Common Infections — MCQs
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According to Public Health England guidance on antimicrobial stewardship, which of the following interventions has the strongest evidence base for reducing antimicrobial resistance in secondary care settings?
A 73-year-old care home resident develops urinary symptoms and is found to have 10⁵ CFU/mL of Escherichia coli sensitive to trimethoprim, nitrofurantoin, and ciprofloxacin but resistant to co-amoxiclav on urine culture. She was treated with co-amoxiclav by her GP two weeks ago for a chest infection. She is clinically well with no fever. According to antimicrobial stewardship principles, what is the most appropriate management?
A 56-year-old man with a history of intravenous drug use presents with painful swelling and erythema of his left hand following injection into the dorsum. X-ray shows soft tissue swelling and subcutaneous gas. Blood tests reveal WCC 22 × 10⁹/L, CRP 312 mg/L, and creatine kinase 4,500 U/L. On examination, the hand is tense, dusky in colour, and exquisitely tender. Which combination of organisms is most likely responsible?
A hospital's antimicrobial stewardship committee notes that 40% of antibiotic prescriptions in the medical assessment unit lack documented indication or review dates. They implement a new intervention requiring a mandatory electronic field for indication and planned review date before prescriptions can be authorized. Three months later, compliance increases to 85%. Which antimicrobial stewardship intervention type best describes this approach?
A 61-year-old woman with poorly controlled type 2 diabetes (HbA1c 89 mmol/mol) presents with a 3-day history of pain and swelling around her right eye. On examination, she has periorbital erythema, chemosis, proptosis, and restricted eye movements with diplopia. Her temperature is 38.7°C. CT scan shows preseptal and orbital soft tissue inflammation with evidence of ethmoid sinusitis but no abscess formation. Which antibiotic regimen is most appropriate?
A 44-year-old man is admitted with community-acquired pneumonia and started on intravenous co-amoxiclav. After 48 hours, he is clinically improved with reduced oxygen requirements and is apyrexial. His CRP has fallen from 245 mg/L to 89 mg/L. According to antimicrobial stewardship principles, what is the most appropriate next step in his antibiotic management?
A 29-year-old woman presents to A&E with a 24-hour history of rapidly progressive pain, swelling, and discolouration of her right forearm following a minor cut while gardening. On examination, the affected area is dusky purple with bullae formation, and there is crepitus on palpation. She has severe pain disproportionate to the clinical findings. Her temperature is 38.9°C, heart rate 118 bpm, and blood pressure 95/60 mmHg. Blood tests show WCC 18.2 × 10⁹/L, CRP 285 mg/L, creatinine 156 μmol/L, and lactate 4.2 mmol/L. What is the most appropriate immediate management?
A hospital antimicrobial stewardship team is reviewing the prescribing practices on surgical wards. They identify that prophylactic antibiotics for elective colorectal surgery are frequently continued beyond 24 hours postoperatively in patients without complications. Which of the following best describes the primary risk of this practice?
A 52-year-old man with type 2 diabetes presents with a carbuncle on the back of his neck. The lesion consists of multiple interconnected furuncles with several draining points. The surrounding area shows erythema extending 3cm beyond the lesion margins. He is apyrexial and haemodynamically stable. What is the most likely causative organism?
A 35-year-old woman presents to her GP with a 4-day history of a red, tender area on her right shin following a minor scratch from her cat. The affected area measures 8cm x 6cm, is warm to touch, and there is no evidence of purulence or lymphangitis. She is systemically well with normal observations. She has no known drug allergies. According to current antimicrobial stewardship principles, what is the most appropriate initial management?
Common Infections UK Medical PG Practice Questions and MCQs
Question 221: According to Public Health England guidance on antimicrobial stewardship, which of the following interventions has the strongest evidence base for reducing antimicrobial resistance in secondary care settings?
