Microbiology - MSK Flashcards

1
Q

List some clinical presentations of acute bone and joint infections

A

Temperature
Pain, redness, swelling
Reduced mobility

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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
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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

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4
Q

What are the main organisms that cause septic arthritis?

A

Staph. aureus

Streptococci

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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

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6
Q

What is the main empirical treatment for septic arthritis?

A

Flucloxacillin (Staph. aureus)

N.B. high-dose IV to maximise uptake

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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

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8
Q

How long does antibiotic treatment for septic arthritis usually last?

A

2-4 weeks

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9
Q

What is osteomyelitis?

A

Inflammation of bone + their medullary cavity

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10
Q

Which organisms cause chronic osteomyelitis?

A

Mycoplasma
Pseudomonas
Salmonella
Brucella (goat’s milk)

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11
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

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12
Q

Which organisms cause type 1 necrotising fasciitis?

A

Mixed anaerobes and other bacteria

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13
Q

Which organism causes type 2 necrotising fasciitis?

A

Group A Strep. (flesh-eating bacteria)

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14
Q

List the mainstay treatment for necrotising fasciitis

A

Surgical debridement

Pencillin + clindamycin

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15
Q

What is gas gangrene?

A

Spores forming in tissue, causing accumulation of gas bubbles

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16
Q

What is tetanus?

A

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

17
Q

When is vancomycin used empirically instead of flucloxacillin?

A

If MRSA, diptherioids, or penicillin-allergic

18
Q

Why is clindamicin useful?

A

Antitoxin properties - effective against PVL, group A Strep.

19
Q

Why do bacteria in biofilms pose a problem?

A

Resistant to immune system and antibiotics

20
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)