Bone infection Flashcards
the most common cause of septic arthritis
staphylococcus aureus
(MRSA)
haemolytic strep
pneumococcal streptococcus
children- Haemophilus, Kinsella
causes of septic native arthritis (bacterial)
- direct haematogenous
- direct inoculation (Trauma) (bite)
- contiguous focus infection (intracapsular metaphysis- boney infection where the infection lies in the capsule of the joint) (diabetic foot)
acute purulent joint management
aspirate/drain blood cultures bacterial and target molecular assays baseline CRP to monitor therapy additional serology (looking for Lyme disease spread by sheep ticks/ Q fever arthritis)
viral and chronic arthritis
usually polyarthropathy due to systemic viral infection parvovirus B19 seroconversion type illness HIV tropical arboviruses (chikungunya)
osteomyelitis definition
infection of the substance of the bone but encompasses many different scenarios.
haematogenous- long bone osteomyelitis in young children
infection following trauma
diabetic feet infection
causes of osteomyelitis
all: staph aureus
foreign body: a bone that’s normal resistance can become infected by low virulence commensals (Coagulase-negative staphylococcal) propionibacteria
nonsocosmial: pseudomonas, candida
ulcers: streptococci, anaerobes
sickle cell: salmonella, pneumococci
bites: Pasteurella, eikinella
children: Kingella, s aureus, HiB, group B strep, strep pneumonia, haemolytic streptococci.
management of osteomyelitis
debridement
removal of implants
long course parenteral antibiotics >6 weeks
chronic osteomyelitis
the body cannot get rid of the dead bone
need to maintain the function of the limb
the ultimate outcome is a chronic retained infection and loss of function
can get a sequestrum which needs to be removed else infection will continue.
can be treated with bone graft, soft tissue flap, skin graft (plastics)
biofilms definition
known as ‘slime’
it’s not mucus or snot
thin films of host and bacterial materials where the organism can live and become quiescent and can continue to cause damage.
host and microbial community which makes abx less effective
why can treatment fail?
poor abx penetration
dead or devitalized tissue
poor vascular supply
bacteria in a quiescent state and presence of biofilm.
principles of abx
ideal regiment effective penetration of biofilm oral cheap safe
rifampicin
never use on its own
always use in combination
good against G+ve to get into biofilms and kills organisms in the quiescence state
acute haematogenous osteomyelitis
*in children
soft tissue problem primarily
surgical intervention if failure to resopnd to abx / local abscess
acute haematogenous osteomyelitis
*in children
soft tissue problem primarily
surgical intervention if failure to respond to abx / local abscess
acute septic arthritis in children
adults
children: drained and open
adult: urgent removal of purulent material from joint space. prevent enzyme related articular cartilage damage
* needle aspiration
* arthroscopic washout
* open washout (big joint)