6- Bone Infections Flashcards
Results from seeding of bone rleated to previous bacterimia
Hematogenous
Osteomyelitis From penetrating injury
Direct implanation
Osteomyletis from direct spread of bacteria overlying wound or ulcer
Contigous
osteomyelitis from prosthetic infection material implanted in bone, spread of organisms to adjacent bone
Infection of prosthetic device
More common osteomyletisi in children?
Hematogenous
MOre common osteomylitis in adults
contigous and prosthetic infection
Common pathogen involved in direct implantation osteomyletis
P. Aeroginosa
Key pathogens for Hematogenous osteomyletis
Staphylococcus aureus, Streptococcus sp.,
gram-negatives, Mycobacterium tuberculosis, Salmonella sp.
(in sickle cell patients).
Pathogens for direct implant?
Pseudomonas aeruginosa in nail injuries
with sneakers
Key pathogens for contiguous osteomyelitis
S. aureus, gram-negatives, Streptococcus sp.,
anaerobes, Candida sp.
(often dt pressure ulcer)
Key pathogens for Prosthetic osteomyelitis
Coagulase negative staphylococci,
S. aureus, gram-negatives, Streptococcus sp.
Some complications of osteomylitis
Often causes chronic infections that are difficult to eradicate.
Damage to the periosteum may result in pieces of dead bone
(sequestrum) or new external bone formation (involucrum);
localized abscesses may also occur (Brodie’s abscesses)
Whats the most effecting imaging to get for suspected osteomyelitis
X-rays may be negative in early infections and in fact are not
very sensitive for osteomyelitis; Bone/WBC scans or MRI
imaging are more effective
Where should we get the culture of bacteria for osteomyelitis to make Dx?
The bacteria causing osteomyelitis can be obtained from bone
biopsies or sometimes from blood cultures
What can be tricky about obtaining a culture in someone with contigious osteomyelitis?
Cultures of open ulcers overlying contiguous osteomyelitis are
notoriously unreliable; the bacteria in the bone underneath
may be entirely different
Why are prosthetic osteomyelitis infections hard to tx
Biofilms can devo and they are resistant to lots of drugs. may need to remove the prosthesis
Describe biofilms
The adherent microorganisms are frequently embedded in a matrix that they produce – called slime or extracellular polymeric substance or glycocalyx.
The biochemistry and physiology of biofilm organisms are different from those of planktonic (suspended) organisms
What drug is a good tx for biofilms
Rituximab
Recommened tx for osteomyeltis infection?
Osteomyelitis treatment requires long courses of antibiotics;
generally 6 weeks of intravenous therapy is used, but in some
cases months of oral antibiotics may also be required
(particularly for prosthetic joint infections)
If antibiotics fail to clear up osteomyelitis, what would be the next step?
Surgery may be needed to remove sequestra or prostheses (in
cases where antibiotics alone fail)
What must be present in order to tx an osteomyeltis and prevent reoccurance?
Antibiotic treatment is only useful if the bone is covered by
tissue - otherwise, new organisms can continuously invade
the bone.
