DS: Joint ant Bone Infections

Question 1

Septic arthritis?

Answer 1

Pyogenic arthritis (synonym)
an invasion of a joint by a pathogenic bacterium causing purulence (pus formation) resulting in an extremely painful and swollen joint

Question 2

Importance of septic arthritis?

Answer 2

bacterial arthritis is more dangerous and destructive
significant damage can occur within 24 hours
mortality around 7-15% despite antibiotic use

Question 3

Diagnosis of septic arthritis?

Answer 3

arthroscopy or open drainage in the operating room

aka, immediate treat, surgery

Question 4

making differential for septic arthritis?

Answer 4

it is a painful, warm arthritis
have to think about other ones of that nature
gout, reactive arthritis, RA, lupus, akylosing spondylolitis, etc

Question 5

why is preexisting arthritis a risk factor for septic arthritis?

Answer 5

more likely to develop an infection in the joint that is already damaged

Question 6

other risk factors for septic?

Answer 6

steroid use
intraarticular injection
diabetes
trauma
history of STDs
other infection

Question 7

Epidemiology of Septic?

Answer 7

usually in patients with preexisting joint problems
most are male
older than 65 yo

Question 8

Source of infection?

Answer 8

Sepsis, spread to the joint from infection is common
trauma to the joint
direct inoculation during joint surgery

Question 9

Etiology of septic arthritis? most common

Answer 9

Staph aureus is most common

Question 10

septic in neonates?

Answer 10

Strep agalactiae

Question 11

septic in sick cell?

Answer 11

step pnuemoniae

Question 12

strep in young children?

Answer 12

Kingella Kingae

Question 13

septic in STDs/ unsafe sex?

Answer 13

Neisseria gonnorhoeae

Question 14

septic in unvaccinated?

Answer 14

hemophilus influenzae

Question 15

septic in endemic areas?

Answer 15

mycobacterium tuberculosis

Question 16

Staph aureus?

Answer 16

gram pos, facultative, catalase pos, coagulase pos

cause abscess formation in skin and subcut tissue

Question 17

Strep pyogenes? (grp A strp)

Answer 17

gram pos cocci in chains
catalase neg, beta hemolytic, sens to bacitracin
cause infections, cellulitis, strep throat, sepsis, rheumatic fever

aka, patient with strep throat, develops joint pain after– has this

Question 18

Strep agalactiae? (grp B strep)

Answer 18

gram pos cocci in chains
beta hemolytic, carried in maternal gential tract
cause meningitis, pneumonia, and sepsis in neonates

Question 19

Strep pneumoniae?

Answer 19

gram pos, lancet shaped, diplocci
alpha hemolytic
sens to optochin
polysaccharide capsule
cause pneumonia, otitis media, meningitis, sepsis

(sickle cell)

Question 20

Neisseria?

Answer 20

gram neg, diplo, coffee bean shape
produce cytochrome oxidase
STD causes urethritis and cervictitis

Question 21

Kingella Kingae?

Answer 21

fastidious aerobic gram-neg coccobacilli
most commonly isolated from blood and synovial fluid
colonize oral mucosa
cause endocarditis and joint infections in young child (2 mo- 2 yrs)

Question 22

Clinical features of septic arthritis?

Answer 22

infection is generally monoarticular
knee is the most common, followed by hip
swollen, hot, painful joint in a patient with fever

Question 23

How do organisms invade in septic?

Answer 23

invade via bloodstream, direct inoculation or by continuous spread from infected periarticular tissue

previous damaged joints are most susceptible, synovial membranes of these joints exhibit neovascularization and increased adhesion factors

Question 24

How does s. aureus bind to joint?

Answer 24

via specific tissue adhesion factors

Question 25

how does s. aureus cause damage and multiply?

Answer 25

organisms pathological properties, chondrocyte proteases, as well as host's polymorphonuclear leukocytes response

Question 26

Pannus formation?

Answer 26

layer of fibrovascular or granulation tissue beings and cartilage erosion occurs at the lateral margins of the joint large effusions impair the blood supply, aseptic necrosis of bone

Question 27

atherocentesis?

Answer 27

to obtain joint fluid

Question 28

lab diagnosis?

Answer 28

atherocentesis, then gram stain joint fluid, cell count and differential, culture joint fluid Staph aureus, step, and neisseria most common

Question 29

Treatment of septic?

Answer 29

arthroscopy or open drainage of joint | antibiotic therapy depends on organism isolated

Question 30

Treat s. aureus?

Answer 30

Naficillin, Vancomycin

Question 31

Treat with penicillin?

Answer 31

S. pyogenes | S. pneumoniae

Question 32

Treat with ceftriaxone?

Answer 32

S. pneumoniae | N. gonnorhoeae

Question 33

Osteomyelitis?

Answer 33

difficult to diagnose until about 50% of the bone matrix must be removed before the lytic process can be visualized no changes occur on a standard x-ray until 10 days after onset of illness

Question 34

Pathophysiology of osteomyelitis?

Answer 34

occurs more frequent in children when long bones grow a trauma disrupts blood vessels and cause hematoma Metaphysis is predisoposed to infection

Question 35

Why is the metaphysis predisposed to infection?

Answer 35

because capillaries make sharp loops close to the growth plate then expand to large sinusoidal vessels that connect to venous network, an increase in diameter slows blood flow, cause sludging, and microclots

Question 36

Diagnosis of Osteomyelitis?

Answer 36

patient will have a fever and severe localized skeletal pain radiologic findings of localized inflammatory process (xray, bone scan, CT/MRI) blood culture, bone aspirate for culture

Question 37

What will a bone scan show?

Answer 37

increased blood flow, pooling, and reactive new bone formation

Question 38

Etiology of Osteomyelitis? Children?

Answer 38

``` S. aureus most common Strep agalactiae (grp B) neonates step pneumo (2 mo- 2yrs) Haemophilus influenza (2 mo-2yrs unvaccinated) Kingella Kingae (2mo to 2 yrs) Strep pyogenes (grp A) school age children ```

Question 39

Etiology of Osteomyelitis in adults?

Answer 39

``` S. aureus most common gram neg rods/ E coli, Klebsiella/Enterobacter Salmonella (sickle cell) Pseudomonas and Serratia (IV drug users) Other (fungir, mycobacteria) ```

Question 40

Treatment of Osteomyelitis?

Answer 40

surgical debridement of necrotic bone material | antibiotics depends on organism isolated (high dose, parenterally, long course)

Question 41

Infections with prostheses?

Answer 41

only .5-1% become infected infection develops at the bone-cement interface, cemeneted with polymethylacrylate source may be introduced through surgery or be from a hematogenous origin

Question 42

Etiology of infections with prostheses?

Answer 42

``` Staphylococcus most common (Staphylococcus epidemidis)- due to slime layer which binds to surface of prosthetic device (Staph aureus) Strep species Gram neg Enterococcus mixed flora other (fungi, mycobacteria) ```

Question 43

Treatment of infections with prostheses?

Answer 43

surgery, often removal of prosthetic is required with debridement of necrotic tissue antiobiotics depend on organism isolated