- A. Automatic stop dates on all antimicrobial prescriptions
- B. Educational outreach visits to prescribers
- C. Restriction of carbapenem use to infectious diseases specialists only
- D. Multifaceted antimicrobial stewardship programmes incorporating audit, formulary restriction, and clinical decision support (Correct Answer)
- E. Monthly feedback of individual prescriber data compared to peers
Explanation: ***Multifaceted antimicrobial stewardship programmes incorporating audit, formulary restriction, and clinical decision support*** - Evidence from **Public Health England** and systematic reviews shows that **multifaceted interventions** are the most effective way to reduce resistance and improve prescribing in hospitals. - Combining approaches like **prospective audit**, **formulary restriction**, and **clinical decision support** creates reinforcing mechanisms that yield stronger, more sustainable outcomes than single interventions. *Automatic stop dates on all antimicrobial prescriptions* - While **automatic stop dates** help prevent unnecessarily prolonged courses, they are considered a single-component structural intervention. - On their own, they are less effective than **comprehensive programmes** that include clinical review and evidence-based feedback. *Educational outreach visits to prescribers* - **Educational outreach** can improve knowledge and individual practice but is often insufficient to change long-term institutional prescribing patterns in isolation. - These visits are most effective when integrated into a broader **clinical decision support** strategy rather than standing alone. *Restriction of carbapenem use to infectious diseases specialists only* - **Formulary restriction** is a powerful tool for controlling specific high-risk drugs, but focusing on a single class does not address systemic resistance issues broadly. - Restrictive policies work best when supported by **audit and feedback** rather than acting as a solo administrative hurdle. *Monthly feedback of individual prescriber data compared to peers* - **Peer-comparison feedback** is a behavioral nudge that can reduce prescriptions, but its impact in secondary care is often limited without **guideline support**. - This intervention is a component of a stewardship programme but lacks the **multifaceted synergy** required for the strongest evidence base.
Question 222: A 73-year-old care home resident develops urinary symptoms and is found to have 10⁵ CFU/mL of Escherichia coli sensitive to trimethoprim, nitrofurantoin, and ciprofloxacin but resistant to co-amoxiclav on urine culture. She was treated with co-amoxiclav by her GP two weeks ago for a chest infection. She is clinically well with no fever. According to antimicrobial stewardship principles, what is the most appropriate management?
- A. Prescribe oral trimethoprim based on sensitivities
- B. No antibiotic treatment required as she is asymptomatic (Correct Answer)
- C. Prescribe ciprofloxacin as first-line therapy
- D. Repeat urine culture in one week before deciding on treatment
- E. Prescribe nitrofurantoin despite care home residence
Explanation: ***No antibiotic treatment required as she is asymptomatic*** - This patient presents with **asymptomatic bacteriuria** (ASB), characterized by significant bacterial counts in urine without clinical symptoms like fever or dysuria. - According to **antimicrobial stewardship** principles, ASB in elderly non-pregnant individuals should not be treated with antibiotics to prevent **antimicrobial resistance** and potential side effects such as **C. difficile infection**. *Prescribe oral trimethoprim based on sensitivities* - While the organism is sensitive, initiating antibiotics for **asymptomatic bacteriuria** is inappropriate and contrary to **antimicrobial stewardship** guidelines. - Unnecessary antibiotic use increases the risk of selecting for **resistant organisms** and potential adverse drug reactions, especially in an elderly patient with recent antibiotic exposure. *Prescribe ciprofloxacin as first-line therapy* - **Ciprofloxacin** is a **broad-spectrum fluoroquinolone** generally reserved for severe or complicated infections due to its potential for **collateral damage** and promotion of **resistance**. - Using it for asymptomatic bacteriuria is a misuse of a vital antibiotic class and carries a higher risk of adverse effects in the elderly. *Repeat urine culture in one week before deciding on treatment* - Repeating the culture is unlikely to change management as **asymptomatic bacteriuria** often persists, and the key determinant for treatment is the presence of **clinical symptoms**, which are absent here. - This approach delays appropriate management (no treatment) and does not align with the principle of avoiding unnecessary investigations and interventions in an asymptomatic patient. *Prescribe nitrofurantoin despite care home residence* - **Nitrofurantoin** is an appropriate choice for symptomatic uncomplicated UTIs, but this patient is **asymptomatic**. - **NICE guidelines** specifically advise against screening for and treating bacteriuria in **care home residents** without symptoms, as it does not improve outcomes and contributes to antibiotic resistance.
