56 Bone and joint infections Flashcards Preview

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Flashcards in 56 Bone and joint infections Deck (26)
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1
Q

What are the three types of bone infection pathogenesis?

A

Haematogenous.
Contiguous focus (spread from adjacent area).
Direct inoculation.

2
Q

What are the four classifications of osteomyelitis?

A

I. Medullary (haematogenous).
II. Superficial (contiguous).
III. Localised: full thickness, stable.
IV. Diffuse: unstable bone.

3
Q

How does osteomyelitis present? (2 + 4).

A

Pain.
Reduced movement of affected limb.
(Soft tissue swelling, erythema, warmth, tenderness).

4
Q

Which organisms cause osteomyelitis? (7).

A
Staphylococcus aureus (60%)
Streptococci.
Enterococci.
Gram -ve bacilli.
Anaerobes.
Mycobacterium tuberculosis, Brucella (indolent spinal).
5
Q

Who gets gram -ve bacilli osteomyelitis? (3).

Organisms? (3).

A

Premature babies, IVDU’s, sickle cell.

Salmonella, Klebsiella, Pseudomonas aeruginosa.

6
Q

How is osteomyelitis diagnosed?

A

Gold standard: cultures + histology of bone biopsy.

Blood cultures +ve in 50%.

7
Q

What is C-reactive protein used for in osteomyelitis?

A

Monitor therapy response.

Limited diagnostic value.

8
Q

In general, how is osteomyelitis treated?

A

IV antimicrobials ± surgery.

Avoid empirical therapy.

9
Q

Which antimicrobials achieve acceptable levels in bone? (5)

A
Clindamycin.
Ciprofloxacin.
Vancomycin.
ß-lactams.
Gentamicin.
10
Q

What is the agent of choice for staph aureus osteomyelitis?

A

Flucloxacillin.

11
Q

Define septic arthritis:

A

Inflammatory reaction in a joint space caused by infection.

12
Q

What is the pathogenesis of a native joint infection?

A

Entrance via blood or trauma.

Synovial tissue is highly vascular and lacks basement membrane -> seeding.

13
Q

What are the predisposing factors to a native joint infection? (4).

A

Immunosuppressive disease.
Intravenous drug use.
Trauma.
Rheumatoid arthritis.

14
Q

What is the pathogenesis of a prosthetic joint infection? (3).

A

Prosthesis/cement provides base for infection.

Phagocytosis difficulty due to biofilm. Macrophages secreting enzymes causes joint instability.

15
Q

What are the predisposing factors to a prosthetic joint infection? (7).

A
Prior surgery.
RA.
Corticosteroid therapy.
Diabetes mellitus.
Poor nutrition.
Obesity.
Advanced age.
16
Q

How does septic arthritis present? (4 + 3).

A

Joint: pain, swelling, tenderness, redness, limited movement.
Fever, chills, night sweats.

17
Q

Which viruses can cause septic arthritis (3) and when?

A

Parvovirus B19, Rubella, Mumps.

As part of systemic illness.

18
Q

Which organisms cause septic arthritis? (5).

A
Staph aureus.
Streptococci.
Gram -ve bacilli.
Anaerobes: peptostreptococci, peptococci.
Mycobacteria.
19
Q

Which organisms specifically cause native septic arthritis? (3).

A

Haemophilus influenzae.
Neisseria gonorrhoea.
Neisseria meningitidis.

20
Q

Which organisms specifically cause prosthetic joint infection? (through contamination from skin) (5)

A
Coagulase negative staphylococci.
Enterococci.
Corynebacteria.
Propionibacteria.
Bacillus spp.
21
Q

Which test is used to exclude gout as a differential with septic joint infection?

A

Crystal examination.

22
Q

How is septic arthritis diagnosed? (4).

A
Joint aspirate exam:
Raised WCC > 75% polymorphs.
Gram stain.
Culture.
? PCR.
23
Q

How is native joint infection treated? (2).

A

Joint drainage/washout.

Empirical then directed IV antimicrobial therapy for 2-4weeks.

24
Q

How is prosthetic joint infection treated?

A

Removal or replacement of prosthesis.

Empirical then directed IV antimicrobial therapy for 6 weeks.

25
Q

Which antimicrobials are used for a prosthetic joint infection with S.aureus?

A

Flucloxacillin plus rifampicin.

26
Q

Which antimicrobials are used for a prosthetic joint infection with coagulase negative staphylococci?

A

Vancomycin IV plus rifampicin.

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