Microbiology Flashcards
What is osteomyelitis?
Inflammation of the bone and medullary cavity, usually located in one of the long bones
How can osetomyelitis be classified?
Acute vs chronic
Contiguous vs haematogenous
Host status - presence of vascular insufficiency
What is an example of how the host status can change oestomyelitis?
Those with sickle cell are susceptible to salmonella ostemomyelitis
What is the gold standard for diagnosis of oesteomyelitis?
Bone biopsy
MRI
If you can see bone or tendon this is DEFINITELY osteomyelitis
When should antibiotics be prescribed for oestomyelitis?
AFTER CULTURES
NEVER EMPIRICAL unless septic or there is systemic upset
What are the hallmarks of inflammation?
Color Dolor Tumor Rubor Function lasea
What risk factors predispose to osteomyelitis?
Open fractures Diabetes/ vascular insufficiency Haematogenous osteomyelitis Vertebral osteomyelitis Prosthetic joint infection Specific hosts and pathogens
When is osteomyelitis likely to occur?
Bone is highly resistant to infection and therefore, will only occur with necrosis +/- high inoculum
How long does an infection bone take to heal?
Debrided bone takes 6 weeks to be revascularised with soft tissue
How long should antibiotics be given for in osteomyelitis?
6 weeks
What bacterium is likely to affect prosthetic joints?
Staphylococcal coagulase negative - staphylococcal epidermidis
How are open fractures managed?
Aggressive debridement
Fixation
Soft tissue cover
What bacteria are likely to infect an open fracture?
Staphylococcus aureus and aerobic gram negative bacteria (pseudomonas, neisseria, e.coli, salmonella, kelbsiella, proteus, shigella)
What is the treatment for diabetic ulcers?
Surgical debridement and antimicrobial’s
Antibiotics CANNOT penetrate abscesses or necrotic tissue - these need surgical removal
What are the three markers you need to evaluate for the presence of osteomyelitis?
Chronic, indolent or deep ulcer
Positive probe-to-bone test
Elevated levels of inflammatory markers (CRP, PV)
What radiological investigations are best for osteomyelitis?
X-ray
Gold standard is MRI
What are appropriate cultures for osteomyelitis?
Per-cutaneous aspirate
Bone biopsy surgically
What is the definition of a mild diabetic foot ulcer?
2 or more: pus, erythema, pain, tender, warmth, in-duration
OR
Cellulitis <2cm confined to skin or subcutaneous
What is the treatment for a mild ulcer?
Flucloxacillin (oral)
What are the main bacterial causes for mild diabetic feet ulcers?
MSSA
MRSA
Streptococci
How long is treatment for feet ulcers?
7 days
10 days if severe
14 days IV if S.aureus bacteraemia