Question 223: A 56-year-old man with a history of intravenous drug use presents with painful swelling and erythema of his left hand following injection into the dorsum. X-ray shows soft tissue swelling and subcutaneous gas. Blood tests reveal WCC 22 × 10⁹/L, CRP 312 mg/L, and creatine kinase 4,500 U/L. On examination, the hand is tense, dusky in colour, and exquisitely tender. Which combination of organisms is most likely responsible?
- A. Staphylococcus aureus and Streptococcus pyogenes (Correct Answer)
- B. Clostridium perfringens and Clostridium septicum
- C. Pseudomonas aeruginosa and Acinetobacter baumannii
- D. Escherichia coli and Klebsiella pneumoniae
- E. Bacteroides fragilis and Peptostreptococcus species
Explanation: ***Staphylococcus aureus and Streptococcus pyogenes*** - This presentation of rapidly progressing, severe soft tissue infection with **subcutaneous gas**, markedly elevated **creatine kinase (CK)**, and high inflammatory markers in an **intravenous drug user (IVDU)** is highly suggestive of **Type II necrotising fasciitis**. - **S. aureus** and **S. pyogenes** (Group A Streptococcus) are the most common causative organisms in **Type II necrotising fasciitis**, often entering through skin breaches like injection sites. *Clostridium perfringens and Clostridium septicum* - These are the classic causes of **gas gangrene (clostridial myonecrosis)**, which involves deep muscle necrosis and significant gas production. - While they cause gas, their primary association is with deep traumatic wounds contaminated with soil or gut perforation, rather than typical IVDU-related superficial soft tissue infections. *Pseudomonas aeruginosa and Acinetobacter baumannii* - These are **gram-negative organisms** often associated with **nosocomial infections**, contaminated water sources, or infections in immunocompromised patients. - They are less common as primary agents in **community-acquired necrotising fasciitis** or acute IVDU-related infections, especially with this specific presentation of subcutaneous gas and high CK. *Escherichia coli and Klebsiella pneumoniae* - These are common **Enterobacteriaceae** associated with **Type I necrotising fasciitis**, which is typically **polymicrobial** and often occurs in the trunk, perineum (**Fournier's gangrene**), or in patients with underlying conditions. - While Type I can produce gas, this patient's presentation with a clear injection site and specific clinical picture (rapid onset, dusky hand, high CK) is more characteristic of Type II, which is typically monomicrobial or involves skin flora. *Bacteroides fragilis and Peptostreptococcus species* - These are **anaerobic bacteria** commonly involved in **polymicrobial infections** and are major components of **Type I necrotising fasciitis**, often originating from gut flora. - They are unlikely to be the sole or primary pathogens in an acute infection following an injection into the dorsum of the hand, which is more prone to contamination with skin flora.
Question 224: A hospital's antimicrobial stewardship committee notes that 40% of antibiotic prescriptions in the medical assessment unit lack documented indication or review dates. They implement a new intervention requiring a mandatory electronic field for indication and planned review date before prescriptions can be authorized. Three months later, compliance increases to 85%. Which antimicrobial stewardship intervention type best describes this approach?
- A. Prospective audit with intervention and feedback
- B. Formulary restriction with prior authorization
- C. Front-end restriction requiring pre-approval
- D. Structural intervention with decision support (Correct Answer)
- E. Post-prescription review and feedback
Explanation: ***Structural intervention with decision support*** - A **structural intervention** modifies the **prescribing system** (like adding mandatory electronic fields) to enforce appropriate antimicrobial use. - By incorporating these fields into the **electronic health record (EHR)**, the system provides **decision support** that ensures essential data (indication, review date) is captured at the point of care. *Prospective audit with intervention and feedback* - This approach involves **external experts** (e.g., pharmacists, ID physicians) reviewing active antibiotic orders and providing personalized recommendations to the prescriber. - It is a **post-prescription backend strategy** that occurs after the initial order, unlike the built-in mandatory fields described. *Formulary restriction with prior authorization* - This strategy limits the use of **specific high-cost** or broad-spectrum antibiotics by requiring approval from an infectious disease expert before the drug is dispensed. - It focuses on **drug selection and access** rather than systematically ensuring documentation of indications for all antibiotic prescriptions. *Front-end restriction requiring pre-approval* - This is synonymous with **prior authorization**, where a prescriber must receive **clinical clearance** (often from a specialist) before initiating a specific therapy. - This intervention is typically **drug-specific** and involves a human consultation, rather than an automated, mandatory field within the prescribing software. *Post-prescription review and feedback* - Also known as PPRF, this typically occurs **48-72 hours** after an initial empiric prescription to adjust therapy based on microbiology results and patient response. - It is a **retrospective audit** of an ongoing patient's therapy to improve appropriateness, not a proactive, structural requirement at the moment of initial computer entry.
