Bacterial Skin Infections Practice Questions

Q: All are correct about the condition shown in the image except: (Recent NEET Pattern 2016-17)

Necrotising Fasciitis. ***Necrotising Fasciitis*** - The image shows widespread superficial blistering and peeling of the skin, resembling a burn, which is characteristic of **Staphylococcal Scalded Skin Syndrome (SSSS)**, not necrotizing fasciitis. - **Necrotizing fasciitis** is a deeper, rapidly spreading infection of the subcutaneous tissue and fascia, characterized by severe pain, dusky skin, bullae, and crepitus, which is not depicted here. *Epidermolysin mediated* - **Staphylococcal Scalded Skin Syndrome (SSSS)** is indeed caused by **exotoxins (epidermolysins A and B)** produced by *Staphylococcus aureus* strains, which target desmoglein 1, leading to widespread epidermal detachment. - These epidermolysins are **serine proteases that specifically cleave desmoglein 1**, causing a systemic toxic effect without direct bacterial invasion of the skin at affected sites. *Staphyloccocal scalded skin syndrome* - The image is pathognomonic for **Staphylococcal Scalded Skin Syndrome (SSSS)**, characterized by generalized erythema, flaccid blisters, and epidermal exfoliation, particularly in infants and young children. - The peeling skin suggests a **positive Nikolsky sign**, where slight rubbing of the skin causes the epidermis to separate from the dermis, a hallmark of SSSS. *Caused by gram positive cocci in clusters* - **Staphylococcal Scalded Skin Syndrome (SSSS)** is caused by specific strains of **Gram-positive cocci in clusters**, namely *Staphylococcus aureus*, which produce exfoliative toxins. - These bacteria are commonly found on the skin and mucous membranes and are responsible for a variety of skin and soft tissue infections.

Q: A 35-year-old obese woman presents with recurrent lesions in both axilla in summer season. Wood lamp examination is shown. The diagnosis is:

Erythrasma. ***Erythrasma*** - Erythrasma is a superficial bacterial infection caused by **Corynebacterium minutissimum**, which commonly presents as red-brown patches in intertriginous areas like the axilla, especially in obese individuals and warm, humid conditions (summer season). - The distinctive **coral-red fluorescence under Wood's lamp** is due to porphyrin production by the bacteria, which is a classic diagnostic feature of erythrasma, as shown in the image. *Ecthyma* - Ecthyma is a deeper form of impetigo characterized by **ulcerative lesions with a thick, adherent crust** that extend into the dermis. - It is typically caused by *Streptococcus pyogenes* and sometimes *Staphylococcus aureus*, and would not exhibit coral-red fluorescence under Wood's lamp. *Impetigo contagiosa* - Impetigo contagiosa (non-bullous impetigo) presents with **honey-colored crusted lesions**, usually on the face and extremities. - While also a bacterial skin infection, it is typically caused by *Staphylococcus aureus* or *Streptococcus pyogenes* and does not show coral-red fluorescence under Wood's lamp. *Bullous impetigo* - Bullous impetigo is characterized by **flaccid bullae** (blisters) that rupture to form thin, varnish-like crusts, primarily caused by *Staphylococcus aureus* producing exfoliative toxins. - Similar to other forms of impetigo, it does not produce the coral-red fluorescence under Wood's lamp.

Q: The following image is diagnostic of which STD?

LGV. ***LGV*** - The image shows significant **inguinal lymphadenopathy** and **swelling** in the groin region, suggestive of buboes commonly seen in Lymphogranuloma Venereum (LGV). - LGV, caused by *Chlamydia trachomatis* serovars L1, L2, or L3, characteristically presents with unilateral or bilateral painful **inguinal lymph nodes** (buboes) that can rupture to form fistulas. *Herpes simplex* - Herpes simplex typically presents with painful **vesicles** or **ulcers** on erythematous bases, which often recur. - While it can cause inguinal lymphadenopathy, the prominent, large, fluctuant swelling visible in the image is not typical of primary herpes infection. *Chancroid* - Chancroid presents as one or more **painful, soft chancres** with irregular, undermined borders and a purulent base. - It also causes painful inguinal lymphadenopathy, but the primary lesion (soft chancre) is usually more prominent than the diffuse swelling seen here. *Donovanosis* - Donovanosis (granuloma inguinale) is characterized by **painless, beefy red, friable ulcerative lesions** that tend to bleed easily and slowly enlarge. - While it can cause pseudobuboes due to subcutaneous granulomas, the image does not show the typical ulcerative lesions associated with Donovanosis.

