Infectious diseases (sepsis, endocarditis) US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Infectious diseases (sepsis, endocarditis). These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Infectious diseases (sepsis, endocarditis) US Medical PG Question 1: A 51-year-old woman is brought into the emergency department following a motor vehicle accident. She is unconscious and was intubated in the field. Past medical history is unknown. Upon arrival, she is hypotensive and tachycardic. Her temperature is 37.2°C (99.1°F), the pulse is 110/min, the respiratory rate is 22/min, and the blood pressure is 85/60 mm Hg. There is no evidence of head trauma, she withdraws to pain and her pupils are 2mm and reactive to light. Her heart has a regular rhythm without any murmurs or rubs and her lungs are clear to auscultation. Her abdomen is firm and distended with decreased bowel sounds. Her extremities are cool and clammy with weak, thready pulses. There is no peripheral edema. Of the following, what is the likely cause of her presentation?
- A. Septic shock
- B. Neurogenic shock
- C. Obstructive shock
- D. Hypovolemic shock (Correct Answer)
- E. Cardiogenic shock
Infectious diseases (sepsis, endocarditis) Explanation: ***Hypovolemic shock***
- The patient's presentation with ***hypotension*** (BP 85/60 mm Hg), ***tachycardia*** (pulse 110/min), ***cool and clammy extremities***, ***weak peripheral pulses***, and a ***firm, distended abdomen*** after a motor vehicle accident strongly suggests internal hemorrhage leading to hypovolemic shock.
- The ***firm and distended abdomen*** is a key indicator of potential intra-abdominal bleeding, significantly contributing to the loss of intravascular volume.
*Septic shock*
- Septic shock is characterized by signs of infection along with organ dysfunction and circulatory compromise, often presenting with **fever** or **hypothermia**, and sometimes **warm extremities** initially due to vasodilation. This patient's temperature is normal, and extremities are cool.
- While hypotension and tachycardia are present, the absence of clear signs of infection and the presence of a firm, distended abdomen make hypovolemia a more immediate concern following trauma.
*Neurogenic shock*
- Neurogenic shock typically follows severe spinal cord injury above T6, leading to a loss of sympathetic tone. This results in **hypotension with bradycardia** and **warm, dry skin** due to widespread vasodilation.
- This patient is tachycardic and has cool, clammy extremities, which contradicts the classic presentation of neurogenic shock.
*Obstructive shock*
- Obstructive shock occurs due to a physical obstruction to central circulation, such as **tension pneumothorax**, **cardiac tamponade**, or **pulmonary embolism**.
- There is no mention of absent breath sounds, jugular venous distention, muffled heart sounds, or other specific signs pointing to an obstructive cause. Lungs are clear to auscultation and heart rhythm is regular.
*Cardiogenic shock*
- Cardiogenic shock results from primary cardiac dysfunction, often presenting with signs of **heart failure**, such as **pulmonary edema** (rales), **jugular venous distention**, gallop rhythms, or new murmurs.
- The patient has clear lungs, a regular heart rhythm, and no murmurs, which makes primary cardiac dysfunction less likely as the immediate cause of shock in this trauma setting.
Infectious diseases (sepsis, endocarditis) US Medical PG Question 2: A 50-year-old man with a history of stage 4 kidney disease was admitted to the hospital for an elective hemicolectomy. His past medical history is significant for severe diverticulitis. After the procedure he becomes septic and was placed on broad spectrum antibiotics. On morning rounds, he appear weak and complains of fatigue and nausea. His words are soft and he has difficulty answering questions. His temperature is 38.9°C (102.1°F), heart rate is 110/min, respiratory rate is 15/min, blood pressure 90/65 mm Hg, and saturation is 89% on room air. On physical exam, his mental status appears altered. He has a bruise on his left arm that spontaneously appeared overnight. His cardiac exam is positive for a weak friction rub. Blood specimens are collected and sent for evaluation. An ECG is performed (see image). What therapy will this patient most likely receive next?
- A. Send the patient for hemodialysis (Correct Answer)
- B. Perform a STAT pericardiocentesis
- C. Prepare the patient for renal transplant
- D. Treat the patient with aspirin
- E. Treat the patient with cyclophosphamide and prednisone
Infectious diseases (sepsis, endocarditis) Explanation: ***Send the patient for hemodialysis***
- This patient presents with symptoms of **uremic encephalopathy** and **uremic pericarditis** in the context of **stage 4 kidney disease**. The altered mental status, weakness, fatigue, nausea, and the development of a bruise (which could indicate uremic coagulopathy) are suggestive of severe uremia. The ECG shows widespread **ST elevation and PR depression**, particularly noticeable in leads like II, V2-V6, which is a classic finding for pericarditis. The **weak friction rub** confirms this clinical suspicion. Hemodialysis is crucial to rapidly remove uremic toxins and resolve both uremic encephalopathy and pericarditis.
