Bone Infections/Osteomyelitis Flashcards
What are the categories of osteomyelitis?
Hematogenous
Direct implantatio
Continguous
Infeciton of Prosthetic
Hematogenous osteomyelitis
resulting from seeding of bone related to a previous bacteremia
Direct Implantation leading to osteomyelitis?
resulting from a penetratin injury
what is contiguous osteomyelitis
resulting ftom direct spread of bacteria from an overlying wound or pressure ulcer
how can infection of prosthetic devide lead to osteomyelitis
resulting from infection of prosthetic material implanted in bone, with spread of oragnisms into the adjacent bone
what is the difference between hematogenous and and contiguous osteomyelitis?
hematogenous is more common in children and is usually monomicrobial, whereas contiguous osteomyelitis (more common in adults) is often polymicrobial
What bugs are associated with hematogenous osteomyelitis?
staph aureus, strep spp, gram negatives, mycobacterium tuberculosis, salmonella sp (in sickle cell)
what bug is common with direct implantation osteomyelitis?
pseudomonas aeruginosa is common n nail injuries with sneakers, but other organisms can be implanted too
what bugs are associated with sontiguous osteomyelitis?
S. aerues, gram negatives, streptococcus sp., anaerobes (usually smelly) candida
what bugs are associated with prosthetic joint infections?
coagulase negative staphylococci (sticks to stuff well) , S. aureus, gram negatives, streptococcus sp. propionibacterium acnes
what accounts for 70-90% of hematogenous osteomyelitis in children?
Staphylococcus aureus
WHat bugs are more frequent in patients with UTIs or infections from IV drug use
gram negatives such as E coli, Pseudomonas, Kelbsiells, enterobacter
1-3% of patients with TB will have bone infections. What are these usually through?
through the blood stream or from direct extension from a pulmonary focus (to ribs or vertebral bodies)
what is another very common std that can infect bone?
syphillis can infect bone (in chronic or congenital cases)
WHat bug has become a very important bug in shoulder replacement infections
Probionibacterium (cutibacterium) acnes has become a very important pathogen in shoulder replacements
Can osteomyelitis become chronic or is it always acute?
- often cause chronic infections that are difficult to eradicate
During osteomyelitis what does damage to the periosteum result in?
peices of dead bone (sequestrum) or new external bone formation (involucrum); localized absesses may also occur (Brodie’s absess)
What is the most effective imaging to look for osteomyelitis?
Bone/WBC scans or MRIS are much more effective!
X-rays can be negative in early infection and infacat are not sensitive
***gold standard to treat is to do a biopsy to figure out what the bug is
what is the gold standard to make sure you are correctly treating the osteomyelitis?
getting a bone biopsy. the bacteria causing osteomyelitis can be obtaines from bone biopsies or sometime from blood cultures
Is a culture of an open ulcer overlying a contiguous osteomyelitis reliable?
NO! they re noticably unreliable. the bacteria in the bone underneath may be entirely different
WHat do yo udo if a bone biopsy cannot be done? or all culture results are negative?
empiric treatment (30-40%)
what type of osteomyelitiis is often difficult to treat and what does this result in?
infections of prosthetic material are paticularly difficult to treat; the prosthesis often needs to be removed o eradicate the infection :( amputation may need to be done
What makes osteomyelitis MUCH more difficult to treat?
biofilm! they may develop on infected bone or particularly on prostheses, making the infections more difficult to treat
What are biofilms?
- aggregationg of microorganisms adherent to a surface, particularly a har dsurface like bones or teeth or prosthetic materials
- the adherent microoragnisms are frequently embedded in a matrix that they produce-called slime or extracellular polymeric substance or glycocalyx
- biochem and physiology or biofilm organisms are different from those of planktonic (suspended) organisms
- biofilm bacteria are liekly to be more reisstant to antibiotics than are planktonic bacteria
**often S. aurues-often sticking via the glycocalyx which looks like tubes
How do we treat osteomyelitis?
- long course of antibiotics; 6 weeks IV, sometimes months of oral antibiotics (particularly for prosthetic joint infections) -**Rifampin often used**
- surgery may be needed to remove sequestra or prostheses (in cases where antibiotics fail)
- antibiotic rifampin is particularly useful for biofilms!!! markedly improved the sucess in therapy of prosthetic joint infections (but only for stahylocci and only those that are suscetible to it)
- Antibotic treatment is only useful if the bone is covered by tissue-otherwise, new organisms can continously invade the bone
what are the common cauative organisms for osteomyelitis?
staphylococci (most common) streptococci, gran negatives, anaerobes, mycobacteria, and fungi (candidia)
When is fever seen during osteomyelitis?
it is seen in acute osteomyelitis, and rare in chronic
