Bacterial Skin Infections Practice Questions

Q: Which of the following statements about Bacillary angiomatosis is NOT true?

Aminoglycosides are useful in treatment. **Bacillary Angiomatosis (BA)** is a vascular proliferative disease caused by Gram-negative rickettsial organisms of the genus *Bartonella*, primarily occurring in immunocompromised individuals (especially those with advanced HIV/AIDS). ### **Explanation of Options:** * **Option C (Correct Answer):** Aminoglycosides are **not** the first-line treatment for BA. The drugs of choice are **Erythromycin** (Macrolides) or **Doxycycline** (Tetracyclines). Treatment is usually prolonged (3–4 months) to prevent relapse. * **Option A:** BA is caused by **Bartonella henselae** (transmitted via cat scratches/fleas) and **Bartonella quintana** (transmitted via human body lice). * **Option B:** *Bartonella* species can cause **Peliosis hepatis**, characterized by blood-filled cystic spaces in the liver, often presenting with hepatomegaly and elevated alkaline phosphatase. * **Option D:** In AIDS patients, systemic involvement is common. Beyond the skin and liver, it can involve the **brain** (causing encephalopathy), bones (osteolytic lesions), and lymph nodes. ### **High-Yield Clinical Pearls for NEET-PG:** * **Histopathology:** Shows lobular proliferation of capillaries with **plump "epithelioid" endothelial cells** and a neutrophilic infiltrate. * **Warthin-Starry Stain:** This silver stain is used to visualize the causative bacilli in tissue sections. * **Differential Diagnosis:** Clinically, BA closely resembles **Kaposi Sarcoma**. However, BA is characterized by a neutrophilic infiltrate, whereas Kaposi Sarcoma shows a lymphocytic infiltrate and spindle cells. * **Key Association:** *B. henselae* is also the causative agent of **Cat Scratch Disease** in immunocompetent hosts.

Q: All of the following are characteristic features of lepromatous leprosy except?

Presence of granulomas subdermally. In Lepromatous Leprosy (LL), the immune system fails to mount an effective response against *Mycobacterium leprae*, leading to specific histopathological and immunological findings. **Why Option D is the Correct Answer:** In LL, the characteristic finding is a **diffuse dermal infiltration** of foamy macrophages (Virchow cells) laden with bacilli. True **granulomas** (organized collections of epithelioid cells, lymphocytes, and giant cells) are a hallmark of **Tuberculoid Leprosy (TT)**, where cell-mediated immunity (CMI) is strong. In LL, the lack of CMI prevents the formation of organized granulomas. **Explanation of Incorrect Options:** * **A. Presence of globi:** Due to high bacterial load (multibacillary), acid-fast bacilli (AFB) aggregate in large clumps within macrophages; these are called globi. * **B. Subepidermal free zone (Grenz zone):** This is a classic histopathological feature of LL. It is a thin layer of normal collagen separating the epidermis from the underlying dermal infiltrate, caused by the lack of a delayed-type hypersensitivity reaction. * **C. Decreased cell-mediated immunity:** LL represents the Th2-dominant pole of the spectrum. There is a specific anergy to *M. leprae* antigens, resulting in a negative Lepromin test. **NEET-PG High-Yield Pearls:** * **Leonine Facies:** Caused by diffuse infiltration of the face in LL. * **Lepromin Test:** Strongly positive in TT (strong CMI) and **negative** in LL (absent CMI). * **Nerve Involvement:** In LL, nerve involvement is **symmetrical** and occurs late, whereas in TT, it is **asymmetrical** and occurs early. * **Foamy Macrophages:** Also known as Lepra cells or Virchow cells.

Q: A patient with HIV infection develops multibacillary leprosy. What is the recommended treatment?

