Bacterial Skin Infections Practice Questions

Q: Lepra cells are seen in abundance in which type of leprosy?

Lepromatous leprosy. **Explanation:** The presence of **Lepra cells** (also known as **Virchow cells**) is a hallmark of **Lepromatous Leprosy (LL)**. These are large, foamy macrophages that have ingested a high number of *Mycobacterium leprae*. In LL, the patient exhibits a deficient Cell-Mediated Immunity (CMI), allowing the bacilli to multiply unchecked. The macrophages become "stuffed" with bacilli, which are often arranged in parallel clusters called **globi**. **Analysis of Options:** * **Lepromatous Leprosy (Correct):** Due to the Th2-dominant cytokine profile and poor CMI, there is a high bacillary load (multibacillary). Macrophages fail to kill the bacteria, leading to the formation of foamy Lepra cells. * **Tuberculoid Leprosy (Incorrect):** This pole is characterized by strong CMI (Th1 response). Bacilli are very rare (paucibacillary), and the histology shows well-formed granulomas with epithelioid cells and Langhans giant cells, rather than foamy Lepra cells. * **Histoid Leprosy (Incorrect):** A variant of LL characterized by spindle-shaped histiocytes arranged in a storiform pattern. While it has a high bacillary load, the characteristic cell is the spindle cell, not the classic foamy Lepra cell. * **Indeterminate Leprosy (Incorrect):** This is an early stage where the immune response hasn't polarized. Histology usually shows only non-specific perineural inflammation. **NEET-PG High-Yield Pearls:** * **Grenz Zone:** A clear subepidermal zone of uninvolved dermis seen in Lepromatous and Histoid leprosy (absent in Tuberculoid). * **Fite-Faraco Stain:** A modified acid-fast stain used to visualize *M. leprae* in tissue sections. * **Globi:** Masses of acid-fast bacilli held together by a mucoid material called **glis**. * **Ridley-Jopling Classification:** The standard 5-group classification based on the immunological spectrum of the disease.

Q: What is the most important cytokine for type II lepra reaction?

TNF alpha. **Explanation:** **Type II Lepra Reaction (Erythema Nodosum Leprosum - ENL)** is a classic example of a **Type III Hypersensitivity reaction** (Immune-complex mediated). It typically occurs in patients with multibacillary leprosy (lepromatous or borderline lepromatous) where there is a high bacterial load. **Why TNF-alpha is the correct answer:** TNF-alpha (Tumor Necrosis Factor-alpha) is the central mediator in the pathogenesis of ENL. During the reaction, there is a massive systemic release of TNF-alpha from activated macrophages and monocytes. This cytokine is responsible for the systemic symptoms (fever, malaise) and the acute inflammatory skin lesions. The clinical effectiveness of **Thalidomide** in treating Type II reactions is specifically due to its potent ability to inhibit TNF-alpha synthesis. **Analysis of Incorrect Options:** * **IL-1 and IL-6:** While these are pro-inflammatory cytokines that may be elevated during systemic inflammation, they are secondary mediators and not the primary drivers or therapeutic targets specific to ENL. * **IFN-gamma:** This is the hallmark cytokine of **Type 1 Lepra Reaction** (Reversal Reaction), which involves a Type IV Delayed Hypersensitivity response and a shift toward a Th1 immune profile. **High-Yield Clinical Pearls for NEET-PG:** * **Type I Reaction:** Type IV Hypersensitivity; involves IFN-gamma and IL-2; treated with Steroids. * **Type II Reaction (ENL):** Type III Hypersensitivity; involves TNF-alpha; treated with **Thalidomide** (drug of choice) or Clofazimine. * **Clinical Presentation of ENL:** Tender evanescent subcutaneous nodules, fever, arthralgia, and iridocyclitis. * **Trigger:** Often precipitated by the initiation of Multidrug Therapy (MDT).

Q: Which of the following statements regarding Botryomycosis is FALSE?

