Common Infections — MCQs
On this page
A 39-year-old injection drug user presents with multiple painful abscesses on both arms. The largest abscess on the left forearm is incised and drained, and pus is sent for culture. He is discharged with dressing advice. Cultures grow meticillin-sensitive Staphylococcus aureus (MSSA) sensitive to all tested antibiotics. He returns 3 weeks later with a new abscess on his right leg. What is the most appropriate management strategy to prevent recurrent MRSA and MSSA skin infections?
A hospital trust implements a mandatory antimicrobial prescribing decision tool that requires clinicians to select from pre-defined clinical indications when prescribing antibiotics electronically. After 12 months, audit data show 98% compliance with documentation of indication, but overall antibiotic consumption has not decreased. Which of the following represents the most likely explanation and appropriate next step?
A 51-year-old woman who keeps tropical fish presents with a painless, slowly progressive nodular lesion on her right hand that developed over 4 weeks following a minor abrasion sustained while cleaning her aquarium. The lesion has a violaceous appearance with central ulceration. She is systemically well and has no lymphadenopathy. Tissue biopsy shows granulomatous inflammation. What is the most likely causative organism?
A 67-year-old man is admitted with severe cellulitis of the right lower limb with systemic features. He is started on intravenous flucloxacillin 2g four times daily. After 48 hours, he has improved clinically with reduced erythema, reduced pain, temperature 37.2°C, and CRP decreased from 185 to 95 mg/L. He is tolerating oral fluids and food. According to the 'Start Smart - Then Focus' approach, what is the most appropriate antimicrobial decision at 48-72 hour review?
A 42-year-old man presents with a carbuncle on his upper back. Incision and drainage is performed and pus is sent for culture. The wound is packed and he is discharged with dressings. The microbiology laboratory reports growth of meticillin-resistant Staphylococcus aureus (MRSA). He remains systemically well with no spreading infection. What is the most appropriate antibiotic management?
A 58-year-old woman with rheumatoid arthritis on methotrexate 15mg weekly and prednisolone 10mg daily presents with a 24-hour history of rapidly spreading erythema, pain, and blistering on her right forearm. Examination reveals crepitus on palpation. Temperature is 38.9°C, heart rate 118/min, BP 95/62 mmHg. Lactate is 3.8 mmol/L. What is the most critical immediate management priority?
A 45-year-old man undergoes open reduction and internal fixation of a tibial fracture. The antimicrobial stewardship team reviews his prescription chart 24 hours post-operatively and notes he is receiving intravenous co-amoxiclav 1.2g three times daily for 'surgical prophylaxis'. His observations are stable, wound appears clean, and temperature is 36.8°C. What represents the most appropriate antimicrobial stewardship action?
A 28-year-old woman presents with a 48-hour history of a painful, erythematous, indurated area on her right thigh measuring 8cm × 6cm. She is systemically well with temperature 37.4°C and no lymphangitis. She has no significant past medical history and takes no regular medications. What is the most appropriate management?
A hospital antimicrobial stewardship committee reviews data showing that the median duration of antibiotic treatment for uncomplicated community-acquired pneumonia has decreased from 7 days to 5 days following implementation of a new guideline. However, 30-day readmission rates have remained unchanged at 8%. What is the most appropriate interpretation of these findings?
A 62-year-old man with type 2 diabetes presents with a 5-day history of progressive swelling, erythema, and pain affecting his left leg from ankle to mid-calf. His temperature is 38.2°C. He is allergic to penicillin (previous anaphylaxis). Blood tests show WCC 15.2 × 10⁹/L, CRP 145 mg/L, creatinine 98 μmol/L. What is the most appropriate antibiotic therapy?
Common Infections UK Medical PG Practice Questions and MCQs
Question 101: A 39-year-old injection drug user presents with multiple painful abscesses on both arms. The largest abscess on the left forearm is incised and drained, and pus is sent for culture. He is discharged with dressing advice. Cultures grow meticillin-sensitive Staphylococcus aureus (MSSA) sensitive to all tested antibiotics. He returns 3 weeks later with a new abscess on his right leg. What is the most appropriate management strategy to prevent recurrent MRSA and MSSA skin infections?
