osteomyelitis: micro

Question 1

most common cause in adults (general… not micro)

Answer 1

direct spread from soft tissue infection

Question 2

most common cause in children (general… not micro)

Answer 2

hematongenous seeding to metaphases of long bones

Question 3

most common cause in IV drug users (general… not micro)

Answer 3

hematogenous seeding to vertebral bodies

Question 4

if no risk factors

Answer 4

staph aureus

Question 5

if IV drug user

Answer 5

staph aureus

pseudomonas

Question 6

if sickle cell disease

Answer 6

Staph aureus is most common

salmonella is second most common

Question 7

if hip replacement

Answer 7

staph epidermis

Question 8

if for puncture wound

Answer 8

pseudomonas

Question 9

if chronic

Answer 9

staph aureus
pseudomonas
enterobacteriaceae

Question 10

if diabetic

Answer 10

polymicrobial
pseudomonas
staph aureus
streptococci
anaerobes

Question 11

Labs

Answer 11

increased WBC count
increased ESR
increased CRP
blood cultures may be (+)

Question 12

imaging

Answer 12

X-rays:

• may be (-) initially
• may show periosteal elevation within 10-14 days

MRI:

• test of choice
• increased signal in bone marrow and assoc soft tissue infection

Question 13

definitive diagnosis made by

Answer 13

bone aspiration with gram stain and culture

or can probe through soft tissue for clinical dx

Question 14

treatment of osteomyelitis

Answer 14

(1) surgical debridement of necrotic infected bone

(2) followed by IV antibiotics for 4-6 weeks

Question 15

Drug for methicillin-sensitive staph aureus

Answer 15

consider

• clindamycin + ciprofloxacin
• ampicillin/sulbactam
• oxacillin/nafcillin

Question 16

drug for MRSA

Answer 16

vancomycin

Question 17

drug for gram (-) bacteria

Answer 17

ceftriaxone or ciprofloxacin

Question 18

complication of long standing chronic osteomyelitis with draining sinus tract

Answer 18

squamous cell carcinoma (Marjolin’s ulcer)