MSK microbiology 03/10/18 Flashcards

1
Q

What is osteomyelitis?

A

Inflammation of bone and medullary cavity

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2
Q

What bones does osteomyelitis usually occur in?

A

long bones

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3
Q

How can osteomyelitis be classified?

A

Acute/Chronic
Contiguous/Haematogenous
Host status

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4
Q

What is the generic treatment for infection?

A

Debridement

Antimicrobials

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5
Q

If you can see a tendon in an open wound or see a bone in a swab what is the diagnosis?

A

Osteomyelitis

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6
Q

What is the gold standard for osteomyelitis?

A

Bone biopsy

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7
Q

Is osteomyelitis a medical emergency?

A

No

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8
Q

When are emperic antibiotics needed in osteomyelitis?

A

NOT UNLESS SEPTIC

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9
Q

Is bone resistant to infection?

A

Yes, very

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10
Q

When can bone infection occur?

A

Necrosis/High inoculum

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11
Q

How long does debrided bone take to be covered by soft tissue?

A

6 weeks

I.e. 6 weeks of treatment

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12
Q

What are the principles of surgery?

A

Remove infected tissue
Drain
Debride

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13
Q

Where does infection of the bone tend to happen?

A

Prosthetic joints - Co-Ag negative staph (epidermidis)
Vertebral osteomyelitis
Post-Traumatic infection
Diabetic foot infection

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14
Q

When does Coag -ve staph become a problem?

A

Any patient with a metal/plastic prosthetic

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15
Q

What are appropriate cultures for osteomyelitis?

A

Percutaneous aspirate

Deep surgical cultures

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16
Q

Who is likely get osteomyelitis?

A
Open fractures
Diabetes/Vascular insufficiency
Haematogenous osteomyelitis
Vertebral osteomyelitis
Prosthetic joint infection
Specific hosts and pathogens
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17
Q

What is early managent of open fracture infections?

A

Aggressive debridement

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18
Q

When is a diabetic wound more likely to get infected?

A

> 2cm for >2months

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19
Q

In diabetic osteomyelitis is it usually one or multiple organisms?

A

Many

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20
Q

What is the type of investigation for diabetic osteomyelitis?

A

Probe to bone (90% specific)

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21
Q

Can an X-ray show changes of osteomyelitis?

A

Yes but only if its been there a long time

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22
Q

What is the best imaging for osteomyelitis?

A

MRI

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23
Q

What is the treatment for sever diiabetic foot ulcer?

A

Gentamicin
Flucloxacillin (vancomycin if Penicillin allergic)
Metronidazole

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24
Q

What is the time frame for Mild, moderate and severe diabetic foot ulcer?

A

7 days
7 days
7-10 days

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25
Q

How long is the treatment for osteomyelitis?

A

6 weeks

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26
Q

What are antibiotics for Gram +ve organisms?

A

Flucloxacillin
Vancomycin
Doxycycline (oral switch)

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27
Q

What are gram -ve antibiotics organisms?

A

Gentamicin/Aztreonam IV

Oral Cotrimoxazole/Doxycyline (oral switch)

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28
Q

What is the treatment for anaerobes?

A

Metronidazole

29
Q

Why is oral switch important?

A

Some antibiotics are not absorbed the same when switched from IV to Oral (vancomycin)
IV antibiotics are expensive and time consuming

30
Q

When is a psuedomonas culture likely to be treated as a causitive organism?

A

The context
Bone biopsy, blood or sputume - yes
Sinus fluid or skin swab - No

31
Q

What organsims are never really ignored?

A

Staph aureus

Group A,B,C or G strep

32
Q

What kind of people get Haematogenous osteomyelitis?

A

Prepubertal children
PWID
Central Lines
Elderly

33
Q

With Haematogenous osteomyelitis is sepsis more or less likely than in osteomyelitis?

A

Yes

34
Q

Where is the most common place for Haematogenous osteomyelitis to occur?

A

Femur

35
Q

If staph aureus is present what should be taken out if present?

A

IV line

36
Q

What should be checked for in staph aureus infection?

A

Endocarditis

37
Q

What types of osteomyelitis can PWID contract?

