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Infection, Pharmacology & VTE MCQs

Practice Set 42 of 68

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 821

Topic: Infection, Pharmacology & VTE

In the management of chronic osteomyelitis, which of the following is considered the MOST crucial aspect of surgical intervention?

. Administration of high-dose intravenous antibiotics
. Stabilization of the affected bone with external fixation
. Thorough debridement of all necrotic and infected bone and soft tissue
. Immediate bone grafting to fill defects
. Application of vacuum-assisted wound therapy (VAC)

Correct Answer & Explanation

. Thorough debridement of all necrotic and infected bone and soft tissue

Explanation

The MOST crucial aspect of surgical intervention for chronic osteomyelitis is thorough debridement of all necrotic and infected bone and soft tissue. Without complete removal of the infected and non-viable tissue, antibiotics alone are unlikely to eradicate the infection. While antibiotics, stabilization, and soft tissue management (like VAC) are important adjunctive therapies, debridement is paramount. Bone grafting is typically performed after infection eradication and soft tissue coverage have been achieved.

Question 822

Topic: Infection, Pharmacology & VTE

A 65-year-old male with a history of recurrent gout presents with acute onset severe pain, swelling, and redness in his left knee. Arthrocentesis reveals a cloudy synovial fluid with negatively birefringent, needle-shaped crystals. What is the MOST appropriate initial medical treatment?

. Intra-articular corticosteroid injection
. Systemic antibiotics
. Colchicine and NSAIDs
. Allopurinol
. Surgical debridement

Correct Answer & Explanation

. Colchicine and NSAIDs

Explanation

The presence of negatively birefringent, needle-shaped crystals in the synovial fluid is pathognomonic for gout (monosodium urate crystal arthropathy). The MOST appropriate initial medical treatment for an acute gout flare includes colchicine and NSAIDs (such as indomethacin) to reduce inflammation and pain. Intra-articular corticosteroids can be used as an alternative if NSAIDs/colchicine are contraindicated or ineffective. Allopurinol is a long-term urate-lowering therapy and is typically not initiated during an acute attack. Antibiotics are for septic arthritis.

Question 823

Topic: Infection, Pharmacology & VTE

What is the most common organism responsible for acute hematogenous osteomyelitis in otherwise healthy children?

. Escherichia coli
. Pseudomonas aeruginosa
. Staphylococcus aureus
. Streptococcus pyogenes
. Kingella kingae

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Staphylococcus aureus is the most common causative organism for acute hematogenous osteomyelitis in all age groups, including otherwise healthy children. While Kingella kingae is an increasingly recognized pathogen in younger children (under 3 years old), S. aureus remains overall the predominant cause. E. coli and Pseudomonas are more common in neonates, immunocompromised individuals, or following puncture wounds (e.g., through a shoe). Streptococcus pyogenes is less common.

Question 824

Topic: Infection, Pharmacology & VTE

In the context of surgical site infection (SSI) prophylaxis, what is the generally accepted optimal timing for administering intravenous antibiotics prior to incision?

. Within 2 hours before incision
. Immediately at the time of incision
. After the incision but before wound closure
. Within 60 minutes before incision
. Postoperatively, for 24 hours

Correct Answer & Explanation

. Within 60 minutes before incision

Explanation

For most surgical procedures, intravenous prophylactic antibiotics should be administered within 60 minutes prior to the surgical incision to ensure adequate tissue concentration at the time of potential contamination. For certain antibiotics (e.g., vancomycin or fluoroquinolones) with longer infusion times, administration may begin up to 120 minutes prior. Administering too early can reduce efficacy, and too late can miss the critical window of contamination. Postoperative continuation beyond 24 hours is generally not recommended for prophylaxis in clean or clean-contaminated cases.

Question 825

Topic: Infection, Pharmacology & VTE

In a patient presenting with suspected septic arthritis of the knee, arthrocentesis is performed. An intra-articular pressure measurement of 45 mmHg is recorded. What is the primary clinical significance of this elevated pressure in the context of septic arthritis?

. It confirms the presence of gram-positive bacteria.
. It indicates increased systemic inflammatory response.
. It signifies increased risk of articular cartilage destruction due to ischemia.
. It suggests a co-existing meniscal tear.
. It is a normal finding in an inflamed joint.

Correct Answer & Explanation

. It signifies increased risk of articular cartilage destruction due to ischemia.

