Osteomyelitis

Question 1

What are the two ways bone can be infected?

Answer 1

Contiguous osteomyelitis (direct extension)
Hematogenous osteomyelitis (seeded by a bacteremia)

Question 2

What are the two clinical presentations of osteomyelitis?

Answer 2

Acute osteomyelitis (cure possible by antimicrobials alone)
Chronic osteomyelitis (refractory to cure by antimicrobials alone)

Question 3

What are two distinct goals of therapy for osteomyelitis?

Answer 3

cure vs suppression

Question 4

Contiguous osteomyelitis is often seen in the context of bone injury and _________

Answer 4

skin ulceration

Question 5

How does diabetes predispose to osteomyelitis

Answer 5

peripheral neuropathy–> soft tissue and bone injury

venous insufficiency–> decreased healing, less able to get antibiotics to the site of wound

Question 6

Differentiate the sites of involvement of hematogenous osteomyelitis in children vs adults

Answer 6

Pediatrics: long bones (different capillary structure around growth plates in children)

Adults: spine, sternoclavicular joint, pubis symphysis

Question 7

What are the most common etiologic agents of osteomyelitis in neonates vs adults

Answer 7

 Neonates: streptococci, S. aureus

 Adults: S. aureus, Gram-negative rods

Question 8

How does host response contribute to the pathology of osteomyelitis?

Answer 8

neutrophilic response–> tissue breakdown
pus in vascular channels–> impedence of bloodflow–> local ischemia–> bone necrosis

= dead bone with thrombosed blood supply

Question 9

Diabetic foot infections that lead to osteomyelitis are often _____

Answer 9

polymicrobial- gram +, gram -, anaerobes

Question 10

______ is the most frequently isolated organism in osteomyelitis

Answer 10

S. aureus

Question 11

Orthopedic devices are associated with osteomyelitis caused by _________

Answer 11

Staph epidermidis, coagulase negative

Question 12

Bites are associated with osteomyelitis caused by ______

Answer 12

streptococci or anaerobes, Pasteurella

Question 13

Nosocomial infections are associated with osteomyelitis caused by ______

Answer 13

enterobacteriacaea

Question 14

Inoculation through the sole of a tennis shoe is associated with osteomyelitis caused by _____

Answer 14

Pseudomonas

also IVDU, malignant otitis externa

Question 15

Sickle cell disease is associated with osteomyelitis caused by _______

Answer 15

Salmonella

Question 16

_______ formation is an external hallmark of osteomyelitis

Answer 16

sinus tract, can spontaneously come and go

Question 17

Acute osteomyelitis is a ______ disease, chronic osteomyelitis is a ______ disease

Answer 17

antibiotic, surgical

Question 18

What lab findings are supportive of a diagnosis of osteomyelitis?

Answer 18

anemia of chronic disease

ESR/ CRP elevated

Question 19

What findings will be seen on plain radiographs in osteomyelitis?

Answer 19

Destruction, periosteal elevation, focal osteopenia

** X rays lag about 2 weeks behind infection, cannot always distinguish from trauma

Question 20

_____ has excellent sensitivity but limited specificity in helping to support a diagnosis of osteomyelitis

Answer 20

MRI

Question 21

CT scans are best for imaging ______ in osteomyelitis

Answer 21

bony sequestra, might need to be surgically removed

Question 22

______ is the gold standard for making a diagnosis of osteomyelitis

Answer 22

bone biopsy

Question 23

Bone biopsy should be done when a patient is off _________ for at least 72 hours

Answer 23

antibiotics

Question 24

Describe the general approach to treating acute osteomyelitis

Answer 24

weeks of IV antibiotics with goal of cure, rarely need surgery

Question 25

Describe the general approach to treating chronic osteomyelitis

Answer 25

surgical debridement is key, followed by mop up antibiotics

goal is suppression, meeting individualized patient needs but not cure

Question 26

It is important to avoid ______ antibiotic therapy in managing osteomyelitis

Answer 26

empiric

Question 27

List some parenteral agents commonly used to treat osteomyelitis

Answer 27

• Nafcillin by continuous infusion (S. aureus)
• Vancomycin (MRSA, coag-negative staph, enterococci)
• Penicillin G by continuous infusion (streptococci)
• Ceftriaxone (streptococci, GNR)
• Cefepime (P. aeruginosa, S. aureus (methicillin-susceptible), mixed)
• Piperacillin/tazobactam by continuous infusion (P. aeruginosa, mixed)

Question 28

List some oral agents commonly used to treat osteomyelitis

Answer 28

• rifampin- never monotherapy
• clindamycin- staph, strep, mixed
• fluoroquinolones- staph, pseudomonas, gram negatives
• TMP/SMX- some MRSA
• minocycline- some MRSA