bone and joint infections Flashcards
most common causative organism
of osteomyelitis (particularly that acquired by hematogenous spead) and septic arthritis: S. aureus***
importance of culture and suscepibility testing
Culture and susceptibility data are essential to guide antimicrobial treatment of osteomyelitis and septic arthritis
joint aspiration and examination of synovial fluid are extremely important to elavuate the possibility of septic arthritis
most important treatment modality of acute osteomyelitis
administration of appropriate antibiotics in adequate doses for a sufficient length of time - must be bactericidal
antibiotics are usually given in high doses so that adequate antimicrobial conc are reached within infected bone and joints
standard treatment duration of osteomyelitis
standard duration of antimicrobial treatment for acute osteomyelitis is 4-6 weeks***
when can oral anitbiotics be used in osteomyelitis?
to complete a parenteral regimen in:
-children who have had a good clinical response to IV antibiotics
-adults without* DM or PVD
organism must be susceptible to oral antibiotic
suitable oral antibiotic must be available
adherence must be ensured
3 most important therapeutic approached to the management of septic arthritis
appropriate antibiotics
joint drainage
joint rest
periosteum
fibrous, cellular envelope surrounding the bone
epiphysis and diapysis are separated by the
epiphyseal growth plate - a rapidly growing are of bone with many blood vessels
bone blood vessels
they supply bone tissue and are predominantly located in the epiphysis and metaphysis
- nutrient arteries enter bone on metaphyseal side of epiphyseal growth plate and lead to cappillaries that form sharp loops within the growth plate
- cappillaries lead to large sinusoidal veins that exit the metaphysis
- blood flow is slowed considerably - infection possible with bacterial colonization
osteomyelitis overview
definition: purulent inflammation of the bone marrow and surrounding bone associated with an infection, caused by bacteria, fungi, mycobacteria
may occur in any bone
can affect all age groups
classified by route that infecting organism reaches the bone - hematogenous spread, contiguous spread, vascular insufficiency
hematogenous spread
pathogen reaches the bone via the bloodstream**
risk factor: transient or persistent bacteremia, sickle cell disease (slow moving blood)
typically involves metaphysis of rapidly growing long bones* (femur, tibia, humerus, fibula) in children and vertebrae* (lumbar, thoracic) in adults
predominantly a diesease of children (1-end of growth) and adults over 50
usually caused by a single organism - S. aureus, gram-negative bacilli
-acute infection process (inflammation, edema, small vessel thrombosis) increases bone pressure - compromises blood flow - necrosis
cytokine release promote osteoclast activity - reduces bone integrity
elevated pressure and necrosis cause fragmentation of diseased bone from healthy bone (sequstrum)
continued spread of infection to outer layers of bone and soft tissue - formation of abscess and draining sinus tracts (hole in done where infection leaks out)
contiguous spread
pathogen reaches the bone from an adjacent soft tissue infection** or direct inoculation during trauma, puncture wounds, surgery
usual age of onset over 40 years
site of infection: femur, tibia, skull, mandible
risk factors: srugery, trauma, cellulitis, joint prosthesis or other orthopedic implants
usually polymicrobial - S. aureus, gram-neg bacilli, anaerobes
vascular insufficiency
subset of contiguous spread - infection develops as an extension of existing localized infections
usual age of onset over 40 years, elderly
site: bones of feet and toes
risk factors: DM or PVD
polymicrobial: S. aureus, coag-negative staph, strep, gram-neg bacilli, anaerobes
osteomyeletis - bacteriology
S AUREUS!!! - neonates, children, adults, post-surgery
diabetes - polymicrobial
