Bacterial Skin Infections Practice Questions

Q: The incubation period of LGV is?

10-30 days. ***10-30 days*** - The incubation period for **Lymphogranuloma Venereum (LGV)**, which is caused by specific serovars of *Chlamydia trachomatis*, typically ranges from 10 to 30 days [1]. - This period reflects the time from exposure to the appearance of initial lesions, such as a **small, painless papule** or ulcer at the site of inoculation [1]. *30-90 days* - This period is generally too long for the primary incubation phase of LGV. - While later stages of LGV can manifest much later, the initial incubation before the appearance of primary lesions or regional lymphadenopathy is shorter. *7-10 days* - This period is generally too short for LGV; many other STIs, like **genital herpes**, may have an incubation period in this range. - LGV's characteristic spread to regional lymph nodes and its presentation generally require a slightly longer incubation. *3-7 days* - This incubation period is more characteristic of conditions like **gonorrhea** or **chancroid**, not LGV. - LGV's distinct pathogenesis, involving deeper tissue penetration and lymphatic spread, necessitates a longer initial period.

Q: Dharmendra's index and Jopling's classification deals with -

Leprosy. Leprosy - Dharmendra's index is a method for classifying leprosy based on the bacillary load in skin smears. - Jopling's classification is a widely used system that categorizes leprosy based on clinical, histological, and immunological features. Polio - Polio is a viral disease primarily affecting the nervous system, leading to paralysis, and is not classified by Dharmendra's index or Jopling's classification. - Diagnosis typically involves detecting the poliovirus in stool samples or throat swabs. Syphilis - Syphilis is a sexually transmitted bacterial infection caused by Treponema pallidum, which is diagnosed through serological tests and clinical presentation. - Its staging (primary, secondary, latent, tertiary) is distinct from the classification systems mentioned. TB - Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis, primarily affecting the lungs, and its classification relates to infection site and drug resistance. - Diagnosis involves sputum tests, chest X-rays, and PPD skin tests, which are unrelated to Dharmendra's index or Jopling's classification.

Q: Regarding Jarisch-Herxheimer reaction in syphilis treatment, which statement is FALSE?

Requires stopping antibiotic therapy. Regarding Jarisch-Herxheimer reaction in syphilis treatment, which statement is FALSE? ***Requires stopping antibiotic therapy*** - The **Jarisch-Herxheimer reaction (JHR)** is a transient immune-mediated response to endotoxins released by dying spirochetes after initiation of syphilis treatment. It is a sign that the treatment is working, and **antibiotic therapy should not be stopped**. - While supportive care (e.g., antipyretics, analgesics) may be necessary to manage symptoms like fever, chills, myalgia, and headache, stopping the antibiotic would interrupt appropriate syphilis treatment. *More common in secondary syphilis* - The **Jarisch-Herxheimer reaction** is indeed most common and severe in **secondary syphilis** due to the high spirochetemia and widespread dissemination of bacteria, leading to a greater antigen load and subsequent immune response. - Symptoms tend to be milder or absent in primary or latent syphilis. *Can cause fetal distress in pregnancy* - In pregnant women, the **Jarisch-Herxheimer reaction** can potentially induce **uterine contractions** and **fetal distress**, especially if it causes significant maternal fever or systemic inflammation. - Although treatment for syphilis is critical during pregnancy, careful monitoring and management of JHR symptoms are important to mitigate risks to the fetus. *Usually occurs within 24 hours of treatment* - The **Jarisch-Herxheimer reaction** typically has a rapid onset, manifesting within **4 to 12 hours** after the first dose of antisyphilitic medication and usually resolving spontaneously within **24 hours** [1]. - This acute, self-limiting nature is characteristic of the reaction.

Q: A patient presents with genital ulcer disease. Which of the following combinations correctly matches the pain characteristics with the causative organism?

Multiple painful - HSV. ***Multiple painful - HSV*** - **Herpes Simplex Virus (HSV)** typically causes a constellation of **multiple, superficial, painful ulcers**, often preceded by tingling or burning sensations [1]. - These lesions evolve from vesicles to pustules and then to ulcers, making them highly characteristic of HSV infection [1]. *Painless - H. ducreyi* - **_Haemophilus ducreyi_** is the causative agent of **chancroid**, which classically presents as **painful, ragged, undermined ulcers** with erythematous bases, not painless ones [1]. - The descriptor "painless" is characteristic of the chancre of syphilis caused by _Treponema pallidum_. *Single painful - C. trachomatis* - **_Chlamydia trachomatis_** (specifically serovars L1-L3) causes **lymphogranuloma venereum (LGV)**, which initially presents with a **small, often painless, transient ulcer or papule** that can go unnoticed, followed by painful inguinal lymphadenopathy [1]. - A single painful ulcer is not the typical presentation for _Chlamydia trachomatis_ in the context of genital ulcer disease. *Painful - T. pallidum* - **_Treponema pallidum_**, the bacterium responsible for **syphilis**, causes a primary lesion known as a **chancre**, which is typically a **single, firm, painless ulcer** with raised, indurated borders [1]. - Painful ulcers are uncharacteristic of primary syphilis.

