Osteomyelitis Flashcards
how does osteomyelitis occur?
vertebral bodies - hematologenous spread or recent surgery in area
contiguous spread osteomyelitis may arise from direct contamination (fracture, joint replacement, orthopic implant)
Wounds - pressure sores, diabetic foot ulcers
adjacent soft tissue infection
clinical presentation of osteomyelitis
subacute or chronic pain over affected region of bone
spontaneous opening of wound accompanied by drainage (sinus tracts) are a late manifestation of infection
when to consider an underlying osteomyelitis infection?
chronic wounds like pressure ulcers do not respond to appropriate therapy
what do we NOT see in presentation of osteomyelitis
rare to see fever, or other systemic symptoms of infection
labs of osteomyelitis
no specific testing can be done
ESR/CRP are elevated and this is suggestive and raises pre-test probability of infection
won’t see any WBC elevation unless in acute hematogenous osteomyelitis
1st imaging study to order for suspected osteomyelitis
XR
- easy and cheap and quick
if negative doesn’t rule out possibility of infection
Test of choice for diagnosis of osteomyelitis
MRI WITH AND WITHOUT contrast is gold standard
if cannot obtain MRI, get CT with IV contrast
can use nuclear medicine studies which are less sensitive or specific for osteomyelitis
bone biopsy is necessary for osteomyelitis because
confirms the presence of pathogen and maximizes the chance that chosen antibiotic regimen will work to treat it
when to get osteomyelitis bone biopsy?
at time of surgery or by image guided biopsy
when can we forego bone biopsy in osteomyelitis
when pts also have positive blood cultures
possible exception to this is IVDA as they have frequent bacteremia and the organism in blood culture may not represent organism in the bone
in culture negative disease of bone biopsy (bone biopsy didn’t reveal a species), what testing can we do to figure out the bacteria causing osteomyelitis?
get a nucleic acid amplification test of bone biopsy and look for possible causative organism but this technique will not tell you the susceptbilities
Treatment duration of osteomyelitis is :
IV antibiotics for 4-6 weeks
Golden rule about osteomyelitis and starting antibiotics
unless there’s systemic signs of sepsis or concomittant soft tissue infection or bacteremia present, you should hold off on empiric antibiotics until bone biopsy is obtained for culture data
hate ER docs who start empiric antibiotics
which antibiotics are preferred for osteomyelitis
IV over PO but some like fluoroquinolones have good bone penetration because they have high bioavailable with oral agents
when to consider osteomyelitis when there is a diabetic ulcer?
when the diabetic foot ulcer is deep (presence of exposed bone)
large in diameter >2cm
chronic (nonhealing after 6 weeks of standard care)
2/3 of pts with diabetic osteomyelitis WILL NOT have elevation in ESR/CRP
what test can you do to check if there’s osteomyelitis on physical exam:
sterile probe to bone test and look for contact with a hard or gritty surface representing bone or joint capsule
if presence of pus or high positive predictive value of probe to bone test is high
non infected ulcer - negative predictive value is high
all pts who have a new diabetic foot infection should get
XR to look for
- new bony abnormalities
- soft tissue gas
- foreign bodies
what bacteria causes most diabetic foot infections?
staph and strep make up 70%
25% have gram negative bacteria
infections can be polymicrobial
duration of treatment for diabetic osteomyelitis?
IV or PO 4-6 weeks but may need longer course if there’s signs of residual necrotic bone
indications for amputation of diabetic foot osteomyelitis:
- persistent sepsis
- inability to tolerate antibiotic therapy
- progressive bone destruction despite appropriate therapy
- bone destruction that compromises the mechanical integrity of the foot.
-pt may choose amputation over prolonged antibiotic therapy. NO need for antibiotics after amputation
risk factors for vertebral osteomyelitis:
older age immunocompromised indwelling catheters HD IVDA
how does osteomyelitis of the vertebrae happen?
have infection that occurs in the intervertebral disc space causing spondylodiskitis and then see adjacent spread to the vertebral bodies.
usually its the lumbar spine, then the thoracic then cervical spine
presentation of vertebral osteomyelitis:
new onset back or neck pain or progressive worsening of chronic pain that is unresponsive to conservative treatment
esp if high levels or ESR/CRP and unexplained neurological symptoms
best diagnostic study for diagnosing vertebral ostemyelitis
MRI
also need to get blood cultures
test for TB for those who are at risk
Brucella serological test is diagnostic without need for biopsy
who needs to get a bone biopsy for vertebral osteomyelitis
if it’s negative blood culture and there’s a spot on MRI concerning for osteomyelitis
if first biopsy is non diagnostic need to get a second biopsy
Treatment for vertebral osteomyelitis is
6 weeks
osteomyelitis in a sickle cell patient and empiric coverage:
samonella coverage and staph coverage
vancomycin and ciprofloxacin
hematogenous osteomyelitis is more common in
children and sickle cell pts and IVDA
occurs in axial skeleteon and pelvic and less commonly in long bones like tibia
can see destruction on XR.