Q: A 30-year-old male patient presents with painful genital lesion after unprotected sexual intercourse. He is non cooperative during genital manipulation done to take culture specimen. All are true about the condition shown except:

Granulomatous lesion associated with endarteritis. ***Granulomatous lesion associated with endarteritis*** - This histopathological description is characteristic of **syphilitic chancre** (primary syphilis) or **gumma** (tertiary syphilis), NOT chancroid - Syphilis shows **granulomatous inflammation** with **obliterative endarteritis** (inflammation and narrowing of blood vessels) - **Chancroid** lesions are **non-granulomatous**, showing acute inflammatory infiltrate with lymphocytes, plasma cells, and neutrophils - This is the feature that is **NOT true** about chancroid, making it the correct answer to this "except" question *Phagedenic ulcer* - TRUE for chancroid - refers to rapidly destructive and spreading ulcers - Severe chancroid can present with extensive tissue destruction and sloughing - The aggressive nature of *Haemophilus ducreyi* infection can lead to phagedenic (rapidly spreading) ulceration *Autoinoculation* - TRUE for chancroid - the infection commonly spreads from existing lesions to other parts of the patient's body through direct contact - Results in multiple or satellite lesions around the primary ulcer - This is a well-recognized feature of *H. ducreyi* infection *Azithromycin single dose treatment* - TRUE for chancroid - **Azithromycin 1g orally as a single dose** is a **recommended first-line treatment** for chancroid - CDC and WHO guidelines support single-dose azithromycin as effective therapy - Other treatment options include ceftriaxone 250mg IM single dose, ciprofloxacin 500mg BD for 3 days, or erythromycin 500mg TDS for 7 days

Q: A patient presents with a genital lesion that has been slowly progressive over several weeks. The lesion is painless, bleeds easily on contact, and there is no associated inguinal lymphadenopathy. What is the diagnosis based on the image and clinical findings shown below?

Donovanosis. ***Donovanosis*** - The image displays genital lesions characterized by **slowly progressive, painless, nodular, ulcerative lesions** which bleed easily on contact, typical of Donovanosis. - This condition is caused by *Klebsiella granulomatis* and often presents with **beefy-red, friable granulation tissue** on the genitals or perineum. - Notably, inguinal lymphadenopathy is absent; any apparent swelling in the groin represents subcutaneous granulomatous spread (pseudobuboes) rather than true lymph node involvement. *Syphilis* - Primary syphilis typically presents as a **single, painless ulcer (chancre)** with a clean base and sharply demarcated, indurated borders. - The clinical history of a slowly progressive, friable, bleeding lesion without induration does not align with a syphilitic chancre. *Chancroid* - Chancroid is characterized by **multiple, painful, soft ulcers** with ragged, undermined edges and a grayish, purulent base. - The lesion here is painless and proliferative, and is not associated with the painful suppurative inguinal nodes typical of chancroid. *Lymphogranuloma Venereum* - LGV usually begins as a **small, transient, painless papule or vesicle** that often goes unnoticed, followed by painful inguinal lymphadenopathy (buboes). - The absence of significant lymphadenopathy and the presence of prominent granulomatous ulceration are not consistent with LGV, which is more focused on lymphatic involvement and systemic symptoms.

