MICRO: HAI, SSI and bone infections

Question 1

What are the most common HAIs in order?

Answer 1

HAP
SSI
UTI
BSI
GI

Question 2

What are the micro features of C diff?

Answer 2

Gram +ve anaerobe that colonises gut

Question 3

What is used for severe C diff?

Answer 3

Vancomycin

Question 4

Which drug for C diff causes less recurrence?

Answer 4

Fidaxomycin

Question 5

When do catheters become colonised?

Answer 5

60% within first 4 days (96hrs)

Question 6

What are the micro features of MRSA?

Answer 6

Gram +ve cocci in clusters

Question 7

What is water tested for in hospitals?

Answer 7

Pseudomonas and Legionella

Question 8

What are building works tested for?

Answer 8

Aspergillus

Question 9

What % of HAI are preventable?

Answer 9

33%

Question 10

What pathogens usually cause SSI?

Answer 10

MRSA, MSSA (i.e. staph), E coli and Pseudomonas

Question 11

How many pathogens increase risk of SSI?

Answer 11

> 10^5

Question 12

What is the most powerful risk factor for SSI following cardiothoracic surgery?

Answer 12

Staph aureus nasal carriage - so nasal decontamination is offered

Question 13

What serum albumin predisposes to SSI?

Answer 13

Low

Question 14

What condition predisposes to septic arthritis?

Answer 14

RhA but also osteoarthritis, crystal arthropathy, joint prosthesis, IVDU, diabetes etc

Question 15

Name a protein in synovium which bacteria adhere to.

Answer 15

Fibronectin e.g. S. aureus has fibronectin-binding protein

Question 16

Which staph toxin can cause fulminant septic arthritis?

Answer 16

PLV - Panton Valentine Leucocidin

Question 17

Absence of which cytokine in staph septic arthritis increases severity of disease?

Answer 17

Absent IL-10

Question 18

List the most common causes of septic arthritis.

Answer 18

1.Staph aureus
2.Streptococci
3.Gram -ves
4.CNS (staph)
Others

Question 19

What WCC suggests septic arthritis in joint aspirate?

Answer 19

> 500,000/ml

Question 20

What are the most common causes of vertebral osteomyelitis?

Answer 20

1. Staph aureus
2. CNS
3. Gram -ve rods
4. Streptococci

Question 21

Name 2 features of chronic osteomyelitis.

Answer 21

Brodies abscess

Sinus tract

Question 22

What limb salvage surgical technique can be used in osteomyelitis?

Answer 22

Papineau bone graft

Question 23

What are the most common causes of prosthetic joint infections?

Answer 23

1. CNS (!)
2. Staph
3. Strep
4. Enterococci
5. Gram -ve rods e.g. Pseudomonas, Enterobacteria
6. Anaerobes
7. Mixed
8. Fungi

Question 24

What XR feature and what CRP suggests prosthetic joint infection?

Answer 24

XR - loosening
Hip = CRP>5 and WCC >4200
Knee= CRP >1700 and WCC > 13.5

Question 25

How do you diagnose PJI?

Answer 25

5 samples taken during surgery around the site; if 3 or more positive then PJI present

Question 26

What are the two surgical treatments for PJI?

Answer 26

Single stage revision (Endo-Klinik) | Two stage revision

Question 27

What does the single stage revision involve?

Answer 27

Implanting new prosthesis with antibiotic impregnated cement and give IV antibiotics

Question 28

What does the two stage revision involve?

Answer 28

Prosthesis removed at stage 1; abx given for 6 weeks IV; debridement and prosthesis insertion (with abx impregnated cement) and sampling of the site (if negative no abx needed)

Question 29

How is histopathological diagnosis of infection made in PJI?

Answer 29

>5 neutrophils per high power field

Question 30

Why should you send several samples if you get a diagnosis of CNS on the first in an infection?

Answer 30

it is a common skin contaminant