Bone and joint infections Flashcards
What is osteomyelitis?
Infection of the bone
What is meant by osteomyelitis being a hetrogeneous disease?
many causes
Many areas of the body that it can occur in
Many types of people can be affected
What are the 3 ways that osteomyelitis can occur (pathogenesis)? Give examples
1) Haematogenous - bacteria in blood seeds the bone e.g. endocarditis
2) Contiguous-focus - spread from adjacent areas of infection e.g. diabetic ulcer
3) Direct inoculation - trauma/surgery
What are the 4 stages of osteomyelitis?
Stage I - Medullary
Stage 2 - Superficial
Stage 3 - Localised
Stage 4 - Diffuse
In Stage III or IV, why are antibiotics alone not useful?
No blood supply present
Therefore antibiotics will not reach the bone
Surgery required to get rid of necrosis
What is the clinical presentation of osteomyelitis?
Pain - localised, nocturnal, not mechanical, progressively worse
Reduced movement
Classical symptoms of inflammation not that common
Systemic symptoms uncommon
What are the 2 most common organisms that cause osteomyelitis?
Staphylococcus aureus
Streptococci (A/B)
What is the gold standard method of diagnosing the pathogen causing osteomyelitis?
cultures and histology of bone biopsy/needle aspirate
What is a potential disadvantage of using biopsy/aspiration to culture pathogens and what alternative can be used?
Invasive
Blood cultures effective around 50% of the time
What form are antibiotics given in treatment for osteomyelitis?
IV as penetration into the bone is low
What is empirical treatment?
Giving antibiotics before you know the cause - broad spectrum
Relevant in some cases but not for osteomyelitis
What pathogen does clindamycin normally target? How is it given?
Orally
Staphococci
Beware of C.Diff risk
What pathogen does ciprofloxacin normally target? How is it given?
Orally
Gram -ve
What pathogen does Flucloxacillin target?
Staphylococcus aureus
What is the definition of septic arthritis?
Inflammatory reaction in the joint space
Caused by infection
Results from direct invasion of the joint
What are the 2 types of septic artheritis? And how do they come about?
Native (natural) joint infection - organism in blood which seeds in synovial membrane
Prosthetic (artificial) joint infection - rganism in blood. Biofilm of polymorphs on the cement from, they cannot phagocytos so they release enzymes that cause damage to the joint
What is the clinical presentation of septic arthritis?
Typical symptoms of inflammation:
Pain, tenderness, swelling, redness, limitation of movement
Systemic i.e. fever, chills, night sweats
Which viruses can cause septic arthritis?
Parvovirus B19
Rubella
Mumps
What 3 bacterial pathogens cause Native joint infection?
Staphylococcus aureus
Streptococci
Haemophilus influenza - less common now due to vaccine
What 3 bacterial pathogens cause prosthetic joint infection?
NORMAL SKIN FLORA
Staphylococcus aureus
Coagulate negative staphylococci (CoNS)
Streptococci
What is analysed to diagnose septic arthritis?
Joint aspiration White cell count - inc polymorphs. Not diagnostic Gram stain Crystal examination Culture PCR
What is the treatment for native septic arthritis?
Washout - removal of purulent material
Antibiotics
What is the treatment for prosthetic septic arthritis?
Removal of implant if loose - add antibiotic cement until treated
If not loose, remove specific parts
Washout
IV antibiotics