sickle cell disease - salmonella*, s. aureus
IV drug uses - GNB (esp. P aeruginosa)
acute osteomyelitis sxs
sxs for few days to few weeks
abrupt onset of fever, localized pain, tenderness and swelling, decreased range of motion
if hematogenous, patients may also have chills, malaise, myalgias
vetebral - localized back pain, tenderness, fever, night sweats, weight less, neurologic sxs
chronic osteomyelitis sxs
sxs present for several weeks, relapsing or unresponsive infection
pain, exudative drainage, sinus tract formation, decreased ROM
clinical osteomyelitis diagnosis
evidence of clinical s/sxs of infections
laboratory osteomyelitis diagnosis
elevated WBC count, ESR, CRP
important to establish bacteriologic diagnosis by culture* or infected bone and blood: bone aspiration, biopsy, surgical debridement, gram stain, if abscess present - drain, gram stain and culture, aerobic and anaerobic cultures
radiologic osteomyelitis diagnosis
X-rays - soft tissue swelling, periosteal thickening or elevation, bone destruction seen 10-14 days after onset of infection (over 50% of matrix must be destroyed before detected)
CT or MRI*** (standard of care) - presence of hardware may preclude use of MRI
nuclear bone scan
osteomyelitis treatment overview
goals: resolution of the infection, prevention of long-term sequelae
best prognsis in acute osteomyelitis - over 80% cute rates with surgery and appropriate antibiotics for 4-6 weeks
chronic - dead bone and necrotic material act as bacterial reservoir, surgical debridement and prolonged antibiotics required
most adults require a combo of medical and surgical therapy for a successful treatment
prompt antimicrobial therapy is necessary to limit bone destruction, mitigate need for surgery, prevent chronic infection, disruption of longitudinal bone growth and angular deformity of the bone
antibiotic choice depends on the most likely pathogens, results of bone culture and susceptibility testing, bone penetration, allergies, etc
high-dose parerenteral antibiotics are typically utilized to ensure adequate bone conc
newborn osteomyelitis empiric treatment
nafcillin or oxacillin 50-150 mg/kg/day IV + cefotaxime 100-200 mg/kg/day IV
NEVER give ceftriaxine - highly protein bound - brain damage
children under 5 osteomyelitis empiric treatment
If vaccinated with HBI: nafcillin 150-200 mg/kg/day IV OR cefazolin 100 mg/kg/day
If not vaccinated with HIB: cefotaxime 100-200 mg/kg/days IV
children over 5 osteomyelitis empiric treatment
nafcillin 150-200 mg/kg/day IV
cefazolin 100 mg/kg/day IV
If allergic: vanc, clind, linezolid
adult osteomyelitis empiric treatment
nafcillin 2 g IV q4h
cefazolin 2 g IV q8h
IV drug use osteomyelitis empiric treatment
cefepime or ceftazidime 2 g IV q8h
ciprofloxacin 750 mg PO q12h
post-op or post-trauma osteomyelitis empiric treatment
pip/tazo 4.5 g q6-8h
cefepime 2 g q8h
meropenem 1 g q8h
add vanc if MRSA is suspect
patients with vascular insufficiency osteomyelitis empiric treatment
pip/tazo 4.5 g IV q6-8h
meropenem 1 g q8h
B-lactam or FQ + metronidazole
add vanc if MRSA suspected
osteomyelitis directed therapy - s. aureus
nafcillin 2 g IV q4h
cefazolin 2 g q8h
If severe allergy: vanc 15-20 mg/kg IV q12h or clindamycin 900 mg IV q8h
if MRSA: vancomycin 15-20 mg/kg IV q12h or daptomycin 6-8 mg/kg/day IV q24h
osteomyelitis directed therapy - streptococci (pen susc)
aq pen G 20-24 million units IV continuous or divided q4h
ceftriaxone 1-2 g IV q24h
osteomyelitis directed therapy - enterococci or streptococci with pen MIC over 0.5
aq pen G 20-24 million units IV cont of divided q4h
ampicillin 12 g IV cont of divided q4h
if severe allergy or Amp-R:
vanc
optional gent 1 mg/kg IV/IM q8h for first 1-2 weeks
osteomyelitis directed therapy - GNB
ceftriaxone 102 g IV q24h
cipro 50 mg PO q12h
osteomyelitis directed therapy - P. aeruginosa
cefepime 2 g IV q8-12h
cipro 750 mg PO q12h
osteomyelitis directed therapy polymicrobial
meropenem 1 g q8h
