Bacterial Skin Infections Practice Questions

Q: In which stage of syphilis does seropositivity typically become evident?

Muco patches (secondary syphilis). ### Explanation **Correct Answer: B. Muco patches (secondary syphilis)** **Medical Concept:** Seropositivity in syphilis refers to the detection of antibodies via non-treponemal (VDRL, RPR) or treponemal (FTA-ABS, TPHA) tests. In **Primary Syphilis**, the immune system has just been exposed to *Treponema pallidum*; therefore, tests are often negative during the first 1–3 weeks of the chancre's appearance (the "seronegative primary" phase) [1]. By the time the disease progresses to **Secondary Syphilis** (characterized by mucous patches, condyloma lata, and maculopapular rashes), the bacterial load is at its peak and the antibody response is fully developed [1]. Consequently, **seropositivity is 100%** in the secondary stage. **Analysis of Incorrect Options:** * **A. Chancre (Primary Syphilis):** Only about 30–50% of patients are seropositive when the chancre first appears. Diagnosis at this stage relies primarily on **Dark Ground Microscopy (DGM)** to visualize spirochetes. * **C. Gumma (Tertiary Syphilis):** While patients are seropositive here, this is a late manifestation occurring years after infection. The question asks when it *typically becomes evident*, which occurs much earlier in the secondary stage. * **D. Congenital Syphilis:** This is a mode of transmission (vertical) rather than a chronological stage of the primary infection sequence in an adult. **NEET-PG High-Yield Pearls:** * **Gold Standard for Primary Syphilis:** Dark Ground Microscopy (DGM). * **Secondary Syphilis:** Known as the "Great Imitator" and represents the most infectious stage [1]. * **Prozone Phenomenon:** Can cause a false-negative VDRL in secondary syphilis due to excessively high antibody titers; requires serum dilution for diagnosis [1]. * **Specific Test of Choice:** FTA-ABS is usually the first serological test to become positive (earlier than VDRL).

Q: Which of the following stages of syphilis is associated with primary bullous lesions?

Congenital syphilis. **Explanation:** The correct answer is **D. Congenital syphilis**. **Why Congenital Syphilis is Correct:** Syphilis is generally a "non-vesiculobullous" disease in adults. However, **Congenital Syphilis** is a notable exception. It is the only stage where primary bullous lesions, known as **Syphilitic Pemphigus**, occur. These are typically present at birth or appear within the first few weeks of life. The bullae are usually found on the palms and soles, are filled with serous or hemorrhagic fluid, and contain a high concentration of *Treponema pallidum*, making them highly infectious. **Why Other Options are Incorrect:** * **Primary Syphilis:** Characterized by a **Chancre**—a solitary, painless, indurated ulcer with a clean base and regional lymphadenopathy. It does not present with bullae. * **Secondary Syphilis:** Known as the "Great Imitator," it presents with a generalized maculopapular rash (including palms and soles), condyloma lata, and mucous patches. While it can be polymorphic, it **never** presents with vesicles or bullae in adults. * **Tertiary Syphilis:** Characterized by **Gummas** (chronic granulomatous lesions) and cardiovascular or neurological involvement. Bullous lesions are not a feature. **High-Yield Clinical Pearls for NEET-PG:** * **Syphilitic Pemphigus:** Always suspect congenital syphilis if a neonate presents with bullae on the palms and soles. * **Hutchinson’s Triad (Late Congenital Syphilis):** Interstitial keratitis, Hutchinson teeth (notched incisors), and Eighth nerve deafness. * **Drug of Choice:** Parenteral **Penicillin G** remains the gold standard for all stages of syphilis. * **Screening vs. Confirmatory:** VDRL/RPR are used for screening and monitoring treatment response, while TPHA/FTA-ABS are specific treponemal tests used for confirmation.

Q: A 35-year-old male presents with a painless indurated ulcer on the penis and enlarged, non-tender genital lymph nodes. What is the most likely diagnosis?

