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Flashcards in Bone Infections Deck (31):
1

What is the most common infecting agent in acute osteomyelitis?

Staph aureus
haemophilus in children
Strep

2

How does acute osteomyelitis occur?

Most post-traumatic/ open fracture
In children or immunosuppressed by haematogenous spread

3

On x-ray what does acute osteomyelitis look like?

Dying necrotic inflammatory tissue

4

What should you do if there is pus?

Let it out!

5

What is the term used to describe the mass that often grows in chronic osteomyelitis?

Involucrum

6

How does septic arthritis occur?

innoculation
metaphyseal spread
Direct haematogenous spread

7

Describe the clinical picture of a joint with septic arthritis?

Severely painful, red, hot, swollen and tender joints with limited movement

8

What are the most common infecting organisms in septic arthritis?

1. Staph aureus #1
2. Streptococci
3. Coagulase negative strep – prosthetic joint
4. Neisseria gonorrheae – sexually active
5. Haemophilus influenzae – preschool – uncommon as HIB vaccine

9

What Ix are required in suspected septic arthritis?

History and examination
Joint aspiration M,C and S
Blood culture if pyrexial- organisms may spill into blood causing bacteraemia
Exclude crystal arthropathy

10

What AB are given for septic arthritis?

Flucloxacillin IV high dose and adjust when organisms are confirmed
If <5yo add cefriaxone to cover H. influenzae

11

What bugs are involved in chronic osteomyelitis?

often slow growing – Mycobacterium TB, Pseudomonas aeruginosa, salmonella, brucella and coliforms (E.coli)

12

What AB should be given for cellulitis?

Cover staph and strep
Flucloxacillin and benzylpenicillin

13

What kinds of surgery can be used for an infected arthroplasty?

Two stage revision 80-90% control of infection

One stage revision (rarely done) 70-80%

14

List some prophylactic measures that can be used to decrease the risk of an arthroplasty becoming infected during surgery.

Laminar flow
24 hours antibiotics starting with induction
Antibiotics in cement
Good hand washing
Good surgical technique

15

How do prosthetic joints become infected?

Early – within a month – with haematoma/ wound sepsis
Late – after one month – contamination at time of operation

16

LIst some risk factors for an arthroplasty becoming infected.

Rheumatoid arthritis
obesity
diabetes
malnutrition

17

If the arthroplasty is infected with staph epidermidis, which antibiotic should be given?

Vancomycin initially

18

What actually is osteomyelitis?

Inflammation of bone and medullary acvity, usually located in long bones.

19

What antibiotic is given initially in osteomyelitis?

High dose flucloxacillin

20

What is necrotizing fasciitis?

Uncommon severe infection of the subcutaneous soft tissue – spreads through fascial planes - medical emergency

21

What are the two types of necrotizinf fasciitis?

Type 1 - anaerobes plus multiple other bacteria "synergistic gangrene"
Type 2 - "flesh eating bacteria"

22

What is the immediate treatment for necrotizing fasciitis?

Surgical debridement and Penicillin (Vanco if pen allergic) and Clindamycin

23

What organism causes gas gangrene?

Clostridium perfringens

24

How do the spores of C. perfringens cause gas gangrene?

Get into tissue by dirt getting in to open wound - normally trauma

25

What is the pathogenic process involved in gas gangrene?

myonecrosis – accumulation of gas bubbles in subcutaneous spaces  gas gangrene

26

What Tx is required for gas gangrene?

Urgent debridement
High dose Penicillin +/- Metronidazole +/- hyperbaric O2

27

What organism causes tetanus?

Clostridium tetani

28

What is the pathogenic process involved in tetanus?

C. tetani produces a neurotoxin --> spastic paralysis (lock jaw)

29

What Tx is required for tetanus?

Surgical debridement #1
Antitoxin
Supportive measures – respiratory intubation and ventilation
Antibiotics – Penicillin and Metronidazole
Booster vaccination (toxoid)

30

What is PVL producing staph aureus?

Toxin that destroys white blood cells

31

What Tx is required for an infection caused by PVL producing staph aureus?

Flucloxacillin, clindamycin, linezolid, depending on sensitivities