This practice set contains high-yield board review questions covering key concepts in Infection, Pharmacology & VTE. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 121
Topic: Infection, Pharmacology & VTE
A 50-year-old man with poorly controlled diabetes presents with a chronic, non-healing ulcer on the plantar aspect of his foot. Probe-to-bone testing is positive. Which imaging modality is the most specific for confirming osteomyelitis in this setting?
Correct Answer & Explanation
. Magnetic resonance imaging (MRI)
Explanation
MRI is highly sensitive and specific for detecting osteomyelitis, particularly in the diabetic foot. It provides superior anatomical detail and can clearly differentiate between bone infection, marrow edema, and surrounding soft tissue infection.
Question 122
Topic: Infection, Pharmacology & VTE
A 55-year-old man develops acute monoarticular knee pain and profound swelling on postoperative day 3 following a lumbar fusion. Joint aspirate reveals a WBC count of 45,000 cells/mm3 and negatively birefringent needle-shaped crystals. Which medication is most appropriate for the immediate acute management of this joint?
Correct Answer & Explanation
. Indomethacin
Explanation
The aspirate findings are diagnostic of an acute gout flare caused by monosodium urate crystals. NSAIDs like indomethacin, or alternatively colchicine or intra-articular steroids, are first-line treatments for acute flares, whereas allopurinol is reserved for chronic prevention.
Question 123
Topic: Infection, Pharmacology & VTE
An 82-year-old woman falls and sustains a displaced femoral neck fracture. She takes warfarin for atrial fibrillation, and her admission INR is 3.5. Which of the following is the most appropriate agent to reverse her coagulopathy for urgent surgical intervention?
Correct Answer & Explanation
. Prothrombin complex concentrate (PCC)
Explanation
Prothrombin complex concentrate (PCC) provides the most rapid and effective reversal of warfarin-induced coagulopathy. It contains factors II, VII, IX, and X, allowing for prompt normalization of the INR prior to urgent orthopedic surgery.
Question 124
Topic: Infection, Pharmacology & VTE
A 65-year-old man is prescribed rivaroxaban for deep vein thrombosis (DVT) prophylaxis following a total hip arthroplasty. What is the mechanism of action of this medication?
Correct Answer & Explanation
. Direct Factor Xa inhibitor
Explanation
Correct Answer: C. Rivaroxaban is an oral anticoagulant that directly inhibits Factor Xa. Unlike low molecular weight heparins, it does not require antithrombin III for its anticoagulant activity.
Question 125
Topic: Infection, Pharmacology & VTE
A 12-year-old boy with sickle cell disease presents with fever, severe left thigh pain, and a limp. An MRI shows diffuse bone marrow edema with a subperiosteal fluid collection. Blood cultures are drawn. While Staphylococcus aureus is the most common overall cause, which organism is characteristically associated with this specific patient population?
Correct Answer & Explanation
. Salmonella typhimurium
Explanation
Patients with sickle cell disease are particularly susceptible to Salmonella osteomyelitis due to autosplenectomy and impaired macrophage function. However, Staphylococcus aureus still remains the most common overall infecting organism.
Question 126
Topic: Infection, Pharmacology & VTE
A 36-year-old primary schoolteacher who works in a deprived area of London presents with increasing shortness of breath accompanied by sudden-onset, right-sided pleuritic chest pain. She gives a history of influenza for a few days before this acute presentation and also says she suffered a pulmonary embolus 2 years ago while taking the contraceptive pill (and describes her pain as identical to that she experienced on that occasion). On further questioning, it transpires that her mother had suffered from recurrent deep vein thrombosis. Arterial blood gases reveal a pO2 of 7.2 kPa on a non-rebreather mask, with a pCO2 of 3.2 kPa. Her chest X-ray reveals a wedge-shaped area of consolidation affecting her right middle and lower lobes. The white blood cell count is normal. Which diagnosis fits best with this clinical picture?
Correct Answer & Explanation
. Recurrent pulmonary embolism
Explanation
The suspicion, given that this patient has had a previous pulmonary embolism while taking the oral contraceptive pill, is that she has an inherited disorder of clotting (e.g., Factor V Leiden, Protein C or Antithrombin III deficiency). The clinical presentation and history are highly suggestive of a recurrent event.
Question 127
Topic: Infection, Pharmacology & VTE
A 68-year-old woman is recovering on postoperative day 4 following an elective right total hip arthroplasty. She suddenly develops pleuritic chest pain, tachypnea, and a heart rate of 115 bpm. An ECG demonstrates sinus tachycardia with an S1Q3T3 pattern. Which of the following is the most likely diagnosis?
Correct Answer & Explanation
. Pulmonary embolism
Explanation
Sudden onset of dyspnea, pleuritic chest pain, tachycardia, and right heart strain signs on ECG (S1Q3T3) in the postoperative period are highly suspicious for a pulmonary embolism. Deep vein thrombosis and PE are major risks following major lower extremity orthopedic surgery.