- A. Long-term oral flucloxacillin prophylaxis 250mg twice daily for 6 months
- B. Decolonization protocol with nasal mupirocin and chlorhexidine body washes for 5 days, combined with wound care education (Correct Answer)
- C. Screening for HIV and immunodeficiency disorders as underlying cause
- D. Intravenous immunoglobulin therapy to boost immune response
- E. Surgical excision of all affected skin areas to remove infected tissue
Explanation: ***Decolonization protocol with nasal mupirocin and chlorhexidine body washes for 5 days, combined with wound care education*** - This strategy aims to eradicate **Staphylococcus aureus** colonization from the **anterior nares** and skin, which is the primary reservoir for recurrent skin and soft tissue infections (SSTIs). - A 5-day regimen of **topical mupirocin** to the nose and **chlorhexidine body washes** is an effective and evidence-based approach to prevent recurrent **MSSA** and **MRSA** infections. *Long-term oral flucloxacillin prophylaxis 250mg twice daily for 6 months* - Long-term systemic antibiotic prophylaxis is generally discouraged due to the risk of **antibiotic resistance** and potential side effects, and it does not effectively eliminate nasal or skin carriage. - Unlike topical decolonization, oral antibiotics do not specifically target the **colonization sites** responsible for recurrent staphylococcal infections. *Screening for HIV and immunodeficiency disorders as underlying cause* - While injection drug use increases the risk of **HIV** and other infections, recurrent staphylococcal abscesses are most often due to **bacterial colonization** rather than a primary immunodeficiency. - Although important for overall health, this screening does not directly address the immediate need to prevent **recurrent S. aureus infections** and is not a management strategy for prevention. *Intravenous immunoglobulin therapy to boost immune response* - **Intravenous immunoglobulin (IVIG)** is a costly and specialized treatment typically reserved for severe, life-threatening infections, or specific diagnosed **primary immunodeficiencies**. - It is not indicated or recommended for the routine prevention of **recurrent community-acquired skin abscesses**. *Surgical excision of all affected skin areas to remove infected tissue* - **Surgical incision and drainage** is crucial for treating acute abscesses, but wide surgical excision of unaffected or healed skin areas is an aggressive and inappropriate approach. - This strategy would cause significant morbidity and does not prevent future infections by addressing the underlying **bacterial colonization**.
Question 102: A hospital trust implements a mandatory antimicrobial prescribing decision tool that requires clinicians to select from pre-defined clinical indications when prescribing antibiotics electronically. After 12 months, audit data show 98% compliance with documentation of indication, but overall antibiotic consumption has not decreased. Which of the following represents the most likely explanation and appropriate next step?
- A. The intervention has failed and should be discontinued as it adds administrative burden without benefit
- B. Documentation alone does not change prescribing behavior; additional interventions such as prescriber feedback and antibiotic review are needed (Correct Answer)
- C. The trust should implement financial penalties for clinicians who prescribe inappropriately to drive behavior change
- D. Antibiotic consumption is an inappropriate outcome measure; the intervention is successful as documentation has improved
- E. The pre-defined indications are too broad; restricting formulary availability would be more effective
Explanation: ***Documentation alone does not change prescribing behavior; additional interventions such as prescriber feedback and antibiotic review are needed*** - Documentation is a **process measure** that creates the infrastructure for stewardship, but it does not inherently limit inappropriate starts or durations. - Successful stewardship requires a **multimodal approach**, including clinical reviews at 48-72 hours (“Start Smart – Then Focus”) and direct **prescriber feedback** to drive actual behavior change.*The intervention has failed and should be discontinued as it adds administrative burden without benefit* - Discontinuing the tool would lose valuable data; documentation is a necessary foundation for identifying **prescribing trends** and targeting audits. - High compliance proves the system is **user-acceptable**, providing a platform to implement more rigorous **clinical decision support** rather than abandoning the effort.*The trust should implement financial penalties for clinicians who prescribe inappropriately to drive behavior change* - **Financial penalties** are punitive measures that can damage the safety culture and are not supported by evidence as effective **clinical stewardship** strategies. - Stewardship focuses on **engagement, education, and peer-to-peer feedback**, which have more sustainable impacts on clinical practice than punishment.*Antibiotic consumption is an inappropriate outcome measure; the intervention is successful as documentation has improved* - While documentation is a success in process, **antibiotic consumption** (e.g., DDD per 1000 bed days) remains a primary **outcome measure** to assess stewardship impact. - Improved documentation without a change in consumption indicates that clinicians are simply selecting an indication to bypass the system's **electronic hurdle**.*The pre-defined indications are too broad; restricting formulary availability would be more effective* - Formulary restriction is a **blunt instrument** that can create delays in urgent care; it does not address the underlying **behavioral patterns** of the prescribers. - Even with specific indications, clinicians may select "incorrect" pre-defined options just to facilitate the order, highlighting the need for **prospective audit and feedback**.
