septic arthritis Flashcards
what is it
a joint infection caused by bacteria or a virus that spreads to the fluid surrounding the joint
needs to be treated immediately
what is the most common organism that causes septic arthritis
staph aureus
others include:
gonococcus - common in sexually active young people
strept.
gram negative bacilli
what are risk factors for septic arthritis
joint disease
chronic kidney disease
immunosuppression
prosthetic joints - recent surgery
what are the clinical features of septic arthritis
acutely inflamed tender, swollen joint (1-2weeks)
reduced range of movement
systemically unwell
what are the investigations for septic arthritis
joint aspiration (synovial fluid aspirate) for microscopy culture and sensitivity - check for crystals (gout)
>the fluid would appear turbid and yellow
blood tests - high white cell count, high ESR/CRP
blood cultures
x-ray of joint
management of septic arthritis
> empirical abx:
gram+ cocci = vancomycin, clindamycin, cephalosporin
gram - infection = ceftriaxone, ciprofloxacin
confirmed: staph aureus/strep = flucloxacillin
gonococcus
-abx should be continued IV for 2 weeks and orally for 4 more weeks
-gonococcal arthritis needs treatment for 7-14 days
> joint washout (?) under general anaesthetic
> physiotherapy after infection resolves
complications of septic arthritis
osteomyelitis
arthritis
ankylosis fusion
A 22-year-old man presents to the emergency department with a painful left ankle. He reports that the pain started this morning and has progressively worsened such that he can no longer weight-bear. His past medical history is relevant only for a previous sexually transmitted infection found incidentally on screening and treated with ceftriaxone and azithromycin. He has no known drug allergies and takes no other regular medications. He reports no history of trauma.
On examination, he appears flushed and systemically unwell. The left ankle appears swollen and erythematous; the range of movement is limited, and passive movement causes him severe pain.
What is the most likely causative organism of this patient’s presentation?
neisseria gonorrhoeae
for young, sexually active individuals this organism is the most common cause of septic arthritis
GI pathology = strept A/B/C
infection of prosthetic joint = staph epidermis
for everyone else = staph aureus
pathophysiology of septic arthritis
haematogenous spread (common)
direct inoculation
what are the risk factors for septic arthritis
IVDUs
DM
older age
underlying joint injury
underlying joint disease
prosthetic joint
immunosuppression
unprotected sex
PVD
alcoholism
management of septic arthritis associated with prosthetic joints
aggressive debridement
amputation
implant replacement/revision surgery
if septic arthritis is suspected in a prosthetic joint and you need to aspirate - where is appropriate to aspirate ?
in theatre always - high risk of infection
never in the emergency department
after aspirating a joint for suspected septic arthritis what is the next best step ?
flucloxacillin 2g IV QDS
in all cases of sepsis IV abx should be administered within the hour
what would the aspiration results look like for a diagnosis of septic arthritis
yellow in appearance
white cell count 20,000mm3
>90% neutrophils
septic arthritis of left knee
