Common Infections — MCQs
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A 67-year-old man with peripheral vascular disease presents with a diabetic foot ulcer on his right heel with surrounding erythema extending 4cm, purulent discharge, and exposed bone visible in the ulcer base. X-ray shows cortical erosion. Temperature is 37.8°C. Deep tissue cultures are pending. According to current guidelines, which statement about antibiotic therapy is most accurate?
A 58-year-old woman with poorly controlled diabetes presents with malignant otitis externa. CT shows skull base osteomyelitis. Tissue cultures grow Pseudomonas aeruginosa with the following sensitivities: ciprofloxacin (sensitive), gentamicin (sensitive), piperacillin-tazobactam (sensitive), meropenem (sensitive). She has normal renal function. Considering both efficacy and antimicrobial stewardship principles, what is the most appropriate long-term oral antibiotic for outpatient therapy?
A 25-year-old intravenous drug user presents with fever (39.1°C), rigors, and multiple painful pustular lesions on his hands and feet. Several lesions have necrotic centres. He has a new cardiac murmur. Blood cultures grow Staphylococcus aureus sensitive to flucloxacillin. Echocardiogram confirms tricuspid valve endocarditis. What is the minimum recommended duration of intravenous antibiotic therapy?
A hospital pharmacy department is implementing an antimicrobial stewardship intervention. Audit data shows that 35% of surgical prophylaxis doses are continued beyond 24 hours post-operatively without documented indication. Which strategy addresses this issue while maintaining patient safety?
A 38-year-old man who recently returned from working on an agricultural farm presents with a rapidly progressive, painful ulcer on his forearm with surrounding purple discoloration and black eschar. He is febrile (38.9°C) and appears unwell. Examination reveals marked oedema extending to the upper arm with regional lymphadenopathy. What is the most likely diagnosis?
Which of the following situations best exemplifies the antimicrobial stewardship principle of 'de-escalation' therapy?
A 72-year-old nursing home resident is treated for aspiration pneumonia with co-amoxiclav. After 10 days, he develops profuse watery diarrhoea (8 episodes/day), abdominal cramping, and fever (38.2°C). Stool sample is positive for Clostridioides difficile toxin. His WCC is 18 × 10⁹/L and creatinine 145 μmol/L (baseline 95 μmol/L). What is the most appropriate treatment?
A 28-year-old woman presents with a 3-day history of a painful, red lump in her axilla. On examination, there is a 3cm tender, fluctuant, erythematous swelling with a visible central punctum. She is apyrexial with normal observations. What is the most appropriate initial management?
A hospital's antimicrobial stewardship committee is reviewing prescribing data and notes that carbapenem use has increased by 40% over 6 months without corresponding changes in case mix or severity of illness. Which intervention is most likely to effectively reduce inappropriate carbapenem use?
A 42-year-old homeless man presents with extensive cellulitis of the left leg with multiple areas of skin breakdown and purulent discharge. Swabs grow meticillin-resistant Staphylococcus aureus (MRSA). He has a documented severe penicillin allergy (anaphylaxis). Which antibiotic is most appropriate for treating his infection?
Common Infections UK Medical PG Practice Questions and MCQs
Question 231: A 67-year-old man with peripheral vascular disease presents with a diabetic foot ulcer on his right heel with surrounding erythema extending 4cm, purulent discharge, and exposed bone visible in the ulcer base. X-ray shows cortical erosion. Temperature is 37.8°C. Deep tissue cultures are pending. According to current guidelines, which statement about antibiotic therapy is most accurate?
