USMLE Step 2 Quiz: Sepsis And Severe Infection

What this quiz covers

This quiz focuses on Sepsis And Severe Infection, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 2.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Schedule elective cholecystectomy after completing antibiotics
2. Urgent endoscopic retrograde cholangiopancreatography for biliary decompression (correct answer)
3. Start oral ursodeoxycholic acid to dissolve gallstones
4. Order magnetic resonance cholangiopancreatography before any intervention
5. Treat pain only and observe for spontaneous stone passage

Explanation: This question tests critical care skills in managing sepsis and severe infections. Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Early recognition and management are crucial to improve outcomes. In the presented scenario, the patient's symptoms and lab findings suggest sepsis, highlighting the need for rapid intervention. Choice B is correct because it aligns with the guidelines for initial sepsis management, emphasizing the importance of biliary decompression via ERCP in cholangitis. Choice A is incorrect because it reflects a common misconception, such as delaying intervention for elective surgery. To help students: Emphasize the importance of early recognition and rapid intervention in sepsis. Teach prioritization of interventions and the use of current guidelines. Encourage practice with clinical scenarios to improve decision-making.

Question 2

1. Continue antibiotics alone because drainage increases fistula risk
2. Perform percutaneous or endoscopic drainage with step-up necrosectomy if needed (correct answer)
3. Start oral pancreatic enzymes and low-fat diet only
4. Repeat computed tomography in 72 hours before any intervention
5. Give high-dose corticosteroids to reduce pancreatic inflammation

Explanation: This question tests critical care skills in managing sepsis and severe infections. Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Early recognition and management are crucial to improve outcomes. In the presented scenario, the patient's symptoms and lab findings suggest sepsis, highlighting the need for rapid intervention. Choice B is correct because it aligns with the guidelines for initial sepsis management, emphasizing the importance of drainage with step-up approach for infected necrosis. Choice A is incorrect because it reflects a common misconception, such as avoiding drainage to prevent fistulas, which delays source control. To help students: Emphasize the importance of early recognition and rapid intervention in sepsis. Teach prioritization of interventions and the use of current guidelines. Encourage practice with clinical scenarios to improve decision-making.

Question 3

1. Administer another 4 liters of isotonic crystalloid before starting vasopressors
2. Start norepinephrine infusion and titrate to maintain mean arterial pressure at least 65 mm Hg (correct answer)
3. Begin dopamine infusion as first-line vasopressor due to bradycardia risk
4. Delay vasopressors until central venous pressure is measured with a pulmonary artery catheter
5. Give intravenous sodium bicarbonate to correct lactic acidosis before pressors

Explanation: This question tests critical care skills in managing sepsis and severe infections. Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Early recognition and management are crucial to improve outcomes. In the presented scenario, the patient's symptoms and lab findings suggest sepsis, highlighting the need for rapid intervention. Choice B is correct because it aligns with the guidelines for initial sepsis management, emphasizing the importance of vasopressor therapy with norepinephrine after initial fluid resuscitation. Choice C is incorrect because it reflects a common misconception, such as preferring dopamine as first-line, which is not recommended due to arrhythmia risks. To help students: Emphasize the importance of early recognition and rapid intervention in sepsis. Teach prioritization of interventions and the use of current guidelines. Encourage practice with clinical scenarios to improve decision-making.

Question 4

1. Ceftriaxone
2. Vancomycin
3. Piperacillin-tazobactam (correct answer)
4. Metronidazole

Explanation: This patient has septic shock from a healthcare-associated infection (catheter-associated UTI from a long-term care facility). Empiric therapy must cover common uropathogens, including multidrug-resistant organisms like Pseudomonas aeruginosa. Piperacillin-tazobactam is a broad-spectrum beta-lactam/beta-lactamase inhibitor that provides excellent coverage against gram-negative rods (including Pseudomonas), gram-positives, and anaerobes, making it an ideal choice. Ceftriaxone lacks reliable Pseudomonas coverage. Vancomycin is for MRSA and is not first-line for urosepsis unless a specific indication exists. Metronidazole is for anaerobic coverage and is not appropriate as monotherapy.

