Septic arthritis Flashcards

1
Q

Summarise septic arthritis.

A

· Infection of 1 or more joints caused by pathogenic inoculation of microbes.
· Occurs either by direct inoculation or via haematogenous spread.

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2
Q

What is the pathophysiology of SA?

A

Bacterial virulence factors as well as the immunological host response determines disease development.

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3
Q

What 3 factors are associated with a poorer prognosis?

A
  1. Older age.
  2. Pre-existing joint disease.
  3. Presence of joint prosthesis.
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4
Q

What is the aetiology of SA?

A

· Predominant causative organisms of SA are staph or strep - 91% of cases.
· Most commonly staphylococcus aureus.

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5
Q

List the most common risk factors.

A

· Underlying joint disease:

  • RA.
  • OA.
· Joint prostheses. 
· IV drug abuse. 
· Alcohol use disorder. 
· Diabetes.
· Previous intra-articular corticosteroid injection. 
· Cutaneous ulcers.
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6
Q

What are the most common signs and symptoms of SA?

A

· Hot, swollen, tender, restricted joint.

· Fever.

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7
Q

What investigations would you request if you suspected SA in a patient? What would the results show?

A
· Synovial fluid Gram stain and culture. 
· Synovial fluid WCC.
· Blood culture - before abx therapy. 
· WCC - elevated.
· CRP and ESR - elevated.
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8
Q

Suggest some differentials.

A

· OA - synovial fluid will not reveal micro-organisms.
· RA/Psoriatic arthritis - synovial fluid will not reveal micro-organisms.
· Gout/Pseudogout.
· Haemarthrosis.
· Trauma.
· Bursitis - swelling is external to the joint and it’ll move freely and painlessly.
· Cellulitis - will be an unrestricted joint.

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9
Q

What are the treatment options for SA?

A

· Joint aspiration.

· IV Abx (dependent on what’s grown in fluid sample).

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10
Q

What complications may arise?

A

· Abx-associated allergic reaction.
· Osteomyelitis - if infection isn’t controlled, it can spread into surrounding bone.
· Joint destruction.

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11
Q

What antibiotics would you give to a SA patient who had a gram-positive stain?

A

· 1ST LINE: vancomycin plus joint aspiration IV

· 2ND LINE: clindamycin or cephalosporin plus joint aspiration IV

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12
Q

What antibiotics would you give to a SA patient who had a gram-negative stain?

A

· 1ST LINE: 3rd gen cephalosporin e.g. ceftriaxone IV.

· 2nd LINE: IV ciprofloxacin plus joint aspiration e.g. ciprofloxacin IV.

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