Common Infections — MCQs
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A 62-year-old man with type 2 diabetes presents with a 3-day history of a red, tender swelling on his upper back. Examination reveals a 4 cm fluctuant mass with multiple pustular heads and surrounding erythema. He is systemically well with normal observations. What is the most appropriate initial management for this condition?
A hospital antimicrobial stewardship committee reviews audit data showing that 68% of patients with uncomplicated community-acquired pneumonia receive dual therapy (beta-lactam plus macrolide) versus 32% receiving beta-lactam monotherapy. Mortality rates are equivalent between groups (3.2% vs 3.4%). Length of stay and costs are significantly higher in the dual therapy group. Microbiological data shows only 8% of isolates are atypical pathogens. Which recommendation best demonstrates evidence-based antimicrobial stewardship?
A 51-year-old woman presents with a 6-day history of progressive pain and swelling of her right index finger. She had a manicure 10 days ago. Examination shows a tense, fluctuant swelling along the flexor aspect of the finger extending into the palm, with the finger held in slight flexion. There is severe pain on passive extension. Temperature 38.3°C. What is the most critical aspect of immediate management?
A 63-year-old man is admitted with severe community-acquired pneumonia and started on IV co-amoxiclav and clarithromycin. On day 3, he develops watery diarrhoea (6 episodes in 24 hours), abdominal cramping, and low-grade fever. White cell count rises from 12 to 19 x 10⁹/L. Which of the following management steps best represents optimal antimicrobial stewardship in this situation?
A 42-year-old woman with rheumatoid arthritis on methotrexate 20mg weekly and prednisolone 10mg daily presents with a 3-day history of a painful erythematous nodule on her shin. It has now developed into a rapidly expanding ulcer with a violaceous undermined border. The base shows purulent exudate. Temperature 37.4°C. She is otherwise systemically well. What is the most appropriate next step in management?
A hospital trust reviews antimicrobial consumption data over 12 months following implementation of a new stewardship programme. Total antibiotic defined daily doses (DDDs) per 1000 bed-days decreased from 850 to 720. However, rates of Gram-negative bacteraemia with carbapenem-resistant organisms increased from 0.8 to 2.1 per 10,000 bed-days. What is the most likely explanation for this paradoxical finding?
A 57-year-old man with poorly controlled diabetes (HbA1c 102 mmol/mol) presents with malaise and a tender swelling in his left upper back over 5 days. Examination reveals a 5cm fluctuant, erythematous mass with multiple pustular points. Temperature 38.1°C, HR 95/min, BP 128/78 mmHg. White cell count 14.2 x 10⁹/L, CRP 87 mg/L. Ultrasound confirms a multiloculated abscess. What is the most appropriate management?
A 29-year-old woman with no past medical history presents with a 24-hour history of severe pain in her right thigh following minor trauma 3 days ago. On examination, she appears toxic (temperature 39.2°C, BP 95/55 mmHg, HR 125/min). The thigh is swollen, tense, with dusky discolouration and bullae. There is crepitus on palpation and severe pain disproportionate to physical signs. Lactate 4.2 mmol/L. What is the most important immediate management step?
A 68-year-old man with end-stage renal failure on peritoneal dialysis presents with abdominal pain and cloudy dialysate effluent. Dialysate cell count shows 450 white cells/μL (90% neutrophils). Gram stain shows no organisms. He is haemodynamically stable. According to International Society for Peritoneal Dialysis guidelines, what is the most appropriate empirical antimicrobial regimen?
A 35-year-old man who recently returned from visiting family in Bangladesh presents with a 5-day history of a painless ulcer with a necrotic centre on his forearm, where he recalls an insect bite. He has fever (38.4°C) and tender axillary lymphadenopathy. The ulcer is 2cm diameter with a black eschar surrounded by erythema and oedema. He works in a textile warehouse. What is the most likely diagnosis?
Common Infections UK Medical PG Practice Questions and MCQs
Question 141: A 62-year-old man with type 2 diabetes presents with a 3-day history of a red, tender swelling on his upper back. Examination reveals a 4 cm fluctuant mass with multiple pustular heads and surrounding erythema. He is systemically well with normal observations. What is the most appropriate initial management for this condition?