Question 5

1. Add an antifungal agent such as fluconazole
2. Obtain repeat blood cultures to guide therapy
3. Arrange for percutaneous drainage of the abscess (correct answer)
4. Administer intravenous hydrocortisone

Explanation: A fundamental principle in managing sepsis is source control. This patient has a large, drainable collection of pus (perinephric abscess) that is serving as an ongoing source of infection and inflammation. Without drainage, medical therapy (antibiotics) alone is unlikely to be successful. Therefore, the most critical next step is to arrange for drainage, typically via percutaneous catheter placement by interventional radiology. Adding antifungals or steroids is not indicated without further evidence, and while repeat cultures are useful, they do not address the primary problem of the undrained abscess.

Question 6

1. Vancomycin and cefepime
2. Ceftriaxone and azithromycin (correct answer)
3. Levofloxacin monotherapy
4. Ampicillin/sulbactam

Explanation: For patients with severe community-acquired pneumonia (CAP) requiring ICU admission, especially those in septic shock, guidelines recommend combination therapy. A beta-lactam (e.g., ceftriaxone) should be combined with either a macrolide (e.g., azithromycin) or a respiratory fluoroquinolone. The combination of ceftriaxone and azithromycin provides excellent coverage for common bacterial pathogens like Streptococcus pneumoniae as well as atypical pathogens like Legionella and Mycoplasma. Vancomycin and cefepime would be for hospital-acquired pneumonia. Levofloxacin monotherapy is an option but combination is often preferred in shock. Ampicillin/sulbactam has less reliable coverage for some CAP pathogens.

Question 7

1. Add daptomycin to the current regimen
2. Obtain a transesophageal echocardiogram
3. Remove the hemodialysis catheter (correct answer)
4. Increase the dose of vancomycin

Explanation: This patient has a catheter-related bloodstream infection (CRBSI) due to MRSA and is clinically unstable (sepsis with persistent hypotension). Prompt removal of the infected catheter is essential for source control and is associated with improved outcomes, especially in severe infections caused by S. aureus. While antibiotic therapy is critical, it will be less effective as long as the infected foreign body remains in place. A TEE is important to rule out endocarditis, but catheter removal is the immediate priority for source control. Adjusting antibiotics is secondary to removing the source.

Question 8

1. Ceftriaxone and azithromycin
2. Vancomycin
3. Piperacillin-tazobactam (correct answer)
4. Levofloxacin

Explanation: This patient has a complicated intra-abdominal infection (perforated diverticulitis) causing sepsis. The infection is polymicrobial, involving gram-negative rods, gram-positive cocci, and anaerobes from the colon. Empiric antibiotic therapy must cover all these organisms. Piperacillin-tazobactam is a broad-spectrum agent that provides excellent coverage for this spectrum of pathogens and is a recommended first-line agent. Ceftriaxone/azithromycin is for CAP. Vancomycin alone is inadequate. Levofloxacin alone lacks anaerobic coverage.

Question 9

1. Hypotension with a systolic blood pressure <90 mmHg and a positive blood culture
2. Two or more SIRS criteria plus a lactate level >4 mmol/L
3. Persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg and a serum lactate >2 mmol/L (correct answer)
4. A qSOFA score of ≥2 and evidence of acute kidney injury

Explanation: The Sepsis-3 international consensus definition for septic shock is a subset of sepsis in which underlying circulatory and cellular/metabolic abnormalities are profound enough to substantially increase mortality. The clinical criteria are: 1) persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) of 65 mmHg or greater, AND 2) a serum lactate level greater than 2 mmol/L, despite adequate fluid resuscitation. This patient has hypotension and an elevated lactate; if she requires vasopressors to raise her MAP, she will meet the criteria for septic shock.