Explanation

Elevated intra-articular pressure, particularly when it exceeds the capillary perfusion pressure (typically around 20-30 mmHg), can lead to ischemia and subsequent necrosis of the articular cartilage. This is a critical mechanism of cartilage destruction in septic arthritis, in addition to enzymatic degradation by bacterial and host enzymes. Prompt decompression (e.g., via aspiration or surgical drainage) is essential to reduce intra-articular pressure and preserve cartilage viability. The pressure itself does not confirm bacterial type, systemic inflammation, or meniscal tears, and it is not a normal finding.

Question 826

Topic: Infection, Pharmacology & VTE

A patient is undergoing open reduction and internal fixation of a distal tibia fracture. The surgeon opts for a sequential compression device (SCD) on the contralateral leg. What is the primary 'pressure-related' benefit of this device?

. To prevent compartment syndrome in the non-operative leg.
. To reduce pain in the non-operative leg.
. To increase arterial blood flow to the non-operative leg.
. To augment venous return and prevent deep vein thrombosis (DVT).
. To measure intracompartmental pressures in the non-operative leg.

Correct Answer & Explanation

. To augment venous return and prevent deep vein thrombosis (DVT).

Explanation

Sequential compression devices (SCDs) work by cyclically inflating and deflating air chambers around the limb, applying external pressure. This intermittent compression helps to milk venous blood proximally, thereby augmenting venous return and preventing venous stasis, which is a major risk factor for deep vein thrombosis (DVT) formation. While they might have minor effects on other parameters, their primary pressure-related benefit is DVT prophylaxis.

Question 827

Topic: Infection, Pharmacology & VTE

What is the physiological basis for using a graduated compression stocking (GCS) in preventing deep vein thrombosis (DVT) in orthopedic patients?

. To increase arterial blood pressure in the lower extremities.
. To apply uniform pressure along the limb, preventing venous stasis.
. To provide maximal compression distally and progressively less compression proximally, augmenting venous return.
. To reduce systemic inflammatory response.
. To inhibit platelet aggregation.

Correct Answer & Explanation

. To provide maximal compression distally and progressively less compression proximally, augmenting venous return.

Explanation

Graduated compression stockings (GCS) are designed to apply maximal pressure at the ankle and progressively decreasing pressure proximally up the leg. This pressure gradient helps to compress superficial veins, decrease venous distention, and augment venous return toward the heart, thereby reducing venous stasis, a key component of Virchow's triad for DVT formation. They do not increase arterial blood pressure, apply uniform pressure, or inhibit platelet aggregation.

Question 828

Topic: Infection, Pharmacology & VTE

An 80-year-old female with a non-displaced wrist fracture is prescribed NSAIDs for pain. She has a history of hypertension controlled with Lisinopril and a baseline creatinine of 1.2 mg/dL. What is the most significant concern regarding NSAID use in this patient related to her blood pressure and renal function?

. Increased risk of hyperkalemia
. Decreased efficacy of Lisinopril and potential for worsening hypertension
. Increased risk of hyponatremia
. Development of nephrogenic diabetes insipidus
. Acute liver injury

Correct Answer & Explanation

. Decreased efficacy of Lisinopril and potential for worsening hypertension

Explanation

NSAIDs can antagonize the antihypertensive effects of ACE inhibitors like Lisinopril by inhibiting prostaglandin synthesis, which otherwise mediates renal vasodilation and contributes to blood pressure control. This can lead to worsening hypertension. Furthermore, NSAIDs can cause acute kidney injury, particularly in elderly patients with pre-existing renal compromise or those on ACE inhibitors, by reducing renal blood flow. They also increase the risk of hyperkalemia when combined with ACE inhibitors. While hyperkalemia is a concern, the question specifically asks about blood pressure and renal function, where the blunting of antihypertensive effect and risk of AKI are prominent. Hyponatremia, diabetes insipidus, and liver injury are less direct or common concerns in this context.

Question 829

Topic: Infection, Pharmacology & VTE

A 30-year-old male with an open calcaneus fracture develops fever (39°C), rash, and eosinophilia post-operatively. He has been receiving IV antibiotics (e.g., cefazolin) and NSAIDs for pain. His serum creatinine rises from 1.0 to 3.0 mg/dL and his urine studies show white blood cells and eosinophils. What is the most likely cause of his acute kidney injury?

. Acute tubular necrosis (ATN)
. Pre-renal azotemia
. Acute interstitial nephritis (AIN)
. Post-renal obstruction
. Hepatorenal syndrome

Correct Answer & Explanation

. Acute interstitial nephritis (AIN)

Explanation

The clinical picture of fever, rash, eosinophilia, and acute kidney injury with eosinophiluria is highly suggestive of Acute Interstitial Nephritis (AIN), a hypersensitivity reaction often triggered by medications like antibiotics (beta-lactams, sulfonamides), NSAIDs, or proton pump inhibitors. While ATN and pre-renal azotemia are common causes of AKI, the systemic allergic features point away from them. Post-renal obstruction would have different signs and symptoms. Hepatorenal syndrome is seen in advanced liver disease. AIN requires withdrawal of the offending agent and sometimes corticosteroids.