- A. Empirical antibiotics should cover Staphylococcus aureus, streptococci, gram-negative organisms, and anaerobes (Correct Answer)
- B. Antibiotics are not indicated as surgical debridement provides adequate source control
- C. Oral antibiotics are adequate regardless of severity given the chronic nature of diabetic foot infections
- D. Empirical therapy should target Pseudomonas aeruginosa as the most likely organism
- E. Duration of antibiotic therapy should be 6 weeks minimum due to osteomyelitis
Explanation: ***Empirical antibiotics should cover Staphylococcus aureus, streptococci, gram-negative organisms, and anaerobes***- This patient has a **moderate-to-severe diabetic foot infection** with **osteomyelitis**, indicated by exposed bone, cortical erosion, purulent discharge, and erythema, which typically involves a **polymicrobial** flora.- Initial **empirical therapy** for severe diabetic foot infections must be broad-spectrum to cover the most common pathogens, including **Staphylococcus aureus**, **streptococci**, various **gram-negative bacilli**, and **anaerobes**, especially given the presence of osteomyelitis and pending cultures.*Antibiotics are not indicated as surgical debridement provides adequate source control*- While **surgical debridement** is crucial for source control in infected diabetic foot ulcers, especially with exposed bone, it does not negate the need for **antibiotic therapy**.- The presence of clear signs of infection (erythema, purulent discharge, elevated temperature) and **osteomyelitis** mandates systemic antimicrobial treatment alongside surgical intervention.*Oral antibiotics are adequate regardless of severity given the chronic nature of diabetic foot infections*- This patient's presentation, including **exposed bone**, **cortical erosion**, **purulent discharge**, significant **erythema (4cm)**, and a **low-grade fever**, indicates a severe infection, likely requiring **intravenous (IV) antibiotics** initially.- Oral antibiotics are generally reserved for **mild-to-moderate infections** without signs of systemic involvement or osteomyelitis, or as step-down therapy after initial IV treatment.*Empirical therapy should target Pseudomonas aeruginosa as the most likely organism*- **Staphylococcus aureus** (including MRSA) and **streptococci** are the most common pathogens in diabetic foot infections, with **gram-negative bacteria** and **anaerobes** also being significant, especially in severe cases.- **Pseudomonas aeruginosa** is typically considered if there are specific risk factors, such as prolonged water exposure, previous **Pseudomonas** isolation, or failed prior broad-spectrum antibiotics, none of which are explicitly mentioned here as primary targets for initial empirical therapy.*Duration of antibiotic therapy should be 6 weeks minimum due to osteomyelitis*- The duration of antibiotic therapy for **diabetic foot osteomyelitis** is variable; while 6 weeks is often cited for medically managed cases or those with incomplete debridement, it can be significantly shortened to **2-4 weeks** if infected bone is completely **resected** during surgery.- The optimal duration depends on the extent of surgical debridement, the patient's clinical response, and the specific pathogens identified.
Question 232: A 58-year-old woman with poorly controlled diabetes presents with malignant otitis externa. CT shows skull base osteomyelitis. Tissue cultures grow Pseudomonas aeruginosa with the following sensitivities: ciprofloxacin (sensitive), gentamicin (sensitive), piperacillin-tazobactam (sensitive), meropenem (sensitive). She has normal renal function. Considering both efficacy and antimicrobial stewardship principles, what is the most appropriate long-term oral antibiotic for outpatient therapy?
