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Infection, Pharmacology & VTE MCQs

Practice Set 2 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 21

Topic: Infection, Pharmacology & VTE

Which of the following clinical examination findings is most characteristic of a psoas abscess developing as a complication of lumbar vertebral osteomyelitis?

. Pain exacerbated by passive hip flexion
. Pain exacerbated by passive hip extension
. Pain exacerbated by internal rotation of the hip
. A positive straight leg raise test radiating to the foot
. Diminished patellar deep tendon reflex

Correct Answer & Explanation

. Pain exacerbated by passive hip extension

Explanation

A psoas abscess causes inflammation of the psoas muscle, leading to a flexion contracture of the hip. Passive extension of the hip stretches the inflamed muscle, eliciting severe pain (a positive psoas sign).

Question 22

Topic: Infection, Pharmacology & VTE

Which of the following laboratory markers is considered the most sensitive and useful for monitoring the clinical response to antibiotic therapy in a patient being treated for pyogenic vertebral osteomyelitis?

. White blood cell (WBC) count
. Erythrocyte sedimentation rate (ESR)
. C-reactive protein (CRP)
. Procalcitonin
. Serial blood cultures

Correct Answer & Explanation

. C-reactive protein (CRP)

Explanation

C-reactive protein (CRP) is the most reliable marker for tracking treatment response in spinal infections as it normalizes much faster than ESR following successful eradication of the infection.

Question 23

Topic: Infection, Pharmacology & VTE

A 12-year-old boy with a known history of sickle cell anemia develops pyogenic vertebral osteomyelitis. While Staphylococcus aureus remains the most common overall cause, which of the following organisms is classically associated with this patient's underlying condition?

. Klebsiella pneumoniae
. Pseudomonas aeruginosa
. Salmonella species
. Escherichia coli
. Proteus mirabilis

Correct Answer & Explanation

. Salmonella species

Explanation

Patients with sickle cell disease have a uniquely higher risk of osteomyelitis caused by Salmonella species, largely due to functional asplenia and bowel wall ischemia allowing bacterial translocation.

Question 24

Topic: Infection, Pharmacology & VTE

Which of the following represents an absolute indication for surgical intervention in a patient with pyogenic vertebral osteomyelitis?

. An ESR persistently elevated greater than 100 mm/hr
. Persistently positive blood cultures despite 2 weeks of antibiotics
. Development of a progressive neurologic deficit
. Severe localized back pain refractory to NSAIDs
. MRI evidence of extensive disc space enhancement

Correct Answer & Explanation

. Development of a progressive neurologic deficit

Explanation

Absolute indications for surgery in spinal infections include a progressive neurologic deficit, spinal instability, significant deformity, or failure of medical management (clinical deterioration despite appropriate antibiotics).

Question 25

Topic: Infection, Pharmacology & VTE

The "Pons sign," characterized by a step-like anterior erosion of the vertebral body seen on plain lateral radiographs or CT, is a classical finding highly suggestive of which infectious process?

. Tuberculosis
. Pyogenic osteomyelitis
. Spinal Brucellosis
. Fungal osteomyelitis
. Chordoma

Correct Answer & Explanation

. Spinal Brucellosis

Explanation

The Pons sign refers to an anterior step-like defect or focal erosion of the superior or inferior anterior vertebral endplate. It is a hallmark radiographic feature of spinal brucellosis.

Question 26

Topic: Infection, Pharmacology & VTE

To minimize the risk of postoperative wound infection, prophylactic intravenous antibiotics for a routine, clean lumbar microdiscectomy should ideally be administered:

. 2 hours before induction of anesthesia
. Within 60 minutes prior to surgical incision
. Immediately at the time of skin closure
. 24 hours postoperatively as a single dose
. 30 minutes after surgical incision

Correct Answer & Explanation

. Within 60 minutes prior to surgical incision

Explanation

Current guidelines strictly recommend that prophylactic antibiotics (such as cefazolin) be administered within 60 minutes prior to surgical incision to ensure optimal tissue and serum bactericidal concentrations during the procedure.

Question 27

Topic: Infection, Pharmacology & VTE

A 45-year-old undergoes a microdiscectomy. Four weeks later, he presents with severe, excruciating back pain and paraspinal spasms. Inflammatory markers are significantly elevated. What is the most appropriate next step in management?

. Immediate surgical debridement
. MRI of the lumbar spine with and without contrast
. CT-guided biopsy followed by 6 weeks of IV antibiotics
. Empiric initiation of vancomycin and ceftriaxone
. Prescription of NSAIDs and physical therapy

Correct Answer & Explanation

. MRI of the lumbar spine with and without contrast

Explanation

The clinical presentation is highly suspicious for postoperative discitis. Gadolinium-enhanced MRI is the diagnostic imaging modality of choice to confirm the diagnosis and assess the extent of infection before any intervention.

