Bone Infection Flashcards Preview

Jonathan's Locomotor > Bone Infection > Flashcards

Flashcards in Bone Infection Deck (26):
1

What's the clinical term for infection of the bone?

osteomyelitis

2

What are the three ways of getting osteomyelitis

Haematogenous
Non-haematogenous direct (fracture/surgery)
Non-haematogenous through local invasion (ulcers)

3

What's the pathogenesis of bone infection

Usually, bacteria enters the looped capillaries for metaphysis. They get stuck at micro-capillaries near the sinusoids, forming abscess resistant to immune clearance. From there, it can spread to outer layer to cause periosteal lifting

4

What are some factors causing the lack of clearance of bacteria in bone?

stuck in and block micro-capillaries
Abscess protected from immune system
pressure from pus limits blood supply

5

What's the most common causative agent for bone infection

Staph aureus

6

Which strep species causes beta-haemolysis?

Strep pyogenes

7

T/F Alpha-haemolysis is complete haemolysis with greening of the plate

False, beta-haemolysis is complete haemolysis, characterised by transparent clearing around the colony

8

Which haemolysis is characterised by greening?

alpha!

9

Which species can cause alpha-haemolysis?

Strep pneumoniae

10

What are the commonest causative agents for osteomyelitis in newborn

Group B strep
Haemophilus influenzae
E Coli
Pseudomonas

11

What are the commonest causative agents for osteomyelitis in post-surgery individual?

coagulase negative staphylococcus

12

What are the commonest causative agents for osteomyelitis in post-chicken pox individual?

Strep pyogenes

13

What are the commonest causative agents for osteomyelitis in an individual with penetrating foot injury?

pseudomonas

14

What are the commonest causative agents for osteomyelitis in developing countries

TB
Haemophilus influenzae type B

15

The route of bone infection can be different in adults vs. infants. How is that case?

infants have communicating vessels across growth plates, providing a passage for bacteria to invade into diaphysis + medullary cavity

16

What are some general clinical presentations for osteomyelitis

pain, fever, warm, inflammation, swelling, limping in children

17

What are the commonest bones for osteomyelitis

humerus, femur, tibia
(long bones)

18

What are some differential diagnosis for osteomyelitis?

septic arthritis
malignancy
cellulitis

19

T/F Blood culture is the most definitive diagnosis for osteomyelitis

False, by the time the person presents with symptoms, bacteria have mostly been cleared from blood

20

What are the two inflammatory markers useful for diagnosing osteomyelitis? How do they differ in terms of timeframe

CRP and ESR
CRP goes up quickly in the first few hours and comes down in a few weeks

ESR rises much slower and goes down slowly as well

21

Is X ray a good technique for diagnosing osteomyelitis?

Yes only if it's late stage detection

22

What's the best test for osteomyelitis?

MRI

23

What's the treatment for gram +ve bacterial infection of bone

IV, high dose flucloxacillin

24

Which generation of cephalosporin is best for
1) gram +ve bacteria
2) gram -ve bacteria

1) 1st gen
2) 3rd gen

25

What's the treatment for neonatal H. influenzae bone infection

flucloxacillin
cefotaxime
can add rifampicin for synergy

26

How long should the treatment be for osteomyelitis

3-5 days IV antibiotics + 3 week course with oral antibiotics in uncomplicated cases