Syphilis. **Explanation:** The clinical presentation of a **painless, indurated ulcer** (Hard Chancre) associated with **non-tender, rubbery lymphadenopathy** is the classic hallmark of **Primary Syphilis** [1], caused by *Treponema pallidum*. **1. Why Syphilis is correct:** The primary chancre typically appears 3 weeks after exposure. Its defining features are its lack of pain and "button-like" induration (firmness). The associated inguinal lymphadenopathy is characteristically bilateral, painless, and non-suppurative, which matches the patient's description perfectly [1]. **2. Why other options are incorrect:** * **Chancroid (*Haemophilus ducreyi*):** Presents as a **painful**, soft ulcer with a ragged edge. The associated lymphadenopathy (bubo) is very painful and often undergoes suppuration [2]. * **Herpes Genitalis (HSV-2):** Presents as multiple, small, **painful vesicles** on an erythematous base that rupture to form shallow ulcers [1]. It is not indurated. * **Lymphogranuloma Venereum (LGV):** The initial primary lesion is a transient, painless papule or ulcer that often heals unnoticed. The dominant clinical feature is painful, massive inguinal lymphadenopathy (the "Groove sign") [2]. **Clinical Pearls for NEET-PG:** * **Investigation of choice:** Dark-field microscopy (to see corkscrew motility) is used for early lesions; VDRL/RPR are used for screening (but may be negative in the first 1-2 weeks of the chancre). * **Treatment:** Benzathine Penicillin G (2.4 million units IM single dose) remains the gold standard. * **Induration:** If an ulcer is firm/hard, think Syphilis; if it is soft/friable, think Chancroid.

Q: Leonine facies is seen in which type of leprosy?

Lepromatous. **Explanation:** **Leonine facies** (lion-like appearance) is a classic clinical hallmark of **Lepromatous Leprosy (LL)**. This occurs due to the hematogenous spread of *Mycobacterium leprae* in a host with low cell-mediated immunity (CMI). The high bacterial load leads to diffuse infiltration of the facial skin, resulting in: * Thickening and furrowing of the forehead and cheeks. * Widening of the nose. * Pendulous earlobes. * Loss of eyebrows (Madarosis), particularly the lateral one-third. **Analysis of Options:** * **Tuberculoid (TT):** Characterized by high CMI and few lesions (paucibacillary). Lesions are well-defined, anesthetic, and do not cause diffuse facial infiltration. * **Borderline Tuberculoid (BT):** Similar to TT but with more lesions and more nerve involvement; it does not present with the massive infiltration seen in LL. * **Borderline (BB):** An unstable form of leprosy that acts as a transition point. While it has more lesions than TT, it lacks the characteristic diffuse infiltration required to produce leonine facies. **High-Yield Clinical Pearls for NEET-PG:** * **Grenz Zone:** A clear sub-epidermal zone seen on histopathology in Lepromatous Leprosy (absent in TT). * **Globi:** Large clusters of acid-fast bacilli (AFB) found within **Virchow cells** (foamy macrophages) in LL. * **Bacteriological Index (BI):** Highest in LL (4+ to 6+), whereas it is 0 in TT. * **Differential Diagnosis:** Leonine facies can also be seen in **Post-Kala-azar Dermal Leishmaniasis (PKDL)**, Mycosis Fungoides (Cutaneous T-cell Lymphoma), and Sarcoidosis.

Q: An 8-year-old boy presents with a 6-month history of an ill-defined, hypopigmented, slightly atrophic macule on the face. What is the most likely diagnosis?

Indeterminate leprosy. ### Explanation The correct diagnosis is **Indeterminate Leprosy**. In the context of the NEET-PG exam, a solitary, ill-defined, hypopigmented macule in a child—especially when associated with **atrophy** or **sensory loss**—should be considered leprosy until proven otherwise. **Why Indeterminate Leprosy is correct:** Indeterminate leprosy is the earliest clinical stage of leprosy. It typically presents as a single, vaguely defined, hypopigmented macule. While sensory loss may be subtle or absent in early stages, the presence of **atrophy** (thinning of the skin) is a strong clinical pointer toward leprosy rather than simple inflammatory conditions. In endemic regions like India, any persistent hypopigmented patch in a child warrants a high index of suspicion for leprosy. **Why other options are incorrect:** * **Pityriasis alba:** This is a very common cause of hypopigmentation in children (often associated with atopy). However, the patches are usually multiple, have fine scaling (furfuraceous), and **never show atrophy** or sensory loss. * **Morphoea (Localized Scleroderma):** While morphoea can cause atrophy, it typically presents with an initial inflammatory "lilac border" followed by **induration (hardening)** of the skin, rather than just a simple hypopigmented macule. * **Calcium deficiency:** This is a common **myth**. Nutritional deficiencies do not cause localized, well-demarcated hypopigmented patches on the face. **Clinical Pearls for NEET-PG:** * **Earliest sign of Leprosy:** Indeterminate leprosy (often self-healing or progresses to other poles). * **Most common site for Indeterminate Leprosy:** Face in children; outer aspect of thighs/arms in adults. * **Histopathology:** Shows non-specific perineural lymphocytic infiltration (AFB is usually negative). * **Differential Diagnosis Tip:** If the patch is anesthetic, it’s Leprosy; if it scales, it’s likely Pityriasis alba or Tinea versicolor.