A

Contiguous
Haematogenous
Direct inoculation

38
Q

Where do PWID get osteomyelitis?

A

Unusual site
SCJ
SChoJ
Pubic Symphusis

39
Q

What kind of osteomyelitis is occurs in patients with sickle cell?

A

Acute long bone osteomyelitis

40
Q

What is gauchers disease?

A

Lysosomal storage disese

41
Q

Where does bone infection usually occur in gauchers?

A

Tibia

42
Q

What type of osteomyelitis is vertebral and what is it associated with?

A
Haematogenous
May be associated with epidural or psoas absess
PWID
IV infections
GU infections
SSTI
43
Q

What percentage of patients with osteomyelitis have a fever?

A

50%

44
Q

What percentage of patients with osteomyelitis have insidious pain and tenderness?

A

95%

45
Q

What comes first, biopsy or antibiotics?

A

Biopsy

46
Q

Do antibiotics get into pus?

A

No

47
Q

When is MRI repeated?

A

Unexplained increase in inflammatory markers
Increasing pain
New anatomincally related signs and symptoms

48
Q

Why is MRI repeat not always accurate?

A

Lags behind

Resolution is occuring but not shown until after

49
Q

What is the name of vertebral TB?

A

Potts disease

50
Q

Is Potts disease infection and does it have systemic symptoms?

A

No

51
Q

What should be checked in kids and Adults in TB?

A

Kids - INF-y R1, IL12 beta 1

Adults - HIV

52
Q

What are risk factors in prosthetic joint infection?

A

Rheumatoid arthritis
Diabetes
Malnutrition
Obesity

53
Q

Why were the obese prophylaxis treatments changed?

A

Set for 70kg

To stop people from getting inadequate dosing

54
Q

What is the mechanism of prosthetic joint infection?

A

Direct inoculation at time of surgery
Manipulation of joint at time of surgery
Seeding of joint at later time

55
Q

What are the classifications for early and late prosthetic joint infections?

A

Early < Month

Late > Month

56
Q

What is biofilm?

A

Community of bacteria that are very difficult to penetrate with antibiotics
That grow slowly covering the prosthetic joint

57
Q

What are the pathogens common in prosthetic joint infection?

A
Staph aureus
Staph epidermidis
Propionibacterium acnes (upper limb)
E.coli
Pseudomonas
58
Q

How are prosthetic joint infections diagnosed?

A

Multuple cultures of perioperative tissue
(if same organism is present this increases significance)
Blood cultures can also be useful
CRP
Radiology

59
Q

What is the treatment of prosthetic joint infections?

A

Removal of prosthetic and cement
6 week therapy
Re-implantation of the joint after aggressive antibiotic therapy
(Depends on the patient context)

60
Q

What is the treatment of prosthetic joint infections?

A

Removal of prosthetic and cement
6 week therapy
Re-implantation of the joint after aggressive antibiotic therapy
(Depends on the patient context)

61
Q

How is PVL noticed?

A

More sick than you expect

Necrotising bacteriaema

62
Q

What causes pyomyositis?

A

90% staphylococcal

Can be tropical

63
Q

What are the 3 types of myositis?

A

Viral - HIV, HTLV, Influenza, CMW, Rabies, Chikungunya and other arboviruses
Fungal
Parasites

64
Q

What is the most common infective cause of seizures?

A

Taenia (when it cysts in the brain)

65
Q

What is the causitive organism of tetanus and what is its characteristics?

A

Clostridium tetani
Gram +ve anaerobic rods
Spore forming

66
Q

What does clostridium tetani produce?

A

Neurotoxin causes spastic paralysis

67
Q

What is the incubation period for clostridium tetani?

A

4 days - several weeks

68
Q

What is shown on culture of clostridium tetani?

A

Anaerobic gram +ve
Terminal drumstick shaped sors
Serum and urine toxin assays

69
Q

What is the treatment of tetanus?

A
Surgical debridement
Antitoxin
Supportive measures - early intubatiions, beta blockers
Antibiotics for 7 to 10 days
Penicillin/Metroniadazole
Booster Vaccination