This duration is insufficient for multibacillary cases, as relapse can occur later. *10 years* - A 10-year follow-up period is generally considered excessive and not the standard recommendation for routine monitoring of treated leprosy cases. - While relapse can occur, 5 years is deemed sufficient for most multibacillary cases. *2 years* - A 2-year follow-up period is too short for multibacillary leprosy, as it significantly increases the risk of missing a potential relapse. - The latency for relapse in multibacillary leprosy can extend beyond this timeframe.

Q: Which of the following parts of the body is not affected by leprosy?

Ovary. ***Ovary*** - The **ovaries** are generally not affected by *Mycobacterium leprae* due to their internal location and higher core body temperature. - The bacterium thrives in **cooler temperatures**, which is why it typically affects superficial tissues and distal extremities. *Testes* - The **testes** are located externally and have a lower temperature, making them susceptible to *Mycobacterium leprae* infection. - Involvement can lead to severe damage, including **atrophy** and **infertility**. *Nasal mucosa* - The **nasal mucosa** is a common site of infection and a major portal of entry and exit for *Mycobacterium leprae*. - Early lesions can cause **nasal stuffiness** and progress to septal perforation and collapse of the nasal bridge. *Axilla* - Peripheral nerves in the **axilla**, such as the median, ulnar, and radial nerves, can be affected by leprosy. - Nerve involvement may lead to **sensory loss** and **motor weakness** in the upper limbs.

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.

Question 1

Which of the following drugs controls lepra reactions in leprosy?

Accepted Answer

Clofazimine

Answer

Dapsone

Answer

Streptomycin

Answer

Ethambutol

Question 2

Apple jelly nodules are characteristic of which condition?

Accepted Answer

Lupus vulgaris

Answer

Erythroderma

Answer

Erythema nodosum

Answer

Cutaneous anaphylaxis

Question 3

A 40-year-old female presented with numerous, non-itchy, erythematous, scaly papules (lesions) on the trunk, with a few oral white mucosal plaques and erosive lesions in the perianal area. The probable diagnosis is

Accepted Answer

Secondary syphilis

Answer

Psoriasis

Answer

Lichen planus

Answer

Disseminated candidiasis

Question 4

Which is the most common type of cutaneous tuberculosis?

Accepted Answer

Lupus vulgaris

Answer

Scrofuloderma

Answer

T.B. verruca cutis

Answer

Erythema induratum

Question 5

Which of the following conditions is associated with pseudo-buboes?

Accepted Answer

Granuloma inguinale

Answer

LGV

Answer

Chancroid

Answer

All of the options

Question 6

In multibacillary leprosy, what is the recommended follow-up examination period after adequate treatment?

Accepted Answer

5 years

Answer

3 years

Answer

10 years

Answer

2 years

Question 7

Which of the following parts of the body is not affected by leprosy?

Accepted Answer

Ovary

Answer

Nasal mucosa

Answer

Testes

Answer

Axilla

Question 8

Leprosy affects all the following except:

Accepted Answer

Ovaries

Answer

Eyes

Answer

Nerves

Answer

Testes

Question 9

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

Accepted Answer

Syphilis

Answer

Gonorrhea

Answer

Lymphogranuloma venereum

Answer

Granuloma inguinale

Question 10

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.

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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