Common Infections — MCQs
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A 48-year-old woman presents with a 4-day history of right upper eyelid swelling and erythema. Yesterday she developed fever (38.4°C) and diplopia. On examination, there is marked periorbital oedema and erythema, proptosis, ophthalmoplegia (particularly on lateral gaze), and reduced visual acuity in the right eye. CT orbits shows inflammatory changes in the right orbit with involvement of the orbital fat and extraocular muscles. What is the most appropriate immediate antimicrobial management?
A 35-year-old man who works as a landscaper presents with a 10-day history of multiple painless, violaceous nodular lesions tracking up his right forearm following a penetrating injury from a rose thorn. He is systemically well with normal observations. Histopathology from a skin biopsy shows granulomatous inflammation. Which organism is most likely responsible and what is the appropriate antimicrobial treatment?
A hospital trust implements a comprehensive antimicrobial stewardship program including prospective audit and feedback, formulary restrictions on carbapenems, and mandatory infectious diseases consultation for certain infections. After 18 months, antimicrobial consumption has decreased by 15%, but an increase in 30-day readmission rates for infections is noted (from 8.2% to 11.7%). How should the antimicrobial stewardship team interpret and respond to these findings?
A 66-year-old man with end-stage renal failure on haemodialysis presents with fever and a painful, erythematous tunnelled dialysis catheter site with purulent discharge. Blood cultures grow methicillin-resistant Staphylococcus aureus (MRSA). The catheter is removed and a new temporary catheter is inserted at a different site. He weighs 78kg. What is the most appropriate vancomycin dosing regimen for this patient?
A 54-year-old woman who is a commercial shellfish processor presents with a 36-hour history of rapidly progressive pain, swelling, and discoloration of her right hand following a minor cut while shucking oysters. On examination, her hand is markedly swollen with haemorrhagic bullae and areas of dusky discoloration. Her temperature is 38.9°C, blood pressure 88/54 mmHg, and heart rate 128 bpm. She has a history of chronic liver disease secondary to alcohol excess. What is the most likely causative organism and appropriate antimicrobial therapy?
A hospital antimicrobial stewardship team conducts an audit of antibiotic prescribing on medical wards. They find that 62% of antibiotic prescriptions have documented indication, microbiology results are reviewed in 45% of cases at 48-72 hours, and IV-to-oral switch occurs at a median of 5 days. The team plans an intervention to improve these metrics. Which intervention is most likely to achieve the greatest improvement in antimicrobial stewardship compliance?
A 52-year-old woman undergoes total abdominal hysterectomy. She received cefuroxime 1.5g intravenously at induction of anaesthesia. The operation lasted 3.5 hours with an estimated blood loss of 800mL. She is clinically stable postoperatively with normal observations. According to antimicrobial stewardship principles and current surgical prophylaxis guidelines, what is the most appropriate antibiotic management?
A 61-year-old man with type 2 diabetes presents with a 5-day history of progressive right lower leg cellulitis. He was started on oral flucloxacillin 1g four times daily by his GP 48 hours ago but has deteriorated. On examination, there is extensive erythema from mid-calf to ankle with blistering and areas of skin necrosis. His temperature is 38.8°C, heart rate 115 bpm, blood pressure 95/60 mmHg, and respiratory rate 24/min. Blood results show: WCC 18.2 × 10⁹/L, CRP 285 mg/L, creatinine 145 μmol/L (baseline 78 μmol/L), lactate 3.8 mmol/L. What is the most appropriate antimicrobial management?
A 43-year-old woman with rheumatoid arthritis on methotrexate 20mg weekly and prednisolone 10mg daily presents with a 3-day history of pain and swelling in her right elbow. On examination, the elbow is erythematous, warm, swollen with a palpable effusion, and severely tender. Her temperature is 38.5°C. Aspiration yields 15mL of turbid fluid. Synovial fluid analysis shows: WCC 45,000/μL (90% neutrophils), no crystals seen on microscopy. What is the most appropriate initial antibiotic regimen while awaiting culture results?