- The ECG findings, including diffuse **ST elevation** with **PR depression**, are characteristic of **pericarditis**. In a patient with end-stage renal disease, **uremia** is a common cause of pericarditis, which can be life-threatening if not promptly treated with dialysis.
*Perform a STAT pericardiocentesis*
- While the patient has pericarditis, there are no immediate signs of **cardiac tamponade**, such as muffled heart sounds, jugular venous distension, or pulsus paradoxus, that would necessitate an emergency pericardiocentesis.
- The primary treatment for **uremic pericarditis** is typically **hemodialysis** to resolve the underlying uremic state, not direct fluid removal unless tamponade is present.
*Prepare the patient for renal transplant*
- **Renal transplant** is a long-term solution for end-stage renal disease, but it is not an acute intervention for immediate life-threatening uremic complications like uremic pericarditis and encephalopathy.
- The patient needs urgent stabilization and treatment of his current acute medical issues before transplant consideration.
*Treat the patient with aspirin*
- While aspirin can be used for some forms of pericarditis, it is generally **contraindicated** in patients with **uremic pericarditis** due to the increased risk of **gastric bleeding** and potential exacerbation of uremic coagulopathy.
- The primary treatment for uremic pericarditis is **dialysis**, not anti-inflammatory medications, as the inflammation is driven by uremic toxins.
*Treat the patient with cyclophosphamide and prednisone*
- **Immunosuppressants** like cyclophosphamide and prednisone are used for autoimmune or inflammatory conditions causing pericarditis, such as systemic lupus erythematosus.
- This patient's pericarditis is clearly linked to **uremia** from kidney disease, not an autoimmune condition, making immunosuppressive therapy inappropriate and potentially harmful.
Infectious diseases (sepsis, endocarditis) US Medical PG Question 3: Blood cultures are sent to the laboratory and empiric treatment with intravenous vancomycin is started. Blood cultures grow gram-negative bacilli identified as Cardiobacterium hominis. Which of the following is the most appropriate next step in management?
- A. Switch to intravenous gentamicin
- B. Switch to intravenous ampicillin
- C. Switch to intravenous ceftriaxone (Correct Answer)
- D. Switch to intravenous cefazolin
- E. Add intravenous rifampin
Infectious diseases (sepsis, endocarditis) Explanation: ***Switch to intravenous ceftriaxone***
- **Cardiobacterium hominis** is part of the **HACEK group** of bacteria, which are known for causing **endocarditis**.
- These organisms are typically susceptible to **beta-lactam antibiotics**, with **third-generation cephalosporins** like ceftriaxone being the drug of choice due to their excellent activity and good penetration.
*Switch to intravenous gentamicin*
- While **aminoglycosides** like gentamicin can be used in combination regimens for serious infections, they are generally **not monotherapy** for HACEK endocarditis and are associated with **nephrotoxicity** and **ototoxicity**.
- The primary treatment for HACEK endocarditis is a **beta-lactam antibiotic**, not an aminoglycoside alone.
*Switch to intravenous ampicillin*
- **Ampicillin** is a beta-lactam, but it may not consistently provide optimal coverage for all HACEK organisms, and some strains may have reduced susceptibility.
- **Third-generation cephalosporins** are preferred due to their broader and more consistent activity against this group.
*Switch to intravenous cefazolin*
- **Cefazolin** is a first-generation cephalosporin and typically has **limited activity** against gram-negative bacilli, especially those like Cardiobacterium hominis which require broader-spectrum beta-lactams.
- Its spectrum of activity is primarily against **gram-positive bacteria** and some **gram-negative cocci**.
*Add intravenous rifampin*
- **Rifampin** is primarily used for **mycobacterial infections** and in combination regimens for specific bacterial infections (e.g., bone and joint infections, prosthetic device infections) often due to resistant staphylococci.
- It is **not a first-line agent** for Cardiobacterium hominis infections and there's no indication for its use here with an organism susceptible to ceftriaxone.