Rifampicin, dapsone, and clofazimine.. The management of leprosy in HIV-positive patients follows the same principles as in HIV-negative patients. According to WHO guidelines and the National Leprosy Eradication Programme (NLEP), the presence of HIV co-infection does not alter the standard Multi-Drug Therapy (MDT) regimen. **Explanation of the Correct Answer:** * **Option B (Rifampicin, dapsone, and clofazimine):** This is the standard WHO MDT regimen for **Multibacillary (MB) leprosy**. It consists of Rifampicin (600 mg once monthly), Clofazimine (300 mg once monthly + 50 mg daily), and Dapsone (100 mg daily) for a duration of 12 months. HIV-infected individuals respond well to this standard therapy, and there is no evidence to suggest that the regimen should be modified or simplified. **Why Other Options are Incorrect:** * **Option A:** Withholding treatment is incorrect as leprosy is a progressive infectious disease that can lead to permanent nerve damage and disability, regardless of HIV status. * **Option C:** This is the regimen for **Paucibacillary (PB) leprosy**. Since the question specifies "multibacillary," clofazimine must be included to prevent drug resistance and ensure efficacy. * **Option D:** Monotherapy with Rifampicin is never recommended for leprosy due to the high risk of developing drug-resistant *Mycobacterium leprae*. **High-Yield Clinical Pearls for NEET-PG:** * **Immune Reconstitution Inflammatory Syndrome (IRIS):** In HIV patients, starting Antiretroviral Therapy (ART) may trigger "Leprosy-IRIS," often presenting as a sudden Type 1 (Reversal) Reaction. * **Drug Interactions:** Be cautious with **Rifampicin** as it is a potent enzyme inducer and can decrease the plasma levels of certain Protease Inhibitors (PIs) and NNRTIs used in HIV treatment. * **MB Leprosy Criteria:** Presence of >5 skin lesions, or >1 nerve involvement, or a positive skin smear at any site.

Q: Which of the following features is NOT associated with Chancroid?

Painless lymphadenopathy. Everything is painful in Chancroid, a sexually transmitted infection caused by **_Haemophilus ducreyi_** [1]. 1. **Why Option B is correct:** In Chancroid, the inguinal lymphadenopathy (buboes) is characteristically **exceedingly painful**, inflammatory, and often unilateral [1]. These buboes may become fluctuant and spontaneously rupture. Painless lymphadenopathy is instead a feature of Primary Syphilis or Lymphogranuloma Venereum. 2. **Analysis of other options:** * **Option A (Painful ulcer):** Unlike the painless chancre of syphilis, the ulcer in Chancroid is soft, friable, and very painful [1]. * **Option C (School of fish appearance):** On Gram stain of the discharge, the organisms arrange themselves in parallel rows or chains, described as a "school of fish" appearance. * **Option D (Azithromycin):** According to CDC guidelines, a single 1g oral dose of Azithromycin is a first-line treatment for Chancroid. **Clinical Pearls for NEET-PG:** * **The "H" Rule:** _**H**. ducreyi_ causes a **H**eavy (large), **H**orrible (painful) ulcer that makes you **"cry"** (ducreyi). * **Syphilis vs. Chancroid:** Syphilis (Chancre) is painless with painless nodes; Chancroid is painful with painful nodes [1]. * **Autoinoculation:** Chancroid ulcers often show "kissing lesions" on opposing skin surfaces due to autoinoculation [1].

Q: A 12-year-old child presents with a painless neck swelling in the supraclavicular region, which started discharging after a few days. What is the most probable diagnosis?

Scrofuloderma. ### **Explanation** **Correct Answer: A. Scrofuloderma** **Scrofuloderma** (Tuberculosis colliquativa cutis) is a form of cutaneous tuberculosis that occurs due to the **contiguous spread** of infection from an underlying tuberculous focus, most commonly a **lymph node** (especially cervical or supraclavicular) or a bone/joint. * **Clinical Presentation:** It typically begins as a firm, painless, subcutaneous nodule that gradually softens (liquefaction) and breaks down to form an **undermined ulcer** or a **discharging sinus**. * **Key Feature:** The classic presentation is a painless neck swelling in a child or young adult that eventually discharges pus or caseous material, often healing with characteristic **puckered (bridged) scars**. --- ### **Why Other Options are Incorrect:** * **B. Actinomycosis:** While it presents with discharging sinuses, it typically involves the **cervicofacial region (mandible)**, is associated with "lumpy jaw," and the discharge contains characteristic **sulfur granules**. * **C. Botryomycosis:** This is a chronic granulomatous bacterial infection (usually *S. aureus*) that mimics fungal infections. It presents with nodules and sinuses, usually on the **extremities** following trauma, rather than isolated supraclavicular nodes. * **D. Fungal Mycetoma:** This presents as a triad of tumefaction (swelling), sinuses, and **grain discharge**, usually on the **foot** (Madura foot). It is rare in the supraclavicular region. --- ### **High-Yield Clinical Pearls for NEET-PG:** * **Most common site for Scrofuloderma:** Cervical/Supraclavicular lymph nodes. * **Lupus Vulgaris:** The most common clinical variant of cutaneous TB overall (presents with "apple-jelly nodules" on diascopy). * **Tuberculosis Verrucosa Cutis (TVC):** Known as "Prosector’s wart," it occurs due to exogenous inoculation in a previously sensitized individual. * **Puckered Scars:** A pathognomonic sign of healed scrofuloderma.

