Osteomyelitis

Osteomyelitis is usually monomicrobial or polymicrobial

monomicrobial

risk factors

anything that increase gram (+) bacteremia risk

• diabetes

• broken bones

• orthopedic surgery

• IVDU

• dialysis

• catheter use

• immunosuppression

which type of osteomyelitis is located in spine?

hematogenous

which type of osteomyelitis is located in hands or feet?

contiguous

which type of osteomyelitis is located in feet?

diabetic

which type of osteomyelitis is bacteria sourced in the bloodstream?

hematogenous

which type of osteomyelitis is bacteria sourced via direct inoculation (trauma, surgery, SSTI)?

contiguous

which type of osteomyelitis is bacteria sourced via vascular insufficiency or direct inoculation?

diabetic

common bacteria for osteomyelitis ?

s.aureus

which type of osteomyelitis has a high amputation rate?

diabetic

clinic presentation of osteomyelitis

typically slow, indolent process (not acute)

When would ABX be CONSIDERED for osteomyelitis?

when pt is presenting with systemic signs of infection (ie fever, chills, fatigue and lethargy)

pt presents with osteomyelitis sx that has been occuring for 2 days - how would you categorize their osteomyelitis?

acute

pt presents with osteomyelitis sx that has been occuring for > 2 weeks - how would you categorize their osteomyelitis?

subacute

pt presents with osteomyelitis sx that has been occuring for > 4 weeks - how would you categorize their osteomyelitis?

chronic

pt presents with osteomyelitis sx characterized by localized and systemic sx - how would you categorize their osteomyelitis?

acute (could have both or either sx)

pt presents with osteomyelitis sx characterized by mild pain over weeks - how would you categorize their osteomyelitis?

subacute

pt presents with osteomyelitis sx characterized by draining sinus tract and dead bone- how would you categorize their osteomyelitis?

chronic

When to initiate ABX for osteomyelitis ?

withold until after culture obtained

best imagine options for osteomyelitis (best to worst)

MRI > CT scan > x ray

labs that can be monitored in osteomyelitis

• CRP → nonspecific but will return to normal w/in a week after taking proper ABX

• ESR → elevated in osteomyelitis but responds slower than CRP

gold standard for osteomyelitis diagnostic cultures + problem

bone biopsy ; difficult to obtain

problem with using wound cultures for osteomyelitis

may capture wrong bugs unless done in sterile surgery

source control for osteomyelitis

surgery - radical debridement until down to living bone

• inadequate debridement → recurrence

• if large dead space → may need reconstruction

last resort = amputation

empiric tx osteomyelitis

vancomycin + ceftriaxone

• but osteomyelitis tx is definitive tx driven !

Definitive TX for osteomyelitis

• streptococcus → penicillin/B-lactam (ceftriaxone)

• MSSA → naf/oxacillin or cefazolin

• MRSA → vancomycin or daptomycin

• GNR (not pseudomonas) → ceftriaxone

Treatment duration for acute osteomyelitis

4-6 weeks

Treatment duration for subacute/chronic osteomyelitis

> 6 weeks (begins when removal of necrotic bone is complete - which takes about 6 weeks)

most likely bugs to cause infection w/ osteomyelitis

s.aureus or s.epidermidis

What ABX do you add for osteomyelitis with hardware? - what does it do?

rifampin 450 mg IV/PO BID ; penetrates biofilm formation on prosthetic material

if you have no cultures, what do you do to TX osteomyelitis?

cover for likely pathogen (s.aureus, streptococci)

• if contaminated/trauma or immunocompromised → consider adding gram (-) coverage

• if diabetes related → consider adding gram (-) and anaerobic coverage

What to monitor to assess clinical improvement in osteomyelitis?

• sx decrease

• improved movement

• CRP and ESR (inflammatory response)

• imaging

what should you monitor regarding vancomycin if using for long duration?

levels, AKI

what should you monitor regarding naf/oxacillin if using for long duration?

AKI, hepatotoxicity, blood dyscrasias

what should you monitor regarding daptomycin if using for long duration?

rhabdomyolysis

what should you monitor regarding FQs if using for long duration?

separate admin from divalent cations

what should you monitor regarding ABX if using for long duration?

c.diff

septic arthritis

infection of joint

septic arthritis is usally caused by bacteria or fungi

bacteria

Risk factors for septic arthritis

• RA or OA

• joint prosthesis

• Intra-articular corticosteroid use

septic arthritis SX

1-2 weeks of erythema, pain, fever and restricted joint movement

ABX usage in place with cultures for septic arthritis

hold prior to cultures unless pt is hemodynamically unstable

most common bugs that cause septic arthritis

s.aureus, streptococci, neisseria gonorrhea, GNRs

ABX regimen for empiritc tx of septic arthritis if NO RISK FACTORS

3 options:

1. naf/oxacillin

2. cefazolin

3. clindamycin

ABX regimen for empiritc tx of septic arthritis if MRSA risk factor

3 options

• Vancomycin

• Linezolid

• Daptomycin

ABX regimen for empiritc tx of septic arthritis if trauma risk factor

3 options

• Vancomycin

• Linezolid

• Daptomycin

ABX regimen for empiritc tx of septic arthritis if surgery risk factor

3 options

• Vancomycin

• Linezolid

• Daptomycin

ABX regimen for empiritc tx of septic arthritis if prosthesis risk factor

3 options

• Vancomycin

• Linezolid

• Daptomycin

ABX regimen for empiritc tx of septic arthritis if young and/or sexually active

add ceftriaxone

ABX regimen for empiritc tx of septic arthritis if IVDU

add cefapime or ceftazidime

Duration of TX septic arthritis

2 weeks of IV tx then 2 weeks of PO tx

Diabetic foot infection pathophysiology

1. poor blood flow → impaired sensation, poor wound healing, decrease O2 dellivery

2. increased risk for complications → increaed infection risk & anaerobes, decreased delivery of ABX

3. poor resolution of infection: surgical debridement & amputation

Empiric regiment for DFI

Cover MSSA/MRSA + GNR ± PSA ± Anaerobes

1. vancomycin AND

2. ceftriaxone (or ciprofloxacin) AND

3. metronidazole (unless using pip/tazo or meropenem)

Definitive TX for DFI

tx culture organisms ± anaerobes

• if adequate debridement → anaerobic coverage not required

Treatment duration for DFI if adequate source control

0-5 days

Treatment duration for DFI if mild (no bone involvement)

1-2 weeks

Treatment duration for DFI if moderate/severe

2-3 weeks

Treatment duration for DFI if osteomyelitis

> 6 weeks (but we would try to avoid this duration by doing amputation)