Question 128
Topic: Infection, Pharmacology & VTE
A 35-year-old woman presents with a swollen, painful knee of 6 months' duration. Radiographs show juxta-articular osteopenia, peripheral osseous erosions, and gradual joint space narrowing. What do these radiographic findings classically represent?
Correct Answer & Explanation
. Phemister triad of tuberculous arthritis
Explanation
The Phemister triad consists of juxta-articular osteopenia, peripherally located osseous erosions, and gradual narrowing of the joint space. It is the classic radiographic presentation of articular tuberculosis.
Question 129
Topic: Infection, Pharmacology & VTE
A 12-year-old boy with homozygous sickle cell disease presents with high fever and severe localized pain in his left thigh. MRI is highly suggestive of acute osteomyelitis of the femoral diaphysis. While Staphylococcus aureus remains a common pathogen, which of the following organisms is uniquely associated with osteomyelitis in this patient population?
Correct Answer & Explanation
. Salmonella species
Explanation
Patients with sickle cell disease are particularly susceptible to osteomyelitis caused by Salmonella species due to functional asplenia and bowel ischemia. Empiric antibiotic therapy must cover both S. aureus and Salmonella.
Question 130
Topic: Infection, Pharmacology & VTE
A 30-year-old man presents with chronic, insidious monoarthritis of the knee. Radiographs reveal juxta-articular osteopenia, peripheral osseous erosions, and gradual narrowing of the joint space. What is the classic eponym for this radiographic triad?
Correct Answer & Explanation
. Phemister's triad
Explanation
Phemister's triad consists of juxta-articular osteopenia, peripheral osseous erosions, and gradual joint space narrowing. It is a classic radiographic hallmark of tuberculous arthritis.
Question 131
Topic: Infection, Pharmacology & VTE
A 70-year-old man requires a total hip arthroplasty. His past medical history is significant for Heparin-Induced Thrombocytopenia (HIT) diagnosed 2 years ago during a hospital admission. Which of the following is the most appropriate pharmacologic deep vein thrombosis (DVT) prophylaxis for this patient?
Correct Answer & Explanation
. Fondaparinux
Explanation
Fondaparinux is a synthetic pentasaccharide that does not cross-react with HIT antibodies, making it a safe and effective DVT prophylaxis agent for patients with a history of HIT. Both unfractionated and low-molecular-weight heparins are strictly contraindicated.
Question 132
Topic: Infection, Pharmacology & VTE
A 12-year-old boy with sickle cell anemia presents with a 3-day history of high fever, left leg pain, and localized swelling over the proximal tibia. Radiographs show a patchy lucency. While Staphylococcus aureus remains a common cause of osteomyelitis, which organism is characteristically more common in this patient population compared to healthy children?
Correct Answer & Explanation
. Salmonella species
Explanation
Patients with sickle cell disease are functionally asplenic and suffer from repeated bowel ischemia, which allows for bacterial translocation. This makes them uniquely susceptible to osteomyelitis caused by encapsulated organisms, characteristically Salmonella species.
Question 133
Topic: Infection, Pharmacology & VTE
The anatomical dead space can be used to calculate alveolar ventilation by subtracting it from the tidal volume and multiplying the result by the respiratory rate. What would you expect the normal anatomical dead space to be in a healthy adult male?
Correct Answer & Explanation
. 150 ml
Explanation
The normal anatomical dead space is approximately 150 ml. If we take the tidal volume to be about 500 ml and the respiratory rate to be about 15/min, this gives a normal alveolar ventilation of (500 – 150) × 15 = 5250 ml/min. The dead space can be increased in diseases that cause an additional physiological dead space, where parts of the lung do not take part in gas exchange (e.g., pneumonia).
Question 134
Topic: Infection, Pharmacology & VTE
A 35-year-old woman with recently diagnosed primary pulmonary hypertension asks you some questions regarding treatment options. She is awaiting transfer to a specialist centre for right heart catheterisation. Which of the following is true?
Correct Answer & Explanation
. She will benefit from taking long-term anticoagulation with warfarin
Explanation
Correct Answer: C- She will benefit from taking long- term anticoagulation with warfarin Explanation She will benefit from taking long-term anticoagulation with warfarin All patients with primary pulmonary hypertension (PPH, a syndrome of pulmonary hypertension of unknown aetiology) are at risk of thromboembolic disease. Several uncontrolled studies have suggested a survival benefit from anticoagulation, although no randomised controlled trials exist. She will be able to have children, as long as she is carefully monitored She will be able to have children, as long as she is carefully monitored is incorrect. Pregnancy is poorly tolerated in patients with PPH. She will benefit from taking lisinopril She will benefit from taking lisinopril is incorrect. Angiotensin-converting enzyme (ACE) inhibitors have no useful effect in PPH. She will benefit from taking the oral contraceptive pill She will benefit from taking the oral contraceptive pill is incorrect. Oral contraceptives increase the risk of venous thromboembolism, so are not advised; however, contraception is very important in management of PPH due to pregnancy being poorly tolerated. She will benefit from taking verapamil She will benefit from taking verapamil is incorrect. Vasodilator studies are performed in patients with PPH to assess vasodilator response. However, verapamil is not used because it has negatively inotropic effects.
