19- Bone and joint infections

Question 1

T/F septic arthritis due to bacterial infection is a destructive form of acute arthritis

Answer 1

T

Question 2

septic arthritis most commonly occurs due to

Answer 2

hematogenous seeding of S aureus (second most common is direct inoculation into the joint)

Question 3

which is more common large or small joint septic arthritis

Answer 3

large

Question 4

can septic arthritis develop via extension of infection from long bone osteomyelitis

Answer 4

Yes

Question 5

etiology of septic arthritis

Answer 5

• most common: monomicrobial S aureus

- streptococcus pneumoniae

Question 6

when can septic arthritis occur due to gram negative bacilli

Answer 6

in older adults, immunosuppresed, IV drug users

- pseudomonas

Question 7

T/F small joint septic arthritis is more likely to be polymicrobial and caused by streptococci Eikenella or anerobic bacteria

Answer 7

T

Question 8

dx of septic arthritis can be done via

Answer 8

synovial fluid analysis and culture

- purulent: WBC 50k-150k cells/mL (neutrophils)

Question 9

what should you send synovial fluid for

Answer 9

gram stain, bacterial culture, WBC, crystal check

Question 10

tx for septic arthritis

Answer 10

joint drainage (its like a closed abscess; it can be done via needle aspiration, arthroscopic damage, arthrotomy) and antibiotics (empiric vs MRSA, and aerobic gram - bacilli)

Question 11

T/F the risk of prosthetic joint infection is greater for knee than hip

Answer 11

T (greater mobility and less protective soft tissue coverage)

Question 12

timings of prosthetic joint infections

Answer 12

early onset <3 months after surgery (often with hematoma formation or superficial necrosis of incisions)
delayed onset 3-12 months
late onset >12 months after surgery
NOTE that the timing of the infection has implications for surgical management (implant retention or removal)

Question 13

the dx of prothetic joint infection can be establised in what circumstances

Answer 13

• sinus tract is present and communicates with the prosthesis
• 2 periprosthetic cultures that have same organisms
• single pos culture with virulent organism

Question 14

define sonification

Answer 14

is a method based on the application of long wave US radiating in a liquid medium, to diagnose infection in case of biofilm presence which makes culture difficult

Question 15

RF for the development of septic arthritis

Answer 15

old, joint dx, joint surgery, immunosuppressed, IV drug user, soft tissue infection, catheters

Question 16

In injection drug users which part of the skeleton is prone to infection

Answer 16

axial (sternoclavicular joint, sternomanubrial)

Question 17

T/F the rate of prosthetic joint infection is higher in the first 2 years post surgery

Answer 17

T

Question 18

PIJ etiology based on onset of infection

Answer 18

• Early onset: S aureus, gram - bacilli, anaerobes, polymicrobial infection
• Delayed onset: coagulase - staphylococci, propionobacterium (aka cutibacterium), enterococci
• Late onset: occurs post hematogenous seeding S aureus; gram - bacilli, B hemolytic streptococci (they have acute onset of sx and dislocation may occur)

Question 19

polyarticular septic arthritis is most likely to occur in which pts

Answer 19

pts with rheumatoid arthritis or CTD

pts with sepsis

Question 20

T/F septic arthritis can be a manifestation of infective endocarditis

Answer 20

T

Question 21

When to use needle aspiration or arthroscopy for joint aspiration

Answer 21

needle: septic arthritis of knee, elbow, ankle, joint
arthroscopy: of hip, shoulder, sternoclavicular joint (difficult to access)

Question 22

T/F in any joint, arthroscopy may facilitate more through irrigation

Answer 22

T

Question 23

When is surgical drainage necessary for septic arthritis

Answer 23

• adequate drainage cannot be acheived by needle aspiration/arthroscopy
• suspisicon of penetrating trauma with a residual foreign body
• joint effusion persists for 7 days of serial aspiration

Question 24

T/F Serial synovial fluid analyses should be performed; as infection is treated, these findings should
demonstrate sterilization of the fluid and decreasing total white blood cell count.

Answer 24

T

Question 25

How long to treat septic arthritis due to S aureus with other bacteria

Answer 25

4 weeks parenteral tx

Question 26

how long to treat septic arthritis due to S aureus witout other bacteria or endocarditis

Answer 26

parenteral antibiotics for 14 days, then oral therapy for 7-14 days

Question 27

For patients with septic arthritis due to organisms that are susceptible to
oral agents with high bioavailability (such as a fluoroquinolone), we favor
treatment with a short course (four to seven days) of parenteral therapy,
followed by 14 to 21 days of oral therapy. Compliance and response to
therapy should be monitored carefully in such cases.

Answer 27

T

Question 28

For patients with septic arthritis due to difficult-to-treat pathogens (such
as P. aeruginosa or Enterobacter spp), longer courses of outpatient
parenteral antibiotic therapy (eg, three to four weeks) may be necessary.

Answer 28

T

Question 29

For patients with septic arthritis and contiguous osteomyelitis, a long (four
to six week) course of antibiotics may be indicated.

Answer 29

T

Question 30

For patients with septic arthritis in the setting of endocarditis, the
duration of therapy is guided by the duration required for treatment of
endocarditis

Answer 30

T

Question 31

T/F PIJ is often associated with persistent joint pain, mechanical loosening causing pain with motion and weight bearing

Answer 31

T

Question 32

Metallosis

Answer 32

the reactive synovitis to metallic debris. Synovial fluid cell count may be higher, but neutrophil percentage is below threshold for PIJ dx

Question 33

TX for PIJ

Answer 33

surgery (debridement, resection arthroplasty, reimplantation, amputation) and antimicrobial therapy

Question 34

Who can get debridement and retention of prosthesis for PIJ

Answer 34

Patients with a well-fixed prosthesis with no
sinus tract within approximately 30 days of
prosthesis implantation or <3 weeks of symptom
onset may be candidates for debridement and
retention of prosthesis, followed by systemic
antibiotic therapy guided by the microbiology of
the infection