- A. Incision and drainage with oral flucloxacillin
- B. Oral flucloxacillin alone for 7 days
- C. Incision and drainage alone without antibiotics (Correct Answer)
- D. Intravenous flucloxacillin and metronidazole
- E. Warm compresses and review in 48 hours
Explanation: ***Incision and drainage alone without antibiotics*** - The patient presents with a **carbuncle**, characterized by a cluster of boils with **multiple pustular heads** and a **fluctuant mass**, for which **incision and drainage (I&D)** is the definitive treatment. - In **systemically well** patients with a simple localized abscess or carbuncle, clinical guidelines recommend I&D alone, as antibiotics provide no additional benefit for a drainable focus. *Incision and drainage with oral flucloxacillin* - While **flucloxacillin** is effective against **Staphylococcus aureus**, it is not routinely required for a localized carbuncle in a **systemically well** patient after adequate drainage. - The patient's **normal observations** and lack of systemic symptoms indicate that surgical drainage alone is sufficient without empirical antibiotics. *Oral flucloxacillin alone for 7 days* - Antibiotics alone are often ineffective for treating abscesses or carbuncles because they cannot achieve therapeutic concentrations within the **walled-off necrotic core** of the lesion. - Surgical intervention via **drainage** is essential to evacuate the pus and allow for resolution of the infection. *Intravenous flucloxacillin and metronidazole* - **Intravenous antibiotics** are reserved for patients with signs of **systemic sepsis**, extensive cellulitis, or rapid progression, none of which are present in this case. - **Metronidazole** specifically targets anaerobic bacteria and is not indicated for carbuncles, which are predominantly caused by aerobic **Staphylococcus aureus**. *Warm compresses and review in 48 hours* - While warm compresses can sometimes aid in the spontaneous drainage of smaller boils, a **4 cm fluctuant mass with multiple pustular heads** represents a significant infection requiring active intervention. - Delaying definitive treatment like **incision and drainage** for such a lesion can lead to increased pain, further tissue damage, and potentially more complicated infection.
Question 142: A hospital antimicrobial stewardship committee reviews audit data showing that 68% of patients with uncomplicated community-acquired pneumonia receive dual therapy (beta-lactam plus macrolide) versus 32% receiving beta-lactam monotherapy. Mortality rates are equivalent between groups (3.2% vs 3.4%). Length of stay and costs are significantly higher in the dual therapy group. Microbiological data shows only 8% of isolates are atypical pathogens. Which recommendation best demonstrates evidence-based antimicrobial stewardship?
- A. Continue current practice as mortality rates are acceptable
- B. Implement guidelines recommending beta-lactam monotherapy for non-severe CAP in absence of specific atypical pathogen risk factors (Correct Answer)
- C. Add fluoroquinolone monotherapy as a third option for all CAP patients
- D. Mandate PCR testing for atypical pathogens before prescribing macrolides
- E. Extend macrolide duration from 3 to 7 days to improve outcomes
Explanation: ***Implement guidelines recommending beta-lactam monotherapy for non-severe CAP in absence of specific atypical pathogen risk factors*** - Evidence shows that for **non-severe community-acquired pneumonia (CAP)**, beta-lactam monotherapy offers equivalent clinical outcomes to dual therapy with fewer side effects. - Over-prescription of macrolides is discouraged when **atypical pathogen** prevalence is low (8% here), as it increases **costs**, **length of stay**, and antimicrobial resistance without lowering mortality. *Continue current practice as mortality rates are acceptable* - Stewardship aims to optimize therapy; since **dual therapy** shows no mortality benefit but carries higher costs and risks, continuing it is poor practice. - Failing to address the 68% rate of dual therapy ignores the **unnecessary antibiotic exposure** and the lack of clinical superiority shown in the audit data. *Add fluoroquinolone monotherapy as a third option for all CAP patients* - Fluoroquinolones are generally reserved as second-line agents due to risks of **Clostridioides difficile** infection and significant **collateral damage** involving resistance. - Adding broad-spectrum options for all patients contradicts **stewardship principles** of using the narrowest spectrum agent effective for the clinical scenario. *Mandate PCR testing for atypical pathogens before prescribing macrolides* - Routine **PCR testing** for atypicals in non-severe CAP is often not cost-effective and may lack the turnaround time needed to guide initial empiric therapy. - Stewardship should focus first on **risk stratification** and guideline adherence rather than mandating expensive diagnostic bundles for low-risk patients. *Extend macrolide duration from 3 to 7 days to improve outcomes* - Extending duration increases **drug exposure** and potential for adverse events without any evidence of improved mortality or clinical success in this cohort. - This action would worsen the identified issues of **increased costs** and **longer length of stay** highlighted by the committee's audit.