A hospital implements a new antimicrobial stewardship intervention requiring pharmacist review of all antimicrobial prescriptions within 72 hours of initiation. During the 'Review' phase of the 'Start Smart - Then Focus' framework, which of the following actions would be LEAST appropriate for the reviewing pharmacist to recommend?
Common Infections UK Medical PG Practice Questions and MCQs
Question 71: A 48-year-old woman presents with a 4-day history of right upper eyelid swelling and erythema. Yesterday she developed fever (38.4°C) and diplopia. On examination, there is marked periorbital oedema and erythema, proptosis, ophthalmoplegia (particularly on lateral gaze), and reduced visual acuity in the right eye. CT orbits shows inflammatory changes in the right orbit with involvement of the orbital fat and extraocular muscles. What is the most appropriate immediate antimicrobial management?
- A. Oral co-amoxiclav 625mg three times daily and urgent ophthalmology review
- B. Intravenous cefuroxime 1.5g three times daily and ophthalmology review within 24 hours
- C. Intravenous ceftriaxone 2g once daily, intravenous metronidazole 500mg three times daily, and urgent ENT/ophthalmology review (Correct Answer)
- D. Intravenous flucloxacillin 2g four times daily and routine ophthalmology follow-up
- E. Intravenous benzylpenicillin 2.4g four times daily and intravenous gentamicin
Explanation: ***Intravenous ceftriaxone 2g once daily, intravenous metronidazole 500mg three times daily, and urgent ENT/ophthalmology review*** - This patient presents with **orbital cellulitis**, evidenced by **proptosis**, **ophthalmoplegia**, and **reduced visual acuity**, which are hallmarks of post-septal involvement and require aggressive treatment. - Treatment requires broad-spectrum IV antibiotics like **ceftriaxone** (covering *S. pneumoniae* and *H. influenzae*) and **metronidazole** (covering anaerobes), plus urgent consultation to evaluate for surgical drainage. *Oral co-amoxiclav 625mg three times daily and urgent ophthalmology review* - **Oral antibiotics** are insufficient for managing orbital cellulitis due to poor penetration and the significant risk of rapid progression to permanent vision loss or **intracranial spread**. - While co-amoxiclav covers many respiratory pathogens, it is inadequate for a patient presenting with systemic symptoms and **sight-threatening complications** requiring intravenous therapy. *Intravenous cefuroxime 1.5g three times daily and ophthalmology review within 24 hours* - Waiting **24 hours** for a specialist review is dangerously slow in orbital cellulitis; immediate assessment is required to prevent **optic nerve compression** and irreversible damage. - Although cefuroxime provides gram-positive and some gram-negative coverage, it often lacks the specific **anaerobic coverage** typically required for infections originating from the paranasal sinuses. *Intravenous flucloxacillin 2g four times daily and routine ophthalmology follow-up* - **Flucloxacillin** is excellent for *S. aureus* skin infections but has a spectrum that is too narrow for the likely **polymicrobial** causes of orbital cellulitis, especially from sinus origin. - A **routine follow-up** is entirely inappropriate for a surgical emergency characterized by systemic fever, compromised cranial nerve function, and potential vision loss. *Intravenous benzylpenicillin 2.4g four times daily and intravenous gentamicin* - This combination lacks adequate **anaerobic coverage** and is not the standard empirical choice for **sinus-derived** orbital infections given the likely polymicrobial nature. - While **gentamicin** covers many gram-negative organisms, the potential for **nephrotoxicity** and the availability of more effective, safer cephalosporins make this an inferior empirical regimen.
Question 72: A 35-year-old man who works as a landscaper presents with a 10-day history of multiple painless, violaceous nodular lesions tracking up his right forearm following a penetrating injury from a rose thorn. He is systemically well with normal observations. Histopathology from a skin biopsy shows granulomatous inflammation. Which organism is most likely responsible and what is the appropriate antimicrobial treatment?