Q: Very numerous, symmetrically distributed, erythematous or copper colored shiny macules/papules are a feature of which condition?

Lepromatous leprosy. ### Explanation The clinical presentation described—numerous, symmetrically distributed, shiny, erythematous, or copper-colored lesions—is a hallmark of **Lepromatous Leprosy (LL)**. #### Why Lepromatous Leprosy (LL) is Correct: In LL, the patient has a **deficient cell-mediated immunity (CMI)** against *Mycobacterium leprae*. This allows for uncontrolled bacillary multiplication and hematogenous spread. Because the spread is systemic, the lesions are: * **Numerous and Symmetrical:** Distributed equally on both sides of the body. * **Morphology:** Macules or papules that are typically small, shiny (due to atrophy/stretching of the skin), and have a characteristic **copper-red or erythematous hue**. * **Sensation:** Unlike other forms, sensation is often **preserved** in early LL lesions because nerve damage occurs much later and is more diffuse. #### Why Other Options are Incorrect: * **Tuberculoid Leprosy (TT):** Characterized by high CMI. Lesions are **few (usually single)**, asymmetrical, well-defined, and **anesthetic** (complete loss of sensation). * **Borderline Tuberculoid (BT):** Lesions are few, asymmetrical, and show significant sensory loss. They often have "satellite lesions" near the main patch. * **Borderline Borderline (BB):** This is the most unstable form. Lesions are moderate in number and show characteristic **"punched-out" or "Swiss-cheese" appearance** with sloping inner borders and well-defined outer borders. #### NEET-PG High-Yield Pearls: * **Leonine Facies:** Advanced LL feature due to diffuse infiltration of the face, loss of eyebrows (**Madarosis**), and thickening of the nose/ears. * **Grenz Zone:** A clear sub-epidermal band seen on histology in LL, separating the epidermis from the dermal leproma. * **Bacteriological Index (BI):** Highest in LL (4+ to 6+), as the lesions are "Multibacillary." * **Lepromin Test:** Strongly **negative** in LL (due to lack of CMI) and positive in TT.

Q: Leprosy affects all organs except which of the following?

Uterus. **Explanation:** Leprosy, caused by *Mycobacterium leprae*, is a chronic granulomatous disease that primarily targets cooler areas of the body. The fundamental principle governing its distribution is the **temperature sensitivity** of the organism; *M. leprae* thrives best at temperatures between **27°C and 30°C**. **Why Uterus is the Correct Answer:** The **Uterus** is located deep within the pelvic cavity, maintaining a core body temperature of approximately **37°C**. This high temperature is inhibitory to the growth and survival of *M. leprae*. Consequently, the uterus (along with the lungs, CNS, and pancreas) is classically considered "immune" or resistant to leprosy. **Analysis of Incorrect Options:** * **Eyes (A):** The anterior segment of the eye is cooler than the core body temperature. Leprosy frequently involves the eyes, leading to lagophthalmos, corneal ulcers, and iridocyclitis. * **Nerves (B):** Peripheral nerves are a primary target. The bacteria have a unique tropism for **Schwann cells**, leading to neuropathy and characteristic nerve thickening. * **Ovary (D):** While internal, the ovaries can occasionally be involved in lepromatous leprosy (LL) due to hematogenous spread, leading to oophoritis, though this is less common than testicular involvement. **NEET-PG High-Yield Pearls:** * **Organs Spared in Leprosy:** CNS (Brain and Spinal Cord), Lungs, Uterus, Pancreas, and the "Warm areas" of the skin (axilla, groin, midline of the back). * **Most Common Nerve Involved:** Ulnar nerve. * **Testicular Involvement:** Very common in LL; can lead to sterility and gynecomastia due to low scrotal temperature. * **Cardinal Signs:** Hypopigmented patches with sensory loss, thickened nerves, and positive skin smears for Acid-Fast Bacilli.

