Skin and soft tissue infections UK Medical PG Practice Questions and MCQs
Practice UK Medical PG questions for Skin and soft tissue infections. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Skin and soft tissue infections UK Medical PG Question 1: A 16-year-old boy presents with a 1-week history of sore throat and fever. He has developed a widespread maculopapular rash after taking amoxicillin prescribed by his GP. What is the most likely underlying diagnosis?
- A. Penicillin allergy
- B. Infectious mononucleosis (Correct Answer)
- C. Scarlet fever
- D. Kawasaki disease
- E. Stevens-Johnson syndrome
Skin and soft tissue infections Explanation: ***Infectious mononucleosis***- The classic triad of **fever**, **pharyngitis** (sore throat), and **lymphadenopathy** in a young patient is highly suggestive of infectious mononucleosis, commonly caused by **Epstein-Barr virus (EBV)**.- A **widespread maculopapular rash** following amoxicillin administration is a very common and characteristic reaction in patients with infectious mononucleosis, often misinterpreted as a penicillin allergy.*Penicillin allergy*- While a rash after amoxicillin can indicate a penicillin allergy, the preceding symptoms of **sore throat and fever** for a week make an underlying infection, specifically mononucleosis, a more likely cause for the rash.- True penicillin allergies often present with **urticaria**, angioedema, or anaphylaxis, rather than a widespread maculopapular rash exacerbated by a viral illness.*Scarlet fever*- Scarlet fever is caused by **Streptococcus pyogenes** and presents with a characteristic **sandpaper-like rash** (finely papular, erythematous) and **strawberry tongue**, which are not described here.- While it causes sore throat and fever, the rash associated with scarlet fever is distinct from a generalized maculopapular rash triggered by amoxicillin in the context of mononucleosis.*Kawasaki disease*- Kawasaki disease primarily affects **young children** (typically under 5 years old) and is characterized by prolonged fever, **conjunctival injection**, **mucosal changes** (strawberry tongue, red lips), **polymorphous rash**, **cervical lymphadenopathy**, and **extremity changes**.- The patient's age (16 years old) and the specific rash reaction to amoxicillin make Kawasaki disease highly unlikely.*Stevens-Johnson syndrome*- **Stevens-Johnson syndrome (SJS)** is a severe mucocutaneous reaction, often drug-induced, characterized by widespread **bullae**, **erosions**, and **mucosal involvement** (oral, ocular, genital) with significant skin detachment (less than 10% total body surface area).- The description of a **widespread maculopapular rash** in this case is not consistent with the severe blistering and erosions typical of SJS.
Skin and soft tissue infections UK Medical PG Question 2: A 25-year-old woman presents with a 2-week history of sore throat, fever, and fatigue. She has cervical lymphadenopathy and splenomegaly. Her throat swab is negative for Group A Streptococcus. What is the most likely diagnosis?
- A. Viral pharyngitis
- B. Infectious mononucleosis (Correct Answer)
- C. Bacterial pharyngitis
- D. Diphtheria
- E. Candidiasis
Skin and soft tissue infections Explanation: ***Infectious mononucleosis***- The constellation of a 2-week history of **sore throat**, **fever**, profound **fatigue**, widespread **cervical lymphadenopathy**, and **splenomegaly** in a young adult is the classic presentation of infectious mononucleosis, primarily caused by **Epstein-Barr Virus (EBV)**.- The **negative throat swab for Group A Streptococcus** further supports a non-bacterial cause, and the prolonged symptoms with significant systemic involvement are key indicators.*Viral pharyngitis*- Typical **viral pharyngitis** is generally milder, resolves more quickly (within 3-5 days), and does not typically cause the significant systemic features such as profound **fatigue** and **splenomegaly** described.- While lymphadenopathy can occur, it is usually less generalized and prominent compared to the widespread involvement seen here.*Bacterial pharyngitis*- The patient's **negative throat swab for Group A Streptococcus** effectively rules out the most common bacterial cause of pharyngitis (strep throat).- Bacterial pharyngitis usually has a more acute onset, a shorter course, and rarely involves systemic findings like significant **fatigue** or **splenomegaly**.*Diphtheria*- **Diphtheria** is primarily characterized by the formation of a thick, adherent, **grayish-white pseudomembrane** over the tonsils and pharynx, which is not mentioned in the patient's presentation.- Although it can cause pharyngitis and fever, the combination of **splenomegaly** and diffuse, persistent lymphadenopathy is not typical for diphtheria.*Candidiasis*- **Oral candidiasis** (thrush) typically presents with creamy **white plaques** on the oral mucosa that can be scraped off, usually in immunocompromised individuals.- This is a localized fungal infection and would not cause the systemic findings of high fever, widespread lymphadenopathy, and **splenomegaly**.
