Bone Infections

Question 1

Categories of osteomyelitis

Answer 1

Hematogenous - Result from seeding of a bone related to a previous bacteremia
Direct implantation - Resulting from penetrating injury
Contiguous - Resulting from direct spread of bacteria from an overlying wound or pressure ulcer
Infection of Prosthetic Device - Resulting from infection of prosthetic material implanted in bone, with spread of organisms into the adjacent bone

Question 2

Commonality of osteomyelitis categoreis by age

Answer 2

Children - Hematogenous more common
Adults - Contigious and prosthetic infections

Question 3

Pathogens by category

Answer 3

• Hematogenous - Staph aureus, Strepto sp., gram-negatives, M. tuberculosis, Salmonella sp. (sickle-cell)
• Direct implantation - Pseudomonas aeruginosa (nail inj. with sneakers)
• Contiguous - S. aureus, gram-negatives, Strepto sp., anaerobes, Candida sp.
• Prosthetic Joint Infections - Coagulase negative staph, S. aureus, gram-negatives, Strep sp.

Question 4

What is the duration of osteomyelitis infections?

Answer 4

Chronic infections

Question 5

Define the following:

Sequestrum
Involocrum
Brodie’s abscesses

Answer 5

• Sequestrum - Dead bone
• Involucrum - External bone formation
• Brodie’s absecces - Localized abscesses

Question 6

Diagnostics for osteomyelitis

Answer 6

X-rays may be negative in early infection, and in fact are not very sensitive for osteomyelitis
Bone/WBC scans or MRI imaging more effective
Bone biopsies or sometimes blood cultures for bacteri

Question 7

Issues with culturing for osteomyelitis

Answer 7

Cultures of open ulcers overlying contigous osteomyelitis are unreliable
Sometimes biopsies cannot be done or the culture results may be negative, forcing empiric treatment

Question 8

Difficulty of prosthetic osteomyelitis

Answer 8

Particularly difficult to treat, especially due to chance of biofilm generation
Prosthesis often needs to be removed for treatment to eradicate infection

Question 9

What are biofilms?
What is special about their arrangement?
How do they compare to planktonic (suspended) organisms?

Answer 9

• Aggregations of microoranisms adhrent to a surface (e.g. bone or prosthetic)
• Embedded in a matrix they produce - slime or extracellular polymeric substance or glycocalyx
• Differences in biochemistry and physiology of biofilm organsm and more resistant to antibiotics

Question 10

Hematogenous Osteomyelitis

Answer 10

Resulting from seeding of bone related to a previous bacteremia.