Question 830

Topic: Infection, Pharmacology & VTE

A 70-year-old male with a history of long-standing diabetes presents with a non-healing foot ulcer requiring debridement and partial amputation. His baseline creatinine is 1.5 mg/dL. He is started on vancomycin and piperacillin/tazobactam. On post-operative day 3, his creatinine rises to 2.8 mg/dL. His urine output is adequate. What is the most likely cause of his acute kidney injury?

. Pre-renal azotemia due to dehydration
. Acute tubular necrosis (ATN) from nephrotoxic antibiotics
. Acute interstitial nephritis (AIN) from antibiotics
. Rhabdomyolysis
. Cholesterol emboli

Correct Answer & Explanation

. Acute tubular necrosis (ATN) from nephrotoxic antibiotics

Explanation

This patient has multiple risk factors for acute kidney injury: advanced age, diabetes, pre-existing renal insufficiency, and exposure to nephrotoxic antibiotics (vancomycin and piperacillin/tazobactam, particularly the combination). While AIN is possible with antibiotics, ATN is a more common form of drug-induced AKI, especially with direct nephrotoxins like vancomycin. Pre-renal azotemia is less likely given adequate urine output. Rhabdomyolysis and cholesterol emboli would have other clinical features not mentioned. The combination of nephrotoxic drugs and risk factors points strongly to ATN.

Question 831

Topic: Infection, Pharmacology & VTE

A 68-year-old female with a femoral neck fracture is undergoing hemiarthroplasty. She has a history of atrial fibrillation on warfarin. Her INR is 2.5 pre-operatively. What is the most appropriate management of her anticoagulation?

. Proceed with surgery as INR 2.5 is acceptable for orthopedic surgery
. Administer 10 mg Vitamin K intravenously
. Administer Fresh Frozen Plasma (FFP) to normalize INR
. Delay surgery and continue warfarin for 3-5 days
. Administer Protamine Sulfate

Correct Answer & Explanation

. Administer Fresh Frozen Plasma (FFP) to normalize INR

Explanation

For emergent orthopedic surgery like a hip fracture repair in a patient on warfarin, an INR of 2.5 is too high and increases the risk of significant perioperative bleeding. The most rapid and effective way to reverse warfarin is to administer Fresh Frozen Plasma (FFP), which contains all clotting factors. Vitamin K works more slowly (6-24 hours). Delaying surgery is associated with increased morbidity and mortality for hip fractures. Protamine sulfate reverses heparin, not warfarin. An INR of 2.5 is generally not acceptable for major orthopedic surgery.

Question 832

Topic: Infection, Pharmacology & VTE

A 60-year-old male undergoing a posterior spinal fusion is placed in the prone position. During the procedure, the anesthesiologist notes a sudden drop in blood pressure and a gradual increase in central venous pressure (CVP). The surgical field appears venous and engorged. What is the most likely cause of these hemodynamic changes?

. Cardiac tamponade
. Pulmonary embolism
. Inferior vena cava (IVC) compression
. Anaphylaxis
. Massive hemorrhage

Correct Answer & Explanation

. Inferior vena cava (IVC) compression

Explanation

In the prone position, especially on an inadequately padded or positioned frame, compression of the inferior vena cava (IVC) by the abdominal contents can occur. This leads to reduced venous return to the heart, causing hypotension. The increased CVP reflects the back-pressure from the obstructed venous flow. A venous, engorged surgical field is also consistent with impaired venous drainage. Cardiac tamponade and pulmonary embolism would also cause hypotension and increased CVP but are less directly related to prone positioning itself. Anaphylaxis would have other systemic signs. Massive hemorrhage would typically cause a decrease in CVP unless the hemorrhage was into a confined space or a massive compensatory fluid load was given.

Question 833

Topic: Infection, Pharmacology & VTE

A 60-year-old male presents with sudden, excruciating pain in his left knee, accompanied by erythema, swelling, and warmth. He has a history of hypertension and hyperuricemia but has never had a prior attack like this. Aspiration of the knee joint reveals negatively birefringent needle-shaped crystals under polarized light microscopy. What is the most appropriate acute management?

. Intra-articular corticosteroid injection.
. Systemic antibiotics.
. NSAIDs, colchicine, or systemic corticosteroids.
. Joint lavage and debridement.
. Allopurinol.

