Therapeutic Discussions-Bone and Joint infections
For each therapeutic topic, use the pre-readings and any additional readings to learn about the
following:
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Pathophysiology
o Hematogenous osteomyelitis
 Occurs most often in children with exception of vertebral (more common in
adults >50-60 years old)
 Blood infection seeds into vasculature in long bones (ex vertebrae)
 The lumbar and thoracic regions of vertebrae are most common
 Blood flows into natural bone into hairpin turns and blood slows doe in in these
areas and allows bacteria to seed
 Less phagocytosis
o Contiguous osteomyelitis
 Infection reaches bone from an adjoining soft tissue infection
 Direct entrance (ie penetrating trauma)
 Occurs more often in older patients
o Vascular insufficiency
 Diabetic foot ulcers
o Infectious arthritis
 Synovial tissue doesn’t have BM so organisms can gain access via penetrating
wounds
Etiology
o Risk factors
 Hematogenous
 Long bones (femur, tibia, humerus)
o Infection (pharyngitis, cellulitis, respiratory infections), trauma,
puncture wounds, anything that can give you give you
bacteremia, sickle cell disease (RBCs are abnormal shape and
when go into vasculature it bangs up the vasculature; these
people also can have salmonella osteomyelitis)
 Vertebrae
o DM, blunt trauma to spine, UTI
 Contiguous
 Trauma, puncture wounds, surgeries, PVD, fractures
 Infectious arthritis
 Can result from spread from adjacent bone infection, direct
contamination of joint space, or hematogenous dissemination (most
common)
 Usually caused by hematogenous spread
o
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Causative organisms
 Hematogenous: S. aureus (vast majority) Group B strep, E. coli (from urinary
tract)
 Vertebrae (staph aureus ~60%; coagulase negative staph but also gram
negatives)
 IVDU gram negatives are responsible for 88% of infections
(pseudomonas is most common, klebsiella, enterobacter, and serratia)
 Streptococcus/coagulase negative staph
 Contiguous
 Staph aureus, gram negative bacilli
 Pseudomonas, streptococcus, E. coli, staph epidermidis and anaerobes
 Fungi is rare  need long duration of therapy for candida osteomyelitis
(ie 6-12 months)
 Infectious arthritis
 Staph aureus
 Prosthetic joint/
o Anaerobes, enterococcus still rare but more than non
prosthetic
 Non-prosthetic
o Staph aureus
o N. gons is common in young woman
Clinical Presentation (think head to toe)
o If bacteremic do echo as bacteria can stick to valves and cause endocarditis
 Generic bone scan +/- WBC (non-spine; technetium) or gallium (spine)
 Bone scan is sensitive and can show infection within 1 day
 X-ray isn’t not as good because it takes much longer to show damage
and can take 10-14 days
 CT or MRI is better but more expensive
o Do these when spines get involved
o
o
o
o
o
Hematogenous
 Tenderness to affected area, pain, swelling, fever, chills, decreased motion and
malaise
 ESR, CRP, WBC, neutrophils counts BCs (50% of people with this will have this)
Contiguous
Chronic (has never properly gone away)
 Just don’t feel wellnon-specifics
Acute
 First episode is more pain, redness etc
Infectious arthritis (common areas: knee, hip, ankle, elbow, wrist and shoulder)
 T 38-40
 Painful swollen joint in absence of trauma
 Effusion, restriction of joint motion, tenderness, warmth of joint
 WBC, and if have N. gons in synovial fluidWBC might not be elevated
 Glucose may be low
 If prosthetic jointwound drainage near site
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Diagnostic Tests
 Needle aspiration
 Purulent fluid indicates presence of septic joint
 Signs and symptoms
 Radiographicalthough not seen for 10-14 days after onset of infection
 MRI
 Bone scanning
 Blood cultures
 CRP, ESR, WBC
Goals of Therapy
o Prevent mortality, prevent morbidity (sepsis, septic shock, organ failure, loss of motion
and function, maintain limb), minimize ADRs, minimize RFs (diabetes or help vascular
insufficiency) , cure infection, normalize surrogates (ESR, CRP, WBC, neutrophils,
imaging), normalize signs and symptoms
Therapeutic Alternatives
o Nonpharmacological
 Drain abscess or joint
 Surgical debridement if want to keep prosthesis
 Remove joint
 1st stage vs. 2 stage
o Pharmacologic
 Start Abx right after you get blood cultures because you can get BCs quickly
 Duration: 4-6 weeks for osteomyelitis and PJI is 6 weeks but if native joint then
4 weeks
 Osteomyelitis
 If septic Vancomycin
 Cloxacillin 2g IV q4h minimum 4 weeks (possibly longer)
 Cefazolin 2 grams IV q8h (even for easy gram negatives and can step
down to clox if just MSSA)
 If gram negative FQs
 Bone penetrationunknown how important this is because a lot of our
drugs have poor penetration
o Important to a degree
o Studies are rabbit studies and they get taken up by bone but
also leave bone
 Don’t get too caught up in this because it was done in
rabbits so keep using the mainstays of therapy
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Therapeutic recommendations
o Evidence and therapeutic controversies
o Monitoring (think head to toe)
Efficacy
Clinical signs of
inflammation
(redness, pain,
swelling, tenderness,
fever)
CRP, ESR
WBC
Culture and
sensitivities
Toxicity
Sign/symptom
Who will monitor
Pharmacist
How often
3x weekly
Pharmacist
Pharmacist
3x weekly
3x weekly