Skin and soft tissue infections UK Medical PG Question 3: A 25-year-old woman presents with a 2-week history of sore throat, fever, and fatigue. She has cervical lymphadenopathy and splenomegaly. Her throat swab is negative for Group A Streptococcus. What is the most likely diagnosis?
- A. Viral pharyngitis
- B. Infectious mononucleosis (Correct Answer)
- C. Bacterial pharyngitis
- D. Diphtheria
- E. Candidiasis
Skin and soft tissue infections Explanation: ***Infectious mononucleosis***- The constellation of prolonged **fever**, **pharyngitis**, diffuse **lymphadenopathy**, and **splenomegaly** in a young adult is the classic presentation of primary infection with **Epstein-Barr Virus (EBV)**.- The relatively long duration of symptoms (2 weeks), the presence of **splenomegaly**, and the **negative Group A Strep swab** strongly suggest infectious mononucleosis.*Viral pharyngitis*- Common viral causes (e.g., rhinovirus, adenovirus) usually result in an acute illness, lasting less than 10 days, and do not typically cause sustained systemic symptoms or significant **splenomegaly**.- While presenting with sore throat and fever, non-EBV viral pharyngitis lacks the profound, persistent **fatigue** and notable **lymphadenopathy** seen in infectious mononucleosis.*Bacterial pharyngitis*- This is typically caused by *Streptococcus pyogenes* (Group A Strep), which was **ruled out by the negative throat swab**.- **Bacterial pharyngitis** rarely causes the sustained constitutional symptoms and concurrent **splenomegaly** seen in this case.*Diphtheria*- The hallmark of **diphtheria** is the presence of a thick, adherent, gray-white **pseudomembrane** on the tonsils and pharynx, which is not described in this patient.- It is rare in vaccinated populations and often leads to severe systemic toxicity (e.g., **myocarditis**) rather than the classic infectious mononucleosis triad.*Candidiasis*- Pharyngeal **candidiasis (thrush)** presents as white, easily removable plaques, often favored by antibiotic use or **immunosuppression**.- It is primarily a localized mucosal infection and usually does not cause the fever, systemic illness, or **splenomegaly** seen here.
Skin and soft tissue infections UK Medical PG Question 4: A 31-year-old man presents with fever, sore throat, and a widespread maculopapular rash after taking amoxicillin prescribed by his GP. What is the most likely underlying diagnosis?