Question 28

Topic: Infection, Pharmacology & VTE

In differentiating tuberculous spondylitis from pyogenic vertebral osteomyelitis on MRI, which of the following is most characteristic of tuberculosis?

. Early destruction of the intervertebral disc
. Relative sparing of the intervertebral disc until late in the disease
. Strictly solitary vertebral body involvement
. Sclerotic reactive bone formation early in the disease process
. Absence of paraspinal soft tissue extension

Correct Answer & Explanation

. Relative sparing of the intervertebral disc until late in the disease

Explanation

Tuberculous spondylitis typically involves the anterior-inferior aspect of the vertebral body and spreads subligamentously, sparing the intervertebral disc until late. Pyogenic infections typically originate in the endplates and rapidly destroy the adjacent disc.

Question 29

Topic: Infection, Pharmacology & VTE

What is the primary arterial route of hematogenous spread of pyogenic infection to the adult vertebral body?

. Direct extension from Batson venous plexus
. Nutrient arterioles originating from the segmental artery
. Anastomotic channels of the posterior longitudinal ligament
. Retrograde flow through the basivertebral vein
. Lymphatic spread via the thoracic duct

Correct Answer & Explanation

. Nutrient arterioles originating from the segmental artery

Explanation

Hematogenous spread of pyogenic vertebral osteomyelitis typically occurs via the arterial route in adults. Bacteria lodge in the rich vascular supply of the subchondral bone adjacent to the vertebral endplates, supplied by nutrient branches of the segmental arteries.

Question 30

Topic: Infection, Pharmacology & VTE

A 60-year-old man with confirmed pyogenic vertebral osteomyelitis has been on appropriate intravenous antibiotics for 4 weeks. His CRP has normalized, but he complains of persistent severe back pain and radiographs show progressive local kyphosis of 25 degrees. What is the most appropriate management?

. Switch to oral antibiotics and provide a thoracolumbosacral orthosis (TLSO)
. Continue intravenous antibiotics for an additional 6 weeks
. Perform a CT-guided repeat biopsy
. Posterior laminectomy alone for decompression
. Anterior debridement, strut grafting, and stabilization

Correct Answer & Explanation

. Anterior debridement, strut grafting, and stabilization

Explanation

Indications for surgical intervention in vertebral osteomyelitis include progressive deformity, neurologic deficit, or failure of medical management. Anterior debridement and reconstruction is indicated to correct progressive kyphotic deformity and stabilize the spine.

Question 31

Topic: Infection, Pharmacology & VTE

For a hemodynamically stable patient with native pyogenic vertebral osteomyelitis successfully treated with targeted intravenous antibiotics and demonstrating a good clinical and laboratory response, what is the IDSA recommended total duration of antimicrobial therapy?

. 2 weeks
. 4 weeks
. 6 weeks
. 12 weeks
. 6 months

Correct Answer & Explanation

. 6 weeks

Explanation

The Infectious Diseases Society of America (IDSA) guidelines recommend a total of 6 weeks of targeted antimicrobial therapy (intravenous or highly bioavailable oral agents) for most cases of native vertebral osteomyelitis without extensive complications.

Question 32

Topic: Infection, Pharmacology & VTE

A 65-year-old male presents with severe back pain and elevated ESR 3 weeks after an uncomplicated microdiscectomy. MRI shows fluid in the disc space with endplate edema. What is the most appropriate initial management step prior to starting antibiotics?

. Empiric IV Vancomycin
. CT-guided aspiration of the disc space
. Open debridement and fusion
. Oral broad-spectrum antibiotics
. Repeat MRI with contrast in 2 weeks

Correct Answer & Explanation

. CT-guided aspiration of the disc space

Explanation

In suspected post-operative discitis, a tissue diagnosis is critical before initiating antibiotics. CT-guided aspiration provides the best yield for targeted therapy.

Question 33

Topic: Infection, Pharmacology & VTE

A patient with pyogenic vertebral osteomyelitis presents with progressive bilateral lower extremity weakness and bowel incontinence. What is the most appropriate next step in management?

. Increase the dose of IV antibiotics
. Start high-dose IV corticosteroids
. Emergent surgical decompression and stabilization
. CT-guided biopsy of the epidural space
. Bracing with a thoracolumbosacral orthosis

Correct Answer & Explanation

. Emergent surgical decompression and stabilization

Explanation

Progressive neurological deficit in the setting of spinal infection is an absolute indication for emergent surgical decompression and stabilization.