- A. Oral ciprofloxacin (Correct Answer)
- B. Oral co-trimoxazole
- C. Oral amoxicillin-clavulanate
- D. Continued intravenous piperacillin-tazobactam via outpatient parenteral therapy
- E. Oral linezolid
Explanation: ***Oral ciprofloxacin*** - **Ciprofloxacin** is a highly effective oral fluoroquinolone with excellent activity against **Pseudomonas aeruginosa**, which is the confirmed pathogen in this case and shown to be sensitive. - It offers superior **oral bioavailability** and **bone penetration**, making it the most appropriate and effective long-term oral treatment for **malignant otitis externa** with **skull base osteomyelitis**, adhering to antimicrobial stewardship principles by avoiding unnecessary IV therapy. *Oral co-trimoxazole* - **Co-trimoxazole** lacks reliable or significant activity against **Pseudomonas aeruginosa**, rendering it ineffective for treating this infection. - It is typically used for pathogens like MRSA, *Pneumocystis jirovecii*, or specific urinary tract infections, which are not the cause here. *Oral amoxicillin-clavulanate* - **Amoxicillin-clavulanate** does not provide coverage for **Pseudomonas aeruginosa** and would be ineffective against this specific pathogen. - Its spectrum primarily covers common community-acquired respiratory and skin pathogens, not serious *Pseudomonas* infections like **skull base osteomyelitis**. *Continued intravenous piperacillin-tazobactam via outpatient parenteral therapy* - Although **piperacillin-tazobactam** is effective, continuing **intravenous therapy** for long-term outpatient management is less desirable due to increased risks of **catheter-related infections**, thrombosis, and higher costs. - **Antimicrobial stewardship** emphasizes transitioning to an effective oral agent when available and appropriate, reducing the burden and risks associated with IV lines. *Oral linezolid* - **Linezolid** is primarily active against **Gram-positive organisms** such as MRSA and VRE; it has no activity against **Gram-negative bacteria**. - Therefore, it would be completely ineffective against **Pseudomonas aeruginosa**, the causative agent of **malignant otitis externa** in this patient.
Question 233: A 25-year-old intravenous drug user presents with fever (39.1°C), rigors, and multiple painful pustular lesions on his hands and feet. Several lesions have necrotic centres. He has a new cardiac murmur. Blood cultures grow Staphylococcus aureus sensitive to flucloxacillin. Echocardiogram confirms tricuspid valve endocarditis. What is the minimum recommended duration of intravenous antibiotic therapy?
- A. 2 weeks
- B. 4 weeks (Correct Answer)
- C. 6 weeks
- D. 8 weeks
- E. 12 weeks
Explanation: ***4 weeks*** - For **native valve endocarditis** caused by **meticillin-sensitive Staphylococcus aureus (MSSA)**, a minimum of **4 weeks** of intravenous bactericidal therapy (such as flucloxacillin) is the standard recommendation. - Although this is **right-sided (tricuspid) endocarditis**, the presence of **metastatic septic emboli** (painful pustular and necrotic skin lesions) indicates disseminated infection and necessitates a full 4-week course. *2 weeks* - A **2-week** course is only considered in highly selected cases of **uncomplicated right-sided endocarditis** without systemic complications, such as a lack of pulmonary or peripheral septic emboli. - This patient's **pustular and necrotic skin lesions** are clear signs of disseminated infection, making a 2-week course inadequate and potentially dangerous for treatment failure. *6 weeks* - **6 weeks** of therapy is generally reserved for patients with **prosthetic valve endocarditis (PVE)**, infections caused by more resistant organisms (e.g., *Enterococcus*), or native valve endocarditis with **local complications** like an abscess. - While longer courses can be used for complicated cases or poor response, 6 weeks is not the standard minimum for native MSSA endocarditis without these specific indications. *8 weeks* - **8 weeks** is not a standard recommended duration for the primary treatment of **native valve MSSA endocarditis**, even with dissemination. - Such prolonged therapy is typically reserved for very severe, deep-seated **chronic infections** or persistent bacteremia despite initial standard treatment, which is not described here. *12 weeks* - **12 weeks** is an excessively long duration for **acute infective endocarditis** and is not supported by current clinical guidelines for *Staphylococcus aureus* endocarditis. - Overly prolonged antibiotic courses increase the risk of **drug toxicity**, **central line-associated bloodstream infections**, and the development of **antibiotic resistance**.
Question 234: A hospital pharmacy department is implementing an antimicrobial stewardship intervention. Audit data shows that 35% of surgical prophylaxis doses are continued beyond 24 hours post-operatively without documented indication. Which strategy addresses this issue while maintaining patient safety?
