Bacterial Skin Infections Practice Questions

Q: Which of the following is NOT a characteristic of secondary syphilis?

It presents with vesicular bullous lesions.. Secondary syphilis is the systemic stage of infection caused by *Treponema pallidum*, occurring 4–10 weeks after the primary chancre. [1] ### **Why Option C is the Correct Answer** Syphilis is famously known as the **"Great Mimicker"** because it can present with almost any type of rash (macular, papular, or pustular) [1]. However, a key diagnostic rule in adult syphilis is that **it never presents with vesicular or bullous (blistering) lesions.** If a patient presents with a generalized blistering rash, syphilis can be clinically ruled out. * *Exception:* Vesiculobullous lesions are only seen in **Congenital Syphilis** (Pemphigus syphiliticus). ### **Analysis of Incorrect Options** * **A. It may be asymptomatic:** While secondary syphilis typically presents with a rash, some patients may have a "latent" transition where clinical signs are minimal or resolve spontaneously while the serology remains positive [1]. * **B. It usually involves palms and soles:** This is a high-yield clinical hallmark. A copper-red, maculopapular rash involving the palms and soles is highly suggestive of secondary syphilis [1]. * **D. Lymphadenopathy is common:** Generalized, painless, non-suppurative lymphadenopathy (especially epitrochlear nodes) is a classic feature of this stage [1]. ### **NEET-PG High-Yield Pearls** * **Condyloma Lata:** Highly infectious, moist, flat-topped papules found in intertriginous areas (e.g., axilla, perineum) [1]. * **Lues Maligna:** A rare, severe form of secondary syphilis with pleomorphic, necrotic ulcers seen in immunocompromised (HIV) patients. * **Snail Track Ulcers:** Mucous patches in the oropharynx. * **Diagnosis:** Screening is done via **VDRL/RPR** (non-specific); confirmation requires **FTA-ABS/TPHA** (specific).

Q: Type 2 lepra reaction occurs in which form of leprosy?

Multi bacillary leprosy. **Explanation:** **Type 2 Lepra Reaction**, also known as **Erythema Nodosum Leprosum (ENL)**, is a Type III hypersensitivity reaction (immune-complex mediated). It occurs due to the deposition of antigen-antibody complexes in tissues, leading to systemic inflammatory symptoms. **Why Option B is correct:** Type 2 reactions occur exclusively in patients with a high bacterial load, specifically those on the lepromatous end of the spectrum (**Lepromatous Leprosy (LL)** and **Borderline Lepromatous (BL)**). These forms are classified as **Multibacillary (MB) leprosy**. The high density of *Mycobacterium leprae* antigens reacts with circulating antibodies to form the immune complexes that trigger the reaction. **Why other options are incorrect:** * **Option A (Paucibacillary):** Paucibacillary leprosy (TT and BT) is characterized by high cell-mediated immunity and a very low bacterial load. Since there are insufficient antigens to form significant immune complexes, Type 2 reactions do not occur here. Instead, these patients are prone to **Type 1 reactions** (Type IV hypersensitivity). * **Option C & D:** These are incorrect as the reaction is specific to the bacterial load status of the patient. **NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Characterized by tender, evanescent, erythematous nodules, high-grade fever, malaise, and systemic involvement (iridocyclitis, neuritis, arthritis, and orchitis). * **Timing:** Usually occurs during or after the initiation of Multi-Drug Therapy (MDT), as killing the bacilli releases massive amounts of antigen. * **Drug of Choice:** **Thalidomide** is the most effective treatment for Type 2 reactions. Oral corticosteroids and Clofazimine are also used. * **Key Distinction:** Type 1 reaction = Delayed Hypersensitivity (Type IV); Type 2 reaction = Immune Complex Mediated (Type III).

Q: Pitted keratolysis affects which of the following areas?

Palm and soles. **Explanation:** **Pitted keratolysis** is a superficial bacterial infection of the stratum corneum, primarily caused by **Kytococcus sedentarius** (formerly *Micrococcus*), *Corynebacterium* species, or *Actinomyces*. 1. **Why Option A is correct:** The bacteria produce **extracellular serine proteases** that digest the keratin of the stratum corneum. This process requires a moist, occlusive environment, which is why it characteristically involves the **weight-bearing areas of the soles** (and occasionally the palms). The digestion of keratin results in the pathognomonic "punched-out" pits (1–7 mm) seen clinically. 2. **Why Options B and C are incorrect:** * **Face:** The facial skin is thinner and lacks the thick stratum corneum required for these specific bacteria to thrive and create deep pits. * **Nails:** This is an infection of the keratinized skin (stratum corneum), not the nail plate (onycho-). 3. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Presentation:** Hyperhidrosis (excessive sweating), Bromhidrosis (foul odor due to sulfur compounds), and non-inflammatory punched-out pits. * **Risk Factors:** Occlusive footwear (boots), tropical climates, and prolonged immersion in water. * **Diagnosis:** Primarily clinical; Wood’s lamp may occasionally show coral-red fluorescence (if *Corynebacterium* is involved). * **Treatment:** Topical antibiotics like **Clindamycin, Erythromycin, or Mupirocin**, combined with measures to keep the feet dry (e.g., aluminum chloride hexahydrate).

