Septic arthritis Flashcards
Summarise septic arthritis.
· Infection of 1 or more joints caused by pathogenic inoculation of microbes.
· Occurs either by direct inoculation or via haematogenous spread.
What is the pathophysiology of SA?
Bacterial virulence factors as well as the immunological host response determines disease development.
What 3 factors are associated with a poorer prognosis?
- Older age.
- Pre-existing joint disease.
- Presence of joint prosthesis.
What is the aetiology of SA?
· Predominant causative organisms of SA are staph or strep - 91% of cases.
· Most commonly staphylococcus aureus.
List the most common risk factors.
· Underlying joint disease:
- RA.
- OA.
· Joint prostheses. · IV drug abuse. · Alcohol use disorder. · Diabetes. · Previous intra-articular corticosteroid injection. · Cutaneous ulcers.
What are the most common signs and symptoms of SA?
· Hot, swollen, tender, restricted joint.
· Fever.
What investigations would you request if you suspected SA in a patient? What would the results show?
· Synovial fluid Gram stain and culture. · Synovial fluid WCC. · Blood culture - before abx therapy. · WCC - elevated. · CRP and ESR - elevated.
Suggest some differentials.
· 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.
What are the treatment options for SA?
· Joint aspiration.
· IV Abx (dependent on what’s grown in fluid sample).
What complications may arise?
· Abx-associated allergic reaction.
· Osteomyelitis - if infection isn’t controlled, it can spread into surrounding bone.
· Joint destruction.
What antibiotics would you give to a SA patient who had a gram-positive stain?
· 1ST LINE: vancomycin plus joint aspiration IV
· 2ND LINE: clindamycin or cephalosporin plus joint aspiration IV
What antibiotics would you give to a SA patient who had a gram-negative stain?
· 1ST LINE: 3rd gen cephalosporin e.g. ceftriaxone IV.
· 2nd LINE: IV ciprofloxacin plus joint aspiration e.g. ciprofloxacin IV.