Question 225: A 61-year-old woman with poorly controlled type 2 diabetes (HbA1c 89 mmol/mol) presents with a 3-day history of pain and swelling around her right eye. On examination, she has periorbital erythema, chemosis, proptosis, and restricted eye movements with diplopia. Her temperature is 38.7°C. CT scan shows preseptal and orbital soft tissue inflammation with evidence of ethmoid sinusitis but no abscess formation. Which antibiotic regimen is most appropriate?
- A. Oral co-amoxiclav alone
- B. Intravenous ceftriaxone and metronidazole (Correct Answer)
- C. Intravenous flucloxacillin and benzylpenicillin
- D. Intravenous vancomycin, ceftazidime, and metronidazole
- E. Oral doxycycline and metronidazole
Explanation: ***Intravenous ceftriaxone and metronidazole*** - This patient has **orbital cellulitis**, evidenced by **proptosis**, **ophthalmoplegia** (restricted eye movements with diplopia), and **fever**, requiring urgent **intravenous antibiotics** to prevent complications like **vision loss** or **intracranial spread**. - **Ceftriaxone** provides broad-spectrum coverage against common respiratory pathogens (e.g., *Streptococcus pneumoniae*, *Haemophilus influenzae*) and some Gram-negatives, while **metronidazole** effectively targets **anaerobic bacteria**, which are frequently involved in sinusitis-related orbital infections. *Oral co-amoxiclav alone* - **Oral antibiotics** are generally insufficient for treating established **orbital cellulitis** due to the severity of the infection and the potential for rapid progression and **sight-threatening complications**. - While **co-amoxiclav** is a broad-spectrum oral antibiotic, it lacks the necessary **bioavailability** and **tissue penetration** to adequately treat a severe, deep-seated infection like orbital cellulitis, which requires **intravenous therapy**. *Intravenous flucloxacillin and benzylpenicillin* - This regimen primarily targets **Gram-positive cocci** such as *Staphylococcus aureus* (flucloxacillin) and *Streptococcus pyogenes* (benzylpenicillin), and some other streptococci. - However, it provides **inadequate coverage** for crucial pathogens in sinusitis-related orbital cellulitis, specifically **Gram-negative bacteria** (e.g., *Haemophilus influenzae*, *Moraxella catarrhalis*) and **anaerobes**, which are frequently implicated. *Intravenous vancomycin, ceftazidime, and metronidazole* - This is a very broad-spectrum regimen, typically reserved for severe, **healthcare-associated infections**, or when there is a high suspicion of **MRSA**, **Pseudomonas aeruginosa**, or highly resistant organisms. - For community-acquired orbital cellulitis secondary to ethmoid sinusitis, this combination is considered **overkill** and can contribute to **antibiotic resistance** without significant additional benefit over a more targeted, yet broad, regimen. *Oral doxycycline and metronidazole* - Similar to other oral regimens, this combination is **inappropriate** for the management of **orbital cellulitis** given the patient's systemic symptoms, **proptosis**, and risk of **vision loss**. - While **doxycycline** has some activity against atypical pathogens and certain Gram-positives, and metronidazole covers anaerobes, the **oral route** does not provide the rapid, high concentrations needed for this emergent condition.
Question 226: A 44-year-old man is admitted with community-acquired pneumonia and started on intravenous co-amoxiclav. After 48 hours, he is clinically improved with reduced oxygen requirements and is apyrexial. His CRP has fallen from 245 mg/L to 89 mg/L. According to antimicrobial stewardship principles, what is the most appropriate next step in his antibiotic management?
