Bone Infections

Question 1

4 categories of Osteomyelitis

What are each one?

Answer 1

1. Hematogenous-seeding from previous bacteremia
2. Direct implantation- penetrating injuries
3. Continguous- infection spreading from overlying wound/ulcer
4. Prosthetic device- infection of prosthesis that spread to the adjacent bone

Question 2

Which types of osteomyelitis are most common in children?

Which types of osteomyelitis are most common in adults?

Answer 2

Hematogenous is most common in children.

contiguous and prosthetic infections are most common in adults.

Question 3

Hematogenous Osteomyelitis Pathogens (4 +1 general)

Answer 3

Staph aureus, 
Streptococcus sp
Gram negatives
mycobacterium tuberculosis
Salmonella sp. (in sickle cell patients

Question 4

Direct Implantation Osteomyelitis pathogens

Answer 4

psuedomonas aeruginosa (nail injuries with sneakers)

Question 5

Continguous Osteomyelitis pathogens

Answer 5

S. aureus
Streptococcus sp. 
gram negatives
anaerobes
candida sp.

Question 6

Prostetic joint osteomyelitis pathogens

Answer 6

coagulase negative staphlococci
staph aureus
streptococcus sp.
gram negative

Question 7

Common bone abnormalities due to damage to bone (3) in osteomyelitis?

Answer 7

Sequestrum-damage to periosteum resulting in dead bone pieces
Involucrum- new external bone formation
Brodie’s abscesses- localized abscesses

Question 8

General features of osteomyelitis

Answer 8

-difficult to eradicate

Question 9

Osteomyelitis
Diagnostic methods
what methods are not reliable? what does this mean?

Answer 9

• Bone/WBC scans or MRI are effective
• bone biopsies and blood cultures
• early infection may not show on x-ray; but more severe ones will
• cultures of open ulcers is not indicative of underlying bone’s condition
• Therefore empiric treatment may be needed.

Question 10

What is a reason that makes bone infections hard to treat? (2 reasons)

Answer 10

Formation of biofilms–microbes embedded in a self made matrix (Extracellular polymeric substance OR Glycocalyx)
-biofilm bacteria may be more resistant to antibiotics

Question 11

Osteomyelitis

Treatment methods (3)
what is a good abx for biofilms?
-what is the criteria for successful treatment?

Answer 11

• 6 week course of IV abx; or some cases months of oral antibiotics
• surgery to remove sequestra or prostheses
• Rifampin (good for biofilm organisms)
• abx tx is only useful if bone is covered by tissue…otherwise new organisms can continuously invade.