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Flashcards in Microbiology and Infections Deck (38)
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1
Q

List some clinical presentations of acute bone and joint infections

A

Temperature
Pain, redness, swelling
Reduced mobility

2
Q

Define SIRS

A
2+ of
Temp less than 36 or more than 38
Heart rate more than 90
Resp rate more than 20
PaCO2 less than 4.3kPa
WBC more than 12k or less than 4k
3
Q

What is septic arthritis? How can it be introduced?

A

Infection of the joint space

Blood spread, direct innoculation or from infected bone

4
Q

What are the main organisms that cause septic arthritis?

A

Staph. aureus

Streptococci

5
Q

List diagnostic investigations for septic arthritis

A

Blood culture if pyrexial
Blood tests
Joint fluid aspirate for microscopy/culture
USS, XR, CT bone

6
Q

What is the main empirical treatment for septic arthritis?

A

Flucloxacillin (Staph. aureus)

N.B. high-dose IV to maximise uptake

7
Q

If there is a child under 5yrs old with septic arthritis, which antibiotic should be added and why?

A

Ceftriaxone for H. influenzae/Kingella cover

8
Q

How long does antibiotic treatment for septic arthritis usually last?

A

2-4 weeks

9
Q

Which organisms cause chronic osteomyelitis?

A

Mycoplasma
Pseudomonas
Salmonella
Brucella (goat’s milk)

10
Q

Treatment and diagnosis of osteomyelitis is similar to septic arthritis. What is the key difference in terms of treatment length?

A

4-8 weeks duration of antibiotic treatment

11
Q

Which organisms cause type 1 necrotising fasciitis?

A

Mixed anaerobes and other bacteria

12
Q

Which organism causes type 2 necrotising fasciitis?

A

Group A Strep. (flesh-eating bacteria)

13
Q

List the mainstay treatment for necrotising fasciitis

A

Surgical debridement

Pencillin + clindamycin

14
Q

What is gas gangrene?

A

Spores forming in tissue, causing accumulation of gas bubbles

15
Q

What is tetanus?

A

Neurotoxin produced by Clostridium tetani prevents release of neurotransmitters, causing locked jaw/spastic paralysis

16
Q

When is vancomycin used empirically instead of flucloxacillin?

A

If MRSA, diptherioids, or penicillin-allergic

17
Q

Why is clindamicin useful?

A

Antitoxin properties - effective against PVL, group A Strep.

18
Q

Why do bacteria in biofilms pose a problem?

A

Resistant to immune system and antibiotics

19
Q

Why are superficial wound swabs a waste of time?

A

Reflect skin flora rather than deep infection (coag neg Staph. are part of flora)

20
Q

What is the main treatment for osteomyelitis?

A

Debridement/ drainage
Biopsy
Antimicrobials (IV)

21
Q

What is the main treatment for diabetic foot ulcer?

A

Debridement

Flucloxicillin

22
Q

What are the two main classifications of osteomyelitis

A

Acute/chronic

Haematogenous (in blood)/ contiguous (adjacent to infection source)

23
Q

How is osteomyelitis typically investigated?

A

Imaging - XR/CT/MRI
Biopsy
Wound swab
Blood culture

24
Q

What is the main management of prosthetic joint infection?

A

Remove prosthesis
6 week therapy
Re-implant after antibiotics

25
Q

What are the main signs of septic arthiritis?

A

Sever pain
Red, hot, swollen
Reduced movement

26
Q

When does chronic osteomyelitis usually develop?

A

After untreated acute osteomyelitis

27
Q

What is the classical clinical sign of necrotizing fasciitis?

A

Crepitus

28
Q

What is the main treatment for cellulitis?

A

Flucloxicillin and benzylpenicllin

29
Q

What investigations are used in prosthetic joint infection?

A

CRP
Joint aspiration
Technetium bone scan
XR

30
Q

What is osteomyelitis?

A

Infection of bone, including its marrow

31
Q

What are the main mechanisms by which bone can become infected?

A

Penetrating trauma/surgeryHaematogenous spread

32
Q

What is a sequestrum?

A

Dead segment of bone

33
Q

What is the significance clinically of sequestrums?

A

Once one develops, antibiotics will not cure infection

34
Q

Why do kids tend to get acute osteomyelitis more than adults?

A

Metaphyses have poor/slow blood flow which enables bacteria to accummulate easier

35
Q

Which organism is the commonest cause of bone infections?

A

Staph. aureus

36
Q

Chronic osteomyelitis cannot be treated by antibiotics alone. True/False?

A

True

Surgical debridement also usually required

37
Q

Which group of people are particularly at risk of osteomyelitis of the spine?

A

IV drug users
Diabetics
Immunocompromised

38
Q

List clinical features of osteomyelitis of spine

A

Constant insidious back pain
Paraspinal muscle spasm
Spinal tenderness
Systemic upset