Q: In a patient with primary syphilis, which of the following indicates the need for CSF examination?

Neurological symptoms. Detailed examination of the central nervous system involvement in syphilis focuses on clinical indicators and diagnostic procedures. ***Neurological symptoms*** - The presence of **neurological symptoms** such as headache, altered mental status, or cranial nerve palsies in a patient with syphilis indicates potential **neurosyphilis** affecting the central nervous system. - A **CSF examination** is crucial in this scenario to assess for pleocytosis, elevated protein, and a reactive VDRL, which are diagnostic of neurosyphilis [1]. *Recent HIV exposure* - While HIV co-infection can alter the course of syphilis and increase the risk of neurosyphilis, recent exposure alone without symptoms or established HIV infection does not automatically necessitate a **CSF examination** in primary syphilis. - HIV-positive patients with syphilis typically require CSF examination only if they have symptoms, high RPR titers, or treatment failure. *Positive VDRL test* - A positive **VDRL test** (Venereal Disease Research Laboratory) is a common serological marker for syphilis infection and is expected in primary syphilis. - It indicates systemic infection but does not specifically point to **CNS involvement** without accompanying neurological symptoms or other risk factors. *High RPR titers* - **Rapid Plasma Reagin (RPR)** titers indicate the activity of the syphilis infection and typically correlate with disease burden. High titers are common in primary syphilis. - While very high RPR titers (e.g., ≥1:32) in HIV-infected individuals, or in non-HIV individuals who fail to respond to treatment, can be an indication for **CSF examination**, high titers alone in primary syphilis without other indicators are not sufficient.

Q: Choose the INCORRECT statement about lymphogranuloma venereum (LGV):

Doxycycline is contraindicated. ***Doxycycline is contraindicated*** - This statement is **incorrect** because **doxycycline** is the **first-line treatment** for lymphogranuloma venereum (LGV), typically administered for a 21-day course. - It is highly effective against *Chlamydia trachomatis* serovars L1, L2, and L3, which cause LGV. *Fistulas are common in late stage* - This statement is **correct**. If left untreated, LGV can progress to a late stage characterized by **chronic inflammation**, **strictures**, and the formation of **fistulas** involving the rectum, vagina, or perineum. - These complications result from extensive tissue damage and scarring, often following the rupture of inflamed lymph nodes. *Primary lesion may be painless* - This statement is **correct**. The primary lesion of LGV is often a **small, painless papule, vesicle, or ulcer** (chancre) that appears at the site of inoculation. - It often goes unnoticed because of its transient and asymptomatic nature, preceding the more prominent lymphadenopathy. *Caused by L1, L2, L3 serovars* - This statement is **correct**. Lymphogranuloma venereum is specifically caused by the **L1, L2, and L3 serovars** of *Chlamydia trachomatis* [1]. - These serovars have a greater invasive capacity compared to other *Chlamydia trachomatis* serovars, leading to systemic infection and severe lymphadenopathy.

Q: Which pattern suggests secondary syphilis rather than pityriasis rosea?

Palmoplantar involvement. ***Palmoplantar involvement*** - **Secondary syphilis** characteristically presents with a rash that affects the **palms and soles**, a distribution that is rare in most other dermatological conditions, including pityriasis rosea. - This specific finding is a crucial diagnostic clue differentiating it from a wide range of other skin eruptions. *Christmas tree distribution* - The "Christmas tree" pattern, characterized by oval lesions following the **Langer's lines** on the trunk, is a classic presentation of **pityriasis rosea**. - This linear orientation is not typical for the rash of secondary syphilis. *Collarette scaling* - **Collarette scaling**, where fine scales are present just inside the periphery of a lesion, is a common feature of the individual lesions in **pityriasis rosea**. - While some scaling can be seen in syphilis, the distinctive collarette pattern is more indicative of pityriasis rosea. *Herald patch presence* - The appearance of a **herald patch** (or mother patch) — a single, larger, oval lesion that precedes the generalized rash — is a pathognomonic sign of **pityriasis rosea**. - No such precursor lesion is typically found in secondary syphilis.

Q: Which nerve biopsy is taken to diagnose neuritic leprosy?

Radial cutaneous nerve. ***Radial cutaneous nerve*** - The **radial cutaneous nerve** (superficial branch of radial nerve) is the **preferred nerve for biopsy** in suspected neuritic leprosy - It is a **purely sensory nerve** with minimal functional consequences if damaged, making it the safest choice for diagnostic biopsy - This nerve is **superficially located** at the wrist and easily accessible for biopsy procedures - Provides excellent diagnostic yield as it is commonly involved in leprosy neuritis *Ulnar nerve* - While the ulnar nerve is frequently **thickened and tender** in leprosy and can be easily palpated, it is **NOT preferred for biopsy** [1] - Contains both **motor and sensory fibers**, so biopsy carries significant risk of functional impairment including weakness of intrinsic hand muscles - Clinical examination and nerve thickening is sufficient for diagnosis; biopsy is avoided due to morbidity risk *Median nerve* - The median nerve can be affected in leprosy but is **not suitable for biopsy** due to its critical motor and sensory functions - Biopsy would risk severe hand dysfunction including loss of thumb opposition and sensory loss in the lateral palm - Deep location also makes it less accessible compared to superficial cutaneous nerves *Radial nerve* - The **main radial nerve trunk** is a mixed nerve with important motor functions (wrist and finger extension) - Its deep location and functional importance make it **unsuitable for diagnostic biopsy** - Risk of wrist drop and significant morbidity makes this an inappropriate biopsy site **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 386.

