Microbiology 8: Wound, Bone And Joint Infections

Question 1

What are the 3 main organisms causing surgical site infections ?

Answer 1

Staphylococcus aureus
E.Coli
Pseudomonas aeruginosa

Question 2

Does shaving a patient using a razor increase or decrease the risk of surgical site infection ?

Answer 2

Increase- you are making micro-abrasions which can be an entry route for skin bacteria.

Question 3

Which of the following is associated with a reduced risk of surgical site infections ?

A) Obesity
B)bactericidal concentration of antibiotics in the serum at time of incision
C)Smoking
D) Diabetes

Answer 3

B

Question 4

List 3 bacterial factors that contribute to the risk of septic arthritis ?

Answer 4

S.Aureus- fibronectin binding proteins
S.Aureus- Panton-Valentine leucocidin
Kingella kingae- bacterial pili

Question 5

Which bacterial factor is associated with more fulminant septic arthritis ?

Answer 5

Panton-valentine Leukocidin (S.aureus)

Question 6

Which organism is the most common cause of septic arthritis ?

Answer 6

S.aureus

Question 7

What is the most common organism responsible for vertebral osteomyelitis ?

Answer 7

S.aureus

Question 8

Which part of the spine is most commonly affected in vertebral osteomyelitis ?

A)Cervical
B)Thoracic 
C) Lumbar
D)Sacral
E)coccyx

Answer 8

C

Question 9

What is the diagnostic investigation for vertebral Osteomyelitis ?

Answer 9

MRI scan

Question 10

Which techniques are used to treat Chronic osteomyelitis ?

Answer 10

Lautenbach technique- debridement of infected/dead bone and insertion of 2 drains that allow delivery of antibiotics, fluids and irrigation.

Papineau technique- complete excision of infected tissue and necrotic bone followed by cancellous bone grafting and skin grafting.

Question 11

What characteristic radiological finding of Prosthetic joint infection ?

Answer 11

Loosening (bone loss along the cement-bone interface)

Question 12

What is the treatment for prosthetic joint infection ?

Answer 12

Single stage revision- The old prosthesis and all infected/necrotic tissue and bone is debrided. A new prosthesis is put in place with antibiotics.

Two stage revision- The old prosthesis and all the infected/necrotic bone and tissue is debrided. A spacer is put in and the area is treated for 6 weeks with Antibiotics before a new prosthesis is put in place.

Question 13

Which organism is the most common cause of Prosthetic joint infection ?

Answer 13

Coagulase negative staphylococci - Staphylococcus epidermidis