Bacterial Skin Infections Practice Questions

Q: A boy from Bihar presents with a non-anesthetic, hypopigmented, atrophic patch over his face. What is the diagnosis?

Indeterminate leprosy. ### **Explanation** The correct diagnosis is **Indeterminate Leprosy**. This is the earliest clinical stage of leprosy, often seen in children. **1. Why Indeterminate Leprosy is Correct:** * **Clinical Presentation:** It typically presents as a single, poorly defined, **hypopigmented patch**, most commonly on the face, outer arms, or thighs. * **Sensory Findings:** Unlike other forms of leprosy, the patch in the indeterminate stage is often **non-anesthetic** (or has only vague sensory loss) because nerve damage is minimal at this early phase. * **Epidemiology:** The patient is from Bihar, an endemic belt for leprosy in India, which increases clinical suspicion. **2. Why Other Options are Incorrect:** * **Pityriasis alba:** Presents as multiple, scaly, hypopigmented patches with indistinct borders, usually associated with atopy. It does not show atrophy. * **Pityriasis versicolor:** A fungal infection (Malassezia) presenting as multiple small, "dusty" scaly macules. It is diagnosed by a "spaghetti and meatballs" appearance on KOH mount, not by atrophy or endemicity. * **Borderline leprosy:** These lesions are usually multiple, well-defined, and show **definite sensory loss** and nerve enlargement, which are absent in this case. **3. NEET-PG High-Yield Pearls:** * **Fate of Indeterminate Leprosy:** About 75% of cases heal spontaneously; the rest evolve into a specific type (Tuberculoid, Borderline, or Lepromatous) based on the patient's CMI (Cell-Mediated Immunity). * **Histopathology:** Shows a non-specific perivascular and periappendageal lymphocytic infiltrate. Acid-fast bacilli (AFB) are rarely found. * **Key Differentiator:** If a hypopigmented patch on a child's face in an endemic area is non-anesthetic, always suspect Indeterminate Leprosy first.

Q: A patient with borderline tuberculoid leprosy presents with the following findings. Which type of hypersensitivity reaction and nerve is enlarged?

Type 4 & greater auricular nerve. ***Type 4 & greater auricular nerve*** - Borderline tuberculoid leprosy is characterized by a strong **cell-mediated immune response** against *Mycobacterium leprae*, which manifests as a **Type 4 (delayed-type) hypersensitivity** reaction leading to granuloma formation. - The image shows a thickened, cord-like structure in the neck, which is characteristic of an enlarged **greater auricular nerve**, the most commonly involved cutaneous nerve of the head and neck in leprosy. *Type 1 & greater auricular nerve* - **Type 1 hypersensitivity** is an immediate, **IgE-mediated** reaction (e.g., anaphylaxis) and is not the immunological basis for nerve damage or skin lesions in tuberculoid leprosy. - The pathogenesis of tuberculoid leprosy involves a **delayed-type** T-cell response, which takes days to develop, unlike the rapid onset of Type 1 reactions. *Type 2 & greater auricular nerve* - **Type 2 hypersensitivity** is an **antibody-dependent cytotoxic** reaction, which is not the primary mechanism in tuberculoid leprosy's pathology. - While immune reactions occur in leprosy, Type 2 is not the correct classification for the T-cell-mediated granulomatous inflammation seen in the tuberculoid form. *Type 3 & anterior auricular nerve* - **Type 3 hypersensitivity** involves **immune-complex deposition** and is characteristic of **Erythema Nodosum Leprosum (ENL)**, a complication typically seen in lepromatous leprosy, not borderline tuberculoid. - The enlarged nerve shown is clearly the **greater auricular nerve** due to its location crossing the sternocleidomastoid muscle; the **anterior auricular nerve** is located more anteriorly and is not typically affected this prominently.

Q: A 30-year-old female presents with a painful red granular lesion on the vulva accompanied by bilateral lymphadenopathy. What is the most likely diagnosis?