Question 34

Topic: Infection, Pharmacology & VTE

When comparing tuberculous spondylitis (Pott's disease) to pyogenic vertebral osteomyelitis on MRI, which of the following features is most characteristic of tuberculosis?

. Early and severe intervertebral disc destruction
. Absence of a paraspinal soft tissue mass
. Relative preservation of the intervertebral disc until late in the disease
. Preferential involvement of the posterior elements only
. Sclerotic changes visible within 48 hours of infection

Correct Answer & Explanation

. Relative preservation of the intervertebral disc until late in the disease

Explanation

Unlike pyogenic infections which produce proteolytic enzymes destroying the disc early, TB lacks these enzymes. This leads to relative preservation of the disc space and larger paraspinal abscesses in TB.

Question 35

Topic: Infection, Pharmacology & VTE

Review the clinical image. A 55-year-old diabetic male presents with insidious onset back pain and night sweats. MRI reveals endplate destruction and disc space enhancement.

Which laboratory marker is most useful for monitoring the resolution of this condition during antibiotic treatment?

. White blood cell count (WBC)
. Erythrocyte sedimentation rate (ESR)
. C-reactive protein (CRP)
. Procalcitonin
. Alkaline phosphatase

Correct Answer & Explanation

. C-reactive protein (CRP)

Explanation

CRP normalizes much faster than ESR following successful treatment of vertebral osteomyelitis, making it the preferred and most sensitive marker for monitoring treatment response.

Question 36

Topic: Infection, Pharmacology & VTE

What is the recommended duration of intravenous (or highly bioavailable oral) antibiotic therapy for uncomplicated pyogenic vertebral osteomyelitis?

. 1 to 2 weeks
. 3 to 4 weeks
. 6 to 8 weeks
. 12 to 16 weeks
. 6 months

Correct Answer & Explanation

. 6 to 8 weeks

Explanation

Uncomplicated pyogenic vertebral osteomyelitis is typically treated with 6 weeks of targeted antimicrobial therapy. Shorter courses are associated with higher recurrence rates.

Question 37

Topic: Infection, Pharmacology & VTE

A 70-year-old man on chronic hemodialysis presents with severe back pain. MRI shows discitis at L3-L4. Blood cultures grow methicillin-resistant Staphylococcus aureus (MRSA). He is treated with IV vancomycin. What is the most important factor in determining the appropriate dosing of his antibiotic therapy?

. The patient's erythrocyte sedimentation rate
. Trough serum vancomycin levels
. The size of the epidural phlegmon on MRI
. Peak serum vancomycin levels
. The severity of his back pain

Correct Answer & Explanation

. Trough serum vancomycin levels

Explanation

Vancomycin efficacy and toxicity correlate closely with trough levels. In a hemodialysis patient, meticulous monitoring of trough levels is crucial to ensure therapeutic dosing and avoid toxicity.

Question 38

Topic: Infection, Pharmacology & VTE

Which of the following patient populations is most at risk for developing fungal vertebral osteomyelitis, particularly with Aspergillus species?

. Healthy pediatric patients
. Patients with isolated trauma
. Severely immunocompromised patients (e.g., prolonged neutropenia)
. Pregnant females in their third trimester
. Patients with a history of recurrent urinary tract infections

Correct Answer & Explanation

. Severely immunocompromised patients (e.g., prolonged neutropenia)

Explanation

Fungal vertebral osteomyelitis, particularly from Aspergillus, is rare and typically seen in severely immunocompromised hosts, such as those with prolonged neutropenia or solid organ transplants.

Question 39

Topic: Infection, Pharmacology & VTE

Which of the following describes the magnetic resonance image (MRI) appearance of vertebral osteomyelitis:

. Increased signal onT1 images, decreased on T2 images
. Decreased signal onT1 images, decreased on T2 images
. Decreased signal onT1 images, increased on T2 images
. Increased signal onT1 images, increased on T2 images
. MRI is usually unable to detect vertebral osteomyelitis

Correct Answer & Explanation

. Decreased signal onT1 images, increased on T2 images

Explanation

Magnetic resonance image (MRI) carries a 95% accuracy rate. Infected disk and vertebral bone appear on MRI with decreased signal onT1 images and increased signal on T2 images. Gadoliniun enhancement is useful in differentiating spinal infection or abscess from epidural scar in the postoperative setting.

Question 40

Topic: Infection, Pharmacology & VTE

Antibiotic treatment for spinal tuberculosis includes all of the following except:

. Isoniazid
. Ethambutol
. Pyrazinamide
. Rifampin
. C efotaxime

Correct Answer & Explanation

. C efotaxime

Explanation

A four-drug regimen against spinal tuberculosis is recommended because of the high prevalence of organism resistance. Cefotaxime is a cephalosporin not active against mycobacterial infection.

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