Bacterial Skin Infections Practice Questions

Q: Pseudo Bubo is seen in which of the following conditions?

Granuloma inguinale (Donovanosis). The correct answer is **Granuloma inguinale (Donovanosis)**. **1. Why Granuloma Inguinale is correct:** In Granuloma inguinale, caused by *Klebsiella granulomatis*, the infection typically presents as painless, beefy-red, highly vascular ulcers. Unlike other sexually transmitted infections, it does **not** involve true regional lymphadenopathy. Instead, it causes subcutaneous inflammatory nodules or granulation tissue in the inguinal region that mimic the appearance of an enlarged lymph node (bubo). Because this swelling is due to subcutaneous involvement rather than actual lymph node enlargement, it is termed a **"Pseudo Bubo."** [1] **2. Why other options are incorrect:** * **Chancroid:** Caused by *Haemophilus ducreyi*, it presents with painful ulcers and **true buboes** (suppurative lymphadenopathy) that are often unilateral and may rupture. [1] * **Lymphogranuloma venereum (LGV):** Caused by *Chlamydia trachomatis* (L1-L3), it is characterized by significant **true lymphadenopathy**. It often presents with the "Groove sign," where the inguinal ligament divides the matted lymph nodes. [1] * **Syphilis:** Primary syphilis presents with a painless chancre and firm, non-suppurative, painless **true regional lymphadenopathy**. **Clinical Pearls for NEET-PG:** * **Donovan Bodies:** Diagnosis of Granuloma inguinale is confirmed by seeing "safety-pin" shaped organisms within macrophages on a Giemsa or Wright stain. * **Beefy Red Ulcer:** A classic descriptor for Donovanosis; these ulcers bleed easily on touch. * **Treatment:** Azithromycin (1g weekly or 500mg daily) is the first-line treatment for Granuloma inguinale. * **Groove Sign:** Pathognomonic for LGV, not Pseudo Bubo.

Q: Which of the following is NOT a primary site of acute gonococcal infection?

Ectocervix. The primary sites of acute gonococcal infection are determined by the type of epithelium present. *Neisseria gonorrhoeae* has a strong predilection for **columnar and transitional epithelium**, while it is resistant to the stratified squamous epithelium found in the adult vagina and ectocervix. **Why Ectocervix is the Correct Answer:** In adult females, the **endocervix** (lined by columnar epithelium) is the most common primary site of infection. The **ectocervix**, however, is covered by **stratified squamous epithelium**, which is resistant to gonococcal invasion. Therefore, it is not a primary site of infection. **Analysis of Other Options:** * **Urethra (A):** Lined by transitional and columnar epithelium, it is the most common site of infection in men and a frequent site in women. * **Bartholin's Glands (B):** These are located in the posterior third of the labia majora. Their ducts are lined by columnar epithelium, making them a common site for acute gonococcal abscess formation. * **Skene's Glands (C):** Also known as paraurethral glands, these are lined by columnar epithelium and are frequently involved in female gonococcal infections. **Clinical Pearls for NEET-PG:** * **Primary Sites in Females:** Endocervix (most common), Urethra, Skene’s glands, and Bartholin’s glands. * **Vulvovaginitis:** While adults are resistant due to squamous epithelium, **pre-pubertal girls** can develop gonococcal vulvovaginitis because their vaginal mucosa is thin and has not yet undergone squamous cornification (due to low estrogen). * **Gold Standard Diagnosis:** Culture on **Thayer-Martin medium** (a selective Chocolate agar). * **Treatment:** Due to rising resistance, the current CDC/WHO recommendation is typically a single dose of **Ceftriaxone (IM)** [1]. Always screen for co-infection with *Chlamydia trachomatis*.

Q: A 48-year-old male presents with a three-month history of non-itchy, generalized papulo-nodular lesions. Physical examination reveals no other abnormalities. Slit smear from a nodule is negative for acid-fast bacilli (AFB). Blood VDRL is reactive at a 1:2 dilution. What is the most likely diagnosis?

