125. Bone and Joint Infections Flashcards
Acute vs subacute infection - timeline?
acute within 2 weeks of onset
subacute 1-several months
Compact bone
compact - shaft of long bone and covers epiphysis
- dense, without cavities, longitudinaly running Haversian systems (house vasculature and nerves)
Trabecular/spongy bone
trabecular - within epiphysis and makes up irregular bone
- bony lattice, traveculae, which located within medullary cavity and contains marrow, more metabolically active
-central Haversian canals in spongy bone parallel to long axis of bone - bloody supply and reticular ct for haversian system
Diaphysis
shaft of bone
compact cortical bone overlying periosteum and medullary canal containing marrow
Metaphysis
junctional region epi and diaphysis
trabecular bone and cortical thins here
Epiphysis
area at either end of a long bone and made of abundant trabecular bone
thin shell cortical bone
Cartilage in a mature adult on the epiphysis of bone - what does this allow?
frictionless movment
Joints - synovial capsule mechanism?
structural integrity
sleeve to attach to articulating bones
Osteomyelitis: ?
infection of bone and medullay cavity
Osteomyelitis: RF for infection?
trauma
distruption of blood flow
large inoculum of bloodborn or external microorganisms
FB
Osteomyelitis: why does infection start at metaphysis
area of turbulent blood flow
Osteomyelitis: why is surgery typically needed?
inflammatory cell migration to the area to help causes edema, vascular congestion and small vessel thrombosis so that IO pressure increases to compromise flow to bone - as such medication hard to get here
Involucrum
new bony tissue growth at area of infection to compensate for tensile stress from lack of blood supply
Why do neonates and infant more often get septic arthritis from OM?
readily advances through joint space
Adult progression of OM to joint space?
post epi plate fusion –> anastomoses between metaphyseal and epiphyseal blood vessel fro infection to spteady to epi, then synovium and joint space
Gram stain can be negative in OM - how?
only picks planktonic/bacteria in a single state (typically those least R) - therefore often times biofilm other stages are still virulent
Definitive diagnosis of OM?
can only be done by culture of synovial fluid aspirate or synovial tissue
Source of spread of bacteria in children’s OM and adult vertebral OM?
hematogenous
Source of spread of bacteria in appenduclar skeleton adult (foot, hand, skul, maxilla, mandible) OM?
contigious source infection
direct implantation (bite, open fracture, surgical instrumentation)
Head and neck OM source of spread?
sinus disease
odontogenic infection
Usual source of spread of septic arthritis?
hematogenous unless direct source into joint
Typical microbiology of septic arthritis: kids
staph aureus > strep > gram neg, neisseria > H influ
Typical microbiology of septic arthritis: young adult
neisseria > staph > strep, gram neg and h influ rare
Typical microbiology of septic arthritis: adult
staph > strep > gram neg > gonorrhea > h influ
Typical microbiology of septic arthritis: older adults
staph > gram neg > strep > rare h influ, gonorrhea
In what pt pop does pseudmonas need to be strongly considered as a source of septic arthritis?
puncture wounds
post surgical
sickle cell anemia
Underlying disease RF for bone-joint infection risk
diabetes
chronic steroid
IVDU
preexisting joint disease (RA)
other immunosuppressed states
Empiric abx for neonate to <3mo with OM
cephalosporin third gen
Penicillinase R pen like amox clav or vanco (if MRSA) +gent
Empiric abx for neonate to <3mo with Septic arthritis
amox clav + ceftriaxone
or amox clav and gent
if MRSA + switch amox clav for vanco
Common organisms OM and septic arthritis for neonates and children <3mo
S aureus
gbs
enterbacteriaceae
Common organisms 3mo- 14y OM
staph aureus
gas
h influ
Common organisms 3mo- 14y septic arthritis
s aureus
strep spp
enterbacteriacease
Tx 3mo-14mo om:
ceftriaxone + amox clav/septra
or vanco and ceftri, chloramphenicol
amox clav or ceftr with allergy pen or clinca with allergy to pen + ceftr
Tx 3mo-14mo septic arhtritis
amox clav/septra and ceftriaxone
Tx 14y- adult: what bug for OM?
s aureus
Tx 14y- adult: septic arthritis
s aureus
strep
enterbacteriaceae
Tx 14y- adult: OM
septra or amox clav
alt vanco
Tx 14y- adult: septic arthritis
amox clav/septra or ceftr
alt: vanco and cetr or penicillin and gent or ceftr
Infection subsets: septic arthritis in a yung sexually active adult or adult with acute arhthrits concern for gonorrhea - tx?
ceftriaxone
or spectinomicin or penicillin if sn
Infection subsets: OM in chronic OM and db foot infrection tx:
amox clav or septra + flq + metronidazole
or amoxclav/septra + ceftr + clinda
Infection subsets: OM in infected prosthesis - bugs?
staoh aureus
staph epidermidis
pseudmonoas
Infection subsets: OM in infected prosthesis - tx?
vanco + flq
alt: imipenem
Infection subsets: septic arthris in infected prosthesis - bugs?
staph aureus
s epidermidis
pseudomonas (same as OM)