Topical Antivirals — MCQs
Topical antiviral drugs are not indicated in:
A pregnant female presents with active herpetic lesions on the vulva. What is the most appropriate management?
A 32-year-old gay male presented to his community STD clinic with perianal condyloma acuminatum. Physical removal was recommended due to the size of the lesions, along with topical immunomodulatory therapy. Which of the following drugs was most likely selected?
Idoxuridine is used for treatment of?
Comment on the image shown:
A child presents with grouped vesicles on an erythematous base on the buttocks. What is the most likely diagnosis?
The following findings on Tzanck smear can be seen in:
Which of the following drug classes is commonly implicated in causing Stevens-Johnson syndrome?
Topical steroids can be used in which of the following keratitis conditions:
A patient developed fixed drug eruptions after taking certain medications. Which of the following drugs is known to cause these skin lesions?
Topical Antivirals Indian Medical PG Practice Questions and MCQs
Question 1: Topical antiviral drugs are not indicated in:
- A. Metaherpetic ulcer (Correct Answer)
- B. Dendritic ulcer
- C. Stromal necrotizing keratitis
- D. All of the options
Explanation: ***Metaherpetic ulcer*** - Metaherpetic ulcers are **neurotrophic ulcers** that develop as a result of chronic epithelial damage and impaired healing after a herpes simplex virus (HSV) infection, but they are not an active viral replication process. - Topical antivirals are ineffective because there is **no replicating virus** to target; management focuses on promoting corneal healing and preventing secondary infections. *Dendritic ulcer* - A dendritic ulcer is a classic sign of **active HSV keratitis** with replicating virus in the epithelial cells. - Topical antiviral drugs (e.g., acyclovir, ganciclovir) are the **first-line treatment** to inhibit viral replication and promote epithelial healing. *Stromal necrotizing keratitis* - This condition involves **inflammation and necrosis** in the corneal stroma, often due to an immune reaction to HSV antigens rather than direct viral invasion. - While topical antivirals may be used to suppress any residual replicating virus, **topical corticosteroids are often necessary** to control the inflammation, and close monitoring is crucial due to the risk of steroid-induced complications. *All of the options* - This option is incorrect because topical antiviral drugs *are* indicated for **dendritic ulcers** and sometimes as adjunctive therapy for **stromal necrotizing keratitis** where active viral replication might be contributing.
Question 2: A pregnant female presents with active herpetic lesions on the vulva. What is the most appropriate management?
- A. Wait & watch
- B. Acyclovir & elective cesarean section (C-section) (Correct Answer)
- C. Acyclovir & allow spontaneous progression of labor
- D. Induction of labor
Explanation: ***Acyclovir & elective cesarean section (C-section)*** - Active **genital herpetic lesions** at the time of delivery pose a significant risk of transmitting **herpes simplex virus (HSV)** to the neonate. - **Acyclovir** can help suppress viral replication, but a **cesarean section** is necessary to prevent direct contact with the lesions during birth, which could lead to severe neonatal HSV infection. *Wait & watch* - This approach is inappropriate due to the high risk of **vertical transmission** of HSV to the neonate if lesions are active during vaginal delivery, potentially causing life-threatening complications. - **Neonatal HSV** can result in significant morbidity and mortality, including neurological damage and disseminated disease. *Acyclovir & allow spontaneous progression of labor* - While **acyclovir** can reduce viral load, it does not completely eliminate the risk of transmission from active lesions during a vaginal birth. - The primary concern is protecting the neonate from direct contact with the **active lesions** in the birth canal. *Induction of labor* - **Induction of labor** does not mitigate the risk of **vertical transmission** from active lesions during a vaginal delivery. - The focus should be on preventing contact with the lesions, not on expediting vaginal birth once active lesions are present.
Question 3: A 32-year-old gay male presented to his community STD clinic with perianal condyloma acuminatum. Physical removal was recommended due to the size of the lesions, along with topical immunomodulatory therapy. Which of the following drugs was most likely selected?
