wound bone and joint infections

Question 1

list the Major Pathogens in Surgical Site Infections

Answer 1

Staph.aureus (MSSA and MRSA)
E.coli

Pseudomonas aeruginosa

Question 2

If surgical site is contaminated with

___ microorganisms per gram of tissue, risk of SSI is increased.

Answer 2

> 10 5

Question 3

The dose of contaminating bacteria required to cause infection is much lower if there is ____ present

Answer 3

foreign material e.g silk suture

Question 4

what are the Three levels of SSI?

Answer 4

Superficial incisional- affect skin and subcutaneous tissue

Deep incisional- affect fascial and muscle layers

Organ/space infection- any part of anatomy other than incision

Question 5

how can hair removal lead to ssi?

Answer 5

Hair removal causes micro abrasions

Question 6

list some ways to prevent SSI?

Answer 6

Antibiotic prophylaxis

showering on day of surgery

Theatre personnel should be kept to a minimum

Maintain positive pressure ventilation

Sterilise all surgical instruments

Normothermia - warm iv and irrigation fluids

and more

Question 7

list the Causative organisms of septic arthritis in order of most popular?

Answer 7

Staph. aureus 46%
- usually COAGULASE negative staph ini PJI too

Gram negative organisms

Streptococci 22%

Question 8

what is the classic presentation of septic arthiirits?

which joints are usually involved?

Answer 8

1-2 week history of red, painful, swollen restricted joint
Monoarticular in 90%
Knee is involved in 50%

Question 9

ivx for septic arthritis

Answer 9

Blood culture before antibiotics are given

Synovial fluid aspiration for microscopy and culture

ESR,CRP

imaging to guide treatment

Question 10

Traditionally a synovial count> 50,000 WBC cells/mm3 used to suggests?

Answer 10

septic arthritis

Question 11

most implicated organism in Vertebral osteomyelitis?

Answer 11

S.aureus- 48.3%

Question 12

most common area affected by Vertebral osteomyelitis

Answer 12

lumbar 43.1%

Question 13

most common symptom in Vertebral osteomyelitis?

what are next 2 most common?

Answer 13

Back pain- 86%
Fever- 60%
Neurological impairment 34%

Question 14

most sensitive test for Vertebral osteomyelitis?

Answer 14

MRI

Question 15

76 year old man
Admitted with a 4 month history of back pain with radiation down left leg
Weight loss of 25kg over the last 6 months
PMH: fracture right femur 25yrs ago in Kuwait. Metal plate inserted.
Arthritis right knee, Hypertension.
MRI: discitis of L2/3
Histology : vague granuloma

diagnosis? why, what are the key features?

Answer 15

Vertebral osteomyelitis

key;
back pain
Exogenous cause - implant associated
discitis

Question 16

Pain
Brodies abscess
Sinus tract

are associated with which condition ?

Answer 16

Chronic Osteomyelitis

Question 17

rx chronic osteomyelitis?

Answer 17

remove infected bone and soft tissue

Question 18

Signs and symptoms of PJI - Prosthetic joint infections?

Answer 18

Pain
Patient complains that the joint was ‘never right’
Early failure
Sinus tract - seen on X-ray

Question 19

which produces higher WCC on Joint aspiration

hip or knee PJI?

Answer 19

HIP PJI

> 4200/ml of WCC

Question 20

what is the difference between single stage and Two stage revision?

Answer 20

2 stage revision - give abs for 6 weeks after taking out prosthesis before late replacing the joint

single stage - replace joint in 1 surgery