- A. Mycobacterium marinum; clarithromycin and rifampicin for 3-4 months
- B. Sporothrix schenckii; oral itraconazole for 3-6 months (Correct Answer)
- C. Nocardia brasiliensis; co-trimoxazole for 6-12 months
- D. Mycobacterium chelonae; clarithromycin and ciprofloxacin for 4-6 months
- E. Chromoblastomycosis; oral terbinafine for 6-12 months
Explanation: ***Sporothrix schenckii; oral itraconazole for 3-6 months*** - The classic presentation of **lymphocutaneous spread** (multiple painless, violaceous nodular lesions tracking up the forearm) following a **rose thorn** injury in a landscaper is highly characteristic of **Sporothrix schenckii**, also known as **Rose Gardener's disease**. - **Oral itraconazole** is the first-line treatment for lymphocutaneous sporotrichosis, typically continued for 3-6 months or longer until resolution and for 2-4 weeks beyond apparent cure to prevent relapse. *Mycobacterium marinum; clarithromycin and rifampicin for 3-4 months* - While *Mycobacterium marinum* can cause a **sporotrichoid pattern** with granulomatous inflammation, it is primarily associated with exposure to **contaminated freshwater** (e.g., aquariums, swimming pools), not typically rose thorn injuries. - Treatment involves combination therapy, often including macrolides and rifampicin, but the epidemiologic context differs. *Nocardia brasiliensis; co-trimoxazole for 6-12 months* - *Nocardia brasiliensis* can cause cutaneous infections and lymphocutaneous spread, often after soil contamination, but it is less commonly linked to rose thorn injuries with this specific clinical picture. - Diagnosis usually requires demonstrating **Gram-positive, weakly acid-fast filamentous bacteria**, and treatment with **co-trimoxazole** is typically for a prolonged duration. *Mycobacterium chelonae; clarithromycin and ciprofloxacin for 4-6 months* - *Mycobacterium chelonae* is a rapid-growing atypical mycobacterium commonly associated with **surgical site infections**, cosmetic procedures, or trauma, presenting as abscesses or nodules, but typically not a classic lymphangitic spread from a thorn. - Its treatment often involves a combination of macrolides and fluoroquinolones, but the specific injury mechanism and clinical progression are less characteristic. *Chromoblastomycosis; oral terbinafine for 6-12 months* - **Chromoblastomycosis** usually presents as chronic, slow-growing, **verrucous (wart-like) plaques** or cauliflower-like lesions, not the acute, linear tracking nodules seen here. - Histopathology characteristically reveals specific fungal structures called **Medlar bodies** (sclerotic cells), which would be a key differentiating feature.
Question 73: A hospital trust implements a comprehensive antimicrobial stewardship program including prospective audit and feedback, formulary restrictions on carbapenems, and mandatory infectious diseases consultation for certain infections. After 18 months, antimicrobial consumption has decreased by 15%, but an increase in 30-day readmission rates for infections is noted (from 8.2% to 11.7%). How should the antimicrobial stewardship team interpret and respond to these findings?
- A. The program has been successful in reducing consumption and the increased readmissions are unrelated; continue current approach
- B. The increased readmissions indicate the program is causing harm; immediately cease all restrictive interventions
- C. Conduct detailed analysis of readmissions to identify if they represent treatment failures, and adjust stewardship interventions accordingly (Correct Answer)
- D. The readmission increase is expected and acceptable given the reduction in antimicrobial use; no changes needed
- E. Increase antibiotic treatment durations across all infection types to reduce readmission rates
Explanation: ***Conduct detailed analysis of readmissions to identify if they represent treatment failures, and adjust stewardship interventions accordingly*** - A core goal of **antimicrobial stewardship (ASP)** is to optimize patient outcomes while reducing consumption; an increase in **30-day readmissions** serves as a potential safety signal that requires investigation. - The team must differentiate between true **treatment failures** (e.g., inadequate dosing or premature de-escalation) and unrelated confounding factors before modifying established protocols. *The program has been successful in reducing consumption and the increased readmissions are unrelated; continue current approach* - This approach is incorrect because it ignores a significant change in **clinical outcome metrics**, which could be directly linked to overly restrictive stewardship. - **Balancing metrics** are essential in ASP to ensure that the primary goal of **patient safety** is not compromised by the secondary goal of cost or usage reduction. *The increased readmissions indicate the program is causing harm; immediately cease all restrictive interventions* - Ceasing all interventions is a premature reaction that lacks **causality analysis**, potentially losing the benefits of reduced **multidrug-resistant organisms (MDROs)**. - Stewardship success should be managed through **data-driven refinements** rather than complete abandonment of evidence-based practices. *The readmission increase is expected and acceptable given the reduction in antimicrobial use; no changes needed* - An increase in infection-related readmissions is never "acceptable," as it impacts **morbidity**, healthcare costs, and overall patient quality of care. - Stewardship programs are ethically obligated to maintain **non-inferiority in clinical outcomes** compared to standard care while improving prescribing habits. *Increase antibiotic treatment durations across all infection types to reduce readmission rates* - Implementing a blanket increase in **treatment duration** contradicts the principles of stewardship and may lead to increased **toxicity** and resistance. - Evidence-based stewardship promotes the **shortest effective duration** of therapy, making arbitrary increases inappropriate without specific evidence of failure.