Question 143: A 51-year-old woman presents with a 6-day history of progressive pain and swelling of her right index finger. She had a manicure 10 days ago. Examination shows a tense, fluctuant swelling along the flexor aspect of the finger extending into the palm, with the finger held in slight flexion. There is severe pain on passive extension. Temperature 38.3°C. What is the most critical aspect of immediate management?
- A. Refer urgently to hand surgery for surgical drainage within hours - this is a surgical emergency (Correct Answer)
- B. Perform bedside incision and drainage in the Emergency Department
- C. Splint the hand, start IV flucloxacillin, and review in 12 hours
- D. Start oral co-amoxiclav and arrange hand surgery review within 24 hours
- E. Arrange ultrasound imaging to confirm abscess before surgical referral
Explanation: ***Refer urgently to hand surgery for surgical drainage within hours - this is a surgical emergency*** - The clinical presentation, including tense fluctuant swelling, flexed posture, tenderness along the flexor aspect, and severe pain on passive extension, represents **Kanavel's four cardinal signs**, pathognomonic for **infectious flexor tenosynovitis**. - This condition is a **surgical emergency** due to the risk of high pressure within the closed tendon sheath leading to **tendon ischemia**, **necrosis**, and permanent functional loss if not drained promptly. *Perform bedside incision and drainage in the Emergency Department* - Bedside drainage is typically **insufficient** for infectious flexor tenosynovitis, as it often requires formal **surgical irrigation and debridement** in an operating room to adequately clear the entire tendon sheath. - Attempting inadequate drainage risks incomplete pus removal and potential iatrogenic injury to critical structures like **neurovascular bundles**. *Splint the hand, start IV flucloxacillin, and review in 12 hours* - While **IV antibiotics** are crucial, they are not effective as a sole treatment for a significant pus collection within a high-pressure, closed space like the flexor tendon sheath. - A **12-hour delay** in surgical intervention is unacceptable for infectious flexor tenosynovitis and significantly increases the risk of irreversible **tendon damage** and **functional impairment**. *Start oral co-amoxiclav and arrange hand surgery review within 24 hours* - **Oral antibiotics** are inadequate for treating a severe deep-space infection with systemic signs such as **fever** and significant local inflammation. - A **24-hour delay** in surgical referral and treatment is too long for this time-sensitive condition, potentially leading to **widespread infection** or digit loss. *Arrange ultrasound imaging to confirm abscess before surgical referral* - Infectious flexor tenosynovitis is primarily a **clinical diagnosis** based on the characteristic physical findings (Kanavel's signs). - Delaying urgent surgical intervention for **imaging studies** can unnecessarily prolong the time to definitive treatment and worsen the patient's prognosis.
Question 144: A 63-year-old man is admitted with severe community-acquired pneumonia and started on IV co-amoxiclav and clarithromycin. On day 3, he develops watery diarrhoea (6 episodes in 24 hours), abdominal cramping, and low-grade fever. White cell count rises from 12 to 19 x 10⁹/L. Which of the following management steps best represents optimal antimicrobial stewardship in this situation?
