Bone and Joint infections

Question 1

How do organisms get into the bone?

Answer 1

• Haemotogenous spread
• Local spread (septic arthritis)
• Compound fracture
• Foreign bodies

Question 2

What do people with sickle cell disease have a predisposition to?

Answer 2

Salmonella

Question 3

What do people who have travelled or were foreign born have a predisposition to?

Answer 3

Brucella

Question 4

What fo people who have a prothesis have a predisposition to?

Answer 4

S. epidermis

Question 5

What do children under 5 have a predisposition to?

Answer 5

H.influenzae

Question 6

What do people who have a UTI have a predisposition to?

Answer 6

E. coli and others

Question 7

What is osteomyelitis?

Answer 7

An infection of the bone

Question 8

Which bones are affected by osteomyelitis?

Answer 8

• Humerus (8-10%)
• Femur (30-35%)
• Tibia (25-30%)
• Fibula (5%)
• Calcaneum (10-12%)

Question 9

Describe haematogenous spread to the bones

Answer 9

• Usually asymptomatic
• Skin sepsis may be present but it is usually absent
• Organisms tend to settle in the growing metaphysis

Question 10

How do foreign bodies enter the bone?

Answer 10

• Trauma
• Shrapnel/Gun shot wounds
• Orthopaedic implants

Question 11

Which are the 3 main organisms responsible for osteomyelitis?

Answer 11

• S. aureus (>80%)
• S. pyogenes (~5%)
• M. tuberculosis

Question 12

What are the symptoms and signs of osteomyelitis?

Answer 12

• Painful swollen site
• Fever
• Reduced movement (may be the only sign in the very young)
• Paraplegia

Question 13

What may chronic myelitis lead to?

Answer 13

Bone destruction

Question 14

What investigations are taken for a suspected osteomyelitis?

Answer 14

• 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)

Question 15

What is the standard empirical therapeutic regimen to treat osteomyelitis?

Answer 15

Flucloxicillin with Fucidin (Flucloxicillin doesn’t get in to the bone well)

Question 16

What is used to treat osteomyelitis if the patient is B lactate allergic?

Answer 16

Fucidin and erythromycin or rifampicin

Question 17

What is used to treat osteomyelitis if salmonella is responsible?

Answer 17

Ciprofloxacin

Question 18

What is used to treat osteomyelitis if tuberculosis is responsible?

Answer 18

Isoniazid, Rifampicin, Pyrazinamide, Ethambutol

Question 19

Aside from the use of drugs, how can osteomyelitis be treated?

Answer 19

Drainage/removal of involucrum

Question 20

Which sites are most affected by septic arthritis?

Answer 20

• Knee
• Hip
• Lumbosacral spine (facets)

Question 21

What are the predisposing conditions of septic arthritis?

Answer 21

• 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)

Question 22

What are the causative organisms of septic arthritis

Answer 22

• S. aureus
• S. pyogenes
• S. epidermis
• M. tuberculosis
• Salmonella
• Brucella

Question 23

How is septic arthritis diagnosed?

Answer 23

• 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)

Question 24

Post- infectious arthritides

Answer 24

I don’t understand this haha

Question 25

What are the primary risk factors for prosthetic joint infection?

Answer 25

* Rheumatoid arthritis * Diabetes mellitus * Poor nutritional status * Obesity * Concurrent UTI * Steroid therapy * Malignancy * Post-operative surgical site infection * NNIS>0

Question 26

What are the risk factors for a prosthetic joint (revision)

Answer 26

* Prior joint surgery * Prelonged operative room time * Preoperative infection

Question 27

What are the causative organisms for an infection in a hip prosthetic? (main to least)

Answer 27

* Staphylococcus aureus * Coagulase-negative staphylococci * Streptococci * Gram negative bacilli * Anaerobic organisms * Enterococcus * Culture negative * Polymicrobial

Question 28

What are the causative organisms for an infection in a knee prosthetic? (main to least)

Answer 28

* Staphylococcus aureus * Coagulase negative staphylococci * Streptococci * Gram negative bacilli * Anaerobic organisms * Enterococcus * Culture negative * Polymicrobial

Question 29

What is Reiter's Syndrome?

Answer 29

* 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