Question 74: A 66-year-old man with end-stage renal failure on haemodialysis presents with fever and a painful, erythematous tunnelled dialysis catheter site with purulent discharge. Blood cultures grow methicillin-resistant Staphylococcus aureus (MRSA). The catheter is removed and a new temporary catheter is inserted at a different site. He weighs 78kg. What is the most appropriate vancomycin dosing regimen for this patient?
- A. Vancomycin 1g intravenously twice daily with trough level monitoring before the third dose
- B. Vancomycin 15-20mg/kg loading dose (approximately 1.5g) then 500mg after each dialysis session (Correct Answer)
- C. Vancomycin 1g intravenously once daily with trough level monitoring after 48 hours
- D. Vancomycin 500mg intravenously four times daily with dose adjustments based on renal function
- E. Vancomycin continuous infusion of 30mg/kg over 24 hours after loading dose
Explanation: ***Vancomycin 15-20mg/kg loading dose (approximately 1.5g) then 500mg after each dialysis session***- In **end-stage renal failure** patients on **haemodialysis**, a weight-based loading dose is essential to rapidly achieve therapeutic concentrations for serious infections like **MRSA**.- Maintenance doses should be administered **post-dialysis** because high-flux membranes significantly remove vancomycin during the procedure, necessitating replenishment to maintain trough levels.*Vancomycin 1g intravenously twice daily with trough level monitoring before the third dose*- This is a standard regimen for patients with **normal renal function**; however, it would cause severe drug accumulation and **ototoxicity** or nephrotoxicity in anuric patients.- Vancomycin's **half-life** is prolonged from ~6 hours to over 100 hours in renal failure, making twice-daily dosing inappropriate.*Vancomycin 1g intravenously once daily with trough level monitoring after 48 hours*- Once-daily dosing is still too frequent for a patient on dialysis and does not align with the intermittent nature of **dialytic clearance**.- Dosing should be linked to the **haemodialysis schedule** rather than a fixed 24-hour interval to ensure stable serum concentrations.*Vancomycin 500mg intravenously four times daily with dose adjustments based on renal function*- Four times daily dosing is never indicated for vancomycin in adults, regardless of renal function, due to the drug's **pharmacokinetic profile**.- In the setting of **anuria**, such frequent dosing would lead to rapid, dangerous toxicity because the drug cannot be cleared via the **renal route**.*Vancomycin continuous infusion of 30mg/kg over 24 hours after loading dose*- Continuous infusion is not standard practice for patients on intermittent **haemodialysis**, as the dialysis sessions would cause massive fluctuations in steady-state levels.- Intermittent **post-dialysis bolus dosing** is the gold standard as it is simpler to manage and allows for reliable **trough level monitoring** before dialysis sessions.
Question 75: A 54-year-old woman who is a commercial shellfish processor presents with a 36-hour history of rapidly progressive pain, swelling, and discoloration of her right hand following a minor cut while shucking oysters. On examination, her hand is markedly swollen with haemorrhagic bullae and areas of dusky discoloration. Her temperature is 38.9°C, blood pressure 88/54 mmHg, and heart rate 128 bpm. She has a history of chronic liver disease secondary to alcohol excess. What is the most likely causative organism and appropriate antimicrobial therapy?
