Bacterial Skin Infections Practice Questions

Q: Which of the following conditions is characterized by 'honey-colored' crusts?

Impetigo. **Explanation:** **Impetigo** is the correct answer. It is a highly contagious, superficial bacterial skin infection most commonly caused by *Staphylococcus aureus* or *Streptococcus pyogenes*. The hallmark clinical feature of **Non-bullous Impetigo** (the most common form) is the formation of thin-walled vesicles or pustules that rupture to release an exudate, which dries into characteristic **"honey-colored" (golden) crusts**. These are typically found on the face, particularly around the nose and mouth. **Why the other options are incorrect:** * **Nummular eczema:** Characterized by coin-shaped, itchy, erythematous plaques. While they can ooze, they do not typically form the classic golden crusts seen in impetigo. * **Herpes zoster:** Presents as painful, dermatomal, grouped vesicles on an erythematous base. The crusts formed after vesicles rupture are usually hemorrhagic or dark, not honey-colored. * **Cutaneous diphtheria:** Caused by *Corynebacterium diphtheriae*, it typically presents as a "punched-out" ulcer with a greyish-white **pseudomembrane**, rather than superficial golden crusting. **High-Yield Clinical Pearls for NEET-PG:** * **Bullous Impetigo:** Always caused by *S. aureus* producing exfoliative toxins (ETA, ETB) that target **Desmoglein 1**. * **Ecthyma:** A deeper form of impetigo that extends into the dermis, resulting in "punched-out" ulcers covered with thick crusts. * **Treatment:** Topical **Mupirocin** or Retapamulin is the first-line treatment for localized lesions. * **Complication:** While impetigo can lead to Post-Streptococcal Glomerulonephritis (PSGN), it does *not* lead to Rheumatic Fever.

Q: A patient presents with bilateral tender lymphadenopathy and a history of sexual contact. The patient is a truck driver by profession. What is the probable causative agent?

Lymphogranuloma venereum. ### Explanation The clinical presentation of **bilateral tender lymphadenopathy** in a patient with a high-risk sexual history (often associated with mobile professions like truck driving) points toward **Lymphogranuloma venereum (LGV)** [1]. **1. Why LGV is the Correct Answer:** LGV is caused by **Chlamydia trachomatis (serotypes L1, L2, L3)**. The disease typically progresses through three stages. The second stage, the **inguinal syndrome**, is characterized by painful, often bilateral, inguinal lymphadenopathy [1]. A classic clinical sign is the **"Groove sign,"** where the inguinal ligament creates a depression between the inflamed superficial and deep inguinal nodes. **2. Why the Other Options are Incorrect:** * **Herpes simplex virus (HSV):** While HSV causes painful lymphadenopathy, it is almost always accompanied by **multiple, painful, grouped vesicles** or shallow ulcers [1]. The primary complaint here is the lymphadenopathy itself. * **Haemophilus ducreyi (Chancroid):** This causes a **painful, soft ulcer** with ragged edges [1]. While it causes tender lymphadenopathy (buboes), they are typically **unilateral** and prone to suppuration/rupture. * **Treponema pallidum (Syphilis):** Primary syphilis presents with a **painless** chancre and **painless, non-tender, rubbery** lymphadenopathy. **3. Clinical Pearls for NEET-PG:** * **Causative Agent:** *Chlamydia trachomatis* L1-L3. * **Diagnosis:** Nucleic Acid Amplification Test (NAAT) is the preferred method. * **Treatment of Choice:** **Doxycycline 100 mg BID for 21 days** [1]. (Note: Standard Chlamydia urethritis only requires 7 days). * **Esthiomene:** A chronic complication of LGV in females involving lymphatic obstruction leading to vulvar elephantiasis. * **Truck Drivers:** Frequently used in Indian medical exams as a social marker for high-risk sexual behavior and STIs [1].