Question 103: A 51-year-old woman who keeps tropical fish presents with a painless, slowly progressive nodular lesion on her right hand that developed over 4 weeks following a minor abrasion sustained while cleaning her aquarium. The lesion has a violaceous appearance with central ulceration. She is systemically well and has no lymphadenopathy. Tissue biopsy shows granulomatous inflammation. What is the most likely causative organism?
- A. Mycobacterium marinum (Correct Answer)
- B. Erysipelothrix rhusiopathiae
- C. Vibrio vulnificus
- D. Aeromonas hydrophila
- E. Streptococcus iniae
Explanation: ***Mycobacterium marinum*** - Exposure to **tropical fish aquariums** followed by a slow-growing, **violaceous nodular lesion** with central ulceration is a classic presentation of **'fish tank granuloma'**. - Histology revealing **granulomatous inflammation** confirms a mycobacterial etiology, as this organism grows optimally at the lower temperatures of cooler body extremities like the hands. *Erysipelothrix rhusiopathiae* - Causes **erysipeloid**, which typically presents as an **acute, painful** reddish-purple lesion, often in people handling raw meat or fish. - It lacks the **chronic, granulomatous** course and central ulceration seen with atypical mycobacterial infections. *Vibrio vulnificus* - Causes a **rapidly progressive**, potentially life-threatening **necrotizing fasciitis** or hemorrhagic bullae rather than a slow, painless nodule. - It is primarily associated with exposure to **warm saltwater** or raw shellfish, particularly in patients with liver disease. *Aeromonas hydrophila* - Presents as an **acute cellulitis** or wound infection that develops rapidly within 24–48 hours after exposure to **freshwater**. - It typically results in a **suppurative infection** rather than a chronic, localized granulomatous lesion. *Streptococcus iniae* - Primarily causes **acute cellulitis** and bacteremia in fish handlers, particularly those preparing **Tilapia**. - The clinical course is too **rapid and acute** to explain a 4-week-old progressive nodule with granulomatous features.
Question 104: A 67-year-old man is admitted with severe cellulitis of the right lower limb with systemic features. He is started on intravenous flucloxacillin 2g four times daily. After 48 hours, he has improved clinically with reduced erythema, reduced pain, temperature 37.2°C, and CRP decreased from 185 to 95 mg/L. He is tolerating oral fluids and food. According to the 'Start Smart - Then Focus' approach, what is the most appropriate antimicrobial decision at 48-72 hour review?
- A. Continue intravenous flucloxacillin until CRP normalizes completely
- B. Switch to oral flucloxacillin 1g four times daily and consider discharge with outpatient follow-up (Correct Answer)
- C. Stop antibiotics as significant clinical improvement has been achieved
- D. Change to intravenous co-amoxiclav to provide broader spectrum coverage
- E. Continue intravenous flucloxacillin for total of 7 days before considering oral switch
Explanation: ***Switch to oral flucloxacillin 1g four times daily and consider discharge with outpatient follow-up*** - The patient meets all criteria for **IV-to-oral switch (IVOS)**, including clinical improvement, a significant reduction in **CRP**, and the ability to tolerate **oral fluids**. - Following the **'Start Smart - Then Focus'** guidelines, switching to a high-dose oral agent like **flucloxacillin** is the most appropriate step to reduce **line-associated risks** and hospital stay. *Continue intravenous flucloxacillin until CRP normalizes completely* - **C-reactive protein (CRP)** levels are a lagging indicator and do not need to reach the normal range before transitioning to **oral therapy**. - Continuing **intravenous antibiotics** without clinical indication increases the risk of **thrombophlebitis** and healthcare-associated infections. *Stop antibiotics as significant clinical improvement has been achieved* - While the patient is improving, **cellulitis** requires a full course of treatment (typically 5 to 7 days) to prevent **relapse** or recurrence. - Stopping therapy at 48 hours for a severe infection with **systemic features** is premature and deviates from established **antimicrobial stewardship** protocols. *Change to intravenous co-amoxiclav to provide broader spectrum coverage* - The patient is responding well to **flucloxacillin**, which is the targeted treatment for **Staphylococcus aureus** and **Group A Streptococcus** in cellulitis. - Escalating to **broad-spectrum antibiotics** like co-amoxiclav is unnecessary and increases the risk of **Clostridioides difficile** infection. *Continue intravenous flucloxacillin for total of 7 days before considering oral switch* - There is no clinical evidence supporting a mandatory **7-day IV course**; the focus should be on switching as soon as **clinical stability** is reached. - Unnecessary prolongation of **parenteral administration** delays discharge and consumes hospital resources without improving **therapeutic outcomes**.