- A. Staphylococcus aureus; intravenous flucloxacillin and surgical debridement
- B. Streptococcus pyogenes; intravenous benzylpenicillin and clindamycin
- C. Vibrio vulnificus; intravenous doxycycline and intravenous ceftazidime (Correct Answer)
- D. Erysipelothrix rhusiopathiae; oral amoxicillin and observation
- E. Aeromonas hydrophila; intravenous ciprofloxacin and metronidazole
Explanation: ***Vibrio vulnificus; intravenous doxycycline and intravenous ceftazidime***- This patient demonstrates a classic triad for **Vibrio vulnificus**: exposure to **shellfish/seawater**, underlying **chronic liver disease** (cirrhosis), and rapidly progressive **hemorrhagic bullae** with septic shock.- Standard treatment requires a combination of a **tetracycline (doxycycline)** and a **third-generation cephalosporin (ceftazidime)** along with urgent surgical debridement.*Staphylococcus aureus; intravenous flucloxacillin and surgical debridement*- While a common cause of **cellulitis** and soft tissue infection, it is less specifically associated with **seawater/shellfish** exposure compared to Vibrio.- Flucloxacillin would be inadequate for the gram-negative coverage potentially required in this high-risk marine exposure scenario and does not cover *Vibrio vulnificus*.*Streptococcus pyogenes; intravenous benzylpenicillin and clindamycin*- Known for causing **necrotizing fasciitis** (Type II), it usually presents with severe pain out of proportion to exam findings rather than a specific link to **shellfish processing**.- While clindamycin helps inhibit **toxin production**, the epidemiological link to **saltwater/shellfish** and **liver disease** strongly favors *Vibrio*.*Erysipelothrix rhusiopathiae; oral amoxicillin and observation*- Commonly causes **erysipeloid** in fish handlers, which is typically a localized, self-limiting skin infection without systemic toxicity.- It does not present with **septic shock** or large **hemorrhagic bullae** in its typical presentation, and the suggested treatment is inadequate for severe infection.*Aeromonas hydrophila; intravenous ciprofloxacin and metronidazole*- *Aeromonas hydrophila* is typically associated with **freshwater** exposure or contaminated soil, not the marine (saltwater) environment associated with **oysters**.- While it can cause necrotizing infections, the specific clinical context of **saltwater/shellfish** and **liver disease** points to *Vibrio vulnificus*.
Question 76: A hospital antimicrobial stewardship team conducts an audit of antibiotic prescribing on medical wards. They find that 62% of antibiotic prescriptions have documented indication, microbiology results are reviewed in 45% of cases at 48-72 hours, and IV-to-oral switch occurs at a median of 5 days. The team plans an intervention to improve these metrics. Which intervention is most likely to achieve the greatest improvement in antimicrobial stewardship compliance?
- A. Weekly educational lectures for junior doctors on antimicrobial prescribing
- B. Implementing mandatory electronic prescribing prompts requiring indication documentation and 48-hour review (Correct Answer)
- C. Distributing pocket cards with local antibiotic guidelines to all prescribers
- D. Monthly feedback emails to consultants showing their team's prescribing data
- E. Introducing a weekly antimicrobial stewardship ward round led by infectious diseases consultants
Explanation: ***Implementing mandatory electronic prescribing prompts requiring indication documentation and 48-hour review***- This intervention represents a **systems-based approach** that integrates directly into the clinical workflow, forcing compliance at the **point of prescribing**.- Evidence confirms that **mandatory electronic prompts** and **decision support tools** are superior to passive education for ensuring documentation and timely clinical reviews.*Weekly educational lectures for junior doctors on antimicrobial prescribing*- While education is necessary, it is a **low-reliability intervention** that depends on individual attendance and memory, often failing to change long-term habits.- Lectures do not address **environmental barriers** or the time pressures that prevent clinicians from following guidelines during busy shifts.*Distributing pocket cards with local antibiotic guidelines to all prescribers*- Pocket cards and printed guidelines are **passive forms of dissemination** that are frequently lost, ignored, or become outdated quickly.- They provide information but do not create the **active accountability** needed to improve clinical audit metrics like review rates.*Monthly feedback emails to consultants showing their team's prescribing data*- Although **audit and feedback** is useful for identifying outliers, a monthly interval is too infrequent to influence rapid daily decisions like an **IV-to-oral switch**.- Prescribers often view retrospective data as disconnected from current patient care, leading to limited **sustained behavioral change**.*Introducing a weekly antimicrobial stewardship ward round led by infectious diseases consultants*- Specialized ward rounds provide high-quality reviews but are **resource-intensive** and only occur once a week, missing daily opportunities for antibiotic de-escalation.- A **weekly** round cannot address the 48-72 hour review requirement for all patients as effectively as a daily **integrated electronic system**.