- A. Acyclovir (antiviral)
- B. 5-Fluorouracil (chemotherapy)
- C. Imiquimod (topical immunomodulator) (Correct Answer)
- D. Podophyllin (antimitotic agent)
Explanation: ***Imiquimod (topical immunomodulator)*** - **Imiquimod** is a topical immunomodulator that stimulates the production of **cytokines**, such as **interferon-alpha**, thereby enhancing the local immune response against **HPV-infected cells**. - It is a common and effective therapy for external **genital** and **perianal warts (condyloma acuminatum)**, often used in conjunction with other treatments, especially for larger lesions. *Acyclovir (antiviral)* - **Acyclovir** is an antiviral drug primarily used to treat infections caused by the **herpes simplex virus (HSV)** and **varicella-zoster virus (VZV)**, not **human papillomavirus (HPV)**. - While condyloma acuminatum is caused by **HPV**, acyclovir has no therapeutic effect against it. *5-Fluorouracil (chemotherapy)* - **5-Fluorouracil** is a **cytotoxic chemotherapy agent** that inhibits **DNA synthesis** and is sometimes used topically for certain skin cancers and actinic keratoses. - While it can be used for warts, it is generally considered an off-label use and is **less commonly chosen** for perianal condyloma acuminatum due to significant local irritation and potential for ulceration. *Podophyllin (antimitotic agent)* - **Podophyllin** is a **cytotoxic agent** that arrests cell division and is used topically to treat some types of warts by causing **necrosis** of the wart tissue. - While effective, its application has to be carefully performed by a clinician, and it is **contraindicated in pregnancy**; it is also not classified as an immunomodulator.
Question 4: Idoxuridine is used for treatment of?
- A. Influenza
- B. RSV
- C. HSV (Correct Answer)
- D. HIV
Explanation: ***HSV*** - **Idoxuridine** is a **pyrimidine analog** that inhibits viral DNA synthesis, making it effective against **herpes simplex virus (HSV)** infections, particularly **herpes keratitis** (ophthalmic use). - Its mechanism involves being incorporated into viral DNA, leading to errors in replication and transcription. - It is applied **topically** for ocular HSV infections due to systemic toxicity concerns. *Influenza* - **Idoxuridine** is not active against **influenza viruses**. - **Antiviral drugs** like **oseltamivir** or **zanamivir** are typically used for influenza treatment. *RSV* - **Idoxuridine** is not indicated for the treatment of **respiratory syncytial virus (RSV)**. - **Ribavirin** is the primary antiviral agent used for severe RSV infections, especially in immunocompromised patients. *HIV* - **Idoxuridine** has no significant activity against **human immunodeficiency virus (HIV)**. - **Antiretroviral therapy (ART)**, a combination of drugs targeting various stages of the HIV life cycle, is used for HIV treatment.
Question 5: Comment on the image shown:
- A. Corn
- B. Callosity (Correct Answer)
- C. Warts
- D. Cutaneous horn
Explanation: ***Callosity*** - The image displays several **thickened, hyperkeratotic patches** on the palm, characteristic of callosities. - Callosities are caused by repeated friction and pressure, leading to **diffuse epidermal thickening** without a central core. *Corn* - A **corn** is a small, well-demarcated lesion with a **central core** that causes localized pain, unlike the diffuse thickening seen here. - They typically occur over bony prominences and are less spread out than the lesions in the image. *Warts* - **Warts** are caused by the **human papillomavirus (HPV)** and present as rough, elevated lesions with characteristic **black puncta** (thrombosed capillaries) upon paring, which are not visible in the image. - They often have a **papillomatous** or verrucous surface, different from the relatively smooth, thickened appearance here. *Cutaneous horn* - A **cutaneous horn** is a conical projection of **hyperkeratotic material** resembling an animal horn, typically developing on sun-exposed areas. - It is usually a solitary lesion and has a different morphology than the multiple, flat, thickened lesions shown.
Question 6: A child presents with grouped vesicles on an erythematous base on the buttocks. What is the most likely diagnosis?