- A. Automatic stop orders for surgical prophylaxis at 24 hours unless reauthorized (Correct Answer)
- B. Pre-printed orders with maximum 24-hour duration for surgical prophylaxis
- C. Pharmacist-led ward rounds to review all post-operative patients
- D. Mandatory infectious diseases consultation for prophylaxis beyond 24 hours
- E. Education sessions for surgeons about appropriate prophylaxis duration
Explanation: ***Automatic stop orders for surgical prophylaxis at 24 hours unless reauthorized*** - **Automatic stop orders** are a highly effective **passive antimicrobial stewardship intervention** that directly prevents the continuation of unnecessary prophylaxis. - This system ensures **patient safety** by requiring a specific **reauthorization** for extended use, preventing prolonged exposure to antibiotics without clinical justification. *Pre-printed orders with maximum 24-hour duration for surgical prophylaxis* - While **pre-printed orders** can promote appropriate initial prescribing, they lack the **enforcement mechanism** to prevent clinicians from extending prophylaxis manually. - This method is more of a **persuasive strategy** and less effective at preventing continuation beyond 24 hours compared to an automatic stop. *Pharmacist-led ward rounds to review all post-operative patients* - This strategy is **resource-intensive** and requires significant **pharmacist time**, making it difficult to implement consistently for all post-operative patients. - It is a **reactive intervention**, identifying issues after they occur, rather than a proactive systemic solution like an automatic stop order. *Mandatory infectious diseases consultation for prophylaxis beyond 24 hours* - Requiring a **mandatory ID consultation** for every extended prophylaxis would place an **unmanageable burden** on infectious disease specialists. - This approach can also introduce **delays in patient care** and is an overly restrictive measure for what should be a straightforward protocol adherence. *Education sessions for surgeons about appropriate prophylaxis duration* - While **education is crucial** for raising awareness, it often has **limited long-term impact** on behavior change when used in isolation. - It relies heavily on individual **memory and compliance**, which may not be sufficient to address a high rate (35%) of non-adherence.
Question 235: A 38-year-old man who recently returned from working on an agricultural farm presents with a rapidly progressive, painful ulcer on his forearm with surrounding purple discoloration and black eschar. He is febrile (38.9°C) and appears unwell. Examination reveals marked oedema extending to the upper arm with regional lymphadenopathy. What is the most likely diagnosis?
- A. Cutaneous anthrax (Correct Answer)
- B. Necrotising fasciitis
- C. Ecthyma gangrenosum
- D. Cutaneous leishmaniasis
- E. Pyoderma gangrenosum
Explanation: ***Cutaneous anthrax*** - The combination of **agricultural exposure**, a rapidly progressive, painful ulcer with **purple discoloration**, **black eschar**, marked surrounding **oedema**, regional lymphadenopathy, and systemic symptoms like fever points strongly to cutaneous anthrax. - While classic anthrax lesions can be painless, severe forms can be painful and accompanied by significant systemic toxicity and extensive oedema, as described. *Necrotising fasciitis* - Typically characterized by excruciating **pain out of proportion** to the initial skin findings, rapid spread along **fascial planes**, and often features like **crepitus** due to gas production, which are not explicitly mentioned in the context of a central black eschar. - Although it involves rapid progression and systemic illness, the specific dermatological lesion with a **black eschar** and the distinct, non-pitting oedema differentiate it from typical necrotising fasciitis. *Ecthyma gangrenosum* - This condition is almost exclusively seen in **immunocompromised** or **neutropenic** patients, often associated with **Pseudomonas aeruginosa septicaemia**, leading to necrotic lesions via **hematogenous spread**. - The patient's presentation does not suggest immunosuppression, and the lesion's etiology is linked to direct exposure rather than a systemic infection causing cutaneous manifestations. *Cutaneous leishmaniasis* - Presents as a **painless, chronic ulcer** that evolves slowly over weeks to months after a **sandfly bite**, often with a raised, indurated border. - The described presentation is of an acutely painful, rapidly progressive ulcer with extensive oedema and systemic illness, which is inconsistent with the indolent nature of cutaneous leishmaniasis. *Pyoderma gangrenosum* - This is a **sterile neutrophilic dermatosis**, not an infection, typically associated with systemic inflammatory diseases such as **inflammatory bowel disease** or rheumatoid arthritis. - It presents with painful ulcers that have characteristic **undermined, violaceous borders** and often exhibit **pathergy**, features not consistent with a rapidly progressive, farm-exposure-related lesion with a black eschar.
