Bacterial Skin Infections Practice Questions

Q: Ridley's scale is used in classification of which disease?

Leprosy. ***Leprosy*** - The **Ridley-Jopling classification** system is a historical and widely used method to classify leprosy based on clinical, histological, and immunological features [1]. - This scale categorizes leprosy into five forms: **tuberculoid (TT), borderline tuberculoid (BT), mid-borderline (BB), borderline lepromatous (BL), and lepromatous leprosy (LL)**, reflecting the patient's immune response to *Mycobacterium leprae* [1]. *Malaria* - Malaria is classified by **parasite species** (*Plasmodium falciparum, vivax, ovale, malariae, knowlesi*) and disease severity (uncomplicated vs. severe malaria). - There is no "Ridley's scale" involved in the classification of malaria. *Measles* - Measles, a viral disease, is typically diagnosed clinically based on its characteristic **rash, fever, cough, coryza, and conjunctivitis**. - Classification primarily involves whether it's uncomplicated or complicated (e.g., with pneumonia or encephalitis), not a specific Ridley's scale. *Tuberculosis* - Tuberculosis (TB) is classified by its **site of infection (pulmonary vs. extrapulmonary)**, bacteriological status (culture-positive or negative), and drug resistance profile. - The disease state is also described as latent TB infection (LTBI) or active TB disease; Ridley's scale is not used for TB.

Q: Genital ulcer followed by painful lymphadenopathy is seen in -

LGV. ***LGV*** - Lymphogranuloma venereum (LGV) is caused by specific serovars of *Chlamydia trachomatis* and classically presents with a **small, often transient and painless genital ulcer**, followed by **tender, suppurative inguinal lymphadenopathy** (buboes) [1]. - The inguinal lymph nodes can become greatly enlarged and may rupture, leading to **fistula formation**. *Granuloma inguinale* - This condition, also known as donovanosis, is characterized by **painless, progressive ulcerative lesions** without regional lymphadenopathy [1]. - The ulcers have a **beefy red, velvety appearance** due to abundant granulation tissue, distinguishing them from LGV. *Chancroid* - Chancroid is characterized by **painful genital ulcers with ragged borders** and an erythematous base, caused by *Haemophilus ducreyi* [1]. - While it can cause **painful inguinal lymphadenopathy**, the primary ulcer is typically much more prominent and painful than the transient lesion of LGV [1]. *Syphilis* - Primary syphilis presents as a **painless chancre** (genital ulcer) with **painless, firm regional lymphadenopathy**. - The classic firm, clean-based chancre and non-tender lymph nodes are key differentiating features from the painful buboes of LGV.

Q: Punched out lesion or inverted saucer appearance are characteristic of which type of leprosy?

Lepromatous. ***Lepromatous*** - **Punched-out lesions**, also known as "inverted saucer appearance," are characteristic of **lepromatous leprosy** due to extensive dermal infiltration and destruction by *Mycobacterium leprae*. - This form of leprosy involves a **weak cellular immune response** allowing widespread bacterial dissemination and visible skin lesions. *Tuberculoid* - Tuberculoid leprosy is characterized by a **strong cell-mediated immune response**, resulting in few, well-demarcated skin lesions with sensory loss. - It is typically **paucibacillary**, meaning few bacteria are present in the lesions, and does not cause punched-out or inverted saucer appearances. *Borderline tuberculoid* - Borderline tuberculoid leprosy presents with **moderate cell-mediated immunity** and a few skin lesions that are more numerous and less well-defined than in tuberculoid leprosy. - While it can be more extensive than tuberculoid, it typically does not exhibit the extensive tissue destruction leading to "punched-out" lesions characteristic of the lepromatous pole. *Borderline lepromatous* - Borderline lepromatous leprosy shows a **weak cellular immune response** and numerous, ill-defined lesions, often with varying sizes and shapes. - While it shares some features of lepromatous leprosy, the classic "punched-out" or "inverted saucer" appearance is more specifically associated with the widespread and uniform dermal infiltration of **full-blown lepromatous leprosy**.

Q: The duration of treatment with rifampicin by which a leprosy patient becomes non-infective is:

72 hours. **72 hours** - **Rifampicin** rapidly kills *Mycobacterium leprae* and significantly reduces bacterial viability, making the patient **non-infective** within a few days of treatment initiation. - This quick action of rifampicin is crucial for preventing further transmission of leprosy. *1 month* - While treatment for leprosy often extends for several months or years, the patient typically becomes **non-infectious much earlier**, specifically within the first few days, due to the rapid bactericidal effect of rifampicin. - A one-month duration refers more to the follow-up or continued treatment phase rather than the time to achieve non-infectivity. *2 weeks* - This duration is longer than necessary to achieve non-infectivity with rifampicin. The rapid action of **rifampicin** means the patient is no longer infectious within approximately **72 hours**. - Two weeks of treatment would further reduce the bacterial load but is not the minimum time for non-infectivity. *1 week* - While closer to the correct answer than 1 month or 2 weeks, **1 week** is still an overestimate for the time it takes for a leprosy patient to become non-infective with rifampicin therapy. - Significant reduction in contagiousness occurs much faster, typically within **72 hours**.