Secondary syphilis. **Explanation:** The clinical presentation of generalized, non-itchy papulo-nodular lesions in an adult, combined with a reactive VDRL, is classic for **Secondary Syphilis**. Known as the "Great Imitator," secondary syphilis typically presents with a polymorphic rash (macular, papular, or nodular) that characteristically involves the palms and soles. A VDRL titer of 1:2, while low, is significant in the context of suggestive clinical lesions. **Why the other options are incorrect:** * **Lepromatous Leprosy:** While it presents with generalized nodules, the **negative slit skin smear (SSS)** for Acid-Fast Bacilli (AFB) effectively rules this out, as lepromatous leprosy (multibacillary) would show a high bacterial index. * **Post Kala-Azar Dermal Leishmaniasis (PKDL):** This typically presents with hypopigmented macules, malar erythema, or nodules following an episode of Visceral Leishmaniasis. It would not cause a reactive VDRL. * **Drug Eruption:** These are usually acute in onset, often pruritic (itchy), and temporally related to drug intake. They do not explain the reactive syphilis serology. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Syphilis:** Always look for involvement of palms and soles, generalized lymphadenopathy (epitrochlear), and "moth-eaten" alopecia. * **Prozone Phenomenon:** In secondary syphilis, very high antibody titers can sometimes cause a false-negative VDRL result; the serum must be diluted to get a positive result. * **VDRL vs. TPHA:** VDRL is a non-specific screening test (titer reflects disease activity), while TPHA/FTA-ABS are specific treponemal tests that remain positive for life.

Q: Erythema nodosum leprosum is seen in a 16-year-old boy. This is a feature of which of the following types of leprosy?

Lepromatous. **Explanation:** **Erythema Nodosum Leprosum (ENL)**, also known as a **Type 2 Lepra Reaction**, is a classic example of a **Type III hypersensitivity reaction** (immune-complex mediated). It occurs due to the deposition of antigen-antibody complexes in tissues, leading to systemic inflammation. 1. **Why Lepromatous (Option A) is correct:** ENL occurs almost exclusively in patients with a high bacterial load (multibacillary) and high humoral (antibody) response. It is most commonly seen in **Lepromatous Leprosy (LL)** and sometimes in **Borderline Lepromatous (BL)** leprosy. It is triggered by the rapid killing of *M. leprae* (often after starting MDT), which releases large amounts of fragmented bacterial antigens into the bloodstream. 2. **Why other options are incorrect:** * **Tuberculoid (TT) and Borderline Tuberculoid (BT):** These are paucibacillary forms with high cell-mediated immunity (CMI) and very low bacterial load. Type 2 reactions (ENL) do not occur here; instead, these patients are prone to **Type 1 Lepra Reactions** (Delayed Hypersensitivity). * **Borderline (BB):** While borderline cases can shift, ENL is specifically associated with the "lepromatous end" of the spectrum where the bacillary index is high. **Clinical Pearls for NEET-PG:** * **Clinical Features:** Characterized by sudden onset of tender, evanescent, erythematous nodules, high-grade fever, malaise, and systemic involvement (neuritis, orchitis, iridocyclitis, and glomerulonephritis). * **Drug of Choice:** **Thalidomide** is the most effective treatment for ENL. Systemic corticosteroids and Clofazimine are also used. * **Timing:** Unlike Type 1 reactions (which occur early), ENL typically occurs later in the course of treatment.

Q: In secondary syphilis, which one of the following features is not found?

Aortitis. **Explanation:** The correct answer is **C. Aortitis**. Syphilis, caused by *Treponema pallidum*, progresses through distinct clinical stages [1]. Understanding the timing of systemic involvement is crucial for the NEET-PG exam. **1. Why Aortitis is the correct answer:** Aortitis is a manifestation of **Tertiary Syphilis** (Late Syphilis), occurring typically 10–30 years after the initial infection. It results from *vasa vasorum* inflammation (endarteritis obliterans), leading to medial necrosis and weakening of the aortic wall [1]. This can result in aortic aneurysms or aortic regurgitation. It is **not** a feature of the secondary stage. **2. Why the other options are incorrect:** * **Maculopapular rashes (Option A):** This is the most common cutaneous manifestation of Secondary Syphilis. The rash is typically widespread, symmetrical, and characteristically involves the **palms and soles** [1]. * **Generalized non-tender lymphadenopathy (Option B):** Secondary syphilis is a systemic spirochaetemic stage. Rubbery, discrete, and non-tender enlargement of lymph nodes (especially epitrochlear nodes) is a hallmark finding. * **Follicular syphilides (Option C):** These are small, papular lesions localized around hair follicles, often seen in secondary syphilis. They can lead to "moth-eaten" alopecia. **Clinical Pearls for NEET-PG:** * **Secondary Syphilis** is known as "The Great Imitator" and is the most florid stage. * **Condyloma Lata:** Highly infectious, moist, flat-topped papules in intertriginous areas (Secondary stage) [1]. * **Lues Maligna:** A severe pleomorphic form of secondary syphilis seen in HIV patients. * **Drug of Choice:** Benzathine Penicillin G remains the gold standard for all stages, though dosages vary.

Q: A single hypopigmented anesthetic patch with a satellite lesion on the forearm is likely diagnosed as which of the following?