- A. Switch pneumonia treatment to IV levofloxacin and start oral vancomycin
- B. Continue current antibiotics and add oral metronidazole 400mg three times daily
- C. Send stool for C. difficile testing, stop clarithromycin, continue co-amoxiclav at minimum effective duration (Correct Answer)
- D. Stop all antibiotics immediately and await stool culture results
- E. Add IV metronidazole and vancomycin while continuing pneumonia treatment
Explanation: ***Send stool for C. difficile testing, stop clarithromycin, continue co-amoxiclav at minimum effective duration*** - Optimal **antimicrobial stewardship** involves reviewing the clinical need for current antibiotics; after 72 hours, the macrolide (**clarithromycin**) can often be stopped if the patient is stable, reducing the risk of further **C. difficile** provocation. - Immediate **C. difficile toxin testing** is essential, while maintaining the minimum necessary coverage for the primary infection (**pneumonia**) to prevent clinical relapse. *Switch pneumonia treatment to IV levofloxacin and start oral vancomycin* - **Fluoroquinolones** like levofloxacin are high-risk triggers for **Clostridioides difficile** infection and should be avoided when a patient already has diarrhea. - Starting **oral vancomycin** empirically without a confirmed diagnosis or signs of severe toxicity (like megacolon) violates stewardship principles by contributing to antibiotic overuse. *Continue current antibiotics and add oral metronidazole 400mg three times daily* - Continuing the inciting antibiotics (**co-amoxiclav and clarithromycin**) without review prolongs the disruption of gut flora, making the **C. difficile** harder to treat. - **Oral metronidazole** is no longer the first-line recommendation for confirmed CDI in many guidelines and shouldn't be added before a stool test result is obtained. *Stop all antibiotics immediately and await stool culture results* - Stopping treatment for **severe community-acquired pneumonia** prematurely on day 3 is dangerous and could lead to respiratory failure or clinical deterioration. - While stewardship aims to minimize unnecessary use, it does not advocate for withdrawing **life-saving therapy** for an active, severe infection. *Add IV metronidazole and vancomycin while continuing pneumonia treatment* - **IV metronidazole** is typically reserved for **fulminant CDI** with ileus; it is less effective than oral routes for standard C. difficile infection. - Adding multiple potent antibiotics without diagnostic confirmation or narrowing the current regimen represents poor **polypharmacy** and stewardship practice.
Question 145: A 42-year-old woman with rheumatoid arthritis on methotrexate 20mg weekly and prednisolone 10mg daily presents with a 3-day history of a painful erythematous nodule on her shin. It has now developed into a rapidly expanding ulcer with a violaceous undermined border. The base shows purulent exudate. Temperature 37.4°C. She is otherwise systemically well. What is the most appropriate next step in management?
- A. Start oral flucloxacillin for staphylococcal cellulitis
- B. Start IV piperacillin-tazobactam for presumed necrotising infection
- C. Take bacterial and fungal cultures, consider biopsy, and refer to dermatology (Correct Answer)
- D. Arrange urgent surgical debridement
- E. Start oral prednisolone 40mg daily for presumed pyoderma gangrenosum
Explanation: ***Take bacterial and fungal cultures, consider biopsy, and refer to dermatology***- This patient's presentation with a **violaceous undermined border** and a rapidly expanding ulcer is classic for **pyoderma gangrenosum (PG)**, which is strongly associated with **rheumatoid arthritis**.- Since PG is a **diagnosis of exclusion**, it is crucial to first perform **bacterial and fungal cultures** and a skin biopsy to rule out infections and malignancy, especially in an **immunosuppressed patient**.*Start oral flucloxacillin for staphylococcal cellulitis*- While cellulitis causes erythema, it typically lacks the characteristic **undermined borders** and rapid, necrotizing ulceration seen here.- Empiric antibiotics alone are inappropriate as they do not address the likely **inflammatory pathology** and delay a tissue-proven diagnosis.*Start IV piperacillin-tazobactam for presumed necrotising infection*- Although the ulcer is rapid, the patient is **systemically well** with a temperature of only 37.4°C, making a life-threatening **necrotizing fasciitis** less likely.- IV antibiotics do not treat the underlying **neutrophilic dermatosis** of pyoderma gangrenosum and have limited role unless secondary infection is confirmed.*Arrange urgent surgical debridement*- Surgical debridement is highly contraindicated in suspected pyoderma gangrenosum due to **pathergy**, where trauma leads to worsening of the lesion.- Debridement can cause significant and rapid **extension of the ulcer**, potentially leading to severe tissue loss and poor outcomes.*Start oral prednisolone 40mg daily for presumed pyoderma gangrenosum*- Although high-dose steroids are the treatment for PG, starting them before **ruling out infection** can be dangerous in an immunocompromised host on **methotrexate**.- A formal diagnosis following **dermatology referral** and biopsy is required to ensure that systemic immunosuppression is safe and appropriate.
Question 146: A hospital trust reviews antimicrobial consumption data over 12 months following implementation of a new stewardship programme. Total antibiotic defined daily doses (DDDs) per 1000 bed-days decreased from 850 to 720. However, rates of Gram-negative bacteraemia with carbapenem-resistant organisms increased from 0.8 to 2.1 per 10,000 bed-days. What is the most likely explanation for this paradoxical finding?
