see also: [[bone and joint infection (paeds)]] see: [Dunn - osteomyelitis](x-devonthink-item://7551D872-6D6E-459F-97A6-1324F91B9B55) > [!key points] > - Osteomyelitis is an inflammatory process of the bone secondary to infection > - S aureus is the most common pathogen in all age groups > - acquired via *haematogenous spread* in children and a/w trauma, surgery, vascular insufficiency, and diabetes in older adults. | Age group | typical bacteria | | ---------------------------------- | ------------------------------------------------------------------- | | newborn - 4 months | staph aureus, group A and group B strep | | children | S aureus, GAS, strep pneumo | | Adults | s aureus, strep species, enterobacter, e coli, other gram negatives | | sickle-cell | salmonella, staph | | diabetes or vascular insufficiency | polymycrobial S aureus and s pyogenes | | IVDU | MRSA + pseudomonas | | unusual | anaerobic bacteria, brucella, mycobacterum tuberculosis, fungi | # clinical features - new onset localised bone pain and fever - enquire about history of injury - pts do not usually appear toxic or unwell - mild fever - warmth, tender, swelling at site of pain - elderly may have fever, non-traumatic back or neck pain, localised tenderness due to involvement of vertebral bodies - diabetic pts may present with painless foot ulcer due to associated neuropathy - lab tests are non-specific > [!tldr] diagnostic criteria > listed in decreasing order of diagnostic utility > - bone biopsy with positive bacterial culture > - imaging studies demonstrating contiguous soft tissue infection or bone destruction > - clinical signs of exposed bone, persistent sinus tract > - chronic wound over a surgical site or fracture > - psitive blood culture, elevated ESR, CRP **DDx** - arthritis - tumours (eg ewing sarcoma or osteoid osteoma) - traumatic injury - gout - septic arthritis may co-exist with osteomyelitis in joints, such as the hip and shoulder. # imaging | modality | best for | | -------- | ----------------------------------------------- | | CT | peripheral and/or chronic osteomyelitis | | MRI | - suspected spinal osteomyelitis / discitis<br> | | | | ## X-rays plain radiographs may suggest dx or exclude other ddxs. XR changes are not seen until the infectious process ahas been present for 10 days to 2-3 weeks ore more; therefore are *of limited value* in diagnosis of early osteomyelitis. first changes in bone are periosteal elevation → next focal lucency, bony resorption, or radiodense, avascularised areas known as *sequestra*. *XR changes ir order of evolution* 1. joint effusions, even if in diaphysis and not involving the joint 2. joint space widening early or loss later 3. avascular areas (sequestra), radio-dense 4. surrounding bony resorption ## ultrasound and bone scan - USS helps to localise the site and extent of infection and provides guidance for dx aspiration or bone biopsy - nuclear medicine scans are *sensitive*, but lack specificity. useful when MRI is contraindicated and/or metalwork affects CT images. ## CT and MRI imaging - CT provides excellent images and identifies subtle changes, especially in long bones. also used for spinal infection if MRI is not available - MRI allows the *earliest detection of osteomyelitis*, usually within 3-5 days after onset, and demonstrates the extent of involvement and activity of the disease. - has the best sensitivity and specificity - investigation of choice in vertebral osteomyelitis and helps to exclude extension to discitis or an epidural abscess. # OM in children - haematogenous spread in children typically affects the long bones - sometimes insidious onset # OM in adults - OM most commonly in the spine, sternoclavicular joints, and sacroiliac joints. can be thracolumbar and lumbosacral in elderly - risk factors: - diabetes - IVDU - alcoholism - long term [[Steroids]] **UTIs** or urinary prcedures greatest risk of spinal osteomyelitis may get discitis due to s aureus # management - all initial abx should include an anti-staphylococcal agent, since this accounts for >80% of cases - vanc if MRSA is suspected - cipro (750mg oral Q12H or 500mg IV Q12H) if sickle cell anaemia to cover for salmonella - vanc 1.5g IV Q12H if IVDU - vanc + pip-taz if diabetes or vascular insufficiency (often polymycrobial) # Related Questions ## epidural abscess - [ ] 12Q: [Back pain](x-devonthink-item://2F267333-5FEC-47E5-83D1-CC05B23EB91A?page=15) -- [Answer](x-devonthink-item://C6CAC39D-CAE8-4F76-9C45-689A0464D936?page=12) - [ ] 13Q: [Back Pain and Fever](x-devonthink-item://FE3157C2-07B3-43F2-9ECE-AFACE1355E13?page=50) -- [Answer](x-devonthink-item://DDC959EB-0C1E-448A-8380-C397BF734322?page=24) - [ ] 14Q: [Back Pain and Fever](x-devonthink-item://CA4D5561-277D-47A1-9EC2-E0DB4C59DCFD?page=14) -- [Answer](x-devonthink-item://2551B51B-0E7C-448E-9FB5-3B547E74974A?page=14) ## septic arthritis - [ ] 30Q: [Septic arthritis](x-devonthink-item://09493372-578D-4C97-972A-EEC617B38B53?page=14) -- [Answer](x-devonthink-item://A0D348CE-FCD4-4ECD-BE21-6CA73F6DE8CD?page=5)