Micro Final

Question 1

what is osteomyelitis?

Answer 1

inflammation of bone, literally

though we usually mean infection of bone due to bacteria most often

Question 2

key features of osteomyelitis?

Answer 2

inflammatory destruction of bone, new bone formed

Question 3

risk factors for osteomyelitis?

Answer 3

trauma, diabetes, decubitus ulcers, IV drug use, surgery

Question 4

what are the three ways infection can get into the bone?

Answer 4

spread from current infection into bone, direct innoculation, hematogenously

Question 5

what locations do hematogenous spread happen in kids and adults?

Answer 5

kids - long bones

adults - vertebral bodies

Question 6

significance of transphyseal vessel?

Answer 6

it closes at 18mo, so epiphysis normally protected in all but children - so kids can get in epiphysis, adults usually dont

Question 7

classical hematogenous spread?

Answer 7

infection enters thru nutrient artery and seed metaphysis, cuases necrosis and abscess formation - this can spread to epiphysis and joint space in kids

Question 8

how does the necrosis spread?

Answer 8

extends within the bone and then out thru compact bone where it raises periosteum from cortex

Question 9

what is the necrosis and new bone formation called?

Answer 9

sequestrum, involcrum

Question 10

how do you get the sequestrum?

Answer 10

the inflammatory pressure compresses the capillaries within haversian canals, so you get necrosis of bone

Question 11

cut off for antibiotics vs. surgery?

Answer 11

if have bone necrosis, likely need surgery, if no necrosis, could potentially just use antibiotics

Question 12

clinical presentation of osteomyelitis?

Answer 12

chills, fevers, sweats, lethargy, malaise, point tenderness, swelling and redness of tissue over bone, draining sinus

Question 13

number one organism to cause it?

Answer 13

staphylococcus aureus

Question 14

why does staph aureus do osteomyelitis so well?

Answer 14

has collagen adhesion protein

created a biofilm which inhibits clearance by immune system and penetration of antibiotics

Question 15

what is the preferred method of imaging for osteomyelitis?

Answer 15

MRI (90%sens,80% spec) preferred

X-Ray (50% sens, 70% specific)

Question 16

what is the problem with imaging for this?

Answer 16

if have trauma in addition, it will be very difficult to discriminate between trauma and infection

Question 17

what are some diagnostic tools, are they good?

Answer 17

probe to bone, blood culture…not very good

definitive diagnosis? bone biopsy and culture in OR

Question 18

when should you start antibiotics?

Answer 18

hold off as long as you can until you know the organism - until after biopsy

Question 19

what parts of the body usually only need antibiotics?

Answer 19

vertebral bodies and terminal digits

Question 20

why are joint infections hard to treat?

Answer 20

no blood supply there, hard to get antibiotics there

Question 21

how do joints get infected?

Answer 21

hematogenous seeding

sometimes by penetrating trauma or complication of joint infection with corticosteroids

Question 22

risk factors for joint infection?

Answer 22

other joint diseases, prosthetic joints, IV drug use, alcoholism, diabetes, cutaneous ulcer, immune suppression

Question 23

clinical presentation?

Answer 23

chills, fever, swollen, red, painful joint, decreased joint mobility
***important: leukocytosis common (unlike in bone)

Question 24

common joints to be affected?

Answer 24

knee, hip, ankle, elbow, wrist, shoulder

Question 25

most common culprit?

Answer 25

staph aureus

Question 26

gonococcal septic arthritis?

Answer 26

SEVERAL hot swollen joints
sometimes have polyarthritis
large joints
often migratory

Question 27

is septic arthritis an emergency?

Answer 27

yes, can cause total joint destruction if not taken care of and can cause death in bacteremia/sepsis

Question 28

how to diagnose?

Answer 28

synovial aspiration and fluid analysis

Question 29

treatment for septic arthritis?

Answer 29

antibiotics and joint drainage