Question 77: A 52-year-old woman undergoes total abdominal hysterectomy. She received cefuroxime 1.5g intravenously at induction of anaesthesia. The operation lasted 3.5 hours with an estimated blood loss of 800mL. She is clinically stable postoperatively with normal observations. According to antimicrobial stewardship principles and current surgical prophylaxis guidelines, what is the most appropriate antibiotic management?
- A. No further antibiotics required
- B. Give one further dose of cefuroxime 1.5g intravenously within 6 hours postoperatively then stop (Correct Answer)
- C. Continue cefuroxime 1.5g three times daily intravenously until oral intake is established
- D. Continue cefuroxime 1.5g three times daily intravenously for 24 hours then switch to oral co-amoxiclav for 5 days
- E. Give intraoperative redose of cefuroxime 1.5g then continue three times daily for 48 hours
Explanation: ***Give one further dose of cefuroxime 1.5g intravenously within 6 hours postoperatively then stop*** - Surgical prophylaxis guidelines recommend **redosing** if the procedure duration exceeds **two half-lives** of the antibiotic (cefuroxime half-life is ~1.5 hours, so >3 hours) or if there is significant **blood loss** (>1500mL or 20mL/kg). Given the 3.5-hour duration and 800mL blood loss, an additional dose is warranted. - Since an intraoperative redose was not administered, a single postoperative dose within **6 hours** is appropriate to maintain adequate **therapeutic tissue levels** during the critical period for preventing surgical site infection (SSI). *No further antibiotics required* - While initial single-dose prophylaxis is standard, the **3.5-hour operation duration** and **800mL blood loss** mean the initial dose's effectiveness would have significantly decreased. - Omitting further antibiotics in this scenario increases the risk of **surgical site infection (SSI)** due to sub-therapeutic antibiotic concentrations during the critical postoperative period. *Continue cefuroxime 1.5g three times daily intravenously until oral intake is established* - Continuing antibiotic prophylaxis beyond the immediate perioperative period (typically up to **24 hours**) is not recommended by **antimicrobial stewardship** principles as it does not further reduce SSI risk for this procedure. - Prolonged intravenous antibiotic administration increases the risk of **adverse effects**, such as **Clostridioides difficile infection** and catheter-related complications, without added benefit. *Continue cefuroxime 1.5g three times daily intravenously for 24 hours then switch to oral co-amoxiclav for 5 days* - This regimen describes **treatment for an active infection**, not prophylaxis. Prophylactic antibiotics should not be extended into multi-day courses or switched to oral regimens unless there is confirmed **evidence of infection**. - Such an extended course of antibiotics significantly contributes to **antimicrobial resistance** and increases the patient's susceptibility to **adverse drug reactions** and superinfections. *Give intraoperative redose of cefuroxime 1.5g then continue three times daily for 48 hours* - An **intraoperative redose** was indeed indicated physiologically. However, the question states it was not given, and the clinical scenario is *postoperative* management. - Continuing prophylaxis for **48 hours** post-surgery is excessive for total abdominal hysterectomy and violates current guidelines, which advocate for **short-duration prophylaxis** to minimize resistance and drug-related harm.
Question 78: A 61-year-old man with type 2 diabetes presents with a 5-day history of progressive right lower leg cellulitis. He was started on oral flucloxacillin 1g four times daily by his GP 48 hours ago but has deteriorated. On examination, there is extensive erythema from mid-calf to ankle with blistering and areas of skin necrosis. His temperature is 38.8°C, heart rate 115 bpm, blood pressure 95/60 mmHg, and respiratory rate 24/min. Blood results show: WCC 18.2 × 10⁹/L, CRP 285 mg/L, creatinine 145 μmol/L (baseline 78 μmol/L), lactate 3.8 mmol/L. What is the most appropriate antimicrobial management?