Tuberculoid leprosy. **Explanation:** The clinical presentation of a **single hypopigmented, anesthetic patch** associated with **satellite lesions** is a classic hallmark of **Tuberculoid Leprosy (TT)**. In Tuberculoid Leprosy, the host possesses high cell-mediated immunity (CMI). This strong immune response localizes the infection to a single or very few lesions (usually 1–3). The hallmark features include well-defined margins, complete loss of sensation (anesthesia) due to nerve damage within the patch, and hair loss (alopecia). **Satellite lesions** (smaller macules or papules near the periphery of the main patch) are characteristic of the polar tuberculoid spectrum. **Analysis of Incorrect Options:** * **Indeterminate Leprosy:** This is the earliest stage. It typically presents as a single hypopigmented macule with *vague* margins and *partial* (not complete) sensory loss. Satellite lesions are not seen here. * **Neuritic Leprosy:** This form involves purely neurological symptoms (nerve thickening, pain, and sensory loss) in the distribution of a nerve, but it is characterized by the **absence** of any visible skin patches. * **Lupus Vulgaris:** This is a form of cutaneous tuberculosis. While it presents as a plaque, it is typically reddish-brown ("apple-jelly" nodules on diascopy) and is **not anesthetic**. **High-Yield Clinical Pearls for NEET-PG:** * **Ridley-Jopling Classification:** TT is the most stable form with the highest CMI. * **Nerve Involvement:** In TT, nerves are often thickened asymmetrically (e.g., ulnar or greater auricular nerve). * **Lepromin Test:** Strongly **positive** in Tuberculoid Leprosy (reflecting high CMI) and negative in Lepromatous Leprosy. * **Histopathology:** Shows well-formed non-caseating granulomas with rare or absent Acid-Fast Bacilli (paucibacillary).

Q: Multibacillary leprosy is characterized by which of the following?

Bacteriological index of 2 or greater. **Explanation:** The classification of Leprosy is a high-yield topic for NEET-PG, primarily following the **WHO Operational Classification**, which simplifies treatment protocols into Paucibacillary (PB) and Multibacillary (MB) types. **Why Option B is Correct:** According to the WHO classification, **Multibacillary (MB) leprosy** is defined by a high bacterial load. A **Bacteriological Index (BI) of ≥ 2+** at any site (using slit-skin smears) is a definitive diagnostic criterion for MB leprosy. Even if a patient has few skin lesions, a positive smear automatically classifies them as MB to ensure they receive the more robust 12-month MDT regimen. **Analysis of Incorrect Options:** * **Option A:** Under the WHO criteria, MB leprosy is characterized by having **more than five ( >5 ) lesions**. The presence of exactly five lesions would still be classified as Paucibacillary (PB), which covers 1 to 5 lesions. * **Option C:** Indeterminate leprosy is typically characterized by a single hypopigmented macule with vague margins and is almost always classified and treated as **Paucibacillary (PB)** due to the low bacterial load. **High-Yield Clinical Pearls for NEET-PG:** * **WHO Classification Criteria for MB Leprosy:** 1. > 5 skin lesions. 2. > 1 nerve involvement (some guidelines state ≥ 2 nerves). 3. Positive skin smear (BI ≥ 2+). * **MDT Regimen for MB:** Rifampicin (600mg once monthly), Clofazimine (300mg once monthly + 50mg daily), and Dapsone (100mg daily) for **12 months**. * **Cardinal Signs:** Definite loss of sensation, thickened nerves, and presence of *M. leprae* on skin smear. * **Ridley-Jopling Scale:** MB typically corresponds to Mid-borderline (BB), Borderline Lepromatous (BL), and Lepromatous Leprosy (LL).

Q: All of the following are true about bullous impetigo EXCEPT?

Lesions have an erythematous base. **Explanation:** Bullous impetigo is a localized form of staphylococcal scalded skin syndrome (SSSS). The hallmark of this condition is the formation of large, flaccid bullae due to the action of **Exfoliative Toxin A** produced by *Staphylococcus aureus*. **Why Option D is the Correct Answer (The Exception):** Unlike non-bullous impetigo, the bullae in bullous impetigo typically arise on **normal-appearing skin** and lack a surrounding halo of erythema. When these bullae rupture, they leave behind a moist, red, "varnish-like" erosive surface, but the base is generally **not erythematous** in the initial stages. **Analysis of Other Options:** * **Option A:** It is caused exclusively by *Staphylococcus aureus* (Phage group II, type 71). This differs from non-bullous impetigo, which can be caused by both *S. aureus* and *S. pyogenes*. * **Option B:** It is most common in neonates (where it is known as Pemphigus neonatorum) and young children due to lack of immunity against the toxin and immature renal clearance. * **Option C:** While it can occur anywhere, the face is a very common site, along with intertriginous areas like the axilla and groin. **NEET-PG High-Yield Pearls:** * **Target Protein:** The exfoliative toxin cleaves **Desmoglein-1** (found in the upper epidermis), leading to subcorneal splitting. * **Nikolsky Sign:** Usually negative in bullous impetigo (localized), but positive in SSSS (generalized). * **Treatment:** Topical Mupirocin for localized lesions; oral anti-staphylococcal antibiotics (e.g., Dicloxacillin or Cephalexin) for extensive cases.