Correct Answer & Explanation

. NSAIDs, colchicine, or systemic corticosteroids.

Explanation

The clinical presentation (acute, excruciating monoarticular arthritis with erythema, swelling, warmth) and the finding of negatively birefringent needle-shaped crystals on joint fluid analysis are diagnostic of acute gouty arthritis. The most appropriate acute management involves NSAIDs (e.g., indomethacin), colchicine, or systemic corticosteroids. Intra-articular corticosteroid injection is an alternative for monoarticular attacks if systemic agents are contraindicated or ineffective. Systemic antibiotics are for septic arthritis (which is in the differential but ruled out by crystal analysis and lack of bacteria). Joint lavage and debridement are for septic arthritis. Allopurinol is a uric acid-lowering therapy used for long-term prevention of gout attacks, not for acute attack management (and can sometimes worsen acute attacks if initiated during one).

Question 834

Topic: Infection, Pharmacology & VTE

Which organism is the most common causative agent of acute hematogenous osteomyelitis in healthy children?

. Pseudomonas aeruginosa.
. Staphylococcus aureus.
. Streptococcus pyogenes.
. Kingella kingae.
. Escherichia coli.

Correct Answer & Explanation

. Staphylococcus aureus.

Explanation

Staphylococcus aureus is by far the most common causative organism of acute hematogenous osteomyelitis in healthy children across all age groups. While other organisms can cause osteomyelitis (e.g., Kingella kingae in infants/toddlers, Pseudomonas in puncture wounds through athletic shoes, E. coli in neonates or immunocompromised), S. aureus remains predominant in the general pediatric population.

Question 835

Topic: Infection, Pharmacology & VTE

A 4-year-old child presents with a limp, fever, and refusal to bear weight on the left leg. On examination, the left hip is held in flexion, abduction, and external rotation. Passive range of motion is severely painful, especially internal rotation. Blood tests show a WBC count of 75,000 cells/µL, 90% neutrophils, and positive Gram stain for Gram-positive cocci in clusters. What is the most appropriate management?

. Immediate intravenous antibiotics and observation.
. Aspiration, culture, and non-weight bearing.
. Urgent surgical irrigation and debridement of the knee.
. Intra-articular corticosteroid injection.
. Arthroscopy with synovectomy.

Correct Answer & Explanation

. Urgent surgical irrigation and debridement of the knee.

Explanation

This is a clear case of septic arthritis of the knee, an orthopedic emergency in children. The presentation (limp, fever, swollen/warm/painful joint), and particularly the synovial fluid analysis (high WBC count, high neutrophils, positive Gram stain) confirms the diagnosis. Urgent surgical irrigation and debridement (arthrotomy or arthroscopy) of the knee is the most appropriate management to remove purulent material, reduce bacterial load, and prevent cartilage destruction. This should be combined with intravenous antibiotics. While aspiration is part of diagnosis, surgical washout is definitive for septic arthritis of a large joint. Immediate IV antibiotics alone without surgical debridement are insufficient to treat severe septic arthritis. Corticosteroid injection is contraindicated. Synovectomy is not the primary goal; debridement and irrigation are.

Question 836

Topic: Infection, Pharmacology & VTE

Which of the following is the most common cause of non-traumatic amputation in adults globally?

. Trauma.
. Malignancy (e.g., osteosarcoma).
. Peripheral vascular disease and diabetes.
. Chronic osteomyelitis.
. Neurological disorders (e.g., severe spasticity).

Correct Answer & Explanation

. Peripheral vascular disease and diabetes.

Explanation

Globally, peripheral vascular disease (PVD) and diabetes mellitus are by far the most common causes of non-traumatic amputations in adults. These conditions lead to critical limb ischemia, diabetic foot ulcers, and infection, ultimately necessitating amputation. While trauma is a significant cause of amputation, it is typically traumatic. Malignancy, chronic osteomyelitis, and neurological disorders also lead to amputation but are less common than PVD/diabetes combined.

Question 837

Topic: Infection, Pharmacology & VTE

A 3-year-old child presents with a limp, fever, and refusal to bear weight on the left leg. On examination, the left hip is held in flexion, abduction, and external rotation. Passive range of motion is severely painful, especially internal rotation. Blood tests show cloudy fluid with a WBC count of 75,000 cells/µL, 90% neutrophils, and positive Gram stain for Gram-positive cocci in clusters. What is the most appropriate management?

. Immediate intravenous antibiotics and observation.
. Aspiration, culture, and non-weight bearing.
. Urgent surgical irrigation and debridement of the knee.
. Intra-articular corticosteroid injection.
. Arthroscopy with synovectomy.

