Section 2: Osteomyelitis and Head & Neck Infections

Question 1

What is the causative organism for rapidly spreading cellulitis and necrotizing fascitis in young healthy patients?

Answer 1

Group A Streptococcus (GAS)

Question 2

Diagnostic Testing for Osteomyelitis

1. Best initial test
2. Best second-line test (if there is high clinical suspicion and x-ray is negative)
3. Most accurate test

Answer 2

1. Plain x-ray
2. MRI
3. Bone biopsy and culture

Question 3

What percent of calcium content of bone is lost before x-ray becomes abnormal?

Answer 3

50%

Question 4

Which of the following is the earliest finding of osteomyelitis on an x-ray?

a. Periosteal elevation
b. Involucrum
c. Sequestrum
d. Punched-out lesions
e. Fracture

Answer 4

A. The earliest finding of osteomyelitis on an x-ray is elevation of the periosteum. Involucrum and sequestrum are terms applied to the formation of abnormal new bone in the periosteum and chunks of bone chipped off from the infection. Punched-out lesions are seen in myeloma, not osteomyelitis. Osteomyelitis does not have an association with fracture

Question 5

A 67-year-old man with diabetes and peripheral arterial disease comes in having had pain in his leg for 2 weeks. There is an ulcer with a draining sinus tract. The x-ray is normal. What is the next best step in determining a diagnosis?

a. Bone scan
b. CT scan
c. MRI
d. ESR
e. Biopsy

Answer 5

The MRI (C) is the next best test to do to determine the diagnosis of osteomyelitis if the x-ray is normal. A bone scan does not have the specificity of an MRI

Question 6

1. Which test has greater sensitivity, the MRI or the bone scan?
2. Which test has greater specificity, the MRI or the bone scan?

Answer 6

1. They are equal in sensitivity. The MRI and bone scan both have an equal ability to exclude osteomyelitis if they are normal
2. MRI

Question 7

How do we know how long to treat if 90 percent of patients have no fever and a normal white cell count?

Answer 7

By following the sedimentation rate.

If the sedimentation rate (ESR) is still markedly elevated after 4– 6 weeks of therapy, further treatment and possible surgical debridement is necessary.

Question 8

1. Which is the most common cause of osteomyelitis?
2. What is the Rx of (1) if sensitive
3. What is the Rx of (1) if resistant
4. What is the duration of Rx

Answer 8

1. Staphylococcus aureus
2. I.V Oxacillin/Nafcillin for 4-6 weeks
3. I.V Vancomycin, linezolid, or daptomycin for 4-6 weeks
4. 4 to 6 weeks

Question 9

1. True or False: To treat osteomyelitis appropriately, a bone biopsy/ culture must be performed
2. Staphylococcus may be treated orally
3. List the gram negative bacilli that commonly cause osteomyelitis
4. True or False: Osteomyelitis from gram negative bacilli may be treated with oral antibiotics

Answer 9

1. True
2. False
3. Salmonella and Pseudomonas
4. True. This is the only form of osteomyelitis that can be successfully and reliably treated with oral antibiotics. – You must confirm it is gram-negative with a bone biopsy. – The organism must be sensitive to antibiotics. – There is no urgency to treating chronic osteomyelitis.