KMU Past Paper Practice

Question:

A 22-year-old student develops recurrent vesicular lesions at the same site on the lower lip. Examination between attacks is normal. Which property of the causative virus best explains the symptom-free interval between episodes?

Options:

Correct Answer:
Persistence in sensory neurons without active epithelial replication

Explanation: HSV remains latent in sensory ganglia between attacks, so the skin may appear normal until reactivation sends virus back to the epithelium.

Question:

A 66-year-old man recovers from a unilateral vesicular eruption over the left thorax but continues to experience burning pain in the same region after the skin lesions have healed. Which structure was most directly affected during the illness?

Options:

Correct Answer:
Sensory nerve fibers and ganglion

Explanation: Herpes zoster involves reactivation in a sensory ganglion and inflammation of the corresponding sensory nerve, explaining persistent neuropathic pain.

Question:

A child has patchy scalp scaling with broken hairs. The physician suspects a dermatophyte infection involving hair shafts. Which organism group has the biological property most relevant to this presentation?

Options:

Correct Answer:
Fungi capable of utilizing keratin

Explanation: Dermatophytes colonize keratinized structures such as stratum corneum, hair and nails because they can utilize keratin.

Question:

A 45-year-old patient has erythematous macerated lesions in opposing skin folds. The clinician suspects Candida rather than dermatophytosis. Which biological feature supports this diagnosis?

Options:

Correct Answer:
Opportunistic overgrowth on moist body surfaces

Explanation: Candida commonly colonizes the body and produces disease when local conditions such as warmth, moisture and occlusion favor excessive growth.

Question:

A school-aged child develops multiple superficial pustules around the nose. The lesions rupture easily and leave crusted erosions without deep tissue involvement. Which pair of organisms is most relevant to this condition?

Options:

Correct Answer:
Staphylococcus aureus and Streptococcus pyogenes

Explanation: Impetigo is a superficial bacterial infection commonly associated with S. aureus and may also be caused by S. pyogenes.

Question:

A 38-year-old man presents with a small erythematous pustule arising exactly at the site of a beard hair. The lesion is superficial and there is no diffuse surrounding swelling. Which structure is the primary site of infection?

Options:

Correct Answer:
Hair follicle

Explanation: Folliculitis is an infection centered on the hair follicle and typically appears as a small erythematous papule or pustule around a hair.

Question:

A patient with a painful swelling has a fluctuant cavity containing pus. Histologically, the center contains large numbers of neutrophils and liquefied tissue debris. Which lesion best corresponds to this process?

Options:

Correct Answer:
Skin abscess

Explanation: A skin abscess is a localized pus-filled cavity produced by neutrophilic inflammation and liquefactive destruction of infected tissue.

Question:

A 47-year-old man has a painful lesion that began as folliculitis and progressed into a single deeper pus-filled nodule. Which term best describes this progression?

Options:

Correct Answer:
Furuncle

Explanation: A furuncle is a deeper extension of follicular infection into surrounding dermis with formation of a localized abscess.

Question:

A patient with a deep soft-tissue infection develops worsening edema and tissue discoloration. The infected region becomes poorly perfused as small vessels are occluded. Which downstream event is most likely to follow?

Options:

Correct Answer:
Ischemic tissue necrosis

Explanation: Vascular thrombosis reduces tissue perfusion in necrotizing infection, causing ischemia and subsequent tissue necrosis.

Question:

A patient with suspected necrotizing soft-tissue infection has comparatively mild erythema but severe deep tenderness and rapidly increasing pain. Why may the skin surface initially underestimate the severity of disease?

Options:

Correct Answer:
The infection primarily spreads along deeper tissue planes

Explanation: Necrotizing infection can advance rapidly through deep fascia and soft tissues before extensive surface changes become visible.

Question:

A patient with a localized superficial bacterial skin infection is given topical fusidic acid. Which general therapeutic effect is expected from this drug?

Options:

Correct Answer:
Suppression of bacterial protein synthesis

Explanation: Fusidic acid interferes with bacterial protein synthesis and is useful against susceptible organisms, especially staphylococci.

Question:

A patient applies a topical antimicrobial repeatedly to a localized lesion and later develops itching and erythema confined to the treated area. There are no systemic symptoms. Which adverse effect best explains the new findings?

Options:

Correct Answer:
Local contact irritation

Explanation: Topical antimicrobials may produce local burning, itching, erythema or contact dermatitis without causing systemic illness.

Question:

A patient with widespread dermatophytosis requires oral therapy. The clinician selects a drug because it acts at a different step of fungal sterol synthesis from azoles. Which pharmacological target is involved?

Options:

Correct Answer:
Squalene epoxidase

Explanation: Terbinafine inhibits squalene epoxidase, disrupting the ergosterol pathway at a different step from azole antifungals.

Question:

A patient receiving treatment for oral candidiasis is prescribed fluconazole. Which cellular structure is most directly affected by the drug’s inhibition of ergosterol synthesis?

Options:

Correct Answer:
Fungal cell membrane

Explanation: Ergosterol is a major fungal membrane component, so azole-mediated reduction of ergosterol disrupts membrane structure and function.

Question:

A patient has a small localized patch of superficial dermatophytosis on the trunk without hair or nail involvement. Which therapeutic principle best supports the initial use of a topical antifungal?

Options:

Correct Answer:
The organism is limited to accessible superficial tissue

Explanation: Localized superficial fungal infection is accessible to topical treatment, whereas extensive hair or nail disease is more likely to need systemic therapy.

Question:

A patient with recurrent localized herpes labialis is prescribed an antiviral preparation. The drug is activated preferentially within infected cells. Which consequence most directly follows its activation?

Options:

Correct Answer:
Suppression of viral DNA synthesis

Explanation: Activated acyclovir inhibits viral DNA polymerase, reducing viral DNA synthesis and thereby limiting herpesvirus replication.

Question:

A 31-year-old man develops a slowly progressive papule on the forearm after repeated outdoor exposure in an endemic region. The lesion later ulcerates. Which step occurs soon after transmission of the causative organism into the skin?

Options:

Correct Answer:
Uptake by tissue macrophages

Explanation: After inoculation by the sandfly, Leishmania is taken up by macrophages, where intracellular multiplication drives the chronic skin lesion.

Question:

A primary-care physician evaluates a patient with a chronic painless ulcer on an exposed limb. The patient is stable and has no rapidly spreading erythema or systemic toxicity. Which feature most strongly supports cutaneous leishmaniasis rather than an acute bacterial soft-tissue infection?

Options:

Correct Answer:
Slow progression over a prolonged period

Explanation: Cutaneous leishmaniasis typically evolves slowly from papule or nodule to chronic ulcer, unlike rapidly progressive pyogenic infection.

Question:

A man with suspected cutaneous leishmaniasis has one lesion on the forearm and another close to the eye. Which feature most strongly increases the need for referral rather than simple local primary-care management?

Options:

Correct Answer:
Presence of a lesion at a difficult anatomical site

Explanation: Lesions at cosmetically or functionally important sites require careful assessment and may need specialist treatment planning.

Question:

A student is asked to match the depth of infection with its likely clinical appearance. Which pairing is most accurate?

Options:

Correct Answer:
Upper dermis and lymphatics — raised sharply defined erythema

Explanation: Erysipelas involves the upper dermis and superficial lymphatics, producing a raised lesion with a relatively sharply defined border.