MICRO: HAI, SSI and bone infections Flashcards
What are the most common HAIs in order?
HAP SSI UTI BSI GI
What are the micro features of C diff?
Gram +ve anaerobe that colonises gut
What is used for severe C diff?
Vancomycin
Which drug for C diff causes less recurrence?
Fidaxomycin
When do catheters become colonised?
60% within first 4 days (96hrs)
What are the micro features of MRSA?
Gram +ve cocci in clusters
What is water tested for in hospitals?
Pseudomonas and Legionella
What are building works tested for?
Aspergillus
What % of HAI are preventable?
33%
What pathogens usually cause SSI?
MRSA, MSSA (i.e. staph), E coli and Pseudomonas
How many pathogens increase risk of SSI?
> 10^5
What is the most powerful risk factor for SSI following cardiothoracic surgery?
Staph aureus nasal carriage - so nasal decontamination is offered
What serum albumin predisposes to SSI?
Low
What condition predisposes to septic arthritis?
RhA but also osteoarthritis, crystal arthropathy, joint prosthesis, IVDU, diabetes etc
Name a protein in synovium which bacteria adhere to.
Fibronectin e.g. S. aureus has fibronectin-binding protein
Which staph toxin can cause fulminant septic arthritis?
PLV - Panton Valentine Leucocidin
Absence of which cytokine in staph septic arthritis increases severity of disease?
Absent IL-10
List the most common causes of septic arthritis.
1.Staph aureus
2.Streptococci
3.Gram -ves
4.CNS (staph)
Others
What WCC suggests septic arthritis in joint aspirate?
> 500,000/ml
What are the most common causes of vertebral osteomyelitis?
- Staph aureus
- CNS
- Gram -ve rods
- Streptococci
Name 2 features of chronic osteomyelitis.
Brodies abscess
Sinus tract
What limb salvage surgical technique can be used in osteomyelitis?
Papineau bone graft
What are the most common causes of prosthetic joint infections?
- CNS (!)
- Staph
- Strep
- Enterococci
- Gram -ve rods e.g. Pseudomonas, Enterobacteria
- Anaerobes
- Mixed
- Fungi
What XR feature and what CRP suggests prosthetic joint infection?
XR - loosening
Hip = CRP>5 and WCC >4200
Knee= CRP >1700 and WCC > 13.5
How do you diagnose PJI?
5 samples taken during surgery around the site; if 3 or more positive then PJI present
What are the two surgical treatments for PJI?
Single stage revision (Endo-Klinik)
Two stage revision
What does the single stage revision involve?
Implanting new prosthesis with antibiotic impregnated cement and give IV antibiotics
What does the two stage revision involve?
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)
How is histopathological diagnosis of infection made in PJI?
> 5 neutrophils per high power field
Why should you send several samples if you get a diagnosis of CNS on the first in an infection?
it is a common skin contaminant