- A. Continue intravenous co-amoxiclav for a total of 7 days
- B. Switch to oral co-amoxiclav and plan for early discharge (Correct Answer)
- C. Change to intravenous piperacillin-tazobactam for broader coverage
- D. Stop antibiotics as he is clinically improved and apyrexial
- E. Continue intravenous antibiotics until CRP normalizes completely
Explanation: ***Switch to oral co-amoxiclav and plan for early discharge*** - The patient meets criteria for an **IV-to-oral switch (IVOS)**, demonstrating **clinical stability** (apyrexial, reduced oxygen requirements) and **biochemical improvement** (falling CRP). - This approach aligns with **antimicrobial stewardship principles**, reducing risks of **IV line complications**, decreasing healthcare costs, and facilitating **early discharge**. *Continue intravenous co-amoxiclav for a total of 7 days* - Continuing intravenous therapy when a patient is clinically improving violates **antimicrobial stewardship** and unnecessarily prolongs hospital stay and risk of **IV-related complications** like **phlebitis**. - Most patients with improving **community-acquired pneumonia (CAP)** can be safely switched to oral antibiotics within **48-72 hours** of clinical stability. *Change to intravenous piperacillin-tazobactam for broader coverage* - Escalating to a **broader-spectrum antibiotic** is inappropriate as the patient is showing clear clinical and biochemical improvement on the current regimen, indicating its effectiveness. - Unnecessary broadening of antibiotic coverage contributes to **antibiotic resistance** and increases the risk of healthcare-associated infections, including ***Clostridioides difficile***. *Stop antibiotics as he is clinically improved and apyrexial* - While the patient is improving, stopping antibiotics after only 48 hours for **pneumonia** is premature and significantly increases the risk of **clinical relapse** or **treatment failure**. - A full course of antibiotics, typically 5-7 days for **moderate-to-severe CAP**, is required to ensure complete **pathogen eradication**. *Continue intravenous antibiotics until CRP normalizes completely* - **CRP** is a **lagging indicator** of inflammation; clinical stability, rather than complete normalization of CRP, is the primary determinant for an **IV-to-oral switch**. - Waiting for CRP to fully normalize would lead to unnecessarily **prolonged intravenous therapy** and extended hospital stays, contrary to good **antimicrobial stewardship**.
Question 227: A 29-year-old woman presents to A&E with a 24-hour history of rapidly progressive pain, swelling, and discolouration of her right forearm following a minor cut while gardening. On examination, the affected area is dusky purple with bullae formation, and there is crepitus on palpation. She has severe pain disproportionate to the clinical findings. Her temperature is 38.9°C, heart rate 118 bpm, and blood pressure 95/60 mmHg. Blood tests show WCC 18.2 × 10⁹/L, CRP 285 mg/L, creatinine 156 μmol/L, and lactate 4.2 mmol/L. What is the most appropriate immediate management?
- A. Start intravenous flucloxacillin and arrange outpatient follow-up in 48 hours
- B. Arrange urgent surgical debridement and start broad-spectrum intravenous antibiotics including clindamycin (Correct Answer)
- C. Perform incision and drainage under local anaesthetic in A&E
- D. Start oral co-amoxiclav and arrange same-day review by the orthopaedic team
- E. Obtain blood cultures and await sensitivities before starting antibiotics
Explanation: ***Arrange urgent surgical debridement and start broad-spectrum intravenous antibiotics including clindamycin*** - The patient presents with classic signs of **necrotising fasciitis**, including **pain disproportionate to findings**, **crepitus**, dusky discolouration, and systemic toxicity (sepsis). - Immediate **surgical debridement** is the definitive life-saving intervention, and **clindamycin** is added to suppress bacterial toxin production. *Start intravenous flucloxacillin and arrange outpatient follow-up in 48 hours* - Flucloxacillin alone is inadequate for a polymicrobial or **Group A Strep** necrotising infection and lacks toxin-inhibiting properties. - Outpatient follow-up is dangerously inappropriate for a patient in **septic shock** with a surgical emergency. *Perform incision and drainage under local anaesthetic in A&E* - This procedure is for localized abscesses and is completely insufficient for a **deep-seated fascial infection** that requires wide excision. - **Local anaesthetic** is ineffective in necrotic or infected tissue and would delay the necessary transfer to the **operating theatre**. *Start oral co-amoxiclav and arrange same-day review by the orthopaedic team* - Oral antibiotics have no place in the management of suspected **necrotising fasciitis** or severe sepsis due to poor bioavailability and severity. - While orthopaedic or general surgery review is needed, the management must be **urgent surgical exploration**, not just an elective-style review. *Obtain blood cultures and await sensitivities before starting antibiotics* - While blood cultures should be taken, **antibiotic therapy** and surgery must never be delayed for culture results in life-threatening infections. - The mortality rate for necrotising fasciitis increases significantly with every hour that **surgical intervention** is postponed.