Question 10

1. Vancomycin
2. Cefepime (correct answer)
3. Doxycycline
4. Ceftriaxone

Explanation: This patient has neutropenic fever and sepsis, a life-threatening emergency. Empiric antibiotic therapy must be started immediately and must cover Pseudomonas aeruginosa, a common and virulent pathogen in this population. The standard of care for high-risk neutropenic fever is monotherapy with an antipseudomonal beta-lactam, such as cefepime, piperacillin-tazobactam, or a carbapenem. Cefepime is an excellent first-line choice. Ceftriaxone lacks reliable Pseudomonas coverage. Vancomycin is not recommended for initial empiric therapy unless there is a specific indication (e.g., suspected catheter infection, severe mucositis, skin infection).

Question 11

1. Obtain an MRI of the thigh to confirm the diagnosis
2. Administer clindamycin to block toxin production
3. Arrange for emergent surgical exploration and debridement (correct answer)
4. Perform a needle aspiration of the affected area for culture

Explanation: This patient's presentation is highly suggestive of necrotizing fasciitis, a rapidly progressive infection of the deep soft tissues that causes vascular occlusion, ischemia, and necrosis. Key features include pain out of proportion to exam findings, systemic toxicity (septic shock), and skin changes like bullae or ecchymosis. Crepitus indicates gas-forming organisms. Necrotizing fasciitis is a surgical emergency. The definitive and life-saving treatment is emergent and aggressive surgical debridement of all necrotic tissue. Delaying surgery for imaging or other procedures significantly increases mortality. While antibiotics (including clindamycin for toxin suppression) are vital, they are an adjunct to, not a replacement for, surgery.

Question 12

1. Change antibiotics to vancomycin and piperacillin-tazobactam
2. Insert a chest tube for drainage (correct answer)
3. Administer intrapleural fibrinolytics
4. Perform a diagnostic bronchoscopy with lavage

Explanation: The patient has developed a complicated parapneumonic effusion, or empyema, as evidenced by the pleural fluid analysis (pH < 7.20, glucose < 60 mg/dL, high LDH, and positive gram stain). This represents a walled-off, undrained collection of infection that will not resolve with antibiotics alone. The cornerstone of management is source control via drainage. Therefore, the most appropriate and necessary next step is the placement of a chest tube (thoracostomy tube) to drain the purulent fluid. While antibiotics may need adjustment based on culture results, drainage is the most critical intervention.

Question 13

1. Administer intravenous hydrocortisone (correct answer)
2. Initiate an epinephrine infusion
3. Administer a 500 mL bolus of 5% albumin
4. Increase the vasopressin infusion to 0.06 units/min

Explanation: This patient has refractory septic shock, defined as persistent hypotension despite adequate fluid resuscitation and requiring high doses of vasopressors. The Surviving Sepsis Campaign guidelines suggest adding intravenous corticosteroids (e.g., hydrocortisone 200 mg/day) for adult patients with septic shock and an ongoing requirement for vasopressor therapy. This is thought to treat relative adrenal insufficiency that can occur in critical illness. Adding a third vasopressor (epinephrine) is an option but steroids are typically considered first in this scenario. Further fluid boluses are unlikely to help and may cause harm. Increasing vasopressin beyond 0.04 units/min is not recommended.

Question 14

1. Administer a furosemide bolus to convert to non-oliguric AKI
2. Start a low-dose dopamine infusion for renal protection
3. Avoid all potentially nephrotoxic medications (correct answer)
4. Initiate immediate continuous renal replacement therapy (CRRT)

Explanation: The management of sepsis-induced AKI focuses on treating the underlying sepsis, maintaining adequate mean arterial pressure to ensure renal perfusion, and avoiding secondary insults to the kidneys. A critical intervention is to review the patient's medication list and discontinue any potentially nephrotoxic agents (e.g., NSAIDs, aminoglycosides, certain IV contrast). While diuretics may be used for volume overload, they do not treat the underlying AKI. 'Renal-dose' dopamine has been proven ineffective. RRT is indicated for severe complications of AKI (e.g., life-threatening electrolyte abnormalities, severe acidosis, uremia, or refractory volume overload), not just for oliguria or elevated creatinine alone.