Q: All of the following skin infections are caused by Staphylococcus aureus, EXCEPT:

Erysipelas. **Explanation:** The primary distinction in bacterial skin infections lies in the causative organism and the depth of involvement. **1. Why Erysipelas is the correct answer:** Erysipelas is a superficial form of cellulitis characterized by sharp, well-demarcated borders and prominent lymphatic involvement. It is classically caused by **Group A Beta-hemolytic Streptococci (Streptococcus pyogenes)**, not *Staphylococcus aureus*. It typically affects the upper dermis and superficial lymphatics. **2. Why the other options are incorrect:** * **Folliculitis:** This is a superficial infection of the hair follicle. **Staphylococcus aureus** is the most common causative agent. * **Furuncle (Boil):** This is a deeper, necrotizing infection of the hair follicle and surrounding tissue, forming an abscess. It is almost exclusively caused by **Staphylococcus aureus**. * **Cellulitis:** While both *Streptococcus* and *Staphylococcus* can cause cellulitis, **Staphylococcus aureus** is a major cause, especially when associated with an open wound, trauma, or abscess. **3. Clinical Pearls for NEET-PG:** * **Erysipelas vs. Cellulitis:** Erysipelas has **raised, sharply defined edges** (superficial), whereas Cellulitis has **indistinct, flat borders** (deep dermis/subcutaneous fat). * **Staphylococcal Scalded Skin Syndrome (SSSS):** Caused by exfoliative toxins (A and B) from *S. aureus*; targets Desmoglein-1. * **Impetigo:** *S. aureus* is the most common cause of both bullous and non-bullous impetigo (though *S. pyogenes* also causes non-bullous). * **Ecthyma:** A deeper form of impetigo extending into the dermis, often caused by *Streptococcus*.

Question 1

Pseudo Bubo is seen in which of the following conditions?

Accepted Answer

Granuloma inguinale (Donovanosis)

Answer

Chancroid

Answer

Lymphogranuloma venereum (LGV)

Answer

Syphilis

Question 2

Which of the following is NOT a primary site of acute gonococcal infection?

Accepted Answer

Ectocervix

Answer

Urethra

Answer

Bartholin's gland

Answer

Skene's gland (paraurethral glands)

Question 3

A 48-year-old male presents with a three-month history of non-itchy, generalized papulo-nodular lesions. Physical examination reveals no other abnormalities. Slit smear from a nodule is negative for acid-fast bacilli (AFB). Blood VDRL is reactive at a 1:2 dilution. What is the most likely diagnosis?

Accepted Answer

Secondary syphilis

Answer

Drug eruption

Answer

Lepromatous leprosy

Answer

Post kala azar dermal leishmaniasis

Question 4

What is the treatment of choice for late cardiovascular syphilis?

Accepted Answer

Benzathine penicillin 7.2 million units in three divided doses

Answer

Benzathine penicillin 2.4 million units single dose

Answer

Benzylpenicillin 12-24 million units for 21 days

Answer

Tetracycline 2g daily

Question 5

Erythema nodosum leprosum is seen in a 16-year-old boy. This is a feature of which of the following types of leprosy?

Accepted Answer

Lepromatous

Answer

Borderline

Answer

Tuberculoid

Answer

Borderline tuberculoid

Question 6

In secondary syphilis, which one of the following features is not found?

Accepted Answer

Aortitis

Answer

Maculopapular rashes

Answer

Generalized non-tender lymphadenopathy

Answer

Follicular syphilides

Question 7

A single hypopigmented anesthetic patch with a satellite lesion on the forearm is likely diagnosed as which of the following?

Accepted Answer

Tuberculoid leprosy

Answer

Indeterminate leprosy

Answer

Neuritic leprosy

Answer

Lupus vulgaris

Question 8

Multibacillary leprosy is characterized by which of the following?

Accepted Answer

Bacteriological index of 2 or greater

Answer

Presence of five lesions

Answer

Indeterminate leprosy

Answer

All of the above

Question 9

All of the following are true about bullous impetigo EXCEPT?

Accepted Answer

Lesions have an erythematous base

Answer

Caused by Staphylococcus aureus

Answer

Common in neonates and infants

Answer

Lesions commonly occur on the face

Question 10

All of the following skin infections are caused by Staphylococcus aureus, EXCEPT:

Accepted Answer

Erysipelas

Answer

Folliculitis

Answer

Furuncle

Answer

Cellulitis

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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