microbiology Flashcards
how do muscle and bone get infected
what are the risk factors for infection of bone and muscle
how to diagnose osteomyelitis
clinical suspicion = fever, pain, inflammation, loss of function
when to test for infection
main pathogens for bone and muscle infection
for children: staph A , Group B strep
for adults: staph A
for elderly: increase of gram -
treatment for bone and muscle infection
what makes up orthopaedic antimicrobial prophylaxis
bread and butter of infection and abx
staph aureus > fluclox
staph epidermis > vancomycin
strept pyo > doxycycline
gram - > clindamycin
anaerobes > metronidazole and cotrimoxazole
what is osteomyelitis
inflammation of bone and medullary cavity
-usually located in one of the long bones
pathogenesis of osteomyelitis
turbulent and slowed blood flow due to looped arteries entering afferent venous sinusoids at the growth plate
makes easier for bacteria to invade - also the lying cells have very little phagocytic property
this can turn into an abscess if bacteria present
this abscess grows down the Volkmann canals as limited by growth plate , can invade subperiostally and elevates periosteum
this infectious process can sometimes erode periosteum and form a sinus through soft tissue and skin ! and so drain externally
haematogenous osteomyelitis
monobacterium
in children: long bones
in adults: vertebrae
contiguous osteomyelitis
polibacterium
young: injuries, surgery
old: pressure sore, vascular insufficiency
DM: soft tissue infection, neuropathy, vascular insufficiency
initial investigations for osteomyelitis
plain XR
inflammatory markers
BC
further investigation for osteomyelitis
CT
MRI
bone scan
molecular test (PCR, 16S)
gold standard investigation for osteomyelitis
bone biopsy
-wound swabs are not always diagnostic