It mainly affects the viscera.. ### **Explanation: Botryomycosis** Botryomycosis is a rare, chronic, granulomatous bacterial infection that clinically mimics fungal infections (like actinomycosis or eumycetoma) but is caused by non-filamentous bacteria. **1. Why Option B is the Correct Answer (The False Statement):** Botryomycosis primarily affects the **integumentary system (skin and subcutaneous tissue)** in approximately 75% of cases. While a visceral form exists (affecting lungs, liver, or brain), it is much less common and typically occurs in severely immunocompromised patients. Therefore, stating that it "mainly" affects the viscera is incorrect. **2. Analysis of Other Options:** * **Option A (Chronic granulomatous disease):** This is **true**. Histologically, it is characterized by a granulomatous inflammatory response surrounding bacterial grains (Splendore-Hoeppli phenomenon). * **Option C (Staphylococcus aureus):** This is **true**. *Staphylococcus aureus* is the most common causative agent (40% of cases), followed by *Pseudomonas aeruginosa*, *E. coli*, and *Proteus*. * **Option D (Sinuses and purulent discharge):** This is **true**. The clinical hallmark is the presence of nodules, abscesses, and multiple draining sinuses that discharge pus containing "grains" (clusters of bacteria). **3. NEET-PG Clinical Pearls:** * **The "Grains":** Unlike Actinomycosis (which has sulfur granules), Botryomycosis grains are composed of masses of **true bacteria** held together by a polysaccharide matrix. * **Splendore-Hoeppli Phenomenon:** An eosinophilic, glassy material surrounding the bacterial colonies seen on H&E stain; it represents an antigen-antibody complex. * **Predisposing Factors:** Often linked to trauma, foreign bodies, or altered host immunity (e.g., Diabetes, HIV). * **Treatment:** Long-term culture-specific antibiotics and occasionally surgical debridement.

Q: Which of the following is NOT true of erysipelas?

Common in tropics. **Explanation:** **Erysipelas** is a distinct superficial form of cellulitis with prominent lymphatic involvement. 1. **Why Option D is the Correct Answer:** Erysipelas is **not** more common in the tropics; it is actually more prevalent in **temperate climates**. In contrast, other pyodermas like impetigo are more frequently seen in tropical, humid environments. This makes Option D the false statement and thus the correct answer. 2. **Analysis of Other Options:** * **Option A (Streptococcal infection):** This is true. The primary causative agent is **Group A Beta-hemolytic Streptococci** (*Streptococcus pyogenes*). Unlike cellulitis, *Staphylococcus aureus* is a rare cause of erysipelas. * **Option B (Contagious and infectious):** This is true. It is an acute infectious process that can spread through autoinoculation or direct contact, especially if there is a break in the skin barrier (e.g., tinea pedis, fissures). * **Option C (Margins are raised):** This is a hallmark feature. Because the infection is superficial (upper dermis), it presents with a **sharply demarcated, raised, and indurated border** (Milian’s ear sign). This distinguishes it from cellulitis, which has ill-defined, non-raised borders. **Clinical Pearls for NEET-PG:** * **Classic Appearance:** "St. Anthony’s Fire" – characterized by a fiery red, painful, shiny, and edematous plaque. * **Milian’s Ear Sign:** Involvement of the pinna (ear) suggests erysipelas because the ear lacks deep subcutaneous tissue, making cellulitis impossible at that site. * **Treatment of Choice:** Parenteral or oral **Penicillin** remains the gold standard. * **Predisposing Factor:** Chronic lymphedema is the most significant risk factor for recurrent erysipelas.

Q: A 12-year-old child with intellectual disability presents with multiple, painful, shiny white discharging lesions around the anus. What is the most probable diagnosis?

Syphilitic condyloma. **Explanation:** The clinical presentation of multiple, painful, shiny white discharging lesions in the perianal region of a child is highly suggestive of **Condyloma Lata**, a hallmark of **Secondary Syphilis**. **Why Syphilitic Condyloma is correct:** Condyloma lata are hypertrophic, papular lesions found in moist intertriginous areas (like the anus or axilla). They are characterized by a "flat-topped," "moist," or "shiny white" appearance due to maceration and are highly infectious, teeming with *Treponema pallidum*. In a child with intellectual disability, this presentation should raise immediate suspicion of sexual abuse leading to an acquired sexually transmitted infection. **Why other options are incorrect:** * **Lupus Vulgaris:** This is a chronic form of cutaneous tuberculosis characterized by "apple-jelly nodules" on diascopy. It typically presents on the face and neck, not as acute discharging perianal lesions. * **Carcinoma:** Squamous cell carcinoma of the anus usually presents as a hard, indurated, non-healing ulcer or mass in older adults, rather than multiple moist lesions in a child. * **Hemorrhoids:** These are vascular cushions. While they can cause pain and bleeding, they do not present as "shiny white discharging" infectious papules. **NEET-PG High-Yield Pearls:** * **Condyloma Lata vs. Condyloma Acuminata:** Lata is flat-topped and moist (Secondary Syphilis); Acuminata is cauliflower-like and warty (HPV 6, 11). * **Dark-field Microscopy:** The gold standard for immediate diagnosis of Condyloma Lata, showing motile spirochetes. * **Screening:** Always perform a VDRL/RPR test. In pediatric cases, a thorough social evaluation for potential abuse is mandatory.

Q: What is the drug of choice for Lymphogranuloma venereum (LGV)?

