6: Microbiology Part 2 Flashcards
The fitting of which materials may lead to infection?
Prosthetic joints
What are some risk factors for prosthetic joint infection?
Immunosuppression - rheumatoid arthritis
Diabetes
Malnutrition
Obesity
What is a biofilm?
Community of different organisms getting up in there and having fun etc.
Orthopaedic theatres are strictly controlled to prevent infection.
What are two mechanisms of prosthetic joint infection at the time of surgery?
Direct inoculation using instruments
Manipulation of joint by surgeons
Seeding of joint by something else
If prosthetic joint occurs early (i.e within a month), what is it likely associated with?
Haematoma / sepsis
If prosthetic joint infection occurs late (i.e after a month), what is the likely cause?
Contamination during surgery (?why)
Biofilms produce a thick ___ which antibiotics struggle to penetrate?
mucus
Which organisms tends to cause prosthetic joint infection?
Staph. aureus still
but also Staph. epidermidis due to involvement of prosthesis
Which organism, found in the skin of the upper limb, may rarely be responsible for upper limb prosthetic joint infections?
Proprionibacterium spp.
Before antibiotics are given, what should be taken from a suspected prosthetic joint infection?
Biopsy (as always)
Coagulase negative Staph. tend to be treated as contaminants unless the patient has what?
Prosthesis
How are prosthetic joint infections treated?
Remove / replace the joint
Antimicrobial therapy (fluclox for the Coag +ve, vancomycin for Coag -ve)
If a patient with prosthetic joint infection is elderly and can’t tolerate surgery, what may be done to treat them?
Cleaning / debridement
prognosis is poor
DAIR
Which drug is added to normal antibiotic therapy for prosthetic joint infections?
Why?
Is the drug ever used by itself?
Rifampicin
Helps other antibiotic to penetrate slime produced by biofilm
No, as Staph. aureus will develop resistance to it
(rearrange) How is septic arthritis diagnosed?
Aspiration of joint fluid via needle