Chancroid. ***Chancroid***- Caused by ***Haemophilus ducreyi***, it presents classically as a **painful, ragged, deep vulvar ulcer** (soft chancre) often described as having an erythematous or granular base.- The condition is characteristically associated with large, sometimes suppurative, **painful unilateral or bilateral inguinal lymphadenopathy** (**buboes**), which fits the combined clinical presentation of pain and lymphadenopathy.*Neisseria Gonorrhoeae Infection*- This infection primarily causes **mucopurulent urethritis** or **cervicitis** and is not typically associated with primary, ulcerative, or granular vulval lesions.- While regional lymphadenopathy may occur, it is usually not a prominent, painful finding defining the clinical presentation.*Granuloma Inguinale*- The characteristic lesion is a **painless, highly vascular, 'beefy red' ulcer** which bleeds easily, consistent with the term "granular" but contradicting the crucial feature of being **painful**.- True regional lymphadenopathy is rare; instead, subcutaneous granulomas may mimic lymph nodes (**pseudo-buboes**).*Lymphogranuloma Venereum*- The primary genital lesion is typically a small, **painless, transient papule** or vesicle that is often overlooked.- While it causes severe, painful inguinal lymphadenopathy, the initial vulval lesion is usually not a prominent, painful, granular ulcer as described.

Q: A person with the H/o long-term sexual relationship presented with painful ulcers on his genitals with tender lymphadenopathy. What is the diagnosis?

Chancroid. ***Chancroid*** - Caused by the bacterium **_Haemophilus ducreyi_**, it classically presents with one or more deep, painful genital ulcers that have ragged, undermined borders and a purulent base. - It is characteristically associated with tender, suppurative inguinal lymphadenopathy, often unilateral, which is consistent with the patient's presentation. *Gonorrhoea* - Caused by **_Neisseria gonorrhoeae_**, it typically presents as **purulent urethritis** or cervicitis with discharge and dysuria. - While it can cause systemic infection, painful genital ulcers are not a characteristic feature of a primary gonococcal infection. *Chlamydia* - Caused by **_Chlamydia trachomatis_** (serovars D-K), it is a leading cause of nongonococcal urethritis and is frequently asymptomatic, especially in women. - This infection does not typically cause painful genital ulcers; its presentation is more commonly urethritis, cervicitis, or pelvic inflammatory disease. *LGV* - Lymphogranuloma venereum (LGV) is caused by invasive serovars (L1, L2, L3) of **_Chlamydia trachomatis_**. - It typically begins with a small, transient, **painless** papule or ulcer, followed by the development of painful inguinal lymphadenopathy (buboes), which differentiates it from the painful ulcers of chancroid.

Q: A 45-year-old truck driver with a history of multiple sex partners presented to the dermatological department, as shown below. What is the likely diagnosis?

Secondary syphilis. ***Secondary syphilis*** - The image shows a classic **maculopapular rash** involving the **palms**, a hallmark feature of secondary syphilis, which is caused by the spirochete **Treponema pallidum**. - The patient's history of **multiple sex partners** is a significant risk factor, and other associated findings can include generalized lymphadenopathy, fever, and **condylomata lata**. *Lichen planus* - Characterized by the "6 P's": **pruritic, polygonal, planar, purple papules and plaques**, often with fine white lines on the surface known as **Wickham's striae**. - The lesions in the image lack these classic features and are not typically pruritic, distinguishing it from the presented case. *Scabies* - This is an intensely **pruritic** infestation caused by the mite **Sarcoptes scabiei**, which creates linear **burrows**, especially in the **interdigital web spaces**, wrists, and axillae. - The rash in secondary syphilis is classically non-pruritic, and the morphology is maculopapular rather than burrow-like. *Psoriasis* - Typically presents as **well-demarcated erythematous plaques** with a **silvery scale** on extensor surfaces like the elbows and knees. - While palmoplantar psoriasis occurs, it usually manifests as hyperkeratotic plaques or pustules, not the diffuse maculopapular rash seen here.

Q: A patient presents with erythematous streaks extending peripherally from a site of infection on the skin. Involvement of which of the following structures leads to this clinical presentation?