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

Intensely pruritic. Secondary syphilis, often called the **"Great Imitator,"** occurs due to the systemic hematogenous spread of *Treponema pallidum*. [1] **Why Option A is the Correct Answer:** The hallmark of the secondary syphilitic rash is that it is **non-pruritic** (not itchy); it is classically described as non-irritable. [1] In dermatology, most generalized rashes are itchy; however, syphilis is a classic exception. If a patient presents with a generalized maculopapular rash that does **not** itch, secondary syphilis should be the first differential diagnosis. **Analysis of Incorrect Options:** * **Option B (Papular/maculopapular):** This is the most common morphology. The rash typically begins as faint pink-to-red macules that evolve into papules. [1], [2] * **Option C (Symmetrical):** The eruption is characteristically widespread and bilaterally symmetrical, involving the trunk and extremities. [1] * **Option D (Pleomorphic):** Secondary syphilis is known for its variety. Lesions can be macular, papular, pustular, or squamous (psoriasiform) occurring simultaneously. [1] However, it **never** presents as vesicular or bullous lesions in adults (except in congenital syphilis). **High-Yield Clinical Pearls for NEET-PG:** * **Palm and Sole Involvement:** A maculopapular rash involving the palms and soles is a high-yield diagnostic clue for secondary syphilis. [1], [2] * **Condyloma Lata:** These are moist, flat-topped, highly infectious papules found in intertriginous areas (e.g., perianal region). [1] * **Lues Maligna:** A rare, severe form of secondary syphilis with necrotic lesions, usually seen in HIV-positive patients. * **Diagnosis:** Screening is done via **VDRL/RPR** (non-treponemal), and confirmation is via **FTA-ABS/TPHA** (treponemal).

Q: Which type of leprosy is characterized by these lesions?

Borderline tuberculoid leprosy. ***Borderline tuberculoid leprosy*** - Characterized by **hypopigmented/erythematous plaques** with **well-defined outer borders** and **less well-defined inner borders**, often with **satellite lesions**. - Shows **paucibacillary** infection with **partial cell-mediated immunity**, resulting in **asymmetric distribution** of lesions. *Tuberculoid leprosy* - Features **single or few lesions** with **sharply defined borders** and complete **anesthesia** within the lesion. - Has **strong cell-mediated immunity** with **no bacilli** found on skin smears, unlike the partial immunity in borderline forms. *Lepromatous leprosy* - Presents with **multiple symmetric nodules** and **infiltrated plaques** without clear borders. - Shows **multibacillary** infection with **poor cell-mediated immunity**, resulting in **bilateral symmetric** distribution. *Histoid leprosy* - Characterized by **firm nodular lesions** with a **histiocytic appearance** on histology. - Typically occurs as a **relapse** in treated lepromatous cases or in **untreated multibacillary** patients with high bacterial load.

Q: Wood's lamp examination in dermatology typically reveals a coral red fluorescence in which of the following conditions?

Erythrasma. **Explanation:** **Erythrasma** is the correct answer. It is a superficial bacterial infection caused by *Corynebacterium minutissimum*. The hallmark diagnostic feature under **Wood’s lamp examination** is a characteristic **coral-red fluorescence**. This occurs because the bacteria produce **coproporphyrin III**, which fluoresces when exposed to ultraviolet light (365 nm). Clinically, it presents as well-demarcated, reddish-brown, macerated plaques in intertriginous areas (axilla, groin, or toe webs). **Analysis of Incorrect Options:** * **Porphyria Cutanea Tarda (PCT):** While PCT involves porphyrins, Wood’s lamp examination of the **urine** (not the skin) typically shows a pink-orange or coral-red fluorescence. Skin lesions themselves do not typically show this fluorescence. * **Livedo Reticularis:** This is a vascular condition characterized by a reticulated (net-like) cyanotic pattern due to altered blood flow. It does not exhibit fluorescence under Wood’s lamp. * **Hypomelanosis (e.g., Vitiligo):** Wood’s lamp is used here to detect pigment loss. Depigmented areas (Vitiligo) appear **milky-white** and accentuated, while hypopigmented areas (Pityriasis versicolor) may show a pale yellow/gold fluorescence. **High-Yield Clinical Pearls for NEET-PG:** * **Tinea Versicolor:** Shows **yellowish-gold** fluorescence (due to *Malassezia*). * **Tinea Capitis (Microsporum):** Shows **bright greenish** fluorescence. * **Pseudomonas (Burn infections):** Shows **apple-green** fluorescence (due to pyoverdin). * **Treatment of Erythrasma:** Topical fusidic acid or clindamycin; oral Erythromycin for extensive cases.

Q: A 20-year-old male presents with multiple painful ulcers over the prepuce and glans, accompanied by suppurative lymphadenopathy, developing two weeks after unprotected sexual intercourse. What is the most probable diagnosis?

