Bone and joint infections

Question 1

What is osteomyelitis?

Answer 1

Infection of the bone

Question 2

What is meant by osteomyelitis being a hetrogeneous disease?

Answer 2

many causes
Many areas of the body that it can occur in
Many types of people can be affected

Question 3

What are the 3 ways that osteomyelitis can occur (pathogenesis)? Give examples

Answer 3

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

Question 4

What are the 4 stages of osteomyelitis?

Answer 4

Stage I - Medullary
Stage 2 - Superficial
Stage 3 - Localised
Stage 4 - Diffuse

Question 5

In Stage III or IV, why are antibiotics alone not useful?

Answer 5

No blood supply present
Therefore antibiotics will not reach the bone
Surgery required to get rid of necrosis

Question 6

What is the clinical presentation of osteomyelitis?

Answer 6

Pain - localised, nocturnal, not mechanical, progressively worse
Reduced movement
Classical symptoms of inflammation not that common
Systemic symptoms uncommon

Question 7

What are the 2 most common organisms that cause osteomyelitis?

Answer 7

Staphylococcus aureus

Streptococci (A/B)

Question 8

What is the gold standard method of diagnosing the pathogen causing osteomyelitis?

Answer 8

cultures and histology of bone biopsy/needle aspirate

Question 9

What is a potential disadvantage of using biopsy/aspiration to culture pathogens and what alternative can be used?

Answer 9

Invasive

Blood cultures effective around 50% of the time

Question 10

What form are antibiotics given in treatment for osteomyelitis?

Answer 10

IV as penetration into the bone is low

Question 11

What is empirical treatment?

Answer 11

Giving antibiotics before you know the cause - broad spectrum
Relevant in some cases but not for osteomyelitis

Question 12

What pathogen does clindamycin normally target? How is it given?

Answer 12

Orally
Staphococci
Beware of C.Diff risk

Question 13

What pathogen does ciprofloxacin normally target? How is it given?

Answer 13

Orally

Gram -ve

Question 14

What pathogen does Flucloxacillin target?

Answer 14

Staphylococcus aureus

Question 15

What is the definition of septic arthritis?

Answer 15

Inflammatory reaction in the joint space
Caused by infection
Results from direct invasion of the joint

Question 16

What are the 2 types of septic artheritis? And how do they come about?

Answer 16

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

Question 17

What is the clinical presentation of septic arthritis?

Answer 17

Typical symptoms of inflammation:
Pain, tenderness, swelling, redness, limitation of movement
Systemic i.e. fever, chills, night sweats

Question 18

Which viruses can cause septic arthritis?

Answer 18

Parvovirus B19
Rubella
Mumps

Question 19

What 3 bacterial pathogens cause Native joint infection?

Answer 19

Staphylococcus aureus
Streptococci
Haemophilus influenza - less common now due to vaccine

Question 20

What 3 bacterial pathogens cause prosthetic joint infection?

Answer 20

NORMAL SKIN FLORA
Staphylococcus aureus
Coagulate negative staphylococci (CoNS)
Streptococci

Question 21

What is analysed to diagnose septic arthritis?

Answer 21

Joint aspiration
White cell count - inc polymorphs. Not diagnostic
Gram stain
Crystal examination
Culture
PCR

Question 22

What is the treatment for native septic arthritis?

Answer 22

Washout - removal of purulent material

Antibiotics

Question 23

What is the treatment for prosthetic septic arthritis?

Answer 23

Removal of implant if loose - add antibiotic cement until treated
If not loose, remove specific parts
Washout
IV antibiotics