Q: Blistering dactylitis is typically caused by which of the following?

Streptococcal infection. **Explanation:** **Blistering Dactylitis** is a localized superficial infection characterized by tense, fluid-filled blisters (bullae) over the volar fat pads of the distal phalanx of the fingers or toes. 1. **Why Option A is Correct:** The most common causative organism is **Group A Beta-hemolytic Streptococcus (Streptococcus pyogenes)**. Occasionally, *Staphylococcus aureus* may be co-isolated, but classic blistering dactylitis is traditionally associated with Streptococcus. The infection typically follows minor trauma or autoinoculation from the nasopharynx, leading to the formation of a characteristic oval bulla on an erythematous base. 2. **Why Other Options are Incorrect:** * **Option B (Staphylococcus):** While *S. aureus* can cause bullous impetigo, it is less frequently the primary isolate in the specific clinical presentation of volar dactylitis compared to Streptococcus. * **Option C (Tuberculosis):** Cutaneous TB (like Lupus Vulgaris) or TB of the bone (Spina Ventosa) can affect the digits, but they present as chronic nodules, ulcers, or "bottleneck" swelling, not acute superficial blisters. * **Option D (Sickle cell anaemia):** This is associated with **Hand-Foot Syndrome** (dactylitis) in infants, which is caused by microinfarction of the small bones, leading to painful, non-blistering inflammatory swelling. **Clinical Pearls for NEET-PG:** * **Target Population:** Most commonly seen in children (2–16 years). * **Clinical Feature:** Tense bullae containing seropurulent fluid over the **volar** aspect of the distal digit. * **Treatment:** Incision and drainage of the bulla followed by a course of oral antibiotics (e.g., Penicillinase-resistant penicillins or Cephalosporins). * **Differential Diagnosis:** Must be distinguished from herpetic whitlow (which presents with grouped vesicles and significant pain) and friction blisters.

Q: Leprosy does NOT affect the axilla, groin, and scalp because:

These are warmer regions of the body. **Explanation:** The causative organism of Leprosy, ***Mycobacterium leprae***, is an obligate intracellular bacterium with a unique temperature sensitivity. It thrives optimally at temperatures slightly lower than the core body temperature, specifically between **30°C and 33°C**. **1. Why Option A is correct:** The axilla, groin, and scalp are considered "warm zones" of the body because they are either well-insulated by skin folds (intertriginous areas) or have high vascularity and hair cover, maintaining a temperature close to the core body temperature (37°C). Because *M. leprae* cannot replicate efficiently at these higher temperatures, these areas are typically spared from clinical lesions. Conversely, the bacteria preferentially affect cooler areas like the nose, ears, and extensor surfaces of the limbs. **2. Why other options are incorrect:** * **Option B:** These areas are physiologically warmer, not colder. Colder regions (like the pinna of the ear) are actually the most common sites for finding the bacilli. * **Option C:** The scalp and groin are actually highly vascular areas. Blood supply does not dictate the distribution of leprosy; temperature does. * **Option D:** These regions have a rich sensory nerve supply. While leprosy is a disease of the nerves, the distribution of lesions is determined by the thermal requirements of the bacteria, not the density of the nerves. **NEET-PG High-Yield Pearls:** * **"Immune Privileged" Sites in Leprosy:** The midline of the back, axilla, groin, and scalp are often referred to as "spared areas." * **Diagnosis:** The **Ear lobe snip** is a classic site for Slit Skin Smear (SSS) because it is one of the coolest peripheral parts of the body. * **Target Organs:** *M. leprae* has a predilection for **peripheral nerves** (Schwann cells) and the **skin**.

Q: Lymphogranuloma venerum is characterized by all of the following except?