- A. Switch to intravenous flucloxacillin 2g four times daily and add intravenous benzylpenicillin 2.4g four times daily (Correct Answer)
- B. Switch to intravenous co-amoxiclav 1.2g three times daily and add intravenous gentamicin
- C. Switch to intravenous vancomycin 1g twice daily and add intravenous metronidazole 500mg three times daily
- D. Switch to intravenous meropenem 1g three times daily
- E. Continue oral flucloxacillin but increase dose to 2g four times daily
Explanation: ***Switch to intravenous flucloxacillin 2g four times daily and add intravenous benzylpenicillin 2.4g four times daily*** - The patient presents with signs of **severe necrotizing soft tissue infection**, indicated by **skin necrosis**, **blistering**, **rapid deterioration**, and **septic shock** (hypotension, elevated lactate, AKI). - This combination provides robust empirical coverage for common causative agents like **Staphylococcus aureus** and **Group A Streptococcus**, essential for this life-threatening condition. *Switch to intravenous co-amoxiclav 1.2g three times daily and add intravenous gentamicin* - While co-amoxiclav offers broad-spectrum coverage, **high-dose benzylpenicillin** is preferred over amoxicillin for suspected **Group A Streptococcus** in necrotizing infections. - **Gentamicin** is an **aminoglycoside** that can exacerbate the patient's existing **acute kidney injury**, making it a less suitable choice here. *Switch to intravenous vancomycin 1g twice daily and add intravenous metronidazole 500mg three times daily* - **Vancomycin** is primarily used for suspected **MRSA** or in patients with severe **beta-lactam allergy**, neither of which is indicated as first-line here. - **Metronidazole** specifically targets **anaerobes**, which are not the primary pathogens in typical monomicrobial necrotizing cellulitis unless there's a specific context like deep abscess or gut origin. *Switch to intravenous meropenem 1g three times daily* - **Meropenem** is a very broad-spectrum **carbapenem** used for highly resistant bacteria or complex polymicrobial infections, and its use here would be **overkill** and contribute to **antimicrobial resistance**. - While it covers many relevant bacteria, it lacks the specific high-dose penicillin activity considered vital for **toxin-producing streptococci** in necrotizing infections. *Continue oral flucloxacillin but increase dose to 2g four times daily* - Continuing oral antibiotics is inappropriate given the patient's **rapid clinical deterioration**, signs of **septic shock**, and evidence of **severe local infection** (necrosis). - **Oral absorption** may be compromised in a critically ill patient, and immediate **intravenous therapy** is mandatory for systemic infection and potential necrotizing process.
Question 79: A 43-year-old woman with rheumatoid arthritis on methotrexate 20mg weekly and prednisolone 10mg daily presents with a 3-day history of pain and swelling in her right elbow. On examination, the elbow is erythematous, warm, swollen with a palpable effusion, and severely tender. Her temperature is 38.5°C. Aspiration yields 15mL of turbid fluid. Synovial fluid analysis shows: WCC 45,000/μL (90% neutrophils), no crystals seen on microscopy. What is the most appropriate initial antibiotic regimen while awaiting culture results?