ertapenem 1 g IV q24h
pip/tazo 4.5 g q6-8h
duration of osteomyelitis treatment
at least 4-6 weeks***
duration will vary depending on clinical response to therapy
duration is often longer in patients with vascular insufficiency, chronic osteomyelitis or prosthetic devices
patients may receive enitre course of therapy IV
osteomyelitis - switching patients to oral therapy
patients may be switched IF:
- response to initial parenteral therapy
- oral agent achieves adequate serum and bone conc
- patient has adequate blood flow to site of infection
- compliance can be ensured
- favorable SE profile
oral antibiotic options for osteomyelitis
MSSA: dicloxacillin, amox/clav, cephalexin, cefadroxil, clinda
MRSA: linezolid
-thrombocytopenia, peripheral neuropathy with long-term use
enterobacteriaceae: FQs
-tendonitis, tendon rupture with long term use
-patients over 60 years, kindey, heart lung transplant recipients, CS use
-drug interactions
septic arthritis overview
inflammatory reaction withing the synovial membrane, synovial fluid, articular cartilage and joint space caused by the presence of a microorganism (bacteria, virus, fungus)
may affect single or multiple joints
may affect any joint
bacterial - a rheumatologic emergency due to potential for rapid joint destruction and irreversible loss of function d/t host inflammatory response to infection
septic arthritis - microbiology
neonates - S. aureus
children - S. aureus
adults 15-40 - N. gonorrhoeae
adults overall, RA, diabetes, malignancy, immuno comp, IV drug - S. aureus!
septic arthritis clinical presentation
monoarticular in 80-90% of cases
knee - most common site of infection in adults; hip most common in children
poly articular in 10-20% of cases - RX, immunosuppress, prolonged bacteremia, usually S. aureus
joint pain, decreased ROM, inflammation, swelling, erythma, warmth, fever, chills
gonococcal arthritis
4 times more common in women
increased risk of dissemination during menstruation, preg, and postpartum
classic triad: dermatitis, tenosynovitis, polyarthralgia
severe joint pain, fever, chills, malaise
gram stain of synovial flui - gram neg diplococci
septic arthritis - diagnosis
clinical - s/sxs
lab - inc peripheral WBC (over 50,000), ESR, CRP
arthrocentesis of affected joint
-purulent, low viscosity synovial fluid w inc PNMs
-decreased synovial glucose, inc protein and LDH
gram stain and culture of synovial fluid
blood cultures
radiology - xrays, CT, MRI
septic arthritis treatment overview
prompt joint drainage and antibiotic therapy to limit articular destruction
no randomized, controlled, clinical studied have evaluated therapy for septic arthritis
initial antibiotic selection is based on gram stain of synovial fluid and most likely infecting pathogen from clinical pres
once organism identified and susceptibility known, direct therapy to causative pathogen
duration of therapy depends on organism and patient response (S. aureus - 4 weeks)
septic arthritis - empiric therapy
gram-positive cocci - vanc 15-20 mg/kg q8-12h
gram negative cocci - ceftriaxone 1g q24h
gram negative bacilli: cefepime, pip/tazo, meropenem; if severe allergy: aztreonam, cipro, levo
gram-stain negative:
VANC** PLUS
-ceftazidime OR
-FQ (cipro, levo) OR
-AG (tob or gent)
prosthetic joint infection overview
definition: infection occuring in prosthetic joint
presentation: sinus tract or persistent wound drainage over a joint prosthesis, pain (acute or chronic), prosthesis becomes loose
prosthetic joint infection - diagnosis
history and exam, Xray, ESR, CRP, blood cultures, arthrocentesis (cell count, differential, aerobic and anaerobic culture), intraoperative histopathological exam of periprosthetic tissue samples
prosthetic joint infection - treatment
antibiotic therapy should be targeted to the common causative organisms: staph (MSSA and MRSA), strep, enterococci, pseudomonas, enterobacteriaceae
duration: 4-6 weeks IV therapy followed by 3-6 months of PO therapy