- A. Bullous impetigo
- B. Dermatitis herpetiformis
- C. Pemphigus
- D. Herpes simplex (Correct Answer)
Explanation: ***Herpes simplex*** - Herpes simplex virus (HSV) classically presents with **grouped vesicles on an erythematous base**, which perfectly matches this clinical presentation. - In **children**, HSV commonly affects the **buttocks** through autoinoculation or direct contact, especially in the diaper area. - The lesions are typically **painful and pruritic**, and may be preceded by tingling or burning sensation. - Diagnosis is confirmed by **Tzanck smear** (multinucleated giant cells), **PCR**, or **viral culture**. - Treatment includes **acyclovir** or other antivirals, especially for severe or recurrent cases. *Dermatitis herpetiformis* - While DH does present with intensely pruritic, grouped vesicles on an erythematous base, it is **extremely rare in children** and typically presents in **adults (3rd-4th decade)**. - Classic sites include **extensor surfaces** (elbows, knees), scalp, and buttocks, but the pediatric presentation makes this diagnosis unlikely. - It is strongly associated with **celiac disease** and responds to **gluten-free diet** and **dapsone**. *Bullous impetigo* - Bullous impetigo presents with **flaccid bullae** that rupture to form **honey-colored crusts**, not grouped vesicles. - It is a **bacterial infection** caused by *Staphylococcus aureus* producing exfoliative toxin. - Common in **young children**, particularly in warm, humid conditions. *Pemphigus* - Pemphigus is **extremely rare in children** and causes **fragile bullae** that easily rupture, leading to erosions. - Typically affects **mucous membranes first** (oral cavity), then skin. - It is an **autoimmune blistering disease** with antibodies against desmoglein, causing intraepidermal acantholysis.
Question 7: The following findings on Tzanck smear can be seen in:
- A. Herpes simplex
- B. Herpes zoster
- C. Paraneoplastic pemphigus
- D. All of the above (Correct Answer)
Explanation: ***All of the above*** - The image displays multiple **acantholytic cells** (keratinocytes that have lost intercellular connections) with prominent nuclei, which are characteristic findings in several dermatological conditions. - A **Tzanck smear** is a rapid cytological test performed by scraping the base of a fresh blister, staining with Giemsa or Wright stain, and examining under microscopy. **Why all three conditions show similar findings:** *Herpes simplex* - Tzanck smear shows **multinucleated giant cells** with molding of nuclei and **balloon degeneration** of keratinocytes - Acantholytic cells are present due to viral cytopathic effect causing cell separation - These findings are **identical** to those seen in Herpes zoster *Herpes zoster* - Cannot be distinguished from Herpes simplex on Tzanck smear morphology alone - Shows the same **multinucleated giant cells** and **acantholytic keratinocytes** - Viral culture, PCR, or direct fluorescent antibody (DFA) testing needed for definitive differentiation *Paraneoplastic pemphigus* - Shows **acantholytic cells** (rounded keratinocytes with hyperchromatic nuclei) due to autoantibody-mediated destruction of intercellular adhesion - Unlike herpes infections, typically shows acantholytic cells **without** multinucleated giant cells - Definitive diagnosis requires direct immunofluorescence (DIF) on skin biopsy showing intercellular and basement membrane zone IgG/C3 deposition **Note**: While Tzanck smear can show acantholytic cells in all three conditions, the **pattern differs** - herpes shows multinucleated giant cells prominently, while pemphigus shows isolated acantholytic cells. Clinical correlation and confirmatory tests are essential for accurate diagnosis.
Question 8: Which of the following drug classes is commonly implicated in causing Stevens-Johnson syndrome?
- A. Antibiotics (Correct Answer)
- B. Corticosteroids
- C. Antifungals
- D. Proton pump inhibitors
Explanation: ***Antibiotics*** - **Antibiotics**, particularly **sulfonamides** (e.g., sulfamethoxazole-trimethoprim) and **beta-lactams** (e.g., penicillins, cephalosporins), are among the most common drug classes implicated in causing **Stevens-Johnson Syndrome (SJS)**. - SJS is a severe **idiosyncratic drug reaction**, and many antibiotics can trigger this immune-mediated response. - **Note:** Other major causative drug classes include **anticonvulsants** (carbamazepine, phenytoin, lamotrigine), **allopurinol**, and **NSAIDs**, but among the options listed, antibiotics are the most commonly implicated. *Corticosteroids* - **Corticosteroids** are typically used in the **treatment** of SJS to suppress the immune response and reduce inflammation, not to cause it. - While they have their own set of side effects, initiating SJS is not one of their known adverse reactions. *Antifungals* - Although some **antifungals** can cause adverse drug reactions, they are **not typically associated** with SJS compared to antibiotics, anticonvulsants, or allopurinol. - The risk of SJS with antifungal medications is generally very low. *Proton pump inhibitors* - **Proton pump inhibitors (PPIs)** are generally well-tolerated and are **rarely implicated** as a cause of SJS. - Their primary side effects are usually gastrointestinal and not severe dermatological reactions.