- A. Penicillin allergy
- B. Infectious mononucleosis (Correct Answer)
- C. Scarlet fever
- D. Kawasaki disease
- E. Stevens-Johnson syndrome
Skin and soft tissue infections Explanation: ***Infectious mononucleosis*** - The combination of **fever**, **sore throat**, and a widespread **maculopapular rash** after taking amoxicillin is a classic presentation for **Epstein-Barr virus (EBV)** infection (infectious mononucleosis). - Approximately 80-90% of patients with infectious mononucleosis develop a non-allergic, diffuse rash when treated with **amoxicillin** or **ampicillin**. *Penicillin allergy* - A true **penicillin allergy** (Type I hypersensitivity) typically manifests as rapid onset **urticaria**, angioedema, or anaphylaxis, or a delayed itchy morbilliform rash, usually without the characteristic mononucleosis triad of symptoms. - The rash in mononucleosis patients taking amoxicillin is a **pharmacological interaction** with the underlying viral process, not a typical immunological allergic reaction. *Scarlet fever* - Characterized by a **sandpaper-like erythrodermic rash** and **circumoral pallor**, caused by *Streptococcus pyogenes* erythrogenic toxins. - The current presentation with a maculopapular rash specifically after amoxicillin is not typical of a streptococcal rash and strongly points towards a viral etiology. *Kawasaki disease* - This is a **medium-vessel vasculitis** primarily affecting **children** (typically under 5 years old), making it a highly unlikely diagnosis in a 31-year-old man. - Diagnosis requires persistent fever plus specific criteria like conjunctivitis, oral changes, peripheral extremity changes, lymphadenopathy, and a polymorphous rash. *Stevens-Johnson syndrome* - SJS is a severe, life-threatening **mucocutaneous reaction** characterized by **atypical target lesions** and prominent involvement of **mucous membranes** (oral, ocular, genital). - This condition involves significant **epidermal detachment** (less than 10% of total body surface area) and is distinct from a simple widespread maculopapular rash.
Skin and soft tissue infections UK Medical PG Question 5: A 58-year-old man with diabetes presents with severe foot pain and a deep ulcer exposing bone. X-ray shows osteolytic changes. What is the most likely complication?
- A. Cellulitis
- B. Osteomyelitis (Correct Answer)
- C. Charcot arthropathy
- D. Peripheral arterial disease
- E. Deep vein thrombosis
Skin and soft tissue infections Explanation: ***Osteomyelitis***- The patient's presentation of a **deep ulcer exposing bone** in the setting of **diabetes**, coupled with **severe foot pain** and **osteolytic changes** on X-ray, are classic indicators of osteomyelitis (bone infection).- **Diabetic foot ulcers** provide a direct pathway for bacterial invasion into the underlying bone, leading to destructive changes visible on imaging like X-rays.*Cellulitis*- Cellulitis is a bacterial infection of the **superficial skin and subcutaneous tissue**, characterized by **erythema**, warmth, and localized swelling.- It typically does not involve the underlying bone and therefore would not present with **bone exposure** or **osteolytic changes** on X-ray.*Charcot arthropathy*- **Charcot arthropathy** is a neuropathic joint degeneration, commonly seen in advanced diabetes, causing progressive joint destruction and deformity, often a **"rocker-bottom" foot**.- While it can lead to foot deformity and subsequent ulceration, it is typically **painless** due to significant neuropathy, contrasting with the patient's **severe pain**, and direct osteolytic changes of infection are not its primary X-ray feature.*Peripheral arterial disease*- **Peripheral arterial disease (PAD)** causes reduced blood flow to the extremities, leading to symptoms like **claudication**, **ischemic ulcers** (often on toes/heels), and rest pain.- While a significant comorbidity in diabetics and a risk factor for ulcers, PAD primarily involves vascular insufficiency and does not directly cause the **osteolytic changes** indicative of bone infection.*Deep vein thrombosis*- **Deep vein thrombosis (DVT)** is a blood clot in a deep vein, typically presenting as **unilateral leg swelling**, pain, and warmth.- It is a vascular issue not primarily associated with ulcers exposing bone, nor does it cause the **osteolytic changes** on a foot X-ray.
Skin and soft tissue infections UK Medical PG Question 6: A 34-year-old woman with Crohn's disease on adalimumab presents with a 10-day history of multiple painful nodules on both shins. The lesions are 2-4cm in diameter, raised, tender, and erythematous without ulceration or pustulation. She reports associated joint pains in her knees and ankles but no fever. Recent colonoscopy showed active inflammation. Blood tests reveal WCC 11.2 × 10⁹/L, CRP 78 mg/L, ESR 65 mm/hr. What is the most likely diagnosis?