Q: A diabetic male presents with a red, tender, and painful swelling on the right buttock with multiple discharging points. The swelling is hard and indurated, accompanied by high-grade fever and malaise. What is the most likely diagnosis?

Carbuncle. ### Explanation The correct diagnosis is **Carbuncle**. **1. Why Carbuncle is correct:** A carbuncle is a deep-seated, inflammatory mass formed by a cluster of interconnecting furuncles. The hallmark clinical feature described—**multiple discharging points** (often likened to a "sieve-like" appearance)—is pathognomonic. It typically occurs in areas with thick skin like the nape of the neck or buttocks. The patient’s profile (diabetic male) is a classic risk factor, as immunocompromised states predispose individuals to deeper, more severe staphylococcal infections. The presence of systemic symptoms like high-grade fever and malaise further points toward this deeper, more extensive infection compared to localized folliculitis. **2. Why other options are incorrect:** * **Folliculitis:** This is a superficial inflammation of the hair follicle. It presents as small, itchy pustules without significant induration or systemic symptoms. * **Furuncle (Boil):** This is a deep-seated infection of a *single* hair follicle. While painful and tender, it presents with a single pointing head, not multiple discharging sinuses. * **Impetigo:** A superficial bacterial infection (usually *S. aureus* or *S. pyogenes*). It presents as honey-colored crusts (non-bullous) or fragile blisters (bullous), typically in children, and lacks deep induration or multiple drainage points. **3. Clinical Pearls for NEET-PG:** * **Etiology:** Most common causative organism is *Staphylococcus aureus*. * **Classic Sign:** The **"Sieve-like" appearance** due to multiple follicular openings discharging pus. * **Predisposing Factors:** Diabetes Mellitus (most common), malnutrition, and immunosuppression. * **Treatment:** Requires systemic antibiotics (e.g., Cloxacillin or Cephalosporins) and often surgical incision and drainage. * **Differential:** Always rule out Hidradenitis Suppurativa if lesions are recurrent in axillary or inguinal regions.

Q: A 38-year-old male presents with swelling in the inguinal region. On examination, inguinal nodes are enlarged along with multiple discharging sinuses from the enlarged lymph nodes. What is the most probable diagnosis?

Lymphogranuloma venereum (LGV). ### Explanation **1. Why Lymphogranuloma Venereum (LGV) is correct:** LGV is caused by **Chlamydia trachomatis (serotypes L1, L2, L3)**. The clinical hallmark of the secondary stage is the **inguinal syndrome**. This involves painful, unilateral or bilateral inguinal lymphadenopathy (buboes). A pathognomonic feature is the **"Groove sign,"** where the inguinal ligament divides the matted nodes. If left untreated, these buboes undergo suppuration and form **multiple discharging sinuses**, as seen in this patient [1]. **2. Why other options are incorrect:** * **Chancroid (*Haemophilus ducreyi*):** Presents with a painful, "soft" ulcer and painful inguinal lymphadenopathy. While buboes can rupture, they typically form a **single** large discharging sinus rather than multiple chronic sinuses [1]. * **Syphilis (*Treponema pallidum*):** Primary syphilis presents with a **painless** hard chancre [2]. The associated lymphadenopathy is typically bilateral, painless, firm, and "shotty," without suppuration or sinus formation. * **Granuloma Inguinale (Donovanosis):** Caused by *Klebsiella granulomatis*. It is characterized by painless, beefy-red, vascular ulcers. It involves "pseudobuboes" (subcutaneous granulation tissue) rather than true lymphadenopathy, and sinuses are not a feature [1]. **3. NEET-PG High-Yield Pearls:** * **Groove Sign:** Pathognomonic for LGV (produced by the inguinal ligament). * **Esthiomene:** Chronic lymphatic obstruction in females leading to vulvar elephantiasis (late-stage LGV). * **Diagnosis:** Nucleic Acid Amplification Test (NAAT) is the preferred method. * **Drug of Choice:** **Doxycycline** (100 mg BID for 21 days). Erythromycin is the alternative for pregnant patients. * **Donovan Bodies:** Safety-pin appearance in tissue smears, diagnostic for Granuloma Inguinale.