Question 228: A hospital antimicrobial stewardship team is reviewing the prescribing practices on surgical wards. They identify that prophylactic antibiotics for elective colorectal surgery are frequently continued beyond 24 hours postoperatively in patients without complications. Which of the following best describes the primary risk of this practice?
- A. Increased risk of surgical site infections due to altered normal flora
- B. Development of antimicrobial resistance and increased risk of Clostridioides difficile infection (Correct Answer)
- C. Higher incidence of postoperative venous thromboembolism
- D. Increased risk of acute kidney injury from nephrotoxic antibiotics
- E. Development of antibiotic-associated hepatotoxicity
Explanation: ***Development of antimicrobial resistance and increased risk of Clostridioides difficile infection*** - Prolonged antibiotic exposure creates **selective pressure** on bacterial populations, leading to the emergence and spread of **multidrug-resistant organisms (MDROs)**. - Extended antibiotic prophylaxis significantly disrupts the **normal gastrointestinal flora**, thereby increasing a patient's risk for **Clostridioides difficile infection (CDI)**, without providing additional surgical benefit. *Increased risk of surgical site infections due to altered normal flora* - While antibiotics do alter normal flora, extending prophylaxis beyond the recommended duration has not been shown to increase the rate of **surgical site infections (SSIs)**; instead, it simply fails to offer further protection. - The primary concern of stewardship for prolonged use is not a paradoxical increase in **SSIs**, but the wider ecological impact and secondary complications of **unnecessary drug exposure**. *Higher incidence of postoperative venous thromboembolism* - There is no direct clinical or physiological association between **extended antibiotic prophylaxis** and an increased risk of **venous thromboembolism (VTE)**. - **VTE risk** in surgical patients is primarily related to factors such as **immobility**, type of surgery, and patient-specific coagulation risks, not the duration of antimicrobial administration. *Increased risk of acute kidney injury from nephrotoxic antibiotics* - While some antibiotics (e.g., aminoglycosides, vancomycin) are known to be **nephrotoxic**, this is a risk specific to certain drug classes and individual patient vulnerabilities, not the primary overarching risk of **prolonged prophylaxis** in general. - Many common prophylactic regimens used in colorectal surgery (e.g., cephalosporins) carry a lower inherent risk of **acute kidney injury (AKI)** compared to the broader threat of resistance. *Development of antibiotic-associated hepatotoxicity* - **Hepatotoxicity** is an adverse drug reaction that can occur with various medications, including some antibiotics (e.g., amoxicillin-clavulanate, erythromycin), but it is often idiosyncratic or dose-dependent and not the most prevalent or critical risk of prolonged prophylactic use. - Antimicrobial stewardship prioritizes the population-level threats of **antimicrobial resistance** and **Clostridioides difficile infection** due to their widespread impact and morbidity/mortality implications in hospital settings.
Question 229: A 52-year-old man with type 2 diabetes presents with a carbuncle on the back of his neck. The lesion consists of multiple interconnected furuncles with several draining points. The surrounding area shows erythema extending 3cm beyond the lesion margins. He is apyrexial and haemodynamically stable. What is the most likely causative organism?
