Bone and Joint Infections Flashcards Preview

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Flashcards in Bone and Joint Infections Deck (40):
1

Osteomyelitis

Infection of the bone

2

3 mechanisms of how bone infection may be brought about

Haematogenous- bacteria in the blood seed bone
Contiguous focus-spread from adjacent area of infection
Direct incoculation-trauma or surgery

3

Stage 1 of osteomyelitis and likely cause

Medullary-necrosis of medullary contents- haematogenous

4

Stage 2 of osteomyelitis

Superficial-necrosis limited to exposed surfaces

5

Cause of stage 2 superficial osteomyelitis

Contiguous- Diabetic foot ulcer, pressure sores

6

Complications of stage 3

Necrosis- no blood supply- can't treat with antibiotics. Surgery required to cure

7

Stage 3 osteomyelitis

Localised- full thickness cortical sequestation, stable before and after debridement

8

Stage 4 osteomyelitis

Diffuse- extensive, unstable bone

9

describe the pain with osteomyelitis

localised pain, not relieved with resting and progressive


10

Clinical presentation of osteomyelitis

Pain
Soft tissue swelling
Erythema
Warmth
Localised tenderness
Reduced movement of affected limb
Systemic upset uncommon (fever, chills, night sweats)

11

Most common causative organism of osteomyelitis (60%)

Staph A

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6 main causative organisms of osteomyelitis

Staph A
Stretococci
Enterococci
Gram -ve bacilli
Anaerobes
M. TB

13

Gold standard diagnostic procedure for osteomyelitis

Cultures and histology of bone biopsy/needle aspirate

14

Name 4 diagnostic tests for osteomyelitis

Gold standard
Blood cultures
Superficial swabs
C-reactive protein

15

When would you give empirical antimicrobial therapy in osteomyelitis?

When signs of sepsis

16

Which 5 antibiotics have acceptable penetrance in bone?

Clindamycin
Ciprofloxacin
Vancomycin
Beta-Lactam
Gentamicin

17

What is the treatment of choice for Staph A. osteomyelitis

Flucloxacillin IV

18

How are antibiotics usually administered in osteomyelitis?

IV

19

Septic arthritis

Inflammatory reaction in joint space (arthritis) caused by infection, resulting from direct invasion of the joint

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2 classifications of septic arthritis

Native (natural) joint infection
Prosthetic (artificial) joint infection

21

2 ways in which organisms enter the joint in native joint infection

Haematogenous or trauma

22

How does synovial tissue facilitate 'seeding'?

Highly vascular and lacks a basement membrane

23

Predisposing factors for native joint infection

RA
Trauma
IVDU
Immunosuppressive disease

24

Prognosis for native joint infection

Not fatal but severe lack of function if not treated

25

How do organisms enter the joint in prosthetic joint infections?

Haematogenous
During surgery or following wound infection after surgery

26

Why are prosthetic joints susceptible to infection?

Cement provides a surface for bacterial attachment

27

How does infection affect the joint in prosthetic infection?

Polymorph infiltration results in tissue damage instability of the prosthesis

28

How does infection affect the joint in native infection?

Cartilage erosion causes joint space narrowing/impaired function

29

Predisposing factors to prosthetic joint infection

Prior surgery at site
RB
Corticosteroid therapy
DM
Poor nutritional status
Obestiy
Age

30

Clincial presentation of septic arthritis

Pain
Swelling
Tenderness
Redness
Limitation of movement
Systemic upset

31

Causative organisms of septic arthritis

Bacteria
Fungi e.g. candida
Viruses e.g. parovirus B19, rubella, mumps (usually self limiting part of systemic illness)

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Name for group A streptococcus

Strep. pyogenes

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Causative organisms for native joint infections

Staph A
Streptococci A, B, C, G
Gram -ve bacilli
Neisseria gonorrheoae
Neisseria meningitidis

34

Causative organisms for prosthetic joint infection

Staph A
Coagulase -ve staphylocoi
Enterococci
Gram -ve bacilli

35

What do you look for in an examination of joint aspirate?

High total WBCs
Lots of polymorphs
Gram stain- not particularly reliable
Crystal examination- gout can mimic infection
Culture
PCR e.g. M.TB

36

Therapy for native joint infection

Removal of purulent material -joint drainage/washout
Empirical followed by directed antimicrobial therapy (after microbiological samples have been taken)
2-4 weeks treatment

37

Difference in therapy for prosthetic joint infection, compared to native

Removal of implant/replacement of some elements if unstable

38

2 stage revision procedure

Take out implant and replace with cement and antimicrobials before replacing

39

Treatment for Staph A in prosthetic joint infection

Flucoxacillin with rifampicin (Staph A. easily becomes resistant to rifampicin, so must always be used in combination for Staph A)

40

Duration of treatment for prosthetic joint infection

6 weeks, IV to oral switch