Orthopedic Infections Flashcards
most common pathogens in both abscess and cellulitis
staph and strep
hemophilus in children
cellulitis vs abscess
- cellulitis: infection of subcutaneous tissue, managed medically
- abscess: localized soft tissue infection, may req surgical
reminders for abscess/cellulitis
- early recognition is key
- prompt iv antibiotics vs gram+ and anaerobes
- beta-lactamase inhibitor and anaerobic coverage if necessary
what is an erysipela
- due to gabhs
- acute, progressively elarging, red, painful, raised plaques
- bacteremia = fever ad toxicity
- tx: penicillinase-resistant penicillin, 1st gen cepha
what is necrotizing fassciitis
- infection of fascia
- group a, c, or g strep, clostridia, polymicrobial with aerobes and anaerobes, mrsa
- tx: aggressive surgical debridement and antibiotics
what is gas gangrene
- due to clostridium, strep, and other gram (-)
- contaminated wounds that were sutured
- progressive pain, distal edema, foul smelling sero-sanguinous discharge
- xray: gas in soft tissues
- tx: surgical debridement, pen g/clinda, metronidazole, hyperbaric o2
what is toxic shock syndrome
- due to staph or group a/b/c/g strep pyogenes
- post-op patients and minor traumatic wounds
- fever, hypotension, erythematous macular rash with serous exudate
- tx: surgical debridement, fluid replacement, iv antibiotics vs gram+
what is foot puncture syndrome
- antbiotic that covers pseudomonas
- tx: surgical debridement, aminoglycosides + piperacillin or ciprofloxacin
what is paronychia
- nailfold infection, can be due to s aureus
- contact with oral mucosa = herpes simplex
- dishwashers = candida
- tx: incision, drainage, medications
what is felon
- infection of fingertip pulp space
- due to s aureus
- tx: incision, drainage, anti-staph infection
what are human bites
- can be due to s viridans, s bacteriodes, s epidermidis, corynebacterium
- eikenella corrodens (tx: penicillin and 2nd gen cephalosporin)
common empiric antibiotics
read
consequences of dm on skin/bones
- tissue hypoperfusion and ischemia
- delayed wound healing
- diabetic neuropathy = deformity and ulcers
how to assess diabetes (foot)
- assess severity of dm
- assess blood flow (palpate distal pulses like dorsalis pedis or post tibial pulse, measure abi)
abi ratios
- <0.95: significant narrowing of one or more blood vessels
- <0.80 pain in the foot, leg, or butt during exercise (intermittent claudication)
- <0.4 symptoms at rest
- <0.25 severe limb threatening peripheral arterial disease
t/f ankle reading is lower than brachial reading
false
other ways to determine blood flow
- gold standard: peripheral angiogram
- duplex us
wager’s classification of diabetic foot diseases
read
treatment for diabetic foot diseases
- cover for polymicrobial infections (gram+, gram-, anaerobic)
- read table of antibiotics!!
- serum glucose control
- improve peripheral blood flow
- wound care
organisms in acute osteomyelitis
- blood brone from remote part of entry
- from adjacent focus (septic arthritis, soft tissues)
- directly introduced
- s aureus!! (g+ > g-)
epi of acute osteomyelitis
- children
- metaphysis of long bones (vascular + hairpin architecture)
diagnostics of acute osteomyelitis
- <2 weeks
- fever, pain, swelling, erythema, inability to move or bear weight
- labs: leukocytosis, elevated crp, elevated csr, positive blood cultures
radiographs in acute osteomyelitis
- demineralization after 10 days to 2 weeks
- penetration at least 1 cm of cortex = seen in xray
- usually normal xray
- whole body bone scan: asymmetry in uptake
significance of whole body radionuclide bone scan in acute osteomyelitis
- shows affected bone
- does not tell what’s the diagnosis (infection vs malignancy)
- subtle/stress fractures
- avascular necrosis
- osteomyelitis
- total hip/knee arthroplasty loosening
- phase studies (3 or 4 phase)
significance of mri in acute osteomyelitis
- shows changes in 3-5 days
- most sensitive test, but too expensive
- edema fluid and pus is low (dark) in t1, and high (bright) in t2
- normal: marrow is dark on t2
treatment of acute osteomyelitis
- antibiotics for 6 wks (7d iv, 5 wks oral) or until esr is normal
- immobilize extremity
- surgical drainage
what is a good response in acute osteomyelitis
- increased well being
- fever lysis
- increased appetite, feeding, activity
recommended antibiotics for s aureus, enterobacteriaceae, gas/gbs in newborns
antibiotics that cover penicillin resistant s pneumoniae and 3rd gen cephalosporin
recommended antibiotics for = 4 yo (h influenzae, strep, s aureus)
cefuroxime or 3rd gen cephalosporin
recommended antibiotics for >4 yo (h influenzae, strep, s aureus)
prsp or first gen cephalosporin
recommended antibiotics in adults (s aureus, enterobacteriaceae, strep)
prsp or first gen cephalosporin
what is chronic osteomyeltitis
- formation of sequestrum (dead bone) and involcrum (new bone)
- inadequately treated acute type or immunocompromised patients
- sinus tracts form and drain chronically (-> squaca)
natural history of untreated osteomyelitis
- metaphyseal abscess
- local extension
- penetrates cortex to form subperiosteal abscess
- penetrates periosteum to form soft tissue abscess
- pathologic fracture development -> invade adjacent joint or form sinus
- chronic osteomyelitis with sequestrum
bone’s dual blood supply
nutrient artery: from medullary cavity (inside)
periosteal artery: from periosteum (outside)
when medullary cavity is filled with pus, __ happens
- periosteum is push away by pus and bone is deprived of blood supply
treatment of chronic osteomyelitis
- resembles local malignant tumor
- removal of all dead tissues and sinus tract
- stabilize bone
- provide soft tissue coverage
- manage bone gap (grafts)
- appropriate antibiotics
mechanisms of septic arthritis
- blood borne organism from remote focus
- contiguous spread from metaphyseal osteomyelitis in children
- secondary to invasive diagnostic or therapeutic joint procedure
patients at risk for septic arthritis
- neonates
- iv drug users
- elderly
- immunocompromised w/ dm
causative organisms of septic arthritis
- s aureus!!
- n gonorrhea (!! in healthy sexually active adolescents and adults)
- pseudomonas (!! iv drug users)
- gram - (e coli, proteus, kleb, enterobacter)
- strep (gbs!! infants, elderly, dm)
- propiiionibacterium acnes (shoulder injury)
- salmonella or spneumoniae
- bartonella henselae (hiv)
- pasturella multocida
- eikenella corrodens
- candida
diagnosis of septic arthritis
- joint aspirate
- extreme joint pain on passive motion !!
- local and systemic signs of infection
- septic hip: (FABER) Flexion, ABduction, External Rotation)
treatment of septic arthritis
- penicillinase-resistant synthetic penicillin + beta lactamase inhibitors
- anti-gonoccocal agents
- anti-pseudomonad aminoglycoside
t/f eptb is usually paucibacillary and non-infectious unless with ptb or during surgical procedures
true
what is potts disease
- tb infection affecting 2 adjacent vertebral bodies
- causes collapse, kyphotic deformity (gibbus) and cord/nerve compression
- sensory, motor, autonomic deficits
- ankylosis at healing
diagnostics for eptb/potts disease
- esr and crp
- clinical trial of anti-koch for 2 weeks
treatment for eptb/potts disease
- quadruple anti-kochs for 6 mos
- hrze 2 mos
- hre 4 mos (or 10 mos)
