Infections Intro Flashcards
What are the 2 types of infections and causes of them
Pyogenic- Staph Aureus
Non Pyogenic- TB
What are the tissues that can be involved and names
Cellulitis (soft tissues only)
Septic arthritis (joints)
Osteitis (cortical bone)
Osteomyelitis (medullary bone)
4 major pathways of infection spread and MC
Hematogenous spread (mc)
Spread from a contigous source
Direct Implantation of infection
post op infection
Infants under 1 vascular anatomy and how it affects infection
Metaphyseal vessels can penetrate the growth plate into the joint
-Creates a higher risk of septic arthritis
Between 1 year and skeletal maturatity vascular anatomy and how it affects spread
No metaphyseal vessels cross physis (remains as osteomyletitis)
Adult vascular anatomy and how it affects spread
Physis no longer present so no barrier to spread; higher incidence of septic arthritis
What is the radiographic latent period for extremities and spine for inf
Extremities= 10 days
Spine=21 days
(need mri or bone scan earlier)
what are the earliest signs of osteomyelitis
soft tissue changes (seen within 3 days)
- Will distort fat planes
- will be hot, red, swollen
What type of bone destruction will you see in infection
Early lesion is moth eaten or permiative pattern usually affecting metaphysis- can spread to epiphysis
What type of periosteal rxn may you see in infection
Often laminated
codmans triangle
Large involucrum may develop
What is the common age of bone infections and sex predominacne
m/c between ages or 2 + 12
3:1 male predominance
IV drug users infection will target these jts usually
Spine
SI jt
Symphis pubis
Sternoclavicualr
(mostly axial)
What type of bac are responsible for IV infections
Usually gram - bac opposed to staph aureus
Dx criteria of infection
- Red/hot/swollen/tender jts
- pus on aspiration
- pos bacterial culture from bone/blood
- elevated WBC
Diagnostic tests for inf
CBC- leukocytosis and anemia in acute (normal chronic)
ESR and C reactive pro usually elevated
Blood culture pos in 50%