Question 9: Topical steroids can be used in which of the following keratitis conditions:
- A. Disciform keratitis (Correct Answer)
- B. Herpetic dendritic keratitis
- C. Bacterial keratitis
- D. Fungal keratitis
Explanation: ***Disciform keratitis*** - This condition is typically an **immune-mediated stromal inflammation** of the cornea, often following a **herpes simplex virus (HSV) infection**. - **Topical corticosteroids** (with concurrent antiviral therapy) are crucial for reducing the inflammation and edema associated with disciform keratitis, preserving corneal clarity. - This represents **HSV stromal keratitis** where the pathology is immunological rather than active viral replication. *Herpetic dendritic keratitis* - This is **active viral replication** of herpes simplex virus in the corneal epithelium, characterized by a **dendritic ulcer**. - **Topical steroids are strictly contraindicated** as they can worsen viral replication, leading to geographic ulcers and potentially corneal perforation. - Treatment requires antivirals only (acyclovir, ganciclovir). *Bacterial keratitis* - This is **acute bacterial infection** of the cornea, typically presenting as a corneal ulcer with purulent infiltrate. - **Topical steroids are contraindicated during active infection** as they suppress the immune response and can worsen bacterial proliferation. - Treatment focuses on intensive topical antibiotics; steroids may only be considered after infection control with close monitoring. *Fungal keratitis* - This is **fungal infection** of the cornea, often following trauma with vegetative matter, presenting with feathery infiltrates and satellite lesions. - **Topical steroids are absolutely contraindicated** as they dramatically worsen fungal infections and can lead to corneal perforation. - Treatment requires prolonged antifungal therapy (natamycin, voriconazole).
Question 10: A patient developed fixed drug eruptions after taking certain medications. Which of the following drugs is known to cause these skin lesions?
- A. Phenolphthalein
- B. Aspirin
- C. Dapsone
- D. All of the above (Correct Answer)
Explanation: **Explanation:** **Fixed Drug Eruption (FDE)** is a unique type of cutaneous drug reaction characterized by the recurrence of a lesion (usually a dusky red or violaceous macule) at the **exact same anatomical site** every time the offending drug is ingested. This occurs due to the persistence of **CD8+ memory T-cells** in the basal keratinocytes at the site of the lesion. **Why Option D is correct:** All three drugs listed are classic and high-yield triggers for FDE: * **Phenolphthalein:** Historically the most common cause (found in older laxatives). * **Aspirin (NSAIDs):** A very frequent trigger in clinical practice. * **Dapsone (Sulfonamides):** Sulfonamides are among the most common drug classes associated with FDE. **Analysis of Options:** * **Phenolphthalein:** Often presents as "bullous" FDE. * **Aspirin:** Along with other NSAIDs (like Ibuprofen and Naproxen), it is a leading cause of multi-focal FDE. * **Dapsone:** As a sulfone, it shares cross-reactivity patterns and is a well-documented cause. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most Common Site:** The **glans penis** is the most common site for FDE, followed by the lips and palms. 2. **Commonest Causes (Overall):** NSAIDs, Sulfonamides (Cotrimoxazole), Tetracyclines, and Anticonvulsants. 3. **Clinical Feature:** Lesions often leave behind **post-inflammatory hyperpigmentation (PIH)** after healing. 4. **Refractory Period:** After an eruption, there is a brief refractory period where the drug may not cause a reaction. 5. **Diagnosis:** Primarily clinical; however, a **Patch Test** performed at the site of the previous lesion (not on the back) can confirm the offending agent.
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