Q: A 23-year-old male presents with a painless penile ulcer and painless lymphadenopathy. What is the most likely diagnosis?

Syphilis. ### Explanation The clinical presentation of a **painless penile ulcer** (chancre) accompanied by **painless regional lymphadenopathy** is the classic hallmark of **Primary Syphilis**, caused by the spirochete *Treponema pallidum*. #### Why Syphilis is Correct: The primary chancre typically appears 3–4 weeks after exposure. It is characterized by a clean base, indurated (hard) edges, and a lack of exudate. Crucially, both the ulcer and the associated inguinal lymphadenopathy are **painless**, which distinguishes it from most other genital ulcerative diseases. #### Why Other Options are Incorrect: * **Chancroid (*Haemophilus ducreyi*):** Presents as a **painful**, soft ulcer with a ragged, undermined edge and a necrotic base. The associated lymphadenopathy (bubo) is also exquisitely painful. * **Donovanosis (Granuloma Inguinale):** Caused by *Klebsiella granulomatis*. It presents as beefy-red, painless, velvety ulcers. However, it is characterized by **pseudobuboes** (subcutaneous granulation) rather than true lymphadenopathy. * **Herpes (HSV-2):** Presents as multiple, small, **painful** vesicles that rupture to form shallow ulcers. It is often associated with systemic symptoms like fever and painful lymphadenopathy. #### NEET-PG High-Yield Pearls: * **Investigation of Choice:** Dark-field microscopy is the gold standard for primary syphilis (shows corkscrew motility). * **Hard Chancre:** Syphilis; **Soft Chancre:** Chancroid. * **Donovan Bodies:** Seen on tissue smears (Wrights/Giemsa stain) as "safety-pin" appearing organisms within macrophages (pathognomonic for Donovanosis). * **Rule of Thumb:** If the ulcer hurts, think Chancroid or Herpes; if it doesn't, think Syphilis or LGV (though LGV usually has painful nodes—the "Sign of the Groove").

Question 1

Which of the following statements about Bacillary angiomatosis is NOT true?

Accepted Answer

Aminoglycosides are useful in treatment

Answer

Caused by Bartonella henselae

Answer

Can cause Peliosis hepatis

Answer

The brain can be involved in AIDS patients

Question 2

All of the following are characteristic features of lepromatous leprosy except?

Accepted Answer

Presence of granulomas subdermally

Answer

Presence of globi

Answer

Subepidermal free zone

Answer

Decreased cell-mediated immunity

Question 3

In leprosy, which nerves are commonly involved?

Accepted Answer

High ulnar, low median

Answer

High median, low ulnar

Answer

Triple nerve palsy

Answer

High radial, low median

Question 4

A patient with HIV infection develops multibacillary leprosy. What is the recommended treatment?

Accepted Answer

Rifampicin, dapsone, and clofazimine.

Answer

No anti-leprosy drug should be given.

Answer

Rifampicin and dapsone.

Answer

Rifampicin only.

Question 5

Which of the following features is NOT associated with Chancroid?

Accepted Answer

Painless lymphadenopathy

Answer

Painful ulcer

Answer

School of fish appearance on staining

Answer

Azithromycin is useful in treatment

Question 6

A 12-year-old child presents with a painless neck swelling in the supraclavicular region, which started discharging after a few days. What is the most probable diagnosis?

Accepted Answer

Scrofuloderma

Answer

Actinomycosis

Answer

Botomycosis

Answer

Fungal mycetoma

Question 7

Very numerous, symmetrically distributed, erythematous or copper colored shiny macules/papules are a feature of which condition?

Accepted Answer

Lepromatous leprosy

Answer

Tuberculoid leprosy

Answer

Borderline borderline leprosy

Answer

Borderline tuberculoid leprosy

Question 8

Leprosy affects all organs except which of the following?

Accepted Answer

Uterus

Answer

Eyes

Answer

Nerves

Answer

Ovary

Question 9

Which of the following organisms is implicated in the causation of botryomycosis?

Accepted Answer

Staphylococcus aureus

Answer

Staphylococcus albus

Answer

Pseudomonas aeruginosa

Answer

Streptococcus pneumoniae

Question 10

A 23-year-old male presents with a painless penile ulcer and painless lymphadenopathy. What is the most likely diagnosis?

Accepted Answer

Syphilis

Answer

Chancroid

Answer

Donovanosis

Answer

Herpes

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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