- A. The stewardship programme was ineffective at reducing overall antibiotic use
- B. Increased use of carbapenems or other broad-spectrum agents despite reduced total DDDs, causing selection pressure (Correct Answer)
- C. Natural variation in resistance patterns unrelated to antibiotic use
- D. Reduced infection control measures coinciding with stewardship implementation
- E. Contamination of surveillance cultures rather than true bacteraemia
Explanation: ***Increased use of carbapenems or other broad-spectrum agents despite reduced total DDDs, causing selection pressure*** - A reduction in **total Defined Daily Doses (DDDs)** does not preclude a shift towards increased use of **specific broad-spectrum antibiotics** like carbapenems, which exert strong **selection pressure**. - This selective increase in **carbapenem** use, even if overall antibiotic consumption declines, directly drives the proliferation of **carbapenem-resistant organisms (CROs)** by favoring their survival and spread. *The stewardship programme was ineffective at reducing overall antibiotic use* - This option is contradicted by the data provided, which explicitly states that total antibiotic DDDs **decreased** from 850 to 720 per 1000 bed-days, indicating some effectiveness in reducing volume. - The ineffectiveness lies not in reducing volume, but potentially in failing to target the **quality or spectrum** of antibiotics that drive specific resistance. *Natural variation in resistance patterns unrelated to antibiotic use* - While some background **epidemiological variation** occurs, such a significant and specific increase in **carbapenem resistance** coinciding with a new stewardship program strongly suggests a causal link to the intervention or local prescribing practices. - Antimicrobial resistance in a hospital setting is largely influenced by **antimicrobial selection pressure**, making a direct link to antibiotic use more probable than unrelated natural variation for such a rapid rise. *Reduced infection control measures coinciding with stewardship implementation* - Poor **infection control** could contribute to the spread of resistant organisms, but it wouldn't directly explain a paradoxical increase in resistance **despite decreased overall antibiotic consumption**. - A general breakdown in infection control would typically lead to an increase in various healthcare-associated infections, not specifically a focused rise in **carbapenem-resistant Gram-negative bacteraemia** linked to antibiotic usage patterns. *Contamination of surveillance cultures rather than true bacteraemia* - **Bacteraemia** implies the presence of bacteria in the blood, confirmed by **blood cultures**, which are typically collected under strict aseptic conditions to minimize contamination risk. - A substantial and consistent increase in documented **bacteraemia rates** across a hospital trust is highly unlikely to be attributed solely to widespread **culture contamination**; it generally signifies a true increase in infection.
Question 147: A 57-year-old man with poorly controlled diabetes (HbA1c 102 mmol/mol) presents with malaise and a tender swelling in his left upper back over 5 days. Examination reveals a 5cm fluctuant, erythematous mass with multiple pustular points. Temperature 38.1°C, HR 95/min, BP 128/78 mmHg. White cell count 14.2 x 10⁹/L, CRP 87 mg/L. Ultrasound confirms a multiloculated abscess. What is the most appropriate management?
- A. Oral flucloxacillin 500mg four times daily for 7 days
- B. Incision and drainage with oral flucloxacillin 500mg four times daily for 5-7 days (Correct Answer)
- C. IV flucloxacillin 2g four times daily for 14 days
- D. Needle aspiration and oral co-amoxiclav 625mg three times daily
- E. Hot compresses and reassess in 48 hours
Explanation: ***Incision and drainage with oral flucloxacillin 500mg four times daily for 5-7 days*** - The patient presents with a **carbuncle**, characterized by a deep, **multiloculated abscess** with multiple pustular points, which requires surgical **incision and drainage** for definitive source control. - **Antibiotics** are indicated in this case because of the lesion's size (>2cm), the presence of **systemic symptoms** (fever, tachycardia), and the patient's **immunocompromised state** due to poorly controlled diabetes. *Oral flucloxacillin 500mg four times daily for 7 days* - Antibiotics alone are insufficient for treating a **fluctuant abscess** or carbuncle as the medication cannot effectively penetrate the abscess cavity. - Failure to perform **drainage** increases the risk of treatment failure, recurrence, and worsening of the infection in a diabetic patient. *IV flucloxacillin 2g four times daily for 14 days* - While the patient has a minor fever, he is **hemodynamically stable** with a BP of 128/78 mmHg, meaning **oral antibiotics** are typically sufficient following drainage. - **Intravenous therapy** is usually reserved for patients with severe sepsis, rapidly progressing cellulitis, or those unable to tolerate oral medications. *Needle aspiration and oral co-amoxiclav 625mg three times daily* - **Needle aspiration** is inadequate for a **multiloculated collection** where multiple septations prevent complete evacuation of pus. - **Flucloxacillin** is the preferred narrow-spectrum choice for **Staphylococcus aureus**, which is the most common causative organism in carbuncles. *Hot compresses and reassess in 48 hours* - **Hot compresses** are only appropriate for very small, simple furuncles or folliculitis to encourage spontaneous drainage. - Delaying active treatment in a patient with **poorly controlled diabetes** and systemic features of infection significantly increases the risk of **necrotizing fasciitis** or sepsis.