Correct Answer & Explanation

. Urgent surgical irrigation and debridement of the knee.

Explanation

This is a clear case of septic arthritis of the knee, an orthopedic emergency in children. The presentation (limp, fever, swollen/warm/painful joint), and particularly the synovial fluid analysis (high WBC count, high neutrophils, positive Gram stain) confirms the diagnosis. Urgent surgical irrigation and debridement (arthrotomy or arthroscopy) of the knee is the most appropriate management to remove purulent material, reduce bacterial load, and prevent cartilage destruction. This should be combined with intravenous antibiotics. While aspiration is part of diagnosis, surgical washout is definitive for septic arthritis of a large joint. Immediate IV antibiotics alone without surgical debridement are insufficient to treat severe septic arthritis. Corticosteroid injection is contraindicated. Synovectomy is not the primary goal; debridement and irrigation are.

Question 838

Topic: Infection, Pharmacology & VTE

Which of the following is a common orthopedic manifestation of renal osteodystrophy in a patient with chronic kidney disease?

. Gouty arthritis.
. Pseudogout.
. Osteomalacia and adynamic bone disease.
. Rheumatoid arthritis.
. Septic arthritis.

Correct Answer & Explanation

. Osteomalacia and adynamic bone disease.

Explanation

Renal osteodystrophy is a complex bone disease that occurs in patients with chronic kidney disease (CKD). It encompasses several bone disorders, including osteomalacia (impaired mineralization), secondary hyperparathyroidism (high bone turnover), and adynamic bone disease (low bone turnover). These conditions lead to bone pain, fractures, and muscle weakness. Gout, pseudogout, rheumatoid arthritis, and septic arthritis are not primary orthopedic manifestations of renal osteodystrophy, although patients with CKD may suffer from them independently. Among the choices, osteomalacia and adynamic bone disease are direct components of renal osteodystrophy.

Question 839

Topic: Infection, Pharmacology & VTE
A 4-year-old child presents with a limp, fever, and refusal to bear weight. X-rays are normal. MRI shows fluid in the hip joint and a small lesion in the adjacent ilium. Labs show elevated CRP and ESR. Urine culture is positive for E. coli. What is the most likely diagnosis?
. Transient synovitis.
. Legg-Calvé-Perthes disease.
. Septic arthritis of the hip.
. Osteomyelitis of the ilium with reactive effusion.
. Juvenile idiopathic arthritis.

Correct Answer & Explanation

. Osteomyelitis of the ilium with reactive effusion.

Explanation

Given the child's fever, limp, refusal to bear weight, elevated inflammatory markers, and a positive urine culture, the presence of a lesion in the ilium along with joint fluid points strongly to osteomyelitis of the ilium with a sympathetic (reactive) effusion in the hip joint. Hematogenous spread from the urinary tract (E. coli UTI) is a common source for osteomyelitis in children. While septic arthritis of the hip is also a possibility, the specific mention of a lesion in the ilium makes osteomyelitis a more fitting primary diagnosis, with the joint effusion being reactive. Transient synovitis typically has normal labs. Legg-Calvé-Perthes disease is avascular necrosis, and JIA is a chronic inflammatory arthritis, neither of which presents acutely with fever and positive cultures like this.

Question 840

Topic: Infection, Pharmacology & VTE
Which of the following statements regarding the management of pressure ulcers in a patient with a T10 complete spinal cord injury is most accurate from an orthopedic perspective?
. Surgical debridement and closure is always the primary treatment for deep pressure ulcers.
. Routine repositioning and specialized mattresses are sufficient for prevention and early stage ulcers.
. Osteomyelitis of underlying bone is a common and serious complication of chronic pressure ulcers.
. Topical antibiotics are the most effective treatment for deep pressure ulcers.
. All pressure ulcers require a full-thickness skin graft for definitive closure.

Correct Answer & Explanation

. Osteomyelitis of underlying bone is a common and serious complication of chronic pressure ulcers.

Explanation

For patients with SCI, chronic deep pressure ulcers (Stage III and IV) frequently involve the underlying bone, leading to osteomyelitis. This is a very common and serious complication that can result in systemic sepsis and requires aggressive management, often including surgical debridement of infected bone and long-term antibiotics. While repositioning and specialized mattresses are crucial for prevention and early stage ulcers, and surgical debridement/closure is often needed for deep ulcers, the orthopedic relevance lies particularly in the high risk of underlying osteomyelitis. Topical antibiotics alone are insufficient for deep ulcers with potential osteomyelitis. Not all ulcers require skin grafts; flaps are often used for deeper wounds.

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