Doxycycline. **Lymphogranuloma venereum (LGV)** is a sexually transmitted infection caused by the **L1, L2, and L3 serovars of *Chlamydia trachomatis***. It typically presents in three stages: a painless primary lesion, a painful secondary stage characterized by regional lymphadenopathy (the "Groove sign"), and a tertiary stage involving chronic inflammation and proctocolitis [1]. 1. **Why Doxycycline is correct:** **Doxycycline (100 mg orally twice daily for 21 days)** is the established **drug of choice** for LGV. Tetracyclines are highly effective against intracellular organisms like *Chlamydia* [1]. The extended 3-week duration is necessary to ensure complete eradication and prevent the late-stage complications of lymphatic destruction and fibrosis. 2. **Why the other options are incorrect:** * **Ampicillin:** This is a beta-lactam antibiotic. *Chlamydia* lacks a traditional peptidoglycan cell wall, making cell-wall synthesis inhibitors like Ampicillin ineffective. * **Erythromycin:** While Erythromycin (500 mg four times daily for 21 days) is an effective alternative for patients who cannot tolerate tetracyclines (e.g., pregnant women), it is not the first-line treatment due to gastrointestinal side effects and a more frequent dosing schedule. * **Ceftriaxone:** This is the drug of choice for *Neisseria gonorrhoeae* and Chancroid, but it has no clinical activity against *C. trachomatis* [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Groove Sign:** Pathognomonic for LGV; it refers to the inguinal ligament dividing matted, enlarged matted lymph nodes (inguinal and femoral). * **Alternative in Pregnancy:** Erythromycin base is the preferred treatment for LGV in pregnant and lactating women. * **Azithromycin:** While a single dose of Azithromycin (1g) treats uncomplicated urethritis/cervicitis (*Serovars D-K*), it is **not** the first-line recommendation for LGV; Doxycycline remains superior for the L-serovars.

Question 1

Lepra cells are seen in abundance in which type of leprosy?

Accepted Answer

Lepromatous leprosy

Answer

Tuberculoid leprosy

Answer

Histoid leprosy

Answer

Intermediate leprosy

Question 2

What is the most important cytokine for type II lepra reaction?

Accepted Answer

TNF alpha

Answer

IL 1

Answer

IL 6

Answer

INF gamma

Question 3

Which of the following statements regarding Botryomycosis is FALSE?

Accepted Answer

It mainly affects the viscera.

Answer

It is a chronic granulomatous disease.

Answer

The causative organism is Staphylococcus aureus.

Answer

It presents with sinuses and purulent discharge.

Question 4

Which of the following statements about leprosy classification is true?

Accepted Answer

In paucibacillary leprosy, the bacterial index is less than 2.

Answer

A bacterial index of 2+ indicates two different sites.

Answer

Seven sites are needed for classification.

Answer

Various sites are needed for classification.

Question 5

A 28-year-old female presented with a syphilitic chancre and was treated with Inj. Benzathine penicillin G, 2.4 million units intramuscularly as a single dose. After initial treatment, she was screened at 6-month intervals and was found to be still seropositive. Which of the following treatment regimens would you recommend?

Accepted Answer

Inj. Benzathine penicillin G, 2.4 million units intramuscularly, weekly for 3 weeks

Answer

Inj. Benzathine penicillin G, 2.4 million units intramuscularly, single dose

Answer

Inj. Benzathine penicillin G, 2.4 million units intramuscularly, twice daily for 1 week

Answer

Inj. Benzathine penicillin G, 2.4 million units intramuscularly, twice weekly for 3 weeks

Question 6

Which of the following is NOT true of erysipelas?

Accepted Answer

Common in tropics

Answer

Streptococcal infection

Answer

Contagious and infectious

Answer

Margins are raised

Question 7

A 12-year-old child with intellectual disability presents with multiple, painful, shiny white discharging lesions around the anus. What is the most probable diagnosis?

Accepted Answer

Syphilitic condyloma

Answer

Lupus vulgaris

Answer

Carcinoma

Answer

Hemorrhoids

Question 8

All statements regarding the diagnosis and classification of leprosy are true, except?

Accepted Answer

A 'plus 2' mean indicates the presence of 2 bacilli in 2 smears.

Answer

At least 7 skin smears should be examined.

Answer

A paucibacillary leprosy classification has a bacterial index less than 2.

Answer

A multibacillary leprosy classification has a bacterial index greater than or equal to 2.

Question 9

A 65-year-old woman has developed thick, erythematous nodules on her ears and nose with significant associated sensory loss. The nodules have grown slowly over many years. Biopsy of the lesions shows dermal granulomas with giant cells but no acid-fast bacteria. Cultures on blood agar and Lowenstein-Jensen medium show no growth. What is the most likely diagnosis?

Accepted Answer

Tuberculoid leprosy

Answer

Cutaneous leishmaniasis

Answer

Onchocerciasis

Answer

Rhinoscleroma

Question 10

What is the drug of choice for Lymphogranuloma venereum (LGV)?

Accepted Answer

Doxycycline

Answer

Ampicillin

Answer

Erythromycin

Answer

Ceftriaxone

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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