Q: Painless ulcer along with painless lymphadenopathy is characteristic of which STD:

Syphilis. ***Syphilis*** - The primary stage of syphilis is characterized by a **painless chancre**, which is a firm, round, and painless ulcer, along with painless regional **lymphadenopathy**. - This presentation is highly suggestive of infection with **Treponema pallidum**. *Chancroid* - Chancroid typically presents with **multiple, painful ulcers** that have ragged, undermined borders. - The associated lymphadenopathy is usually **painful** and may suppurate, forming a **bubo**. *Donovanosis* - Donovanosis (granuloma inguinale) is characterized by **painless, progressive ulcerative lesions** that are often beefy red and bleed easily. - While it causes ulceration, prominent and discreet **painless lymphadenopathy** is not a classic initial feature; rather, it can present with pseudobuboes or subcutaneous granulomas. *LGV* - Lymphogranuloma venereum (LGV) initially presents with a **small, often unnoticed, painless ulcer or papule**. - Its hallmark is pronounced, **painful inguinal lymphadenopathy** (buboes), which can rupture and drain, contrasting with the painless lymphadenopathy described.

Q: What is the diagnosis of a child with a small abrasion over the face who develops fever with chills, induration, and fiery red swelling over the face extending to the ear?

Erysipelas. ***Erysipelas*** - The presentation of **fiery red swelling** with well-demarcated, raised borders, rapidly extending from a small abrasion, especially on the face and involving the ear, is classic for erysipelas. - It also includes systemic symptoms like **fever and chills** and **induration**, which are characteristic of this superficial skin infection usually caused by **Streptococcus pyogenes**. *Anthrax* - Cutaneous anthrax typically presents with a papule that develops into a **vesicle**, then a painless ulcer with a distinctive **black eschar**, which is not described here. - While it can cause fever, the characteristic skin lesion is distinct from the red, spreading swelling seen in this case. *Carbuncle* - A carbuncle is a deep infection involving multiple hair follicles, presenting as a painful, interconnected lesion with **multiple draining sinuses**. - It is typically more localized, deeper, and pus-filled than the superficial, rapidly spreading, fiery red swelling described. *Cellulitis* - Cellulitis is a deeper infection of the dermis and subcutaneous fat, presenting with redness, warmth, and tenderness, but its borders are typically **less well-demarcated** and not as raised as in erysipelas. - While it can also occur on the face and cause systemic symptoms, the description of "fiery red" and "extending to the ear" with sharp borders makes erysipelas a more precise diagnosis.

Q: Which stage of LGV infection is associated with bubos?

Second stage. **Second stage** - The **second stage** of LGV (lymphogranuloma venereum) is characterized by the development of **buboes**, which are swollen, painful lymph nodes, most commonly in the inguinal region [1]. - These buboes result from the **lymphatic spread** of the *Chlamydia trachomatis* infection [1]. *Third stage* - The **third stage** of LGV involves chronic complications such as **genital elephantiasis**, **strictures**, and **fistulas** due to persistent inflammation and scarring. - While it follows the bubo formation, buboes themselves are not the primary feature of this later, chronic stage. *First stage* - The **first stage** of LGV is marked by the appearance of a **painless papule, vesicle, or ulcer** at the site of inoculation, which often goes unnoticed because it is transient and resolves quickly. - This stage does not typically involve the development of buboes, as lymphatic spread to regional lymph nodes has not yet become clinically evident. *Throughout all stages* - Buboes are a **distinctive feature** of the second stage of LGV, not a consistent finding across all stages. - The initial stage is a transient lesion, and the third stage involves chronic, destructive changes, making the presence of buboes ubiquitous across all stages inaccurate.

