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Year 2 - Musculoskeletal (DP) > Microbiology > Flashcards

Flashcards in Microbiology Deck (59):
1

What organisms are typically involved in a prosthetic joint infection?

Coagulase negative Staph
Staph aureus
Strep spp
Propionibacterium acnes

2

What organisms typically cause septic arthritis?

Staph aureus
Strep spp

3

What organisms tend to be responsible for post-traumativ infections?

Staph aureus
Polymicrobial
Coliforms
Pseudomonas

4

What bacteria are often involved in vertebral osteomyelitis?

Staph aureus
Coliforms
Strep spp
Mycobacterium tuberculosis

5

What organisms typically cause diabetic foot infections?

Staph aureus
Strep spp
Coliforms
Pseudomonas
Anaerobes

6

What bacteria is a less common infective organism but is more common in kids under 5 years old?

Kingellin

7

A 3 year old child presents with pain in his right hip. his mother says he hasn't been feeding very well. On examination his temperature is 39.1, and there is obvious swelling and erythema over his right hip. Any attempt to touch or move the hip is met with obvious pain.

Acute bone and joint infection

8

How do we classify Systemic Inflammatory Response Syndrome (SIRS)?

Two or more of:
- Temperature >38 or 20 or PaCO2 12,000 cells/mm^3 OR 90

9

What are some rarer causes of septic arthritis?

Haemophilus influenzae
Neisseria gonorrhoea

10

When would a blood culture be carried out?

If the patient is pyrexial

11

What is the empiric treatment for septic arthritis in:
1. Adults
2. Kids

1. High dose flucloxacillin
2. High dose flucloxacillin and ceftriaxone

12

How long does septic arthritis treatment continue?

2-4 weeks

13

What is osteomyelitis?

Inflammation of bone and medullary cavity

14

Where does osteomyelitis tend to occur?

Long bones
Vertebrae

15

What are acute causes of osteomyelitis?

MSSA
Strep spp

16

What bacteria may cause chronic osteomyelitis?

Mycobacterium tuberculosis
Pseudomonas
Salmonella
Brucella
Coliforms

17

How long does acute osteomyelitis last?

Few days to

18

How might osteomyelitis spread into the joint space?

Since metaphysis is intracapsular in these joints:
- Shoulder
- Ankle
- Hip
- Elbow

19

Why are infants at an increased risk of septic arthritis after osteomyelitis?

Vessels cross into epiphysis

20

What processes occur that may lead to chronic osteomyelitis?

1. Abscess
2. Permanent damage
3. Septicaemia

21

Why is there not an immediate need for antibiotics in chronic osteomyelitis?

SIRS is usually absent

22

When would we start antibiotics in chronic osteomyelitis?

Once we achieve culture results

23

What is the empiric treatment for osteomyelitis?

High dose flucloxacillin:
- Modify after culture
- 4 to 8 weeks

24

Which of the following is not a risk factor for a prosthetic joint infection:
- RA
- DM
- Malnutrition
- URTI
- Obesity

URTI

25

What are the three types of implant infection?

Early postoperative (0-3 months)
Delayed (Low grade) (3-24 months)
Late (> 24 months)

26

A patient presents with persistent pain in her left hip. She had a hip replacement 18 months ago. She is a diabetic and has a BMI of 32.

Delayed PJI

27

What features of CoNS make them difficult to treat?

Produce a biofilm over prosthesis

28

What cultures may aid in the diagnosis of a PJI?

Tissue and bone (multiple)

29

How do we treat a PJI?

Remove prosthesis and cement
Treat with antibiotics
Wait > 6 weeks until joint is re-implanted

30

How do we treat necrotising fasciitis?

Surgical debridement
Empirical antibiotics (Strep pyogenes):
- Penicillin - Kills bacterial
- Clindamycin - Reduces toxin production

31

What bacteria causes gas gangrene?

Clostridium perfringens:
- Gram positive bacilli
- Strictly anaerobic

32

What is the pathogenesis of gas gangrene?