Question 236: Which of the following situations best exemplifies the antimicrobial stewardship principle of 'de-escalation' therapy?
- A. Switching from IV to oral antibiotics when a patient can tolerate oral medication
- B. Narrowing from piperacillin-tazobactam to amoxicillin after blood cultures grow sensitive Streptococcus pneumoniae (Correct Answer)
- C. Reducing antibiotic duration from 14 to 7 days based on clinical improvement
- D. Stopping prophylactic antibiotics 24 hours post-operatively
- E. Changing from IV flucloxacillin to oral flucloxacillin for cellulitis
Explanation: ***Narrowing from piperacillin-tazobactam to amoxicillin after blood cultures grow sensitive Streptococcus pneumoniae*** - **De-escalation** is defined as narrowing the antimicrobial spectrum from broad empirical coverage to **targeted therapy** once a specific pathogen is identified and its sensitivities are known. - Replacing a broad-spectrum agent like **piperacillin-tazobactam** (effective against many gram-positive, gram-negative, and anaerobic bacteria) with a narrow-spectrum agent like **amoxicillin** (highly effective against susceptible *Streptococcus pneumoniae*) significantly reduces selective pressure and the risk of **antimicrobial resistance**. *Switching from IV to oral antibiotics when a patient can tolerate oral medication* - This process is known as **IV-to-oral switch** or sequential therapy, which focuses on **route optimization** rather than narrowing the spectrum of antimicrobial activity. - It aims to reduce **catheter-related infections** and hospital costs but is distinct from microbiological de-escalation. *Reducing antibiotic duration from 14 to 7 days based on clinical improvement* - This represents **duration optimization**, an important antimicrobial stewardship principle aimed at minimizing cumulative drug exposure and the development of resistance. - It does not involve changing the **antimicrobial spectrum** of the drug being used, only the length of treatment. *Stopping prophylactic antibiotics 24 hours post-operatively* - This is an example of adhering to **appropriate surgical prophylaxis** guidelines, which recommend short-course, usually single-dose, antibiotics to prevent surgical site infections. - It is a matter of **discontinuation** of a prophylactic regimen, not de-escalating a therapeutic regimen based on culture results. *Changing from IV flucloxacillin to oral flucloxacillin for cellulitis* - This is a classic **IV-to-oral conversion** where the spectrum of activity remains identical because the drug itself (flucloxacillin) has not changed. - It primarily improves **patient mobility** and facilitates discharge but does not constitute a narrow-spectrum de-escalation of therapy.
Question 237: A 72-year-old nursing home resident is treated for aspiration pneumonia with co-amoxiclav. After 10 days, he develops profuse watery diarrhoea (8 episodes/day), abdominal cramping, and fever (38.2°C). Stool sample is positive for Clostridioides difficile toxin. His WCC is 18 × 10⁹/L and creatinine 145 μmol/L (baseline 95 μmol/L). What is the most appropriate treatment?
