Bone and Joint infections Flashcards
How do organisms get into the bone?
- Haemotogenous spread
- Local spread (septic arthritis)
- Compound fracture
- Foreign bodies
What do people with sickle cell disease have a predisposition to?
Salmonella
What do people who have travelled or were foreign born have a predisposition to?
Brucella
What fo people who have a prothesis have a predisposition to?
S. epidermis
What do children under 5 have a predisposition to?
H.influenzae
What do people who have a UTI have a predisposition to?
E. coli and others
What is osteomyelitis?
An infection of the bone
Which bones are affected by osteomyelitis?
- Humerus (8-10%)
- Femur (30-35%)
- Tibia (25-30%)
- Fibula (5%)
- Calcaneum (10-12%)
Describe haematogenous spread to the bones
- Usually asymptomatic
- Skin sepsis may be present but it is usually absent
- Organisms tend to settle in the growing metaphysis
How do foreign bodies enter the bone?
- Trauma
- Shrapnel/Gun shot wounds
- Orthopaedic implants
Which are the 3 main organisms responsible for osteomyelitis?
- S. aureus (>80%)
- S. pyogenes (~5%)
- M. tuberculosis
What are the symptoms and signs of osteomyelitis?
- Painful swollen site
- Fever
- Reduced movement (may be the only sign in the very young)
- Paraplegia
What may chronic myelitis lead to?
Bone destruction
What investigations are taken for a suspected osteomyelitis?
- Blood culture - not often positive - 3 need to be taken at different times (may be negative early on)
- X ray - may not be sensitive enough
- MRI/CT/Bone scan
- Pus - may not be acquired
- Operative sample (may not be obtained)
What is the standard empirical therapeutic regimen to treat osteomyelitis?
Flucloxicillin with Fucidin (Flucloxicillin doesn’t get in to the bone well)
What is used to treat osteomyelitis if the patient is B lactate allergic?
Fucidin and erythromycin or rifampicin
What is used to treat osteomyelitis if salmonella is responsible?
Ciprofloxacin
What is used to treat osteomyelitis if tuberculosis is responsible?
Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
Aside from the use of drugs, how can osteomyelitis be treated?
Drainage/removal of involucrum
Which sites are most affected by septic arthritis?
- Knee
- Hip
- Lumbosacral spine (facets)
What are the predisposing conditions of septic arthritis?
- Rheumatoid arthritis- inflammation, more likely for th bugs to settle
- Injection of joint (taking bugs from outside to inside with it)
- Prosthetic joint (1- operative procedure, failure of sterile environment, 2- it is a foreign body which allows the organisms to settle)
What are the causative organisms of septic arthritis
- S. aureus
- S. pyogenes
- S. epidermis
- M. tuberculosis
- Salmonella
- Brucella
How is septic arthritis diagnosed?
- Blood culture x3
- Joint aspirate (removal of fluid around a joint with a needle and syringe)
- Joint X ray (more to plan treatment than to diagnose)
Post- infectious arthritides
I don’t understand this haha
What are the primary risk factors for prosthetic joint infection?
- Rheumatoid arthritis
- Diabetes mellitus
- Poor nutritional status
- Obesity
- Concurrent UTI
- Steroid therapy
- Malignancy
- Post-operative surgical site infection
- NNIS>0
What are the risk factors for a prosthetic joint (revision)
- Prior joint surgery
- Prelonged operative room time
- Preoperative infection
What are the causative organisms for an infection in a hip prosthetic? (main to least)
- Staphylococcus aureus
- Coagulase-negative staphylococci
- Streptococci
- Gram negative bacilli
- Anaerobic organisms
- Enterococcus
- Culture negative
- Polymicrobial
What are the causative organisms for an infection in a knee prosthetic? (main to least)
- Staphylococcus aureus
- Coagulase negative staphylococci
- Streptococci
- Gram negative bacilli
- Anaerobic organisms
- Enterococcus
- Culture negative
- Polymicrobial
What is Reiter’s Syndrome?
- Synovitis (inflammation of synovial membrane)
- Conjunctivitis
- Sacroiliitis (inflammation is sacroiliac joint(s))
- Aortitis (inflammation of the aortic wall)
- Circinate balinitis (skin lesions on penis)
- Keratoderma blennorrhagica (lesions)
- HLA B27
- Associated with chlamydial infection