1. Spores in bowel/environment
2. Spores move into tissue
3. Spores germinate
4. Gas bubble accumulation
5. 'Crepitus'

33

What factors predispose to gas gangrene?

Dead tissue
Anaerobic conditons

34

How is gas gangrene treated

1. Urgent surgical debridement
2. High dose antibiotics
- Penicillin
- +/- Metronidazole
3. +/- Hyperbaric oxygen

35

What causes tetanus?

Clostridium tetani:
- Gram positive bacilli
- Strictly anaerobic

36

Where are the spores that cause tetanus found?

Soil
Gardens
Animal bites

37

What happens in tetanus?

1. Neurotoxin produced
2. Neurotoxin binds to inhibitory neurones
3. Neurotransmitter release prevented
4. Spastic paralysis

38

Are the bacteria that cause tetanus invasive?

No
(All toxin driven)

39

How is tetanus treated?

Surgical debridement
Antitoxin
Supportive measures
Antibiotics:
- Penicillin
- Metronidazole
Booster vaccine:
- 2, 3 and 4 months

40

What are the choice antibiotics for Staph and Strep?

Flucloxacillin
Vancomycin
Clindamycin

41

What other uses exist for vancomycin?

Diphtheroids
CoNS
MRSA
If penicillin allergic

42

What is clindamycin effective in?

Antitoxin:
- PVL
- GAS

43

What antibiotic choices treat coliforms?

Gentamicin
Cephalosporins:
- Ceftriaxone
Sometimes PO ciprofloxacin

44

What is a biofilm composed of?

Protein
Polysaccharide

45

What does a biofilm do?

Protects bacteria from:
- Immune system
- Antibiotics

46

What environment does a biofilm produce?

Low pH - 5
Reduced oxygen
Free nucelic acids

47

What is the Tayside Protocol for PJI?

1. No pre-op antibiotics
2. Minimum three bone/tissue/pus culture samples
3. Minimum 6 weeks antibiotics before clean surgery

48

Why do we take three bone samples for culture?

Superficial swabs useless
Bone samples can be contaminated with skin flora
Some infections caused by skin flora:
- eg. CoNS

49

What is the Tayside Protocol for PJIs caused by gram positive bacteria?

Flucloxacillin
If penicillin allergic - Vancomycin
If MRSA - Teicoplanin

50

What is the Tayside Protocol for PJIs caused by gram negative bacteria?

Cot-trimoxazole OR
Amoxicillin OR
Ciprofloxacin OR
Ceftriaxone

51

How long do the following antibiotic treatments last:
1. DAIR (Debridement, Antibiotics, Irrigation, Retention of prosthesis)
2. One stage
3. Two stage
4. Hip PJI
5. Knee PJI

1. 4 weeks IV then 8 weeks PO
2. 4 weeks IV then implant then 8 weeks PO
3. 6 weeks IV then 6 weeks nothing then implant
4. Treatment minimum 3 months
5. Treatment minimum 6 months

52

How can we assess response in PJI?

Repeat MRI/CT

53

How long til we can be sure a PJI has been cured?

> 2 years

54

What are the general principles for surgical prophylaxis (SIGN 104)?

1. 1st dose within 60 minutes of start of procedure
2. Prophylaxis should not last > 24 hours
3. Needs to be in tissue at time of surgery and cover relevant pathogens

55

When is surgical prophylaxis used in orthopaedics?

Prosthetic joint implant:
- Co-amoxiclav
> 1.2g peri-operatively
> Plus two post-operative doses

56

What do we do if MRSA is discovered pre-op?

Decolonise
Restart peri-op antibiotics

57

What surgical prophylaxis is used if a patient is penicillin allergic?

Co-trimoxazole

58

What type of vaccine is used to prevent tetanus?

Toxoid

59

If a patient was bitten by a dog during a trip to India what other vaccination should be considered?

Rabies