Q: A 22-year-old college student with a history of sexual exposure with a commercial sex worker presents with painful genital lesions and lymphadenopathy in the right inguinal region. What is the diagnosis?

Chancroid. **Explanation:** The clinical presentation of **painful genital ulcers** associated with **painful inguinal lymphadenopathy** (buboes) is classic for **Chancroid**, caused by the gram-negative coccobacillus *Haemophilus ducreyi*. **1. Why Chancroid is correct:** The hallmark of Chancroid is the "Painful" ulcer (mnemonic: "Do cry" for *ducreyi*). Unlike other STIs, the lesions are typically soft, ragged, and exquisitely tender. The associated lymphadenopathy is usually unilateral, painful, and may progress to a fluctuant bubo that can rupture. **2. Why other options are incorrect:** * **Syphilis (Primary):** Characterized by a **painless**, indurated (hard) ulcer called a Chancre. The associated lymphadenopathy is also typically painless and bilateral. * **Lymphogranuloma venereum (LGV):** Caused by *Chlamydia trachomatis* (L1-L3). While it features significant inguinal lymphadenopathy (the "Groove sign"), the initial genital ulcer is small, **painless**, and often heals before the patient seeks medical attention. * **Gonorrhea:** Primarily presents as urethritis with purulent discharge rather than discrete genital ulcers. **3. High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** *H. ducreyi* shows a characteristic **"School of fish"** or "Railroad track" appearance on Gram stain. * **Culture:** Requires enriched media like **Mueller-Hinton agar** with vancomycin or Chocolate agar. * **Treatment:** A single dose of Azithromycin (1g) or Ceftriaxone (250mg IM). * **Differential Diagnosis Tip:** If the ulcer is painful and vesicular/grouped, think Herpes Simplex (HSV); if painful and non-vesicular, think Chancroid.

Question 1

In which stage of syphilis does seropositivity typically become evident?

Accepted Answer

Muco patches (secondary syphilis)

Answer

Chancre (primary syphilis)

Answer

Gum ma (tertiary syphilis)

Answer

Congenital syphilis

Question 2

Which of the following stages of syphilis is associated with primary bullous lesions?

Accepted Answer

Congenital syphilis

Answer

Primary syphilis

Answer

Secondary syphilis

Answer

Tertiary syphilis

Question 3

A 35-year-old male presents with a painless indurated ulcer on the penis and enlarged, non-tender genital lymph nodes. What is the most likely diagnosis?

Accepted Answer

Syphilis

Answer

Chancroid

Answer

Herpes genitalis

Answer

Lymphogranuloma venereum (LGV)

Question 4

What is the recommended treatment for latent syphilis?

Accepted Answer

Penicillin

Answer

Erythromycin

Answer

Tetracycline

Answer

Ciprofloxacin

Question 5

Leonine facies is seen in which type of leprosy?

Accepted Answer

Lepromatous

Answer

Tuberculoid

Answer

Borderline

Answer

Borderline tuberculoid

Question 6

Which of the following is NOT true regarding Jarisch-Herxheimer reaction?

Accepted Answer

Ophthalmic involvement is typically worsened.

Answer

It occurs in late syphilis.

Answer

It is an acute febrile reaction.

Answer

Prednisolone for 3 days is given in treatment.

Question 7

An 8-year-old boy presents with a 6-month history of an ill-defined, hypopigmented, slightly atrophic macule on the face. What is the most likely diagnosis?

Accepted Answer

Indeterminate leprosy

Answer

Pityriasis alba

Answer

Morphoea

Answer

Calcium deficiency

Question 8

A diabetic male presents with a red, tender, and painful swelling on the right buttock with multiple discharging points. The swelling is hard and indurated, accompanied by high-grade fever and malaise. What is the most likely diagnosis?

Accepted Answer

Carbuncle

Answer

Folliculitis

Answer

Furuncle

Answer

Impetigo

Question 9

A 38-year-old male presents with swelling in the inguinal region. On examination, inguinal nodes are enlarged along with multiple discharging sinuses from the enlarged lymph nodes. What is the most probable diagnosis?

Accepted Answer

Lymphogranuloma venereum (LGV)

Answer

Chancroid

Answer

Syphilis

Answer

Granuloma inguinale

Question 10

A 22-year-old college student with a history of sexual exposure with a commercial sex worker presents with painful genital lesions and lymphadenopathy in the right inguinal region. What is the diagnosis?

Accepted Answer

Chancroid

Answer

Syphilis

Answer

Lymphogranuloma venereum (LGV)

Answer

Gonorrhea

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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