- A. Oral flucloxacillin 1g four times daily
- B. Intravenous flucloxacillin 2g four times daily (Correct Answer)
- C. Intravenous vancomycin 1g twice daily
- D. Intravenous ceftriaxone 2g once daily and intravenous flucloxacillin 2g four times daily
- E. Intravenous piperacillin-tazobactam 4.5g three times daily
Explanation: ***Intravenous flucloxacillin 2g four times daily*** - High-dose **intravenous flucloxacillin** is the recommended first-line empirical therapy for native joint **septic arthritis**, as it provides excellent coverage against **Staphylococcus aureus** and **Streptococcus species**.- The clinical presentation of a warm, swollen joint, fever, and a synovial white cell count of **45,000/μL** (predominantly neutrophils) strongly indicates a bacterial infection requiring urgent IV antibiotics.*Oral flucloxacillin 1g four times daily* - Oral administration is inadequate for the initial management of **septic arthritis**, which is a medical emergency requiring high peak **serum and synovial concentrations** achieved through IV dosing.- Transition to oral therapy is only considered after clinical improvement and once **culture and sensitivity** results are available to guide targeted treatment.*Intravenous vancomycin 1g twice daily* - **Vancomycin** is indicated for empirical therapy only when there is a high suspicion of **MRSA**, a history of MRSA colonization, or if the patient has a severe **penicillin allergy**.- It is not the standard first-line choice for community-acquired native joint sepsis in patients without specific risk factors for resistant organisms.*Intravenous ceftriaxone 2g once daily and intravenous flucloxacillin 2g four times daily* - This combination is typically reserved for patients where **Gram-negative** organisms are strongly suspected, such as the frail elderly, those with recent abdominal surgery, or those with suspected **disseminated gonococcal infection**.- Although the patient is taking methotrexate, high-dose flucloxacillin monotherapy remains the standard empirical choice unless there are clear risk factors for **atypical pathogens** or Gram-negative sepsis.*Intravenous piperacillin-tazobactam 4.5g three times daily* - This agent is unnecessarily **broad-spectrum** and is generally reserved for healthcare-associated infections or patients with significant **neutropenia**.- Escalating to this level of coverage is inappropriate before culture results demonstrate a resistant **Gram-negative** or anaerobic organism not covered by standard penicillin-based regimens.
Question 80: A hospital implements a new antimicrobial stewardship intervention requiring pharmacist review of all antimicrobial prescriptions within 72 hours of initiation. During the 'Review' phase of the 'Start Smart - Then Focus' framework, which of the following actions would be LEAST appropriate for the reviewing pharmacist to recommend?
- A. Switching from intravenous to oral antibiotics when the patient is clinically improving and able to take oral medications
- B. Discontinuing antibiotics when clinical and laboratory evidence suggests a non-infective diagnosis
- C. Extending the duration of therapy from 5 to 10 days for cellulitis that is responding well to treatment (Correct Answer)
- D. De-escalating from broad-spectrum to narrow-spectrum antibiotics based on microbiology culture results
- E. Adjusting antibiotic doses based on renal function and therapeutic drug monitoring results
Explanation: ***Extending the duration of therapy from 5 to 10 days for cellulitis that is responding well to treatment*** - This action is **least appropriate** because antimicrobial stewardship principles advocate for the **shortest effective duration** of therapy to minimize resistance and side effects. - Current guidelines suggest that uncomplicated **cellulitis** typically responds well to 5–7 days of treatment; extending this unnecessarily increases antibiotic exposure without additional clinical benefit. *Switching from intravenous to oral antibiotics when the patient is clinically improving and able to take oral medications* - This is a core component of the **IV-to-oral switch (IVOS)** strategy, which reduces the risk of line-related infections and decreases hospital stay length. - It is one of the key **"Focus"** decisions in the stewardship framework used when patients meet clinical stability criteria. *Discontinuing antibiotics when clinical and laboratory evidence suggests a non-infective diagnosis* - A primary goal of the **"Review"** phase is to **stop** antibiotics promptly if further investigation suggests a non-infectious etiology, such as stasis dermatitis or gout. - This prevents unnecessary **selective pressure** on the patient's microbiome and reduces the risk of adverse drug reactions. *De-escalating from broad-spectrum to narrow-spectrum antibiotics based on microbiology culture results* - Known as **narrowing**, this action utilizes **culture and sensitivity** data to target the specific pathogen, which is a hallmark of good stewardship. - It helps preserve the efficacy of **broad-spectrum** agents for more severe, undiagnosed infections and limits the risk of *C. difficile*. *Adjusting antibiotic doses based on renal function and therapeutic drug monitoring results* - **Dose optimization** ensures that the patient receives a therapeutic amount of the drug while minimizing **dose-dependent toxicity**, such as nephrotoxicity from aminoglycosides. - This is an essential pharmacist intervention during the review phase to ensure both **patient safety** and maximal antibiotic efficacy.
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