MSK Infections Flashcards
what is osteomyelitis
inflammation or bone and medullary cavity usually in one of long bones
what are symptoms of osteomyelitis
fever, chills, fatigue, lethargy or irritability classic signs of inflammation include local pain, swelling or redness if you can see tendon or probe bone - deffs osteomyelitis
what are most common causes of osteomyelitis in newborns (<4 months)
staph aureus
enterobacter sp
group A and B strep
what are most common causes of osteomyelitis in children (aged 4 months to 4 years)
staph aureus
group A strep
haemophilus influenzae
enterobacter sp
what are most common causes of osteomyelitis in children / adolescents (aged 4 years to adult)
staph aureus (80%)
group A strep
H influenzae enterobacter sp
what are most common causes of osteomyelitis in adults
staph aureus
occasionally enterobacter or streptococcus
what are most common causes of osteomyelitis in sickle cell anaemia patients
staph aureus most common
salmonella species common and unique to SCA
what causes prosthetic joint osteomyelitis
mostly staph aureus or epidermis
rarely: propionibacterium acnes (upper limb), e coli, pseudomonas aeruginosa
what are causes of contiguous osteomyelitis
open fractures diabetes / venous insufficiency
what are haematogenous causes of osteomyelitis
PWID (viridans common here, pseudomonas, candida in heroin, eikenella corrodens in needle lickers and M tuberculosis)
Dialysis
Gauchers disease (lysosomal storage disorder)
Vertebral (most common, associated w epidural, psoas abscess, PWID, IV site infection, GU infection, SSTI, post op)
what causes skeletal osteomyelitis
vertebral TB (potts) = often no systemic symptoms
kids = check reduced receptors for IFN-gammma R1, IL12 beta 1
adults = offer HIV test
causes gibbous deformity
how is osteomyelitis diagnosed
indirect (scan) or direct (bone biopsy is gold standard)
might want to do MRI to make sure
how is osteomyelitis treated
debridement / drainage / removal of joint
antibiotics for 6 weeks = do not give empirically, wait for results
acute = flucloxacillin IV (2 weeks) then 4 weeks oral therapy
chronic = oral flucloxacillin (if MRSA or allergy = doxycycline or co-trimoxazole)
if coliforms = seek advice
what is septic arthritis
inflammation of joint space caused by infection
what causes septic arthritis
can be blood borne organisms, extension of local infection, or by direct inoculation (following injection of joint or trauma)
*previously damaged joints ie RA more susceptible
what are causative organisms in septic arthritis
staph aureus
streptococci
coagulase -ve staph (epidermis) = prosthetic joint
neisseria gonorrheae = sexually active patients
haemophillus influenze = pre school, not common now
what are symptoms of septic arthritis
severe pain, red, hot, swollen plus limited movement
how is septic arthritis diagnosed
clinical picture
joint fluid = yellow-green due to elevated nucleated cells
blood culture if pyrexial
exclude crystals
how is septic arthritis treated
presumptive treatment to cover staph aureus = flucloxacillin clindamycin if allergic
if <5 years old, add cefriaxone for H influenzae cover
adjust when organisms confirmed
what is knee bursitis
inflammation of small fluid filled sac (bursa) situated near knee joint
what is pyomyositis
bacterial infection in skeletal muscles which results in pus-filled abscesses
what causes pyomyositis
90% staph aureus
perineum = GNB
immunosuppressed = pseudomonas
B haemolytic strep
enterococcus clostridial infection = contaminated wounds (inject heroin)
what are symptoms of pyomyositis
common in tropical areas but can also occur in temperate zones
how is pyomyositis diagnosed
pus discharge culture and sensitivity
xray to rule out osteomyelitis
creatine phosphokinase (when muscle damaged, this leaks into blood)
MRI useful