Q: A 25-year-old woman presents with skin lesion on left supra-orbital margin. Eye examination is within normal limits. CXR done was normal. Diascopy shows apple jelly nodules. The image shows presence of:

Lupus vulgaris. ***Lupus vulgaris*** - The presence of **apple-jelly nodules** on diascopy is a classic and highly characteristic feature of **lupus vulgaris**, a type of cutaneous tuberculosis. - The lesion's location on the **supra-orbital margin** is a common site for this chronic, progressive skin infection. - Histopathologically, lupus vulgaris shows **tuberculoid granulomas**; caseation is often absent or minimal. The **tuberculin (Mantoux) test is commonly positive**, while direct mycobacterial detection and culture may be negative, as lupus vulgaris is paucibacillary — features that help distinguish it from cutaneous sarcoidosis, which shows non-caseating granulomas and negative mycobacterial testing. *Lupus pernio* - **Lupus pernio** is typically associated with **sarcoidosis**, presenting as violaceous plaques on the nose, cheeks, ears, and fingers. - Sarcoidal lesions may also show an apple-jelly appearance on diascopy; however, the overall morphology and clinical location of this lesion favor **lupus vulgaris** over lupus pernio. *Erythema marginatum* - **Erythema marginatum** is a transient, non-pruritic rash with red margins and clear centers, classically associated with **acute rheumatic fever**. - It does not manifest as nodular lesions or show translucency on diascopy. *Leprosy* - **Leprosy** can cause various skin lesions, but **apple-jelly nodules** on diascopy are not typical of its presentation; instead, thickened nerves and sensory loss are key features. - While it can affect the face, the specific description of diascopy findings points away from leprosy.

Q: A child presents with the skin lesions shown in the image. The most likely diagnosis is:

Impetigo contagiosa. ***Impetigo contagiosa*** - The image shows **honey-colored crusted lesions** around the mouth, which are highly characteristic of **impetigo contagiosa (non-bullous impetigo)**. - This form of impetigo is typically caused by *Staphylococcus aureus* or *Streptococcus pyogenes* and primarily affects superficial layers of the epidermis. *Bullous impetigo* - Characterized by **flaccid bullae** (blisters) that rupture to leave a thin, varnish-like crust, rather than the thick honey-colored crusts seen here. - It is exclusively caused by **Staphylococcus aureus** strains producing exfoliative toxins. *Ritter disease* - Also known as **Staphylococcal Scalded Skin Syndrome (SSSS)**, this condition involves widespread **erythema and exfoliation** resembling a burn. - It is a severe, systemic illness with widespread skin involvement, not localized crusted lesions like those pictured. *Ecthyma* - This is a more **deep-seated skin infection** that penetrates into the dermis, characterized by **"punched-out" ulcers** with thick, adherent crusts and often leaves scars. - While also caused by *Staphylococcus aureus* and/or *Streptococcus pyogenes*, its lesions are typically more severe and destructive than what is depicted.

Q: A patient presents with discoloration and dystrophy of the fingernail. The following appearance under Wood's lamp examination of the affected nail is seen in:

Pseudomonas. ***Pseudomonas*** - The image depicts a **greenish-yellow fluorescence** under Wood's lamp, which is characteristic of *Pseudomonas aeruginosa* infection, often due to the production of **pyoverdin**. - This is commonly seen in conditions like **green nail syndrome** or in wounds infected with Pseudomonas. *Tinea capitis* - Certain species of *Tinea capitis* (e.g., *Microsporum canis*, *Microsporum audouinii*) can fluoresce, typically emitting a **bright green fluorescence** under Wood's lamp. - However, susceptible Microsporum species cause fluorescence of infected hair shafts, which is less typical for the appearance seen in the image. *Pityriasis -Versicolor* - *Pityriasis versicolor* (caused by *Malassezia furfur*) can show a **pale yellow to coppery-orange fluorescence** under Wood's lamp, due to fluorescent Malassezia metabolites such as pityrialactone. - The fluorescence in the image is distinctly greenish-yellow, not typical for pityriasis versicolor. *Cutaneous amyloidosis* - **Cutaneous amyloidosis** typically does not exhibit any specific fluorescence under Wood's lamp. - Diagnosis usually involves **biopsy with Congo Red staining** to reveal amyloid deposits.