Question 105: A 42-year-old man presents with a carbuncle on his upper back. Incision and drainage is performed and pus is sent for culture. The wound is packed and he is discharged with dressings. The microbiology laboratory reports growth of meticillin-resistant Staphylococcus aureus (MRSA). He remains systemically well with no spreading infection. What is the most appropriate antibiotic management?
- A. No antibiotics required - incision and drainage alone is adequate treatment (Correct Answer)
- B. Oral doxycycline 200mg loading dose then 100mg twice daily for 7 days
- C. Oral flucloxacillin 500mg four times daily for 5 days
- D. Intravenous vancomycin 1g twice daily for 7 days
- E. Topical mupirocin to the wound three times daily for 5 days
Explanation: ***No antibiotics required - incision and drainage alone is adequate treatment*** - For a simple **carbuncle** or abscess in a systemically well patient, **incision and drainage (I&D)** is the definitive treatment and often eliminates the need for antibiotics. - Clinical guidelines state that even if **MRSA** is isolated, antibiotics are not indicated unless there is **significant cellulitis** (>5cm), systemic symptoms (fever/tachycardia), or immunocompromise.*Oral doxycycline 200mg loading dose then 100mg twice daily for 7 days* - While **doxycycline** provides effective oral coverage for community-acquired **MRSA**, it is unnecessary in this case as the patient is **systemically well** and the infection is localized. - Antibiotic use in this scenario increases the risk of side effects and **antimicrobial resistance** without providing clinical benefit over I&D alone.*Oral flucloxacillin 500mg four times daily for 5 days* - **Flucloxacillin** is ineffective against **MRSA** due to altered **penicillin-binding proteins (PBP2a)** which provide resistance to all beta-lactams. - This medication would be appropriate for methicillin-sensitive S. aureus (MSSA) but has no role once **MRSA** is confirmed.*Intravenous vancomycin 1g twice daily for 7 days* - **Vancomycin** is reserved for **severe, systemic infections** or hospitalized patients who cannot tolerate oral therapy. - Using an intravenous glycopeptide for a localized, drained skin lesion is inappropriate **antibiotic stewardship** and carries risks like nephrotoxicity.*Topical mupirocin to the wound three times daily for 5 days* - **Mupirocin** is primarily used for **MRSA decolonization** of the nares or for very superficial infections like **impetigo**. - It is not an appropriate treatment for a deep-seated infection like a **carbuncle**, as it lacks the necessary tissue penetration.
Question 106: A 58-year-old woman with rheumatoid arthritis on methotrexate 15mg weekly and prednisolone 10mg daily presents with a 24-hour history of rapidly spreading erythema, pain, and blistering on her right forearm. Examination reveals crepitus on palpation. Temperature is 38.9°C, heart rate 118/min, BP 95/62 mmHg. Lactate is 3.8 mmol/L. What is the most critical immediate management priority?