Chancroid. ### **Explanation** The clinical presentation of **painful ulcers** associated with **suppurative lymphadenopathy** (buboes) is the classic hallmark of **Chancroid**, caused by the Gram-negative coccobacillus *Haemophilus ducreyi* [1]. #### **Why Chancroid is Correct:** 1. **Painful Ulcers:** Unlike syphilis, the ulcers in chancroid are characteristically painful, soft, and often have ragged, undermined edges with a gray/yellow purulent base [1]. 2. **Suppurative Lymphadenopathy:** About 50% of patients develop painful inguinal lymphadenitis. These "buboes" are typically unilateral and frequently progress to suppuration (pus formation) and spontaneous rupture [1]. 3. **Incubation Period:** The 2-week timeline fits the typical 3–14 day incubation period of *H. ducreyi* [1]. #### **Why Other Options are Incorrect:** * **Herpes Simplex (HSV-2):** While painful, HSV presents as multiple small, superficial **vesicles** on an erythematous base that later rupture into shallow ulcers [1]. Lymphadenopathy is usually bilateral and non-suppurative. * **Molluscum Contagiosum:** Presents as **painless**, firm, pearly, umbilicated papules. It does not cause ulcers or suppurative lymphadenopathy. * **Syphilis (Primary):** Caused by *Treponema pallidum*, the classic chancre is **painless**, indurated (hard), and associated with painless, non-suppurative regional lymphadenopathy [1]. #### **NEET-PG High-Yield Pearls:** * **School of Fish Appearance:** On Gram stain, *H. ducreyi* shows a characteristic "railroad track" or "school of fish" pattern. * **The "P" Rule:** Remember **Chancroid = Painful** (Soft Chancre) vs. **Syphilis = Painless** (Hard Chancre). * **Treatment:** A single dose of **Azithromycin (1g orally)** or Ceftriaxone (250mg IM). * **Differential for Buboes:** If the lymphadenopathy is associated with a small, transient, *painless* ulcer, consider **Lymphogranuloma Venereum (LGV)** (Chlamydia trachomatis L1-L3) [1].

Q: What is the recommended treatment for granuloma inguinale?

Azithromycin. **Explanation:** **Granuloma Inguinale (Donovanosis)** is a chronic bacterial infection caused by the Gram-negative intracellular organism *Klebsiella granulomatis*. It is characterized by painless, beefy-red, vascular ulcerative lesions that bleed easily on contact. **Why Azithromycin is correct:** According to the current **CDC and WHO guidelines**, **Azithromycin (1g orally once a week or 500mg daily) for at least 3 weeks** is the first-line treatment of choice. It is preferred due to its high intracellular concentration, long half-life, and superior efficacy in achieving complete healing of the lesions compared to older regimens. Treatment must be continued until all lesions have completely epithelialized. **Analysis of Incorrect Options:** * **A. Tetracycline:** While Doxycycline (a tetracycline) is a recommended alternative, it is no longer the first-line agent due to the superior dosing convenience and safety profile of Azithromycin. * **C. Clarithromycin:** Although it belongs to the same Macrolide class as Azithromycin, it is not the standard protocol for Donovanosis and requires more frequent dosing. * **D. Streptomycin:** This was historically used but is now obsolete for this condition due to the risk of ototoxicity, nephrotoxicity, and the requirement for parenteral administration. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Sign:** Presence of **Donovan bodies** (safety-pin appearance) within macrophages on a Giemsa or Wright stain. * **Clinical Presentation:** "Painless but progressive" ulcers; pseudobuboes (inguinal swelling due to granulation tissue, not lymphadenopathy). * **Alternative Regimens:** Doxycycline (100mg BID), Erythromycin, or Trimethoprim-Sulfamethoxazole. * **Pregnancy:** Azithromycin remains the drug of choice for pregnant women with Donovanosis.

Q: A leprosy patient on multidrug therapy develops a type II lepra reaction. What is the recommended next course of action?

Start steroids and clofazimine. **Explanation:** Type II Lepra Reaction (Erythema Nodosum Leprosum - ENL) is a **Type III hypersensitivity reaction** (immune-complex mediated) occurring primarily in lepromatous (LL) and borderline lepromatous (BL) leprosy. It is characterized by tender, evanescent subcutaneous nodules, fever, and systemic involvement (neuritis, arthritis, or orchitis). **Why Option C is Correct:** The management of ENL requires controlling the acute inflammation while preventing recurrences. 1. **Systemic Steroids (Prednisolone):** These are the first-line agents to rapidly suppress the acute inflammatory response and prevent nerve damage. 2. **Clofazimine:** This drug has both anti-mycobacterial and **anti-inflammatory** properties. In ENL, it is used in higher doses (up to 300 mg/day) to allow for the tapering of steroids and to prevent future episodes of ENL. **Why Other Options are Wrong:** * **Option A:** Multidrug Therapy (MDT) should **never** be stopped during a lepra reaction. Stopping MDT leads to drug resistance and disease progression. * **Option B:** While steroids are essential, using them alone (without clofazimine) often leads to "steroid dependence" or frequent relapses once the dose is tapered. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** For severe/recurrent ENL, **Thalidomide** is the most effective drug (though contraindicated in pregnancy due to phocomelia). * **Type I vs. Type II:** Type I is a Type IV hypersensitivity (Delayed) occurring in borderline cases; Type II is a Type III hypersensitivity (Immune-complex) occurring in multibacillary cases. * **MDT Protocol:** Always continue WHO-MDT during both Type I and Type II reactions.