Question 148: A 29-year-old woman with no past medical history presents with a 24-hour history of severe pain in her right thigh following minor trauma 3 days ago. On examination, she appears toxic (temperature 39.2°C, BP 95/55 mmHg, HR 125/min). The thigh is swollen, tense, with dusky discolouration and bullae. There is crepitus on palpation and severe pain disproportionate to physical signs. Lactate 4.2 mmol/L. What is the most important immediate management step?
- A. Arrange urgent MRI to define tissue planes involved
- B. Start IV benzylpenicillin and clindamycin and arrange immediate surgical exploration (Correct Answer)
- C. Take deep tissue cultures and start IV co-amoxiclav
- D. Perform urgent CT imaging to assess extent of infection
- E. Arrange surgical debridement within 6 hours and start broad-spectrum antibiotics
Explanation: ***Start IV benzylpenicillin and clindamycin and arrange immediate surgical exploration*** - The presentation of **pain disproportionate to physical signs**, **crepitus**, **bullae**, **dusky discolouration**, and **septic shock** (temperature 39.2°C, BP 95/55 mmHg, HR 125/min, lactate 4.2 mmol/L) is highly indicative of **necrotizing fasciitis**, a surgical emergency. - **Immediate surgical debridement** is critical to remove necrotic tissue and halt progression, complemented by **broad-spectrum IV antibiotics** including **clindamycin** for its vital **antitoxin effect** against Group A Strep and other toxin-producing bacteria. *Arrange urgent MRI to define tissue planes involved* - **MRI**, while detailed for soft tissue, should **never delay emergent surgical intervention** for suspected necrotizing fasciitis, especially in a patient exhibiting signs of **septic shock**. - Time-consuming diagnostic imaging would unacceptably postpone **life-saving debridement**, worsening patient outcomes in this rapidly progressive infection. *Take deep tissue cultures and start IV co-amoxiclav* - **Co-amoxiclav** alone may not provide adequate coverage for severe necrotizing fasciitis (e.g., against MRSA or certain anaerobes) and, crucially, **lacks the antitoxin effect** provided by clindamycin, which is vital in toxin-mediated infections. - While cultures are important for guiding definitive antibiotic therapy, they should be obtained **intraoperatively** without delaying the initiation of empiric antibiotics and **immediate surgery**. *Perform urgent CT imaging to assess extent of infection* - **CT imaging** can reveal gas in tissues but is **not required to diagnose** necrotizing fasciitis clinically and should **not delay immediate surgical exploration**. - Spending time on imaging for a condition requiring **immediate surgical debridement** in a patient with **septic shock** significantly increases morbidity and mortality. *Arrange surgical debridement within 6 hours and start broad-spectrum antibiotics* - A delay of "**within 6 hours**" for surgical debridement is **unacceptable and dangerous** in necrotizing fasciitis, which requires **immediate** surgical intervention to prevent rapid spread and systemic deterioration. - The infection spreads aggressively, and even short delays in **surgical debridement**, which is the primary treatment, significantly increase mortality and morbidity.
Question 149: A 68-year-old man with end-stage renal failure on peritoneal dialysis presents with abdominal pain and cloudy dialysate effluent. Dialysate cell count shows 450 white cells/μL (90% neutrophils). Gram stain shows no organisms. He is haemodynamically stable. According to International Society for Peritoneal Dialysis guidelines, what is the most appropriate empirical antimicrobial regimen?