- A. Urgent surgical debridement and intravenous clindamycin plus benzylpenicillin (Correct Answer)
- B. CT scan of the affected limb to determine the extent of tissue involvement
- C. Intravenous flucloxacillin and fluid resuscitation then surgical review within 6 hours
- D. Blood cultures, MRI of forearm, and liaison with microbiology for antibiotic advice
- E. Intravenous broad-spectrum antibiotics and senior surgical review within 2 hours
Explanation: ***Urgent surgical debridement and intravenous clindamycin plus benzylpenicillin*** - This patient presents with **necrotizing fasciitis**, a surgical emergency indicated by **rapidly spreading erythema, pain, blistering, crepitus**, and **septic shock** (hypotension, tachycardia, elevated lactate). The immunosuppression from methotrexate and prednisolone increases the risk. - **Immediate surgical debridement** is the cornerstone of treatment to remove necrotic tissue and halt progression, coupled with appropriate antibiotics like **clindamycin** (for toxin suppression) and **benzylpenicillin** (for Group A Streptococcus, a common pathogen). *CT scan of the affected limb to determine the extent of tissue involvement* - While imaging like CT can identify **gas in soft tissues**, it should **never delay** definitive surgical intervention in a patient with clear clinical signs of necrotizing fasciitis and hemodynamic instability. - Delaying surgery to obtain a **CT scan** significantly increases mortality, as this condition progresses rapidly and requires urgent source control. *Intravenous flucloxacillin and fluid resuscitation then surgical review within 6 hours* - **Flucloxacillin** alone is insufficient for suspected necrotizing fasciitis, which often involves **polymicrobial infection** including Gram-negative bacteria and anaerobes, not just *Staphylococcus aureus*. - A **6-hour delay** for surgical review is unacceptable; necrotizing fasciitis is a **surgical emergency** requiring intervention within hours, not half a day. *Blood cultures, MRI of forearm, and liaison with microbiology for antibiotic advice* - Although **blood cultures** are important for guiding specific antibiotic therapy, they should not delay **life-saving surgical debridement** in a patient with suspected necrotizing fasciitis. - An **MRI** is too time-consuming and unnecessary in a patient with obvious clinical signs of gas gangrene and **hemodynamic instability**, who requires immediate surgical exploration. *Intravenous broad-spectrum antibiotics and senior surgical review within 2 hours* - While **broad-spectrum antibiotics** are crucial, specific choices like **clindamycin** for toxin inhibition and coverage for Group A Strep are critical, which this option doesn't specify. - A **2-hour delay** for surgical review is still too long for a patient presenting with **crepitus** and signs of **septic shock** from necrotizing fasciitis, where time to debridement is paramount.
Question 107: A 45-year-old man undergoes open reduction and internal fixation of a tibial fracture. The antimicrobial stewardship team reviews his prescription chart 24 hours post-operatively and notes he is receiving intravenous co-amoxiclav 1.2g three times daily for 'surgical prophylaxis'. His observations are stable, wound appears clean, and temperature is 36.8°C. What represents the most appropriate antimicrobial stewardship action?
- A. Continue current antibiotics for total of 5 days as per local orthopaedic protocol
- B. Stop antibiotics immediately as surgical prophylaxis should be single dose only (Correct Answer)
- C. Switch to oral co-amoxiclav to complete 48 hours of prophylaxis
- D. Change to intravenous flucloxacillin to provide narrower spectrum coverage
- E. Continue current antibiotics for 24 hours then stop if patient remains clinically well
Explanation: ***Stop antibiotics immediately as surgical prophylaxis should be single dose only*** - For clean orthopedic surgeries like **ORIF**, surgical prophylaxis is most effective when given as a **single dose** at induction; evidence does not support continuation beyond the intra-operative period. - Prolonged prophylaxis increases the risk of **C. difficile infection**, adverse drug reactions, and **antimicrobial resistance** without reducing the rate of surgical site infection. *Continue current antibiotics for total of 5 days as per local orthopaedic protocol* - A five-day course for prophylaxis is excessive and violates **antimicrobial stewardship** principles, as clinical observations and the wound appear normal. - Local protocols generally align with national guidelines (e.g., **NICE** or **SIGN**) which advocate against multi-day prophylaxis for uncomplicated clean surgeries. *Switch to oral co-amoxiclav to complete 48 hours of prophylaxis* - Switching to **oral administration** still constitutes an unnecessary extension of prophylaxis that provides no clinical benefit for a clean wound. - **Surgical prophylaxis** is intended to provide adequate tissue levels of antibiotic only during the window of potential contamination (the surgery itself). *Change to intravenous flucloxacillin to provide narrower spectrum coverage* - While **narrow-spectrum** agents are preferred for treatment, the primary issue here is the **duration** of therapy, not just the spectrum of the antibiotic used. - Even a narrow-spectrum antibiotic should not be continued post-operatively for prophylaxis in a patient with **stable observations** and a clean wound. *Continue current antibiotics for 24 hours then stop if patient remains clinically well* - Continuing for another 24 hours (reaching 48 hours total) is unnecessary as the **prophylactic window** closed once the surgical incision was sutured. - This approach demonstrates a failure of the **'Start Smart - Then Focus'** stewardship principle, which requires an immediate stop when a prophylaxis indication is exceeded.