Q: Which statement is true regarding gonococcal urethritis?

Most patients present with symptoms of dysuria.. Explanation: **Gonococcal Urethritis** is caused by the Gram-negative diplococcus *Neisseria gonorrhoeae*. In males, it typically presents as an acute, symptomatic infection of the anterior urethra. 1. **Why Option C is correct:** Dysuria (painful urination) and a profuse, purulent urethral discharge [1] are the hallmark symptoms of gonococcal urethritis. In males, more than 90% of cases are symptomatic, with dysuria being the most common presenting complaint. 2. **Why Option A is incorrect:** Symptoms are significantly **more severe in males** than in females. In females, the primary site of infection is the endocervix, and the infection is often asymptomatic or presents with mild, non-specific symptoms (vaginal discharge or intermenstrual bleeding). 3. **Why Option B is incorrect:** The rectum and prostate are **not resistant**. *N. gonorrhoeae* can infect any mucosal surface lined with columnar or cuboidal epithelium. Prostatitis is a known local complication in males [3], and proctitis is common in individuals practicing receptive anal intercourse. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Short, typically 2–7 days [1] (compared to 7–14 days for Chlamydia). * **Diagnosis:** Gram stain showing **Gram-negative intracellular diplococci** within polymorphonuclear leukocytes (PMNs) is highly sensitive (95%) in symptomatic males. **NAAT** (Nucleic Acid Amplification Test) is the gold standard for screening. * **Treatment:** Due to increasing resistance, the current CDC/WHO recommendation is a single dose of **Ceftriaxone (IM)** [2]. Always co-treat for Chlamydia (e.g., Doxycycline) if it hasn't been ruled out. * **Complications:** If untreated, it can lead to Epididymitis in males and Pelvic Inflammatory Disease (PID) or Fitz-Hugh-Curtis syndrome in females.

Question 1

Which of the following conditions is characterized by 'honey-colored' crusts?

Accepted Answer

Impetigo

Answer

Nummular eczema

Answer

Herpes zoster

Answer

Cutaneous diphtheria

Question 2

A patient presents with bilateral tender lymphadenopathy and a history of sexual contact. The patient is a truck driver by profession. What is the probable causative agent?

Accepted Answer

Lymphogranuloma venereum

Answer

Herpes simplex virus

Answer

Haemophilus ducreyi

Answer

Treponema pallidum

Question 3

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

Accepted Answer

Intensely pruritic

Answer

Papular/maculopapular eruption

Answer

Symmetrical

Answer

Pleomorphic

Question 4

Which type of leprosy is characterized by these lesions?

Accepted Answer

Borderline tuberculoid leprosy

Answer

Tuberculoid leprosy

Answer

Lepromatous leprosy

Answer

Histoid leprosy

Question 5

Wood's lamp examination in dermatology typically reveals a coral red fluorescence in which of the following conditions?

Accepted Answer

Erythrasma

Answer

Porphyria cutanea tarda

Answer

Livedo reticularis

Answer

Hypomelanosis

Question 6

A 20-year-old male presents with multiple painful ulcers over the prepuce and glans, accompanied by suppurative lymphadenopathy, developing two weeks after unprotected sexual intercourse. What is the most probable diagnosis?

Accepted Answer

Chancroid

Answer

Herpes simplex

Answer

Molluscum contagiosum

Answer

Syphilis

Question 7

What is the recommended treatment for granuloma inguinale?

Accepted Answer

Azithromycin

Answer

Tetracycline

Answer

Clarithromycin

Answer

Streptomycin

Question 8

A leprosy patient on multidrug therapy develops a type II lepra reaction. What is the recommended next course of action?

Accepted Answer

Start steroids and clofazimine

Answer

Stop multidrug therapy

Answer

Start steroids

Answer

None of the above

Question 9

Which statement is true regarding gonococcal urethritis?

Accepted Answer

Most patients present with symptoms of dysuria.

Answer

Symptoms are more severe in females than in males.

Answer

The rectum and prostate are resistant to gonococci.

Answer

All of the above.

Question 10

A 35-year-old male with a history of multiple sex partners presents with urethral discharge. What is the best treatment option?

Accepted Answer

Cefixime + azithromycin

Answer

Ceftriaxone + quinolone

Answer

Erythromycin

Answer

Ceftriaxone + doxycycline

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

On this page

Practice by Chapter

Want unlimited practice?