Question 135
Topic: Infection, Pharmacology & VTE
A 65-year-old man complains of lethargy, fever, dry cough, headache, chest pain and increasing shortness of breath. He returned from a cruise 2 days ago. His chest X-ray shows bilateral consolidation and his Po2 is 8.35 kPa. What is the most likely diagnosis?
Correct Answer & Explanation
. Legionella pneumonia
Explanation
Legionella infection is the cause of around 2–5% of cases of community-acquired pneumonia admitted to hospital. The incubation period is usually 2–10 days. Typically, the illness starts fairly abruptly with high fever, shivers, severe headache and muscle pains. A history of a recent hotel holiday or cruise can alert the clinician to the possible diagnosis.
Question 136
Topic: Infection, Pharmacology & VTE
A 5-year-old child presents with a fever of 39°C, inability to bear weight on the left leg, and exquisite tenderness over the proximal tibial metaphysis. MRI confirms acute hematogenous osteomyelitis without an abscess. What is the most appropriate initial management?
Correct Answer & Explanation
. Empiric intravenous antibiotics and observation
Explanation
In pediatric acute hematogenous osteomyelitis without a discrete drainable abscess, empiric intravenous antibiotics are the first-line treatment. Surgery is reserved for cases that fail to respond clinically within 48-72 hours or present with a subperiosteal collection.
Question 137
Topic: Infection, Pharmacology & VTE
A 72-year-old woman is admitted with sudden-onset, left-sided pleuritic chest pain with shortness of breath. She is being treated for asthma, which has been well controlled on a low dose of inhaled corticosteroids and long-acting beta-agonist. She underwent a left hemiarthroplasty 12 days ago and was discharged because she was doing well. Her chest is clear on auscultation. She is tachycardic (132 bpm) and an electrocardiogram shows sinus tachycardia. Her peak expiratory flow rate (PEFR) is 300 l/min (best 400 l/min). Arterial blood gases are as follows: pH 7.34, PaO2 7.6 kPa, PaCO2 3.5 kPa. She is started on oxygen. A chest X-ray is normal. What would be the most appropriate immediate action you as the medical FY2 should take?
Start low-molecular-weight heparin, suspecting pulmonary embolus, and request computed tomographic pulmonary angiography (CTPA). A CTPA is the imaging investigation of choice in this case, after starting low-molecular-weight heparin.
Question 138
Topic: Infection, Pharmacology & VTE
A 24-year-old medical student (height 165 cm, weight 78 kg) has been complaining of a few months' history of shortness of breath on exertion and of coughing up blood once. She is a few days away from her final examinations and smokes 20 cigarettes per day. She takes no medication except for the oral contraceptive pill. Her only past medical history of note is a DVT after a long flight from Australia. What is the most likely diagnosis?
Correct Answer & Explanation
. Pulmonary embolism
Explanation
Correct Answer: C - Pulmonary embolism. Acute pulmonary embolism can present in diverse ways. A syndrome of pleuritic pain or haemoptysis, in the absence of circulatory collapse, is the most frequent mode of presentation. Obesity and a high oestrogen content in oral contraceptives have been linked to thromboembolic events. Most patients with pulmonary embolism were found to have smoked at one time or to be active smokers. Goodpasture syndrome may present with pulmonary haemorrhage, but the duration of symptoms is too long for this diagnosis to be likely. Hyperventilation syndrome does not cause haemoptysis. Sarcoidosis and tuberculosis are less likely given the specific risk factors for thromboembolism (obesity, previous DVT, contraceptive use, and smoking).
Question 139
Topic: Infection, Pharmacology & VTE
A 4-week-old neonate presents with pseudo-paralysis of the right leg and fever. An ultrasound reveals a significant hip effusion. Joint aspiration confirms septic arthritis. Which of the following is the most appropriate empiric antibiotic regimen?
Correct Answer & Explanation
. Vancomycin and Cefotaxime
Explanation
In neonates, common pathogens include S. aureus, Group B Strep, and Gram-negatives. Empiric therapy requires an anti-staphylococcal agent (Vancomycin) and a 3rd-generation cephalosporin (Cefotaxime, avoiding ceftriaxone due to biliary sludging).
Question 140
Topic: Infection, Pharmacology & VTE
A 40-year-old hiker from the northeastern United States presents with monoarticular arthritis of the knee. Joint fluid analysis is negative for crystals but demonstrates a high leukocyte count. Serology is positive for Borrelia burgdorferi. What is the first-line treatment for this stage of the disease?
Correct Answer & Explanation
. Oral doxycycline for 28 days
Explanation
Lyme arthritis is a late manifestation of Lyme disease. The first-line treatment for Lyme arthritis without neurologic involvement is a 28-day course of oral doxycycline or amoxicillin.
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