Q: The following appearance on Wood's lamp is seen in?

Erythrasma. ***Erythrasma*** - Erythrasma, caused by *Corynebacterium minutissimum*, is characterized by a **coral-red fluorescence** under Wood's lamp due to the production of **porphyrins**. - The image clearly shows this characteristic coral-red and purplish fluorescence, which is pathognomonic for erythrasma. *Erythroderma* - Erythroderma is a serious inflammatory skin condition affecting more than 90% of the body surface with **generalized redness and scaling**. - It does not exhibit any specific fluorescence under Wood's lamp; the diagnosis is purely clinical. *Ecthyma* - Ecthyma is a **deep skin infection** resembling impetigo but extending into the dermis, forming **ulcers** with a crusted surface. - It does not produce a characteristic fluorescence under Wood's lamp; diagnosis is based on clinical appearance of ulcerative lesions. *Erysipelas* - Erysipelas is a **superficial cellulitis** primarily involving the upper dermis and superficial lymphatics, typically presenting as a rapidly spreading, erythematous, raised, and warm plaque with a distinctive border. - While it is a bacterial skin infection, it does not show any specific fluorescence under Wood's lamp.

Question 1

All are correct about the condition shown in the image except: (Recent NEET Pattern 2016-17)

Accepted Answer

Necrotising Fasciitis

Answer

Epidermolysin mediated

Answer

Staphylococcal scalded skin syndrome

Answer

Caused by gram positive cocci in clusters

Question 2

A child presents with skin lesions that started as vesicles that enlarged into flaccid bullae, which ruptured leaving annular erosions with peripheral collarettes. A Gram stain of the lesion shows Gram-positive cocci in clusters. The diagnosis is:

Accepted Answer

Bullous impetigo

Answer

Ecthyma

Answer

Impetigo contagiosa

Answer

Erythrasma

Question 3

A 35-year-old obese woman presents with recurrent lesions in both axilla in summer season. Wood lamp examination is shown. The diagnosis is:

Accepted Answer

Erythrasma

Answer

Ecthyma

Answer

Impetigo contagiosa

Answer

Bullous impetigo

Question 4

The following image is diagnostic of which STD?

Accepted Answer

LGV

Answer

Herpes simplex

Answer

Chancroid

Answer

Donovanosis

Question 5

A 30-year-old male patient presents with painful genital lesion after unprotected sexual intercourse. He is non cooperative during genital manipulation done to take culture specimen. All are true about the condition shown except:

Accepted Answer

Granulomatous lesion associated with endarteritis

Answer

Phagedenic ulcer

Answer

Azithromycin single dose treatment

Answer

Autoinoculation

Question 6

A patient presents with a genital lesion that has been slowly progressive over several weeks. The lesion is painless, bleeds easily on contact, and there is no associated inguinal lymphadenopathy. What is the diagnosis based on the image and clinical findings shown below?

Accepted Answer

Donovanosis

Answer

Syphilis

Answer

Chancroid

Answer

Lymphogranuloma Venereum

Question 7

A 25-year-old woman presents with skin lesion on left supra-orbital margin. Eye examination is within normal limits. CXR done was normal. Diascopy shows apple jelly nodules. The image shows presence of:

Accepted Answer

Lupus vulgaris

Answer

Lupus pernio

Answer

Erythema marginatum

Answer

Leprosy

Question 8

A child presents with the skin lesions shown in the image. The most likely diagnosis is:

Accepted Answer

Impetigo contagiosa

Answer

Bullous impetigo

Answer

Ritter disease

Answer

Ecthyma

Question 9

A patient presents with discoloration and dystrophy of the fingernail. The following appearance under Wood's lamp examination of the affected nail is seen in:

Accepted Answer

Pseudomonas

Answer

Pityriasis versicolor

Answer

Tinea capitis

Answer

Cutaneous amyloidosis

Question 10

The following appearance on Wood's lamp is seen in?

Accepted Answer

Erythrasma

Answer

Erythroderma

Answer

Ecthyma

Answer

Erysipelas

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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