Impetigo and drug-induced skin disorders: management MCQs With Answer

Impetigo and drug-induced skin disorders: management MCQs With Answer

This quiz collection is designed for M.Pharm students studying Pharmacotherapeutics I (MPP 102T). It focuses on clinical management, pharmacology, and practical decision-making for impetigo and drug-induced cutaneous reactions (including SJS/TEN, DRESS, AGEP). Questions emphasize drug selection (topical vs systemic), mechanisms of action, resistance and MRSA considerations, dosing/duration principles, adjunctive measures, and evidence-based approaches to severe immune‑mediated skin reactions — including when to stop offending drugs and use systemic immunomodulators (steroids, IVIG, cyclosporine). Answers are provided to reinforce learning and prepare students for clinical reasoning and examination-level problem solving.

Q1. Which organism is the predominant cause of non-bullous impetigo in children?

• Staphylococcus aureus (predominant cause)
• Streptococcus pneumoniae
• Pseudomonas aeruginosa
• Candida albicans

Correct Answer: Staphylococcus aureus (predominant cause)

Q2. What is the recommended first-line topical antibiotic for localized impetigo in most guidelines?

• Mupirocin ointment
• Topical clotrimazole
• Topical hydrocortisone cream
• Oral amoxicillin

Correct Answer: Mupirocin ointment

Q3. For extensive impetigo requiring systemic therapy in a pediatric patient, which oral antibiotic is commonly preferred targeting methicillin-sensitive Staphylococcus aureus (MSSA)?

• Oral flucloxacillin (anti-staphylococcal penicillin)
• Oral amoxicillin–clavulanate
• Oral azithromycin
• Oral metronidazole

Correct Answer: Oral flucloxacillin (anti-staphylococcal penicillin)

Q4. If community-associated MRSA is a suspected cause of impetigo, which oral agent is an appropriate outpatient choice for older children or adults?

• Trimethoprim–sulfamethoxazole (effective against community MRSA)
• Penicillin V
• Oral cephalexin (ineffective against many MRSA strains)
• Topical amphotericin B

Correct Answer: Trimethoprim–sulfamethoxazole (effective against community MRSA)

Q5. What is the typical recommended duration of topical mupirocin treatment for localized impetigo?

• 3 days
• 5 days
• 10 days
• 14 days

Correct Answer: 5 days

Q6. What is the primary mechanism of antibacterial action of mupirocin?

• Inhibition of bacterial isoleucyl‑tRNA synthetase
• Inhibition of peptidoglycan cross-linking (transpeptidase)
• DNA gyrase inhibition
• 30S ribosomal subunit blockade

Correct Answer: Inhibition of bacterial isoleucyl‑tRNA synthetase

Q7. Which statement best describes the role of antiseptic washes (e.g., chlorhexidine) in impetigo management?

• They are first-line monotherapy for extensive impetigo
• They are useful adjuncts to reduce skin bacterial colonization and household transmission
• They cure systemic complications of impetigo
• They should be avoided because they increase resistance

Correct Answer: They are useful adjuncts to reduce skin bacterial colonization and household transmission

Q8. Which post-infectious complication is classically associated with streptococcal impetigo?

• Post‑streptococcal glomerulonephritis
• Rheumatoid arthritis
• Stevens‑Johnson syndrome
• Herpes zoster reactivation

Correct Answer: Post‑streptococcal glomerulonephritis

Q9. Which drug-induced reaction is characterized by widespread epidermal necrosis with full‑thickness epidermal detachment and mucosal involvement?

• Stevens–Johnson syndrome / toxic epidermal necrolysis (SJS/TEN)
• Drug reaction with eosinophilia and systemic symptoms (DRESS)
• Acute generalized exanthematous pustulosis (AGEP)
• Fixed drug eruption

Correct Answer: Stevens–Johnson syndrome / toxic epidermal necrolysis (SJS/TEN)

Q10. What is the immediate first step when a severe cutaneous adverse reaction (e.g., SJS/TEN, DRESS) is suspected?