Superficial lymphatics. ***Superficial lymphatics*** (Assuming the image shows signs of **lymphangitis** or **cellulitis**, characterized by **red streaks** spreading from an infected site.)- The classic presentation of **acute lymphangitis** involves **erythematous streaks** extending peripherally from a site of infection (often a wound or cellulitis), which are typically visible superficial structures.- This pattern suggests inflammation and infection tracking along the **superficial lymphatic vessels** which drain the peripheral skin and subcutaneous tissues.*Deep lymphatics*- Involvement of the **deep lymphatics** (e.g., those alongside major blood vessels) typically leads to **lymphedema** (swelling) of the entire limb, rather than the visible **red streaking** seen in acute superficial lymphangitis.- They are located deeper and their inflammation is less likely to produce the superficial, linear rash visible on the skin.*Superficial veins*- Inflammation and thrombosis of superficial veins (**superficial thrombophlebitis**) typically presents as a localized, **palpable, tender cord** rather than multiple linear streaks that spread over distance, which are characteristic of lymphatic tracing.- This condition would primarily involve blood flow obstruction, not the characteristic infection tracking seen in lymphangitis.*Skin*- Although the signs are *visible* on the skin, the primary pathological process causing the streaks is the infection spreading *within* the **lymphatic vessels** beneath the skin surface, not solely a primary skin disease (like **erysipelas** or **cellulitis** alone).- Cellulitis is often the source, but the visible tracking (streaks) follows the path of the **superficial lymphatics**.

Q: A 45-year-old man with multiple sexual partners presents with a palmoplantar rash as seen below. On examination, he has epitrochlear lymphadenopathy. Which of the following is the likely diagnosis?

Secondary syphilis. ***Secondary syphilis*** - The classic rash of secondary syphilis is a diffuse, maculopapular eruption that characteristically involves the **palms and soles**, as seen in the image. A history of multiple sexual partners is a major risk factor. - **Epitrochlear lymphadenopathy** is a highly suggestive, though not pathognomonic, sign of secondary syphilis. Other systemic symptoms may include fever, malaise, and **condylomata lata**. *Psoriasis* - While psoriasis can affect the palms and soles (**palmoplantar psoriasis**), it typically presents as well-demarcated, erythematous plaques with a silvery scale, which differs from the rash shown. - Psoriasis is an autoimmune condition and is not associated with **epitrochlear lymphadenopathy** or risk factors like multiple sexual partners. *Meningococcemia* - This is an acute, life-threatening infection that presents with a **petechial or purpuric rash** that can become necrotic, not a papular rash on the palms and soles. - Patients with **meningococcemia** are typically systemically unwell with high fever, hypotension, and signs of meningitis, which are absent in this presentation. *Steven Johnson syndrome* - SJS is a severe mucocutaneous reaction characterized by **targetoid lesions**, bullae, and epidermal detachment, which are not features of the rash shown. - A key feature of SJS is severe involvement of at least two **mucous membranes** (e.g., oral, ocular, genital), which is not mentioned in this case.

Q: A patient presents with an indurated plaque on the cheek with central atrophy. Chest X-ray reveals apical calcification. Which of the following tests is most appropriate to confirm the diagnosis?

PCR. ***PCR*** - The clinical picture of an indurated plaque (often exhibiting **apple-jelly nodules** on diascopy) with central atrophy, coupled with radiological evidence of old pulmonary TB (apical calcification), strongly suggests **Lupus Vulgaris** (cutaneous tuberculosis). - **PCR (Polymerase Chain Reaction)** is the most sensitive and specific method for confirming the diagnosis by detecting *Mycobacterium tuberculosis* DNA, which is essential as Lupus Vulgaris is typically a **paucibacillary** condition where AFB staining and culture often fail. *Mantoux test* - The **Mantoux test** assesses delayed-type hypersensitivity (Type IV reaction) to tuberculin antigens and indicates prior exposure to TB or BCG vaccination. - It is useful for screening but **does not confirm active disease** (Lupus Vulgaris) and can be negative in immunocompromised patients or anergic forms. *Slit skin smear* - **Slit skin smear** is the diagnostic method primarily used to detect **acid-fast bacilli** (*M. leprae*) and classify **Leprosy** (Hansen's disease). - It is **not the investigation of choice** for diagnosing tuberculosis. *Probe test* - Nucleic acid **probe tests** (hybridization) are molecular techniques used to identify *M. tuberculosis* but are generally less sensitive than modern **PCR** assays, especially when dealing with limited tissue samples or low bacterial load. - **PCR** is the superior and more widely employed molecular diagnostic standard for confirming paucibacillary TB.