Infectious diseases (sepsis, endocarditis) US Medical PG Question 4: Three days after admission to the hospital following a motor vehicle accident, a 45-year-old woman develops a fever. A central venous catheter was placed on the day of admission for treatment of severe hypotension. Her temperature is 39.2°C (102.5°F). Examination shows erythema surrounding the catheter insertion site at the right internal jugular vein. Blood cultures show gram-positive, catalase-positive cocci that have a high minimum inhibitory concentration when exposed to novobiocin. Which of the following is the most appropriate pharmacotherapy?
- A. Clarithromycin
- B. Vancomycin (Correct Answer)
- C. Metronidazole
- D. Penicillin G
- E. Polymyxin B
Infectious diseases (sepsis, endocarditis) Explanation: ***Vancomycin***
- The description of **gram-positive, catalase-positive cocci** that are **novobiocin-resistant** (high MIC) strongly points to **Staphylococcus epidermidis** or other coagulase-negative staphylococci. *S. epidermidis* is the most common cause of **catheter-related bloodstream infections** and is often **methicillin-resistant**, making **vancomycin** the drug of choice.
- The presence of erythema at the catheter site and fever in a patient with a central venous catheter indicates a **central line-associated bloodstream infection (CLABSI)**, for which empiric coverage with vancomycin is standard until sensitivities are known.
- The novobiocin resistance test helps differentiate *S. epidermidis* (resistant) from *S. saprophyticus* (sensitive).
*Clarithromycin*
- **Clarithromycin** is a macrolide antibiotic primarily used for respiratory tract infections and *Mycobacterium avium complex*.
- It is **not effective** against methicillin-resistant staphylococci and would not be appropriate for a suspected CLABSI.
*Metronidazole*
- **Metronidazole** is an antibiotic mainly used for **anaerobic bacterial infections** and certain parasitic infections.
- It has **no activity** against gram-positive cocci like staphylococci.
*Penicillin G*
- **Penicillin G** is a narrow-spectrum penicillin effective against some gram-positive cocci, like **Streptococcus pyogenes**.
- However, virtually all staphylococci, especially those causing hospital-acquired infections, are **resistant to penicillin G** due to beta-lactamase (penicillinase) production.
*Polymyxin B*
- **Polymyxin B** is an antibiotic primarily effective against **gram-negative bacteria**, particularly those with multi-drug resistance such as **Pseudomonas aeruginosa** and **Acinetobacter baumannii**.
- It has **no significant activity** against gram-positive cocci like staphylococci.
Infectious diseases (sepsis, endocarditis) US Medical PG Question 5: A 46-year-old male was found unconscious in the field and brought to the emergency department by EMS. The patient was intubated in transit and given a 2 liter bolus of normal saline. On arrival, the patient's blood pressure is 80/60 mmHg and temperature is 37.5°C. Jugular veins are flat and capillary refill time is 4 seconds.
Vascular parameters are measured and are as follows:
Cardiac index - Low
Pulmonary capillary wedge pressure (PCWP) - Low
Systemic vascular resistance - High
Which of the following is the most likely diagnosis?
- A. Septic shock
- B. Anaphylactic shock
- C. Cardiogenic shock
- D. Hypovolemic shock (Correct Answer)
- E. Neurogenic shock
Infectious diseases (sepsis, endocarditis) Explanation: ***Hypovolemic shock***
- The patient presents with **hypotension**, **flat jugular veins**, **prolonged capillary refill**, and a **low cardiac index** and **low pulmonary capillary wedge pressure (PCWP)**, all indicative of inadequate intravascular volume.
- The **high systemic vascular resistance** is a compensatory mechanism to maintain blood pressure in the setting of decreased circulating volume.
*Septic shock*
- Septic shock typically presents with **vasodilation**, leading to a **low systemic vascular resistance**, which contradicts the findings in this patient.
- While patients can be hypotensive, the vascular parameters, especially SVR, do not align with septic shock.
*Anaphylactic shock*
- This type of shock is characterized by widespread **vasodilation** and increased capillary permeability, leading to a **low systemic vascular resistance** and often significant **edema** or **urticaria**, none of which are suggested here.
- While it can cause hypotension and low PCWP due to fluid shifts, the high SVR makes it less likely.
*Cardiogenic shock*
- Cardiogenic shock is characterized by **pump failure**, leading to a **low cardiac index** but a **high PCWP** due to fluid backup in the pulmonary circulation.
- This directly contrasts the patient's low PCWP.
*Neurogenic shock*
- Neurogenic shock involves a loss of **sympathetic tone**, resulting in widespread **vasodilation** and a **low systemic vascular resistance**, often accompanied by **bradycardia**.
- The high SVR in this patient rules out neurogenic shock.
More Infectious diseases (sepsis, endocarditis) US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
