osteomyelitis Flashcards
osteomyelitis is…
infection of the bone, can be bacterial or fungal
what are the sources of osteomyelitis?
hematogenous spread
invasion from a contiguous focus of infection (diabetic foot)
skin breakdown (vascular insufficiency or trauma)
hematogenous spread results from ____
bacteremia
who is at risk for hematogenous spread?
sickle cell anemia (salmonella)
elderly
IV drug users (staph aureus)
diabetes
sxs of osteomyelitis
fever-absent or low grade
bone or joint tenderness/pain
elevated acute phase reactants- CRP, ESR
bone can be probed with a swab from the wound site
wound > 6 weeks in duration
what are the risk factors for osteomyelitis?
bone fracture any condition that causes weakening of the immune system (diabetes, organ transplant, chemotherapy, AIDS) kidney failure IV drug abuse joint replacement/ orthopedic hardware placement peripheral neuropathy peripheral vascular disease sickle cell anemia
how is the diagnosis of osteomyelitis made?
plain film X-ray of suspected area
showing bone abnormalities, cortical erosion, periosteal reaction, and lucency or osteolysis (may not be apparent until 7-15 days after the onset of acute clinical osteomyelitis)
MRI if x ray is negative and osteomyelitis is suspected
labs
acute phase reactants
CBC (WBC might be elevated)
what is the treatment for osteomyelitis?
debridement of bone
minimum of 6 weeks of IV antibiotics targeted to organism (keep in mind bone penetration ability of selected abx)
continued monitoring
what are empiric abx choices for osteomyelitis?
vancomycin 1 gram IV q 12 hours +/- rifampin AND Ceftriaxone 2 grams IV q24 hours
(target therapy when cultures become available, Nafcillin is preferred for MSSA)
What is Brodie’s abscess?
bone abscess that can be walled off by body’s immune defenses for years
what is the most common organism in Brodie’s abscess?
most commonly isolated organism is Staph aureus
what bone is most commonly affected in Brodie’s abscess?
tibia
in non-diabetic patients with osteomyelitis, what is the most commonly associated organism and what is the treatment?
staph
MSSA- Nafcillin 2 grams IV q 4 hours OR cefazolin 2 grams IV q 8 hours
MRSA- vancomycin 1 gram IV q 12 hours +/- rifampin 300-450 mg po bid
in diabetic patients with osteomyelitis, was is the most commonly associated organism?
polymicrobic in diabetics- debride and get cultures, usually no empiric therapy- wait for culture
what is the usual duration of therapy for osteomyelitis ?
6 weeks of IV antibiotic therapy
nail through tennis shoe into foot…
what is the organism you are concerned about?
what is the drug of choice?
what are the other parts of the treatment plan?
tetanus
cipro
diabetes testing, look for foreign body
What is infectious arthritis?
aka septic arthritis
direct invasion of joint space by bacteria
who is at the most risk for developing infectious arthritis?
elderly- 45% of cases are above 65 years old
56% male
prosthetic joint infection 2-10%
what is the most common etiology in infectious arthritis?
most are caused by staph aureus
in younger, sexually active people, neisseria gonorrhoeae
what is the mechanism of infection in infectious arthritis?
direct inoculation
contiguous spread
bacteremia- most common
previously damaged joints, especially in RA, most susceptible
what is reactive arthritis?
Joint pain and swelling triggered by an infection in another part of the body
postexposure
What patient population is reactive arthritis more common in?
HLAB27 positive patients
what organisms is reactive arthritis commonly caused by?
chlamydia trachomatis, various GI bugs (salmonella, Yersinia, Campylobacter, C diff)