• Immediately discontinue the suspected offending drug(s)
• Start high‑dose oral antibiotics
• Apply topical steroids and continue the drug
• Perform patch testing before stopping drugs

Correct Answer: Immediately discontinue the suspected offending drug(s)

Q11. Which is the most appropriate initial inpatient management strategy for a patient with extensive epidermal detachment from TEN?

• Immediate transfer to a burn or specialized intensive care unit for supportive care (fluid, electrolytes, wound management)
• Routine dermatology outpatient follow‑up
• High‑dose oral antibiotics only
• Topical antiseptics at home

Correct Answer: Immediate transfer to a burn or specialized intensive care unit for supportive care (fluid, electrolytes, wound management)

Q12. Which drug is classically implicated as a common trigger of DRESS syndrome?

• Allopurinol
• Paracetamol (acetaminophen)
• Topical corticosteroids
• Oral probiotics

Correct Answer: Allopurinol

Q13. Which laboratory finding is most characteristic of DRESS syndrome?

• Eosinophilia with evidence of systemic organ involvement (e.g., elevated liver enzymes)
• Neutropenia without other abnormalities
• Isolated thrombocytopenia only
• Normal blood counts and chemistry always

Correct Answer: Eosinophilia with evidence of systemic organ involvement (e.g., elevated liver enzymes)

Q14. What is the mainstay of pharmacologic therapy for severe DRESS with organ involvement?

• Systemic corticosteroids (e.g., oral prednisone or IV methylprednisolone)
• Topical emollients only
• Long‑term oral antibiotics
• Oral antihistamines alone

Correct Answer: Systemic corticosteroids (e.g., oral prednisone or IV methylprednisolone)

Q15. Which statement about systemic corticosteroid use in SJS/TEN is most accurate?

• Systemic corticosteroids are universally recommended and clearly reduce mortality in all cases
• Their use is controversial; they may help if given very early but can increase infection risk and are not uniformly recommended
• They are contraindicated in all cases of SJS/TEN
• They should always be given topically instead of systemically

Correct Answer: Their use is controversial; they may help if given very early but can increase infection risk and are not uniformly recommended

Q16. Intravenous immunoglobulin (IVIG) is proposed to benefit SJS/TEN by which primary mechanism?

• Neutralization of Fas‑mediated keratinocyte apoptosis
• Direct antibacterial activity against skin flora
• Stimulation of epidermal proliferation
• Blockade of histamine H1 receptors

Correct Answer: Neutralization of Fas‑mediated keratinocyte apoptosis

Q17. Cyclosporine has been used in severe SJS/TEN. What is its main therapeutic action relevant to these reactions?

• Inhibition of T‑cell activation via calcineurin blockade
• Direct keratinocyte antibacterial effect
• Activation of eosinophils
• Enhancement of complement activation

Correct Answer: Inhibition of T‑cell activation via calcineurin blockade

Q18. Which class of drugs is most commonly associated with acute generalized exanthematous pustulosis (AGEP)?

• Beta‑lactam antibiotics (e.g., aminopenicillins)
• Topical retinoids
• Proton pump inhibitors
• Statins

Correct Answer: Beta‑lactam antibiotics (e.g., aminopenicillins)

Q19. Which diagnostic test can be useful in identifying the culprit drug in certain delayed T‑cell mediated cutaneous drug reactions?

• Patch testing (useful for some delayed drug eruptions)
• Skin prick testing (best for delayed reactions)
• Serum IgE specific testing for all delayed reactions
• Urine drug levels

Correct Answer: Patch testing (useful for some delayed drug eruptions)

Q20. For recurrent household impetigo with S. aureus carriage, which decolonization strategy is recommended to reduce transmission?

• Intranasal mupirocin plus chlorhexidine body washes for household contacts
• Year‑long oral antibiotics for all family members
• Daily topical steroids to carriers
• Immediate vaccination against S. aureus

Correct Answer: Intranasal mupirocin plus chlorhexidine body washes for household contacts

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