Bone Infections Flashcards

1
Q

Categories of osteomyelitis

A

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

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2
Q

Commonality of osteomyelitis categoreis by age

A

Children - Hematogenous more common
Adults - Contigious and prosthetic infections

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3
Q

Pathogens by category

A
  • 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.
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4
Q

What is the duration of osteomyelitis infections?

A

Chronic infections

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5
Q

Define the following:

Sequestrum
Involocrum
Brodie’s abscesses

A
  • Sequestrum - Dead bone
  • Involucrum - External bone formation
  • Brodie’s absecces - Localized abscesses
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6
Q

Diagnostics for osteomyelitis

A

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

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7
Q

Issues with culturing for osteomyelitis

A

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

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8
Q

Difficulty of prosthetic osteomyelitis

A

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

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9
Q

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

A
  • 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
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10
Q

Hematogenous Osteomyelitis

A

Resulting from seeding of bone related to a previous bacteremia.

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