- A. Cellulitis secondary to immunosuppression
- B. Pyoderma gangrenosum
- C. Erythema nodosum (Correct Answer)
- D. Sweet's syndrome (acute febrile neutrophilic dermatosis)
- E. Subcutaneous nodular panniculitis from adalimumab injection sites
Skin and soft tissue infections Explanation: ***Erythema nodosum***
- This patient presents with classic **tender, erythematous nodules** on the **shins** and associated **arthralgia** in the knees and ankles, which is a common extraintestinal manifestation of **Crohn's disease**.
- The active intestinal inflammation noted on colonoscopy and elevated **CRP** and **ESR** correlate well with the onset of erythema nodosum, which often reflects underlying disease activity.
*Cellulitis secondary to immunosuppression*
- Typically presents as a **unilateral**, diffuse area of skin erythema and warmth, often with a spreading border, rather than discrete, **bilateral nodules**.
- Usually accompanied by systemic features such as **fever** and significant pain upon touch, which are not explicitly reported here as the primary presenting features.
*Pyoderma gangrenosum*
- Characterized by rapidly enlarging, **painful ulcers** with **undermined violaceous borders** and purulent bases, whereas this patient has non-ulcerated nodules.
- While also associated with **Inflammatory Bowel Disease (IBD)**, its distinctive ulcerative morphology is a key differentiator from the patient's presentation.
*Sweet's syndrome (acute febrile neutrophilic dermatosis)*
- Typically presents with the sudden onset of painful, edematous, **erythematous plaques** or nodules frequently associated with a **high fever** and marked **peripheral neutrophilia**.
- The absence of fever and the nodular presentation without prominent plaques make this diagnosis less likely compared to erythema nodosum.
*Subcutaneous nodular panniculitis from adalimumab injection sites*
- These reactions would be localized strictly to the **site of injection**, commonly the **abdomen or thighs**, and would not typically manifest as widespread bilateral shin nodules.
- Such reactions are usually local inflammatory responses and not typically indicative of a systemic flare-up of Crohn's disease with corresponding elevated inflammatory markers like **CRP** and **ESR**.
Skin and soft tissue infections UK Medical PG Question 7: A 72-year-old man with chronic obstructive pulmonary disease is admitted with an exacerbation and started on prednisolone 30mg daily. On day 3 of admission, he develops a painful, erythematous rash on his right shin. The affected area is warm and tender with a well-demarcated, raised border and has a characteristic orange-peel (peau d'orange) appearance. His temperature is 38.4°C. Blood tests show WCC 16.2 × 10⁹/L, CRP 128 mg/L. Which organism is most likely responsible for this infection?
- A. Staphylococcus aureus
- B. Streptococcus pyogenes (Group A Streptococcus) (Correct Answer)
- C. Pseudomonas aeruginosa
- D. Haemophilus influenzae
- E. Pasteurella multocida
Skin and soft tissue infections Explanation: ***Streptococcus pyogenes (Group A Streptococcus)***- This patient presents with **erysipelas**, a superficial skin infection most commonly caused by **Group A Streptococcus**.- Characteristic features include a **well-demarcated**, raised border and a **peau d'orange** appearance due to involvement of the superficial lymphatics.*Staphylococcus aureus*- More commonly associated with **cellulitis**, which involves deeper dermis and subcutaneous fat with less defined borders.- Often linked to **purulent infections** and abscess formation, rather than the clear-cut edges seen here.*Pseudomonas aeruginosa*- Typically associated with **hot tub folliculitis** or infections following exposure to **contaminated water/moist environments**.- Usually presents in **immunocompromised patients** as ecthyma gangrenosum, which features necrotic ulcers rather than orange-peel skin.*Haemophilus influenzae*- A rare cause of skin infections in adults, occasionally causing facial cellulitis in **unvaccinated children**.- Clinical presentation usually lacks the specific **well-demarcated raised border** seen in this patient’s shin lesion.*Pasteurella multocida*- Primarily associated with cellulitis following **animal bites or scratches**, particularly from **cats or dogs**.- Onset is typically very rapid (within 24 hours of a bite), which does not correlate with this hospital-acquired presentation.