- A. Oral vancomycin 125mg four times daily (Correct Answer)
- B. Oral metronidazole 400mg three times daily
- C. Intravenous metronidazole 500mg three times daily
- D. Oral fidaxomicin 200mg twice daily
- E. Stop co-amoxiclav and observe
Explanation: ***Oral vancomycin 125mg four times daily***- This patient has **severe Clostridioides difficile infection (CDI)**, defined by a **White Cell Count (WCC) > 15 × 10⁹/L** and an **acute rise in creatinine** (> 50% above baseline).- Current clinical guidelines recommend **oral vancomycin** as the first-line treatment for the first episode of severe CDI due to superior cure rates and high **intraluminal concentrations**.*Oral metronidazole 400mg three times daily*- Historically used for mild disease, it is no longer recommended as a first-line agent because it is **less effective** than vancomycin in achieving clinical cure.- It should only be considered if vancomycin or fidaxomicin are unavailable or contraindicated in **non-severe** cases.*Intravenous metronidazole 500mg three times daily*- This route is reserved for patients with **life-threatening (fulminant) CDI**, such as those with **ileus**, toxic megacolon, or hypotension.- It is typically administered in combination with **high-dose oral/nasogastric vancomycin** to ensure the antibiotic reaches the colon via the bloodstream when oral transit is compromised.*Oral fidaxomicin 200mg twice daily*- While it is as effective as vancomycin and reduces the risk of **recurrence**, it is often reserved for patients at high risk of recurrence or those with a **first relapse**.- In many protocols, it is used as a second-line option for a first episode unless specific local guidelines or patient risk factors prioritize it over vancomycin.*Stop co-amoxiclav and observe*- While **discontinuing the offending antibiotic** (co-amoxiclav) is a necessary step in management, it is insufficient as mono-management for severe CDI.- Severe infection with systemic symptoms like **fever** and **leukocytosis** requires prompt initiation of targeted anti-clostridial pharmacotherapy to prevent complications.
Question 238: A 28-year-old woman presents with a 3-day history of a painful, red lump in her axilla. On examination, there is a 3cm tender, fluctuant, erythematous swelling with a visible central punctum. She is apyrexial with normal observations. What is the most appropriate initial management?
- A. Incision and drainage with oral flucloxacillin
- B. Oral flucloxacillin without drainage
- C. Incision and drainage alone (Correct Answer)
- D. Warm compresses and analgesia only
- E. Aspiration with a wide-bore needle and oral antibiotics
Explanation: ***Incision and drainage alone*** - The patient has a localized **cutaneous abscess**, characterized by **fluctuance** and erythema; surgical **source control** via incision and drainage is the gold standard for management. - **Antibiotics** are not routinely indicated for simple abscesses in **immunocompetent** patients who are **apyrexial** and lack signs of systemic infection or significant surrounding cellulitis. *Incision and drainage with oral flucloxacillin* - Routine use of **antibiotics** following successful drainage of a simple abscess does not significantly improve cure rates or reduce recurrence in healthy patients. - Adding **flucloxacillin** should be reserved for those with **systemic upset**, extensive spreading cellulitis, or comorbidities like **diabetes**. *Oral flucloxacillin without drainage* - Antibiotics have poor penetration into the necrotic, **avascular center** of an abscess, making drainage necessary for resolution. - Relying solely on medication without addressing the **fluctuant collection** often leads to treatment failure and prolonged pain. *Warm compresses and analgesia only* - While warm compresses can help a very early, small furuncle to **localize** or spontaneously drain, they are insufficient once a 3cm **fluctuant mass** has formed. - Definitive **surgical intervention** is required at this stage to relieve pressure and evacuate the purulent material effectively. *Aspiration with a wide-bore needle and oral antibiotics* - **Needle aspiration** is associated with higher failure and **recurrence rates** compared to a formal incision and drainage for cutaneous abscesses. - Combining sub-optimal drainage with **unnecessary antibiotics** goes against **antimicrobial stewardship** principles when the patient is otherwise well.
Question 239: A hospital's antimicrobial stewardship committee is reviewing prescribing data and notes that carbapenem use has increased by 40% over 6 months without corresponding changes in case mix or severity of illness. Which intervention is most likely to effectively reduce inappropriate carbapenem use?