Q: 'Coral red' color on Wood's lamp is seen in

Erythrasma. ***Erythrasma*** - Erythrasma, caused by *Corynebacterium minutissimum*, produces characteristic **porphyrins** that fluoresce **coral red** under Wood's lamp. - This specific fluorescence pattern is a key diagnostic feature for distinguishing erythrasma from other intertriginous dermatoses. *Pityriasis rosea* - This condition presents with a characteristic **herald patch** followed by smaller, oval, salmon-colored lesions in a "Christmas tree" pattern, without any specific fluorescence under Wood's lamp. - Its etiology is thought to be viral, and it does not involve the bacterial production of porphyrins. *Tinea corporis* - Also known as ringworm, tinea corporis is a dermatophyte infection that typically shows **no fluorescence** or sometimes a dull green fluorescence with some species (e.g., *Microsporum canis*), but never coral red. - Diagnosis is usually made by KOH direct microscopy of skin scrapings showing **hyphae and spores**. *Tuberous sclerosis* - This is a neurocutaneous disorder characterized by **ash-leaf spots** (hypopigmented macules) that may enhance as bright white under Wood's lamp due to loss of melanin. - It does not produce a coral red fluorescence and is a genetic condition, not an infection.

Q: Incubation period of syphilis is:

9-90 days. ***9-90 days*** - The incubation period for primary syphilis, from exposure to the appearance of a **chancre**, typically ranges from **9 to 90 days**, with an average of 21 days [1]. - This variability depends on the **inoculum size** and the host's immune response [1]. *10-14 days* - This period is generally **too short** for the typical development of a primary syphilitic lesion, the chancre. - Incubation periods for other infections, such as **gonorrhea**, might fall within this range. *3-6 months* - This duration is usually **too long** for the incubation period of primary syphilis, as chancres typically appear much sooner. - Syphilis may progress to secondary or latent stages within this timeframe if untreated [1]. *30-60 days* - While this period falls within the broader range, it is **not the complete or most accurate representation** of the full incubation period for syphilis. - It captures a common average but omits the earlier and later ends of the known range.

Q: Symptoms of secondary syphilis are all except:

Generalized and tender lymphadenopathy. **Generalized and tender lymphadenopathy** - Secondary syphilis typically presents with **generalized, non-tender lymphadenopathy** [1]. - **Tender lymphadenopathy** is more characteristic of acute infections or inflammatory conditions rather than the chronic inflammation seen in syphilis. *Localized or diffuse mucocutaneous lesion* - **Mucocutaneous lesions**, including **rashes on palms and soles**, are very common and characteristic manifestations of secondary syphilis [1]. - These lesions can be maculopapular, pustular, or ulcerative and are often widespread [1]. *Condyloma lata is seen* - **Condyloma lata** are moist, wart-like lesions that occur in intertriginous areas (e.g., groin, perianal region) [1]. - They are highly infectious and a classic sign of secondary syphilis, resulting from a proliferation of spirochetes [1]. *Self resolving* - The symptoms of secondary syphilis, if left untreated, typically **resolve spontaneously** within a few weeks to months [1]. - However, the disease then progresses to a latent stage, and without treatment, can lead to tertiary syphilis [1].

Question 1

Ridley's scale is used in classification of which disease?

Accepted Answer

Leprosy

Answer

Malaria

Answer

Measles

Answer

Tuberculosis

Question 2

Genital ulcer followed by painful lymphadenopathy is seen in -

Accepted Answer

LGV

Answer

Granuloma inguinale

Answer

Chancroid

Answer

Syphilis

Question 3

Punched out lesion or inverted saucer appearance are characteristic of which type of leprosy?

Accepted Answer

Lepromatous

Answer

Tuberculoid

Answer

Borderline tuberculoid

Answer

Borderline lepromatous

Question 4

The duration of treatment with rifampicin by which a leprosy patient becomes non-infective is:

Accepted Answer

72 hours

Answer

1 month

Answer

2 weeks

Answer

1 week

Question 5

Painless ulcer along with painless lymphadenopathy is characteristic of which STD:

Accepted Answer

Syphilis

Answer

Chancroid

Answer

Donovanosis

Answer

LGV

Question 6

What is the diagnosis of a child with a small abrasion over the face who develops fever with chills, induration, and fiery red swelling over the face extending to the ear?

Accepted Answer

Erysipelas

Answer

Anthrax

Answer

Carbuncle

Answer

Cellulitis

Question 7

Which stage of LGV infection is associated with bubos?

Accepted Answer

Second stage

Answer

Third stage

Answer

First stage

Answer

Throughout all stages

Question 8

'Coral red' color on Wood's lamp is seen in

Accepted Answer

Erythrasma

Answer

Pityriasis rosea

Answer

Tinea corporis

Answer

Tuberous sclerosis

Question 9

Incubation period of syphilis is:

Accepted Answer

9-90 days

Answer

10-14 days

Answer

3-6 months

Answer

30-60 days

Question 10

Symptoms of secondary syphilis are all except:

Accepted Answer

Generalized and tender lymphadenopathy

Answer

Localized or diffuse mucocutaneous lesion

Answer

Condyloma lata is seen

Answer

Self resolving

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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