- A. Intraperitoneal vancomycin and gentamicin (Correct Answer)
- B. Intravenous flucloxacillin and gentamicin
- C. Intraperitoneal cefazolin and ceftazidime
- D. Oral co-amoxiclav and remove peritoneal dialysis catheter
- E. Intravenous meropenem monotherapy
Explanation: ***Intraperitoneal vancomycin and gentamicin*** - Empirical therapy for **peritoneal dialysis-associated peritonitis** must provide broad cover against both **Gram-positive** (e.g., Staphylococci) and **Gram-negative** (e.g., Pseudomonas, E. coli) organisms. - The **intraperitoneal (IP)** route is superior to intravenous administration because it achieves higher drug concentrations at the site of infection and correlates with better clinical outcomes. *Intravenous flucloxacillin and gentamicin* - This regimen uses the **intravenous route**, which fails to achieve the high local dialysate concentrations required for optimal treatment of peritonitis. - **Flucloxacillin** provides poor coverage against **MRSA**, which is a common pathogen in long-term dialysis patients, making vancomycin a safer empirical choice. *Intraperitoneal cefazolin and ceftazidime* - While this combination is a valid alternative per **ISPD guidelines**, vancomycin is preferred in settings with high **MRSA prevalence** or for patients with penicillin allergies. - This patient's stability and the lack of Gram stain results make the **vancomycin/aminoglycoside** combination the traditional and highly reliable first-line choice in many clinical practices. *Oral co-amoxiclav and remove peritoneal dialysis catheter* - **Oral antibiotics** are inappropriate as initial therapy because they cannot match the efficacy of **intraperitoneal administration** in acute PD peritonitis. - **Catheter removal** is not indicated at presentation and is typically reserved for cases that are **refractory**, fungal, or involve the exit site/tunnel infection. *Intravenous meropenem monotherapy* - **Meropenem** is an unnecessarily broad-spectrum carbapenem for initial empirical therapy and contributes to increased **antimicrobial resistance**. - Like other **intravenous options**, it is less effective than intraperitoneal delivery for treating the peritoneal membrane and effluent infection.
Question 150: A 35-year-old man who recently returned from visiting family in Bangladesh presents with a 5-day history of a painless ulcer with a necrotic centre on his forearm, where he recalls an insect bite. He has fever (38.4°C) and tender axillary lymphadenopathy. The ulcer is 2cm diameter with a black eschar surrounded by erythema and oedema. He works in a textile warehouse. What is the most likely diagnosis?
- A. Cutaneous anthrax (Correct Answer)
- B. Cutaneous leishmaniasis
- C. Ecthyma gangrenosum
- D. Rickettsial spotted fever
- E. Buruli ulcer
Explanation: ***Cutaneous anthrax***- The classic presentation of a **painless ulcer** that develops into a **black necrotic eschar** (malignant pustule) surrounded by **erythema and significant non-pitting edema**, along with **fever** and **tender regional lymphadenopathy**, is highly characteristic of *Bacillus anthracis* infection.- Occupational exposure in a **textile warehouse** (handling animal fibers or products) and recent travel to **Bangladesh** (an area where anthrax is endemic) significantly increase the risk of contact with anthrax spores.*Cutaneous leishmaniasis*- While it can cause a painless ulcer, **cutaneous leishmaniasis** typically has a much **slower progression** over weeks to months, rather than the acute 5-day history presented here.- The lesions are often more nodular or plaque-like, eventually ulcerating, but generally lack the acute systemic symptoms and the specific **black eschar** surrounded by marked edema.*Ecthyma gangrenosum*- This condition is primarily associated with **immunocompromised patients**, especially those with **severe neutropenia**, and is typically caused by **Pseudomonas aeruginosa** bacteremia.- The lesions are often multiple and rapidly progressive, but the patient's general health and the specific occupational and travel history do not align with the typical risk factors for ecthyma gangrenosum.*Rickettsial spotted fever*- Some rickettsial infections can cause an **eschar (tache noire)** at the bite site, but this is usually accompanied by a **widespread maculopapular rash**, which is not mentioned in this case.- While fever and lymphadenopathy can be present, the distinctive **black eschar** with extensive surrounding **edema** and the strong epidemiological links point more strongly to anthrax.*Buruli ulcer*- Caused by *Mycobacterium ulcerans*, **Buruli ulcer** presents as a **chronic, slow-growing, painless ulcer** with **undermined edges** and typically lacks the acute onset of fever and tender lymphadenopathy.- The rapid progression over 5 days and the distinct **black eschar** are not characteristic features of Buruli ulcer.
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