Skin and soft tissue infections UK Medical PG Question 8: A 61-year-old man presents with a 4-day history of a painful red swelling on his upper back. On examination, there is a 5cm area of indurated, erythematous skin with multiple pustular openings discharging purulent material from several adjacent hair follicles. His temperature is 37.8°C. He has well-controlled type 2 diabetes. What is this lesion called?
- A. Furuncle
- B. Carbuncle (Correct Answer)
- C. Hidradenitis suppurativa
- D. Folliculitis
- E. Erysipelas
Skin and soft tissue infections Explanation: ***Carbuncle***- A **carbuncle** is a deep, painful infection involving a cluster of interconnected **furuncles** that coalesce to form a single inflammatory mass with **multiple pustular openings** discharging purulent material from several adjacent hair follicles.- It commonly occurs in areas like the **upper back** and neck, often associated with systemic symptoms like fever and risk factors such as **type 2 diabetes mellitus**.*Furuncle*- A **furuncle**, or boil, is a deep infection of a **single hair follicle** and surrounding tissue, presenting as a solitary, tender nodule.- Unlike a carbuncle, it does not involve the **coalescence of multiple adjacent follicles** or widespread induration with multiple drainage points.*Hidradenitis suppurativa*- This is a chronic inflammatory condition primarily affecting **apocrine gland-bearing areas** such as the axillae, groin, and inframammary folds, not typically the upper back.- It is characterized by recurrent abscesses, **sinus tracts**, and significant **scarring**, features not described in this acute presentation.*Folliculitis*- **Folliculitis** is a superficial inflammation limited to the **hair follicle** itself, presenting as small, individual follicular pustules.- It lacks the deep induration, extensive size (5cm), and **multiple purulent openings** characteristic of a carbuncle.*Erysipelas*- **Erysipelas** is a superficial skin infection of the **upper dermis** and lymphatics, typically caused by *Streptococcus pyogenes*.- It presents as a bright red, edematous plaque with **sharply demarcated borders**, without the deep suppuration and **multiple follicular drainage points** seen in a carbuncle.
Skin and soft tissue infections UK Medical PG Question 9: A hospital trust implements a new antimicrobial stewardship intervention where all prescriptions for restricted antibiotics (carbapenems, colistin, linezolid, daptomycin, tigecycline) require approval from the on-call microbiology consultant before administration. After 6 months, audit data shows a 35% reduction in use of restricted antibiotics, but there have been 8 incidents where patients experienced delayed antibiotic administration due to difficulty contacting the on-call microbiologist. What modification to this intervention would best maintain stewardship benefits while improving patient safety?
- A. Allow approval by infectious diseases specialty trainees (ST4 and above) as well as consultants
- B. Implement a policy allowing administration of the first dose pending approval, with mandatory review within 24 hours (Correct Answer)
- C. Restrict the approval requirement to working hours only (9am-5pm, Monday-Friday)
- D. Provide a 24-hour dedicated antimicrobial stewardship telephone hotline with guaranteed response within 30 minutes
- E. Allow junior doctors to prescribe restricted antibiotics with consultant countersignature within 12 hours
Skin and soft tissue infections Explanation: ***Implement a policy allowing administration of the first dose pending approval, with mandatory review within 24 hours***
- This modification aligns with the **'Start Smart - Then Focus'** framework, ensuring timely administration of urgent therapy while maintaining strict **prospective audit and feedback**.
- It eliminates **delays in treatment** for critically ill patients, directly addressing the safety incidents while preserving the 35% reduction in long-term inappropriate use.