Q: Most specific sign of secondary syphilis is:

Condyloma lata. ***Condyloma lata*** - These are **flat-topped, moist, wart-like lesions** that appear in warm, moist areas like the anogenital region or skin folds. They are highly contagious and are considered the most specific sign of secondary syphilis due to their unique appearance and association. - Their distinct morphology and location help differentiate them from other dermatological conditions, making them a key diagnostic feature. *Mucous patches* - While **mucous patches** are characteristic of secondary syphilis, appearing as painless, whitish lesions on mucous membranes, they are less specific as similar lesions can be seen in other conditions. - They are often overlooked or mistaken for other oral or genital lesions, making them less distinct than condyloma lata for specific diagnosis. *Copper colored rash* - A **diffuse, copper-colored macular or papular rash** is a common manifestation of secondary syphilis, often affecting the trunk and extremities. - However, similar rashes can be seen in various viral exanthems or drug reactions, making it less specific than condyloma lata. *Palm/sole lesions* - **Lesions on the palms and soles** are a highly suggestive, though not entirely specific, sign of secondary syphilis, presenting as macules or papules. - While very characteristic, other conditions like Rocky Mountain spotted fever or hand-foot-and-mouth disease can also cause palmoplantar lesions, reducing their specificity compared to condyloma lata.

Q: Which feature best differentiates folliculitis from furuncle?

Depth of involvement. ***Depth of involvement*** - **Folliculitis** is a superficial infection involving only the **hair follicle ostium**. - A **furuncle** (boil) is a deeper infection that extends into the **dermis** and subcutaneous tissue, often originating from a hair follicle. *Age of presentation* - Both conditions can occur at **any age**, although certain types of folliculitis (e.g., hot tub folliculitis) might be more common in specific age groups due to exposure. - Age itself is **not a distinguishing factor** in terms of disease pathology or differentiation. *Causative organism* - Both folliculitis and furuncles are **most commonly caused by *Staphylococcus aureus***. - While other organisms can sometimes cause folliculitis (e.g., *Pseudomonas* for hot tub folliculitis), the primary causative agent is similar for both. *Site of occurrence* - Both folliculitis and furuncles typically occur in **hair-bearing areas** of the body. - The site of occurrence does not inherently differentiate between a superficial infection of the follicle and a deeper, more extensive infection.

Question 1

The incubation period of LGV is?

Accepted Answer

10-30 days

Answer

30-90 days

Answer

7-10 days

Answer

3-7 days

Question 2

Dharmendra's index and Jopling's classification deals with -

Accepted Answer

Leprosy

Answer

Polio

Answer

Syphilis

Answer

TB

Question 3

Regarding Jarisch-Herxheimer reaction in syphilis treatment, which statement is FALSE?

Accepted Answer

Requires stopping antibiotic therapy

Answer

More common in secondary syphilis

Answer

Can cause fetal distress in pregnancy

Answer

Usually occurs within 24 hours of treatment

Question 4

A patient presents with genital ulcer disease. Which of the following combinations correctly matches the pain characteristics with the causative organism?

Accepted Answer

Multiple painful - HSV

Answer

Painless - H. ducreyi

Answer

Single painful - C. trachomatis

Answer

Painful - T. pallidum

Question 5

In a patient with primary syphilis, which of the following indicates the need for CSF examination?

Accepted Answer

Neurological symptoms

Answer

Recent HIV exposure

Answer

Positive VDRL test

Answer

High RPR titers

Question 6

Choose the INCORRECT statement about lymphogranuloma venereum (LGV):

Accepted Answer

Doxycycline is contraindicated

Answer

Fistulas are common in late stage

Answer

Primary lesion may be painless

Answer

Caused by L1, L2, L3 serovars

Question 7

Which pattern suggests secondary syphilis rather than pityriasis rosea?

Accepted Answer

Palmoplantar involvement

Answer

Christmas tree distribution

Answer

Collarette scaling

Answer

Herald patch presence

Question 8

Which nerve biopsy is taken to diagnose neuritic leprosy?

Accepted Answer

Radial cutaneous nerve

Answer

Median nerve

Answer

Radial nerve

Answer

Ulnar nerve

Question 9

Most specific sign of secondary syphilis is:

Accepted Answer

Condyloma lata

Answer

Mucous patches

Answer

Copper colored rash

Answer

Palm/sole lesions

Question 10

Which feature best differentiates folliculitis from furuncle?

Accepted Answer

Depth of involvement

Answer

Age of presentation

Answer

Causative organism

Answer

Site of occurrence

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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