Question 108: A 28-year-old woman presents with a 48-hour history of a painful, erythematous, indurated area on her right thigh measuring 8cm × 6cm. She is systemically well with temperature 37.4°C and no lymphangitis. She has no significant past medical history and takes no regular medications. What is the most appropriate management?
- A. Oral flucloxacillin 500mg four times daily for 7 days (Correct Answer)
- B. Observation without antibiotics and reassessment in 24-48 hours
- C. Ultrasound scan to exclude abscess formation before treatment decision
- D. Oral co-amoxiclav 500/125mg three times daily for 5 days
- E. Blood cultures and intravenous flucloxacillin 1g four times daily
Explanation: ***Oral flucloxacillin 500mg four times daily for 7 days*** - This patient presents with typical **cellulitis**, and **flucloxacillin** is the first-line antibiotic choice to cover the most common pathogens, **Staphylococcus aureus** and **Streptococcus pyogenes**. - Since she is systemically well (stable temperature, no lymphangitis), she can be managed in a primary care setting with a **7-day course** of oral antibiotics. *Observation without antibiotics and reassessment in 24-48 hours* - Delaying treatment is inappropriate as the patient already shows a clear 8cm × 6cm area of **erythema and induration** consistent with active infection. - Untreated **cellulitis** can rapidly progress to systemic illness, sepsis, or necrotizing fasciitis, necessitating prompt antibiotic initiation. *Ultrasound scan to exclude abscess formation before treatment decision* - An **ultrasound scan** is not routinely indicated for simple cellulitis unless there is clinical evidence of **fluctuance** or failure to respond to initial therapy. - Waiting for imaging would unnecessarily delay the administration of effective **empiric antibiotics** for this uncomplicated skin infection. *Oral co-amoxiclav 500/125mg three times daily for 5 days* - **Co-amoxiclav** is broader spectrum than required and is generally reserved for animal bites, facial cellulitis, or infections involving **anaerobes**. - Using a broader-spectrum agent for simple cellulitis contributes to **antibiotic resistance** and provides no additional clinical benefit over flucloxacillin. *Blood cultures and intravenous flucloxacillin 1g four times daily* - **Intravenous antibiotics** and blood cultures are reserved for patients with signs of **systemic toxicity**, significant comorbidities, or Eron Class III/IV infections. - This patient is **hemodynamically stable** and systemically well, making outpatient oral therapy the most appropriate and cost-effective management strategy.
Question 109: A hospital antimicrobial stewardship committee reviews data showing that the median duration of antibiotic treatment for uncomplicated community-acquired pneumonia has decreased from 7 days to 5 days following implementation of a new guideline. However, 30-day readmission rates have remained unchanged at 8%. What is the most appropriate interpretation of these findings?