- A. Mandatory infectious diseases consultation for all carbapenem prescriptions
- B. Prospective audit with feedback and formulary restriction requiring approval (Correct Answer)
- C. Educational lectures for junior doctors about carbapenem resistance
- D. Email reminders to all prescribers about antimicrobial stewardship
- E. Removal of carbapenems from the hospital formulary
Explanation: ***Prospective audit with feedback and formulary restriction requiring approval***- This approach is considered the **gold standard** for antimicrobial stewardship, involving real-time review of prescriptions by experts followed by direct **communicated recommendations** to the clinician.- **Formulary restriction** provides immediate control over high-priority drugs like carbapenems, while the **audit and feedback** component ensures long-term behavioral change through clinical education.*Mandatory infectious diseases consultation for all carbapenem prescriptions*- While effective, this strategy is highly **resource-intensive** and can lead to significant delays in initiating treatment for critically ill patients.- It may create friction between departments and is often less scalable compared to a **system-wide stewardship** audit process.*Educational lectures for junior doctors about carbapenem resistance*- Passive education alone has a **minimal and unsustainable** impact on prescribing patterns when used as a standalone intervention.- While important for knowledge, it lacks the **real-time clinical decision support** required to alter prescribing behaviors in a high-pressure hospital environment.*Email reminders to all prescribers about antimicrobial stewardship*- This is a low-intensity intervention that often suffers from **alert fatigue**, leading clinicians to ignore the messaging.- It lacks the **active oversight** and clinical nuance required to handle specific cases involving potential multidrug-resistant organisms.*Removal of carbapenems from the hospital formulary*- This is clinically impractical and dangerous, as carbapenems are essential for managing **ESBL-producing organisms** and severe sepsis.- Total removal would force clinicians to use other broad-spectrum agents, potentially causing **collateral damage** and shifting resistance patterns to other antibiotic classes.
Question 240: A 42-year-old homeless man presents with extensive cellulitis of the left leg with multiple areas of skin breakdown and purulent discharge. Swabs grow meticillin-resistant Staphylococcus aureus (MRSA). He has a documented severe penicillin allergy (anaphylaxis). Which antibiotic is most appropriate for treating his infection?
- A. Intravenous vancomycin (Correct Answer)
- B. Intravenous teicoplanin
- C. Oral linezolid
- D. Intravenous daptomycin
- E. Oral doxycycline
Explanation: ***Intravenous vancomycin***- **Intravenous vancomycin** is the gold-standard, first-line treatment for severe **MRSA** skin and soft tissue infections requiring hospitalization and provides reliable bactericidal activity.- As a **glycopeptide**, it does not exhibit cross-reactivity with **beta-lactams**, making it the safest and most appropriate choice for a patient with a history of **penicillin-induced anaphylaxis**.*Intravenous teicoplanin*- While also a **glycopeptide**, it is generally considered an alternative to vancomycin and often requires complex **loading doses** to reach therapeutic levels rapidly.- In clinical practice, vancomycin is preferred for initial stabilization of serious **MRSA infections** due to a more robust evidence base in acute settings.*Oral linezolid*- **Linezolid** is typically reserved for cases where **glycopeptides** are contraindicated, such as significant **renal impairment** or documented resistance.- It carries a higher risk of adverse effects like **bone marrow suppression** and **serotonin syndrome** and is significantly more expensive than vancomycin.*Intravenous daptomycin*- Although effective against Gram-positive bacteria, **daptomycin** is usually reserved for **MRSA bacteraemia** or right-sided endocarditis rather than primary cellulitis.- It is not the standard first-line agent for skin infections in the UK unless other options have failed or are unsuitable.*Oral doxycycline*- **Oral doxycycline** is insufficient for severe, extensive cellulitis with skin breakdown, which requires the rapid bioavailability and potency of **intravenous therapy**.- While it can be used for minor **community-acquired MRSA**, it lacks the systemic efficacy needed for a patient with purulent discharge and potential systemic involvement.
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