Microbiology 12 : wound, bone and joint infections Flashcards
major pathogens causing surgical site infections (SSIs
S.aureus
E.coli
Pseudomonas aeruginosa
three levels of SSIs
Superficail incisional - skin + subset
Deep incisional - fascia and muscle
organ/space infection - any part of anatomy other than the incision
Rheumatoid arthritis patients are at risk of surgical site infections. What steps are taken to prevent SSIs in these patients?
Stop DMARDs 4 weeks before and 8 weeks after op
why is obesity a risk factor for SSI?
Adipose tissue is poorly vascularised –> poor access to immune system
what is the most powerful risk factor for SSI following cardiothoracic surgery?
S.aureus carriage in the nose –> offer nasal decontamination
type of ventilation in theatre
positive pressure so air flows from within theatre to outside
How does temperature in surgery affect risk of acquiring SSI?
Low temp –> vasoconstriction –> less oxygenation –> increased risk of SSI
main risk factor for septic arthritis
rheumatoid arthritis
top 2 organisms in septic arthritis
Staph
Strep
which strain of staph can cause fulminant septic arthritis
S.aureus producing cytotoxin PVL
How does S aureus cause septic arthritis? i.e. how does it do its damage
Has fibronectin binding protein and PVL toxin
mx of septic arthritis
IV Abx 4-6 weeks OP + drainage of the joint
number 1 organism in osteomyelitis
S.aureus
best imaging modality for osteomyelitis?
MRI
Vertebral osteomyelitis - which part is most commonly affected?
Lumbar spine
presentation of chronic osteomyelitis
pain
Brodies abscess
sinus tract
diagnosis of chronic osteomyelitis
MRI + bone biopsy for culture + histology
management of osteomyelitis
IV Abx (3 weeks inpatient and 6 weeks OP) + Debridement second line
most common causative organism for prosthetic joint infection
CoNS (Coagulase negative staphylococcus)
Radiology of prosthetic joint infection shows…?
Loosening of joint
Management of prosthetic joint infection?
single stage revision - remove foreign material and dead bone + re-inplant new prosthesis
two stage revision
How to confirm diagnosis of prosthetic joint infection?
5 tissue samples from around implant for microscopy
