DS: Joint ant Bone Infections Flashcards
Septic arthritis?
Pyogenic arthritis (synonym) an invasion of a joint by a pathogenic bacterium causing purulence (pus formation) resulting in an extremely painful and swollen joint
Importance of septic arthritis?
bacterial arthritis is more dangerous and destructive
significant damage can occur within 24 hours
mortality around 7-15% despite antibiotic use
Diagnosis of septic arthritis?
arthroscopy or open drainage in the operating room
aka, immediate treat, surgery
making differential for septic arthritis?
it is a painful, warm arthritis
have to think about other ones of that nature
gout, reactive arthritis, RA, lupus, akylosing spondylolitis, etc
why is preexisting arthritis a risk factor for septic arthritis?
more likely to develop an infection in the joint that is already damaged
other risk factors for septic?
steroid use intraarticular injection diabetes trauma history of STDs other infection
Epidemiology of Septic?
usually in patients with preexisting joint problems
most are male
older than 65 yo
Source of infection?
Sepsis, spread to the joint from infection is common
trauma to the joint
direct inoculation during joint surgery
Etiology of septic arthritis? most common
Staph aureus is most common
septic in neonates?
Strep agalactiae
septic in sick cell?
step pnuemoniae
strep in young children?
Kingella Kingae
septic in STDs/ unsafe sex?
Neisseria gonnorhoeae
septic in unvaccinated?
hemophilus influenzae
septic in endemic areas?
mycobacterium tuberculosis
Staph aureus?
gram pos, facultative, catalase pos, coagulase pos
cause abscess formation in skin and subcut tissue
Strep pyogenes? (grp A strp)
gram pos cocci in chains
catalase neg, beta hemolytic, sens to bacitracin
cause infections, cellulitis, strep throat, sepsis, rheumatic fever
aka, patient with strep throat, develops joint pain after– has this
Strep agalactiae? (grp B strep)
gram pos cocci in chains
beta hemolytic, carried in maternal gential tract
cause meningitis, pneumonia, and sepsis in neonates
Strep pneumoniae?
gram pos, lancet shaped, diplocci alpha hemolytic sens to optochin polysaccharide capsule cause pneumonia, otitis media, meningitis, sepsis
(sickle cell)
Neisseria?
gram neg, diplo, coffee bean shape
produce cytochrome oxidase
STD causes urethritis and cervictitis
Kingella Kingae?
fastidious aerobic gram-neg coccobacilli
most commonly isolated from blood and synovial fluid
colonize oral mucosa
cause endocarditis and joint infections in young child (2 mo- 2 yrs)
Clinical features of septic arthritis?
infection is generally monoarticular
knee is the most common, followed by hip
swollen, hot, painful joint in a patient with fever
How do organisms invade in septic?
invade via bloodstream, direct inoculation or by continuous spread from infected periarticular tissue
previous damaged joints are most susceptible, synovial membranes of these joints exhibit neovascularization and increased adhesion factors
How does s. aureus bind to joint?
via specific tissue adhesion factors
how does s. aureus cause damage and multiply?
organisms pathological properties, chondrocyte proteases, as well as host’s polymorphonuclear leukocytes response
Pannus formation?
layer of fibrovascular or granulation tissue
beings and cartilage erosion occurs at the lateral margins of the joint
large effusions impair the blood supply, aseptic necrosis of bone
atherocentesis?
to obtain joint fluid
lab diagnosis?
atherocentesis, then gram stain joint fluid, cell count and differential, culture joint fluid
Staph aureus, step, and neisseria most common
Treatment of septic?
arthroscopy or open drainage of joint
antibiotic therapy depends on organism isolated
Treat s. aureus?
Naficillin, Vancomycin
Treat with penicillin?
S. pyogenes
S. pneumoniae
Treat with ceftriaxone?
S. pneumoniae
N. gonnorhoeae
Osteomyelitis?
difficult to diagnose until about 50% of the bone matrix must be removed before the lytic process can be visualized
no changes occur on a standard x-ray until 10 days after onset of illness
Pathophysiology of osteomyelitis?
occurs more frequent in children when long bones grow
a trauma disrupts blood vessels and cause hematoma
Metaphysis is predisoposed to infection
Why is the metaphysis predisposed to infection?
because capillaries make sharp loops close to the growth plate then expand to large sinusoidal vessels that connect to venous network, an increase in diameter slows blood flow, cause sludging, and microclots
Diagnosis of Osteomyelitis?
patient will have a fever and severe localized skeletal pain
radiologic findings of localized inflammatory process (xray, bone scan, CT/MRI)
blood culture, bone aspirate for culture
What will a bone scan show?
increased blood flow, pooling, and reactive new bone formation
Etiology of Osteomyelitis? Children?
S. aureus most common Strep agalactiae (grp B) neonates step pneumo (2 mo- 2yrs) Haemophilus influenza (2 mo-2yrs unvaccinated) Kingella Kingae (2mo to 2 yrs) Strep pyogenes (grp A) school age children
Etiology of Osteomyelitis in adults?
S. aureus most common gram neg rods/ E coli, Klebsiella/Enterobacter Salmonella (sickle cell) Pseudomonas and Serratia (IV drug users) Other (fungir, mycobacteria)
Treatment of Osteomyelitis?
surgical debridement of necrotic bone material
antibiotics depends on organism isolated (high dose, parenterally, long course)
Infections with prostheses?
only .5-1% become infected
infection develops at the bone-cement interface, cemeneted with polymethylacrylate
source may be introduced through surgery or be from a hematogenous origin
Etiology of infections with prostheses?
Staphylococcus most common (Staphylococcus epidemidis)- due to slime layer which binds to surface of prosthetic device (Staph aureus) Strep species Gram neg Enterococcus mixed flora other (fungi, mycobacteria)
Treatment of infections with prostheses?
surgery, often removal of prosthetic is required with debridement of necrotic tissue
antiobiotics depend on organism isolated