Question 15

1. 0.45% Saline
2. Lactated Ringer's solution (correct answer)
3. 5% Dextrose in water (D5W)
4. 25% Albumin

Explanation: The Surviving Sepsis Campaign guidelines recommend using isotonic crystalloids for initial fluid resuscitation. Both normal saline (0.9% NaCl) and balanced crystalloids like Lactated Ringer's solution are acceptable choices. However, balanced crystalloids are often preferred because large volumes of normal saline can cause a non-anion gap hyperchloremic metabolic acidosis. Hypotonic solutions like 0.45% saline and D5W are inappropriate for volume expansion as they rapidly leave the intravascular space. Colloids like albumin are not recommended for initial resuscitation and are typically reserved for specific situations, such as when patients require substantial amounts of crystalloids.

Question 16

1. Progression of dementia
2. Sepsis (correct answer)
3. Simple dehydration
4. Myocardial infarction

Explanation: This patient meets the Sepsis-3 criteria for sepsis, which includes a suspected infection plus evidence of organ dysfunction (a SOFA score increase of ≥2). Her organ dysfunction is indicated by her altered mental status (lethargy), tachypnea (RR > 22), and acute kidney injury (creatinine rise >0.5 mg/dL). Elderly patients with sepsis may not mount a febrile response. The leukocytosis further supports an infectious etiology. While dehydration may be present, the acute organ dysfunction in the setting of leukocytosis makes sepsis the most encompassing diagnosis.

Question 17

1. Obtain two sets of blood cultures
2. Administer a 30 mL/kg bolus of isotonic crystalloid (correct answer)
3. Administer empiric broad-spectrum antibiotics
4. Order a stat CT scan of the abdomen and pelvis

Explanation: This patient is in septic shock, characterized by hypotension and signs of infection. The immediate priority is to restore tissue perfusion and organ function. According to the Surviving Sepsis Campaign guidelines, rapid administration of 30 mL/kg of isotonic crystalloid is the first-line treatment for sepsis-induced hypotension. While obtaining blood cultures and administering antibiotics are also critical components of the hour-1 bundle and should be done concurrently, hemodynamic stabilization with fluids is the most immediate life-saving intervention for a hypotensive patient.

Question 18

1. Central venous pressure (CVP)
2. Serial serum lactate measurements (correct answer)
3. Mixed venous oxygen saturation (SvO2)
4. Pulmonary artery occlusion pressure

Explanation: Current sepsis guidelines recommend guiding resuscitation to normalize lactate in patients with elevated lactate levels, as this is a marker of tissue hypoperfusion. Lactate clearance (a decrease over time) is a key therapeutic goal and is strongly associated with improved survival. While CVP, PAOP, and SvO2 have been used in the past, they are more invasive, and static measures like CVP have been shown to be poor predictors of fluid responsiveness and are no longer recommended as primary targets for resuscitation.

Question 19

1. Cardiogenic shock
2. Septic shock (correct answer)
3. Hypovolemic shock
4. Anaphylactic shock

Explanation: This patient meets the Sepsis-3 criteria for septic shock. He has a presumed source of infection (pneumonia), evidence of sepsis-related organ dysfunction (confusion, elevated lactate), and persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) ≥65 mmHg (implied by the failure to respond to an initial fluid bolus) along with a lactate >2 mmol/L. Cardiogenic shock would likely present with signs of pulmonary edema and possibly a history of cardiac disease, without a clear infectious source. Hypovolemic shock would typically respond to fluid administration. Anaphylactic shock is an acute allergic reaction, often with urticaria or angioedema, which is not present here.

Question 20

1. Obtain an MRI of the leg to assess for abscess
2. Administer a dose of subcutaneous insulin
3. Establish IV access and begin fluid resuscitation (correct answer)
4. Consult surgery for possible debridement

Explanation: This patient presents with systemic signs of sepsis (fever, hypotension, tachycardia, tachypnea) likely secondary to cellulitis. The immediate priority in managing a patient with sepsis and hypotension is hemodynamic stabilization (the 'C' of ABCs). Therefore, establishing large-bore intravenous access and initiating a rapid bolus of isotonic crystalloids is the most critical first step. While managing her hyperglycemia, obtaining imaging, and considering surgical consultation are all important, they are secondary to initial resuscitation.