*Allow approval by infectious diseases specialty trainees (ST4 and above) as well as consultants*
- While this increases the number of available staff, it does not solve the **fundamental barrier** of clinical urgency where even a short delay in contacting someone can be harmful.
- **Safety incidents** may still occur if the trainee is busy in clinic or theater, failing to guarantee immediate access for the first dose.
*Restrict the approval requirement to working hours only (9am-5pm, Monday-Friday)*
- This significantly weakens the **antimicrobial stewardship** intervention, as a large volume of antibiotic prescribing occurs during out-of-hours and weekend shifts.
- It creates a **"weekend effect"** where restricted drug use could spike, undermining the goal of reducing overall institutional resistance patterns.
*Provide a 24-hour dedicated antimicrobial stewardship telephone hotline with guaranteed response within 30 minutes*
- Even a **30-minute delay** can be clinically significant in cases of **sepsis** or septic shock, where every hour delay in antibiotics increases mortality.
- This solution is **resource-intensive** and may not be sustainable or scalable for many hospital trusts compared to a policy-based change.
*Allow junior doctors to prescribe restricted antibiotics with consultant countersignature within 12 hours*
- This shift in responsibility to **non-specialist consultants** may lead to "prescriber creep" where stewardship goals are bypassed by clinicians less familiar with resistance profiles.
- It lacks the **expert oversight** of a microbiologist or ID specialist during the critical initial decision-making phase, potentially increasing inappropriate use.
Skin and soft tissue infections UK Medical PG Question 10: A 43-year-old woman with ulcerative colitis on infliximab presents with a 3-day history of painful vesicular lesions on her right buttock and posterior thigh following a dermatomal distribution. The lesions are at various stages with some showing crusting. She is immunosuppressed but otherwise systemically well with no fever. What is the most appropriate management?
- A. Oral aciclovir 800mg five times daily for 7 days
- B. Intravenous aciclovir 10mg/kg three times daily for 7-10 days (Correct Answer)
- C. Oral valaciclovir 1g three times daily for 7 days
- D. Topical aciclovir 5% cream five times daily for 5 days
- E. Oral famciclovir 500mg three times daily for 7 days
Skin and soft tissue infections Explanation: ***Intravenous aciclovir 10mg/kg three times daily for 7-10 days***
- Patients on **biologic therapy** such as **infliximab** are considered severely **immunocompromised**, necessitating intravenous treatment to prevent **disseminated** or visceral disease.
- **IV aciclovir** ensures higher systemic levels compared to oral routes, which is vital in preventing complications like **meningoencephalitis** or **organ involvement** in suppressed hosts.
*Oral aciclovir 800mg five times daily for 7 days*
- While this is a standard dose for **immunocompetent** patients, it has **poor bioavailability** and is insufficient for those on potent immunosuppressants.
- Oral therapy carries a higher risk of **treatment failure** and progression to **disseminated zoster** in this clinical context.
*Oral valaciclovir 1g three times daily for 7 days*
- Although **valaciclovir** has better oral bioavailability than aciclovir, it is still not the preferred gold standard for **severely immunosuppressed** patients.
- It is generally reserved for patients with more **moderate immunosuppression** or those who are transitionally stable from IV therapy.
*Topical aciclovir 5% cream five times daily for 5 days*
- **Topical antivirals** have no clinical role in the management of **herpes zoster** (shingles) as they do not address the viral replication in the **dorsal root ganglion**.
- Relying on topical treatment would significantly increase the risk of **post-herpetic neuralgia** and systemic spread.
*Oral famciclovir 500mg three times daily for 7 days*
- **Famciclovir** is a prodrug of penciclovir used for uncomplicated shingles in **immunocompetent individuals** and is not recommended as monotherapy here.
- The severity of the patient's **immunosuppression** from TNF-alpha inhibitors overrides the convenience of oral administration in favor of **parenteral therapy**.
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