Metronidazole is an effective treatment.. **Lymphogranuloma Venereum (LGV)** is a sexually transmitted infection caused by **Chlamydia trachomatis serovars L1, L2, and L3**. ### Explanation of Options: * **Option C (Correct Answer):** Metronidazole is an antiprotozoal and anaerobic antibacterial agent; it has no activity against *Chlamydia*. The **first-line treatment for LGV is Doxycycline** (100 mg twice daily for 21 days). Erythromycin or Azithromycin are alternatives. * **Option A:** The primary lesion is typically a small, painless papule or ulcer that is transient and often goes unnoticed. It **heals rapidly without leaving a scar**, which distinguishes it from the scarring seen in Syphilis or Chancroid. * **Option B:** LGV is a systemic disease. Beyond local lesions, patients frequently present with **systemic symptoms** such as fever, chills, malaise, and myalgia, especially during the secondary stage (lymphatic spread) [1]. * **Option C:** The **"Groove Sign" (Greenblatt’s sign)** is a pathognomonic clinical finding. It occurs when the inguinal ligament divides matted, enlarged inguinal and femoral lymph nodes, creating a visible depression or "groove" between the two groups of nodes [1]. ### NEET-PG High-Yield Pearls: * **Stages:** 1° (Primary ulcer) → 2° (Inguinal syndrome/Buboes) → 3° (Anogenital syndrome/Strictures). * **Esthiomene:** A chronic complication involving hypertrophic ulceration and elephantiasis of the female external genitalia due to lymphatic obstruction. * **Diagnosis:** Nucleic Acid Amplification Test (NAAT) is the preferred diagnostic method. Frei’s test is a historical skin test (now obsolete). * **Proctocolitis:** Common in MSM (Men who have sex with men), presenting with rectal discharge, pain, and tenesmus [1].

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

Scrofuloderma. ### Explanation **Correct Answer: A. Scrofuloderma** **Concept:** Scrofuloderma (Tuberculosis colliquativa cutis) is a form of **cutaneous tuberculosis** that occurs due to the direct extension of an underlying tuberculous focus (most commonly a **cervical lymph node**) to the overlying skin. In this clinical scenario, the "painless neck swelling" represents a cold abscess of the lymph node. As the infection progresses, the skin breaks down, leading to the formation of a **discharging sinus** or ulcer with undermined edges. The supraclavicular and cervical regions are the most classic sites for this presentation in children. **Analysis of Incorrect Options:** * **B. Actinomycosis:** While it presents with discharging sinuses, it typically involves the **mandibular region** ("lumpy jaw"). The discharge characteristically contains **sulfur granules**, and the lesions are usually indurated (woody hard) rather than a simple painless swelling. * **C. Botryomycosis:** This is a chronic granulomatous bacterial infection (usually *S. aureus*) that mimics fungal infections. It typically affects the extremities and presents with nodules and sinuses, but is not the primary diagnosis for a pediatric supraclavicular neck mass. * **D. Fungal Mycetoma:** This is a chronic infection of the subcutaneous tissue, usually involving the **foot** (Madura foot). It presents with a triad of tumefaction, sinuses, and discharge of macroscopic grains. **High-Yield Clinical Pearls for NEET-PG:** * **Lupus Vulgaris:** The most common clinical variant of secondary cutaneous TB; characterized by "apple-jelly nodules" on diascopy. * **Scrofuloderma:** The most common form of cutaneous TB in children in India. * **Tuberculosis Verrucosa Cutis (TVC):** Also known as "Prosector’s wart," it occurs due to exogenous inoculation in individuals with high immunity. * **Histopathology:** Look for acid-fast bacilli (AFB) and caseating granulomas.

Q: What is the treatment for severe ulnar neuritis in borderline tuberculoid leprosy?

MDT plus steroids. **Explanation:** The correct answer is **MDT plus steroids**. In leprosy, **neuritis** (nerve inflammation) is often a manifestation of a **Type 1 Lepra Reaction** (Reversal Reaction), which is common in Borderline Tuberculoid (BT) leprosy. Severe ulnar neuritis indicates an acute inflammatory process that can lead to irreversible nerve damage and physical disability (e.g., claw hand) if not treated aggressively. 1. **Why MDT plus Steroids is correct:** While MDT (Rifampicin and Dapsone for BT) treats the underlying *Mycobacterium leprae* infection, it does not stop the acute immunological reaction damaging the nerve. **Systemic corticosteroids** (typically Prednisolone) are the gold standard to reduce edema and inflammation within the nerve sheath, thereby preventing permanent paralysis. 2. **Why other options are wrong:** * **MDT only:** Insufficient for neuritis; it kills bacilli but doesn't address the immune-mediated nerve destruction. * **Wait and watch:** Dangerous; delay in treatment leads to permanent nerve fibrosis and disability. * **MDT plus Thalidomide:** Thalidomide is the drug of choice for **Type 2 Lepra Reaction** (Erythema Nodosum Leprosum), which occurs in lepromatous poles, not Type 1 reactions seen in BT leprosy. **High-Yield Clinical Pearls for NEET-PG:** * **Type 1 Reaction:** Delayed hypersensitivity (Cell-mediated); seen in BT, BB, BL; treated with Steroids. * **Type 2 Reaction:** Humoral immunity (Arthus phenomenon); seen in BL, LL; treated with Thalidomide, Clofazimine, or Steroids. * **Silent Neuritis:** Nerve damage without pain/tenderness; also requires urgent steroid therapy. * **WHO MDT Duration (BT):** 6 months (Paucibacillary regimen).