Q: A male presents with lesions as shown in the image and a history of unprotected sexual intercourse a few months ago. What is the most appropriate investigation to confirm the diagnosis?

Serology. ***Serology*** - The clinical presentation (diffuse body rash, often involving the palms and soles, following recent unprotected sexual exposure) is highly suggestive of **Secondary Syphilis**. - **Serological tests** (Non-treponemal tests like RPR/VDRL and specific Treponemal tests like TPPA/FTA-ABS) are the definitive and most appropriate confirmatory investigation for syphilis. *Tzanck smear* - This test is used primarily for the rapid diagnosis of vesicular lesions caused by herpes viruses, such as **Herpes Simplex Virus (HSV)** or **Varicella-Zoster Virus (VZV)**. - It is not indicated for the diagnosis of the typical maculopapular rash seen in secondary syphilis. *KOH* - **Potassium hydroxide (KOH) preparation** is a direct microscopy test specifically used to identify structures like hyphae and spores in the diagnosis of **superficial fungal infections**. - The patient's presentation with a rash secondary to sexually transmitted infection is not typically investigated using KOH. *Biopsy* - While a skin biopsy might confirm the diagnosis histologically (showing characteristic perivascular infiltrate), it is **invasive** and generally reserved for cases where serology is equivocal or the presentation is atypical. - **Serology** provides a systemic assessment and is the standard initial confirmatory test for syphilis.

Question 1

A young man presents with asymptomatic macules and erythematous painless lesions over the glans with generalized lymphadenopathy. What is the treatment of choice for this condition?

Accepted Answer

Benzathine penicillin

Answer

Ceftriaxone

Answer

Acyclovir

Answer

Fluconazole

Question 2

A boy from Bihar presents with a non-anesthetic, hypopigmented, atrophic patch over his face. What is the diagnosis?

Accepted Answer

Indeterminate leprosy

Answer

Pityriasis alba

Answer

Pityriasis versicolor

Answer

Borderline leprosy

Question 3

A patient with borderline tuberculoid leprosy presents with the following findings. Which type of hypersensitivity reaction and nerve is enlarged?

Accepted Answer

Type 4 & greater auricular nerve

Answer

Type 1 & greater auricular nerve

Answer

Type 3 & anterior auricular nerve

Answer

Type 2 & greater auricular nerve

Question 4

A 30-year-old female presents with a painful red granular lesion on the vulva accompanied by bilateral lymphadenopathy. What is the most likely diagnosis?

Accepted Answer

Chancroid

Answer

Neisseria Gonorrhoeae Infection

Answer

Lymphogranuloma Venereum

Answer

Granuloma Inguinale

Question 5

A person with the H/o long-term sexual relationship presented with painful ulcers on his genitals with tender lymphadenopathy. What is the diagnosis?

Accepted Answer

Chancroid

Answer

LGV

Answer

Chlamydia

Answer

Gonorrhoea

Question 6

A 45-year-old truck driver with a history of multiple sex partners presented to the dermatological department, as shown below. What is the likely diagnosis?

Accepted Answer

Secondary syphilis

Answer

Lichen planus

Answer

Scabies

Answer

Psoriasis

Question 7

A patient presents with erythematous streaks extending peripherally from a site of infection on the skin. Involvement of which of the following structures leads to this clinical presentation?

Accepted Answer

Superficial lymphatics

Answer

Skin

Answer

Superficial veins

Answer

Deep lymphatics

Question 8

A 45-year-old man with multiple sexual partners presents with a palmoplantar rash as seen below. On examination, he has epitrochlear lymphadenopathy. Which of the following is the likely diagnosis?

Accepted Answer

Secondary syphilis

Answer

Psoriasis

Answer

Meningococcemia

Answer

Stevens-Johnson syndrome

Question 9

A patient presents with an indurated plaque on the cheek with central atrophy. Chest X-ray reveals apical calcification. Which of the following tests is most appropriate to confirm the diagnosis?

Accepted Answer

PCR

Answer

Mantoux test

Answer

Slit skin smear

Answer

Probe test

Question 10

A male presents with lesions as shown in the image and a history of unprotected sexual intercourse a few months ago. What is the most appropriate investigation to confirm the diagnosis?

Accepted Answer

Serology

Answer

Tzanck smear

Answer

KOH

Answer

Biopsy

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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