- A. Streptococcus pyogenes
- B. Pseudomonas aeruginosa
- C. Staphylococcus aureus (Correct Answer)
- D. Escherichia coli
- E. Proteus mirabilis
Explanation: ***Staphylococcus aureus*** - A **carbuncle** is a severe skin infection characterized by a cluster of interconnected **furuncles** with multiple draining points, overwhelmingly caused by **Staphylococcus aureus**. - **Type 2 diabetes mellitus** is a significant risk factor, predisposing individuals to *S. aureus* skin infections due to compromised immune responses and increased skin colonization. *Streptococcus pyogenes* - While *S. pyogenes* is a common cause of superficial skin infections, it typically manifests as diffuse infections like **erysipelas** or **cellulitis**, not the deep, purulent, and multi-loculated presentation of a carbuncle. - It is not the primary pathogen associated with **folliculitis** and deep abscess formation originating from hair follicles. *Pseudomonas aeruginosa* - This organism is commonly associated with specific exposures like **hot tub folliculitis**, **burn wound infections**, or infections in severely **immunocompromised** individuals. - It is an uncommon cause of **community-acquired carbuncles** in a patient who is otherwise stable and apyrexial. *Escherichia coli* - **Escherichia coli** is predominantly a cause of **urinary tract infections** and intra-abdominal infections, and rarely causes primary skin and soft tissue infections like carbuncles. - It lacks the typical **virulence factors** to initiate and sustain deep, localized purulent follicular infections on the skin. *Proteus mirabilis* - Like *E. coli*, **Proteus mirabilis** is a gram-negative rod primarily associated with **urinary tract infections** and hospital-acquired wound infections. - It is not a recognized common cause of **furuncles or carbuncles** in the community setting or in diabetic patients without specific predisposing factors like surgical wounds.
Question 230: A 35-year-old woman presents to her GP with a 4-day history of a red, tender area on her right shin following a minor scratch from her cat. The affected area measures 8cm x 6cm, is warm to touch, and there is no evidence of purulence or lymphangitis. She is systemically well with normal observations. She has no known drug allergies. According to current antimicrobial stewardship principles, what is the most appropriate initial management?
- A. Prescribe oral flucloxacillin 500mg four times daily for 7 days
- B. Mark the area with a pen, provide safety-netting advice, and review if worsening (Correct Answer)
- C. Prescribe oral co-amoxiclav 625mg three times daily for 7 days
- D. Arrange same-day hospital admission for intravenous antibiotics
- E. Prescribe oral clarithromycin 500mg twice daily for 5 days
Explanation: ***Mark the area with a pen, provide safety-netting advice, and review if worsening***- According to **antimicrobial stewardship** principles, mild cases where the patient is **systemically well** with **localized erythema** may be managed by **watchful waiting** or marking the boundary to monitor spread.- This approach avoids **unnecessary antibiotic exposure**, reduces the risk of **antibiotic resistance**, and is appropriate for small, stable areas of inflammation that do not show rapid progression.*Prescribe oral flucloxacillin 500mg four times daily for 7 days*- **Flucloxacillin** is typically the first-line treatment for cellulitis caused by Gram-positive bacteria, but immediate antibiotics may not be necessary for a **very minor, localized scratch**.- Prescribing antibiotics without evidence of **systemic involvement** or significant spreading goes against the principle of minimizing unnecessary antimicrobial use in a localized, mild presentation.*Prescribe oral co-amoxiclav 625mg three times daily for 7 days*- **Co-amoxiclav** is usually reserved for **infected animal bites** where polymicrobial coverage including **Pasteurella multocida** is needed, rather than minor scratches.- Using a **broad-spectrum antibiotic** when there is no clear evidence of significant infection or systemic illness contributes to the development of **antimicrobial resistance**.*Arrange same-day hospital admission for intravenous antibiotics*- Hospital admission for **intravenous antibiotics** is indicated for patients with **systemic sepsis**, facial involvement, or rapidly progressing infection despite oral therapy.- This patient is **systemically well** with **normal observations**, localized symptoms, and no signs of rapid progression, making hospital-based management clinically unnecessary.*Prescribe oral clarithromycin 500mg twice daily for 5 days*- **Clarithromycin** is an alternative for patients with a **penicillin allergy**, which this patient explicitly does not have.- Like flucloxacillin, immediate antibiotic therapy with macrolides is not the most appropriate first step for a **well patient** with a stable, minor localized reaction, adhering to **antimicrobial stewardship**.
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