Q: Which of the following is NOT a characteristic feature of Hutchinson's triad?

Cataract. **Explanation:** Hutchinson’s triad is a classic clinical presentation of **Late Congenital Syphilis** (symptoms appearing after 2 years of age). It is caused by the transplacental transmission of *Treponema pallidum*. **Why Cataract is the correct answer:** Cataract is **not** a component of Hutchinson’s triad. While congenital syphilis can cause various ocular issues, the specific ocular component of the triad is **Interstitial Keratitis**, which involves inflammation of the corneal stroma leading to scarring and potential blindness, rather than opacification of the lens (cataract). **Analysis of other options:** * **Interstitial Keratitis (Option A):** A hallmark of the triad, usually appearing between ages 5 and 15. It presents with ground-glass corneal edema. * **Notched Incisors (Option B):** Also known as **Hutchinson’s teeth**. These are permanent upper central incisors that are small, widely spaced, and peg-shaped with a central notch on the biting edge. * **Deafness (Option C):** Specifically, **Sensorineural hearing loss** caused by eighth cranial nerve (vestibulocochlear) involvement. It often develops suddenly around puberty. **High-Yield Clinical Pearls for NEET-PG:** * **Mulberry Molars:** Another dental finding in late congenital syphilis characterized by multiple rudimentary cusps on the first molars. * **Saber Shin:** Anterior bowing of the tibia due to periostitis. * **Clutton’s Joints:** Symmetrical painless swelling of the knees. * **Early Congenital Syphilis signs:** Snuffles (syphilitic rhinitis), palmoplantar rash, and condyloma lata. * **Drug of Choice:** Penicillin G remains the treatment of choice for all stages of syphilis.

Question 1

Which of the following is NOT a characteristic of secondary syphilis?

Accepted Answer

It presents with vesicular bullous lesions.

Answer

It may be asymptomatic.

Answer

It usually involves palms and soles.

Answer

Lymphadenopathy is common.

Question 2

Type 2 lepra reaction occurs in which form of leprosy?

Accepted Answer

Multi bacillary leprosy

Answer

Pauci bacillary leprosy

Answer

Both of the above

Answer

None of the above

Question 3

Pitted keratolysis affects which of the following areas?

Accepted Answer

Palm and soles

Answer

Face

Answer

Nails

Answer

All of the above

Question 4

Large bilateral painless effusions of the knees occurring in late congenital syphilis in patients between ages 8 to 18 are designated as?

Accepted Answer

Clutton's joints

Answer

Ramsey's joints

Answer

Charcot's joints

Answer

Mercer's joints

Question 5

Blistering dactylitis is typically caused by which of the following?

Accepted Answer

Streptococcal infection

Answer

Staphylococcus

Answer

Tuberculosis

Answer

Sickle cell anaemia

Question 6

Leprosy does NOT affect the axilla, groin, and scalp because:

Accepted Answer

These are warmer regions of the body

Answer

These are colder regions of the body

Answer

These areas have less blood supply

Answer

These areas have less sensory nerve supply

Question 7

Lymphogranuloma venerum is characterized by all of the following except?

Accepted Answer

Metronidazole is an effective treatment.

Answer

Primary lesions heal without scarring.

Answer

Commonly develop systemic infection.

Answer

Groove sign is seen characteristically.

Question 8

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

Accepted Answer

Scrofuloderma

Answer

Actinomycosis

Answer

Botryomycosis

Answer

Fungal mycetoma

Question 9

What is the treatment for severe ulnar neuritis in borderline tuberculoid leprosy?

Accepted Answer

MDT plus steroids

Answer

Multidrug therapy (MDT) only

Answer

Wait and watch

Answer

MDT plus thalidomide

Question 10

Which of the following is NOT a characteristic feature of Hutchinson's triad?

Accepted Answer

Cataract

Answer

Interstitial keratitis

Answer

Notched incisors

Answer

Deafness

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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