- A. The intervention has failed as readmission rates have not decreased, indicating inadequate treatment duration
- B. The intervention is successful as it demonstrates that shorter duration therapy is safe without increasing readmissions (Correct Answer)
- C. The data are inconclusive as patient-reported outcomes and quality of life measures were not assessed
- D. The intervention should be reversed as maintaining readmission rates while reducing treatment duration suggests emerging resistance
- E. The intervention requires modification as 5 days is too short for community-acquired pneumonia regardless of readmission data
Explanation: ***The intervention is successful as it demonstrates that shorter duration therapy is safe without increasing readmissions*** - The primary goal of **antimicrobial stewardship** for **uncomplicated community-acquired pneumonia (CAP)** is to optimize antibiotic use by safely reducing unnecessary exposure, which this intervention achieved by shortening treatment from 7 to 5 days. - The fact that **30-day readmission rates** remained stable (8%) indicates that the shorter 5-day therapy was **clinically safe** and did not compromise patient outcomes or lead to treatment failures. *The intervention has failed as readmission rates have not decreased, indicating inadequate treatment duration* - The objective of this **stewardship intervention** was to reduce **antibiotic exposure**, not necessarily to lower existing **readmission rates**, which can be influenced by numerous other patient-specific and systemic factors. - Stable **readmission rates** actually confirm that the reduced duration of therapy was *not* inadequate and did not result in increased treatment failures or relapses. *The data are inconclusive as patient-reported outcomes and quality of life measures were not assessed* - While **patient-reported outcomes (PROs)** and **quality of life** are valuable metrics, they are not primary indicators required to assess the success of an **antimicrobial stewardship program** focused on **safety** (readmission rates) and process measures (antibiotic duration). - The objective finding of reduced antibiotic duration with maintained **patient safety** (stable readmission rates) provides sufficient evidence for a positive conclusion regarding the intervention's success. *The intervention should be reversed as maintaining readmission rates while reducing treatment duration suggests emerging resistance* - Shortening antibiotic duration, when appropriate, is a key strategy to *reduce* **antimicrobial resistance** by decreasing **selective pressure** on bacteria, rather than contributing to it. - **Emerging resistance** is typically identified through microbiological surveillance, culture data, and resistance patterns, not inferred from stable **30-day hospital readmission rates**. *The intervention requires modification as 5 days is too short for community-acquired pneumonia regardless of readmission data* - Current **evidence-based guidelines** from leading organizations like the **Infectious Diseases Society of America (IDSA)** and **American Thoracic Society (ATS)** recommend a minimum of 5 days of therapy for **uncomplicated CAP** in clinically stable patients. - Dismissing objective clinical data showing maintained patient safety (stable readmission rates) for a 5-day course contradicts principles of **antimicrobial stewardship** and **evidence-based medicine**.
Question 110: A 62-year-old man with type 2 diabetes presents with a 5-day history of progressive swelling, erythema, and pain affecting his left leg from ankle to mid-calf. His temperature is 38.2°C. He is allergic to penicillin (previous anaphylaxis). Blood tests show WCC 15.2 × 10⁹/L, CRP 145 mg/L, creatinine 98 μmol/L. What is the most appropriate antibiotic therapy?
- A. Oral doxycycline 200mg loading dose, then 100mg twice daily
- B. Intravenous clarithromycin 500mg twice daily (Correct Answer)
- C. Oral clindamycin 300mg four times daily
- D. Intravenous vancomycin 1g twice daily
- E. Oral ciprofloxacin 500mg twice daily
Explanation: ***Intravenous clarithromycin 500mg twice daily*** - This patient has **cellulitis** with **systemic inflammation** (fever, elevated WCC and CRP), necessitating **intravenous (IV)** antibiotics for effective treatment. - **Clarithromycin** is a suitable **macrolide** alternative for patients with a history of **penicillin anaphylaxis**, providing good coverage against common causes of cellulitis like *Streptococcus pyogenes* and *Staphylococcus aureus*. *Oral doxycycline 200mg loading dose, then 100mg twice daily* - **Doxycycline** is effective against common skin pathogens but the **oral route** is generally insufficient for a patient with **systemic signs of infection** and high inflammatory markers. - Initial management of **severe cellulitis** or cellulitis with systemic features usually requires **intravenous antibiotics** to achieve adequate tissue concentrations rapidly. *Oral clindamycin 300mg four times daily* - While **clindamycin** has activity against Gram-positive skin pathogens and is an alternative for penicillin allergy, the **oral route** is inappropriate for systemic infection. - For severe infections, **intravenous clindamycin** at higher doses would be considered, but oral therapy is reserved for milder cases or step-down treatment. *Intravenous vancomycin 1g twice daily* - **Vancomycin** is primarily used for serious infections, especially those caused by **methicillin-resistant *Staphylococcus aureus* (MRSA)**. - In community-acquired cellulitis without specific risk factors for MRSA or failure of first-line therapy, **vancomycin** is typically **overkill** and contributes to antimicrobial resistance. *Oral ciprofloxacin 500mg twice daily* - **Ciprofloxacin** is a fluoroquinolone primarily targeting **Gram-negative bacteria**, with limited activity against the most common causes of cellulitis, such as *Streptococcus* species. - Its use in uncomplicated cellulitis without a specific Gram-negative indication would likely result in **treatment failure** due to inadequate coverage of typical Gram-positive pathogens.
Practice by Chapter
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free