osteomyelitis

Question 1

osteomyelitis is…

Answer 1

infection of the bone, can be bacterial or fungal

Question 2

what are the sources of osteomyelitis?

Answer 2

hematogenous spread
invasion from a contiguous focus of infection (diabetic foot)
skin breakdown (vascular insufficiency or trauma)

Question 3

hematogenous spread results from ____

Answer 3

bacteremia

Question 4

who is at risk for hematogenous spread?

Answer 4

sickle cell anemia (salmonella)
elderly
IV drug users (staph aureus)
diabetes

Question 5

sxs of osteomyelitis

Answer 5

fever-absent or low grade
bone or joint tenderness/pain
elevated acute phase reactants- CRP, ESR
bone can be probed with a swab from the wound site
wound > 6 weeks in duration

Question 6

what are the risk factors for osteomyelitis?

Answer 6

bone fracture 
any condition that causes weakening of the immune system (diabetes, organ transplant, chemotherapy, AIDS)
kidney failure 
IV drug abuse 
joint replacement/ orthopedic hardware placement 
peripheral neuropathy 
peripheral vascular disease 
sickle cell anemia

Question 7

how is the diagnosis of osteomyelitis made?

Answer 7

plain film X-ray of suspected area
showing bone abnormalities, cortical erosion, periosteal reaction, and lucency or osteolysis (may not be apparent until 7-15 days after the onset of acute clinical osteomyelitis)
MRI if x ray is negative and osteomyelitis is suspected

Question 8

labs

Answer 8

acute phase reactants

CBC (WBC might be elevated)

Question 9

what is the treatment for osteomyelitis?

Answer 9

debridement of bone
minimum of 6 weeks of IV antibiotics targeted to organism (keep in mind bone penetration ability of selected abx)
continued monitoring

Question 10

what are empiric abx choices for osteomyelitis?

Answer 10

vancomycin 1 gram IV q 12 hours +/- rifampin AND Ceftriaxone 2 grams IV q24 hours

(target therapy when cultures become available, Nafcillin is preferred for MSSA)

Question 11

What is Brodie’s abscess?

Answer 11

bone abscess that can be walled off by body’s immune defenses for years

Question 12

what is the most common organism in Brodie’s abscess?

Answer 12

most commonly isolated organism is Staph aureus

Question 13

what bone is most commonly affected in Brodie’s abscess?

Answer 13

tibia

Question 14

in non-diabetic patients with osteomyelitis, what is the most commonly associated organism and what is the treatment?

Answer 14

staph
MSSA- Nafcillin 2 grams IV q 4 hours OR cefazolin 2 grams IV q 8 hours
MRSA- vancomycin 1 gram IV q 12 hours +/- rifampin 300-450 mg po bid

Question 15

in diabetic patients with osteomyelitis, was is the most commonly associated organism?

Answer 15

polymicrobic in diabetics- debride and get cultures, usually no empiric therapy- wait for culture

Question 16

what is the usual duration of therapy for osteomyelitis ?

Answer 16

6 weeks of IV antibiotic therapy

Question 17

nail through tennis shoe into foot…
what is the organism you are concerned about?
what is the drug of choice?
what are the other parts of the treatment plan?

Answer 17

tetanus
cipro
diabetes testing, look for foreign body

Question 18

What is infectious arthritis?

Answer 18

aka septic arthritis

direct invasion of joint space by bacteria

Question 19

who is at the most risk for developing infectious arthritis?

Answer 19

elderly- 45% of cases are above 65 years old
56% male
prosthetic joint infection 2-10%

Question 20

what is the most common etiology in infectious arthritis?

Answer 20

most are caused by staph aureus

in younger, sexually active people, neisseria gonorrhoeae

Question 21

what is the mechanism of infection in infectious arthritis?

Answer 21

direct inoculation
contiguous spread
bacteremia- most common
previously damaged joints, especially in RA, most susceptible

Question 22

what is reactive arthritis?

Answer 22

Joint pain and swelling triggered by an infection in another part of the body
postexposure

Question 23

What patient population is reactive arthritis more common in?

Answer 23

HLAB27 positive patients

Question 24

what organisms is reactive arthritis commonly caused by?

Answer 24

chlamydia trachomatis, various GI bugs (salmonella, Yersinia, Campylobacter, C diff)

Question 25

What is the clinical presentation of infectious arthritis?

Answer 25

fever 
pain (acute onset/worsening) at joint
erythema of joint 
impaired range of motion of joint 
usually monoarticular

Question 26

what are the most common joints involved in infectious arthritis?

Answer 26

knee
hip
shoulder

Question 27

What is the clinical presentation of gonococcal arthritis?

Answer 27

fever
arthralgias of multiple joints
disseminated bacteria from cervix, urethra, or pharynx
asymmetric tenosynovitis

Question 28

what joint is typically affected with gonococcal arthritis?

Answer 28

typically hands with progression to other joints- skin pustules any location

Question 29

how can the dx of gonococcal arthritis be made?

Answer 29

fluid aspirate and culture
blood cultures
xray

Question 30

what is the treatment for infectious arthritis?

Answer 30

targeted to organism
antibiotics- gonococcal vs non-gonococcal
fluid drainage