Table of Contents
Definition / general | Pathophysiology | Sites | Radiology description | Radiology images | Treatment | Case reports | Gross description | Microscopic (histologic) description | Microscopic (histologic) imagesCite this page: Borys D. Bacterial osteomyelitis (acute). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonebacterialosteomyelitis.html. Accessed March 6th, 2021.
Definition / general
- Rare due to use of antibiotics
- Usually pyogenic
- Designated as acute, subacute or chronic, based on clinical duration of disease
- Chronic osteomyelitis: develops in 15-30% due to delayed treatment, inadequate antibiotics, incomplete surgical debridement of necrotic bone, weakened host defenses
- May develop sinus tract lined by squamous epithelium that forms large epidermal inclusion cyst within bone; rarely transforms to well differentiated squamous cell carcinoma with excellent prognosis
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Sclerosing osteomyelitis of Garré:
- In jaw, associated with extensive new bone formation that obscures underlying osseous structure
- Also called periostitis ossificans (J Craniofac Surg 2002;13:765)
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Brodie abscess:
- Small intraosseous abscess in cortex, walled off by reactive bone with no periosteal reaction
- Cavity may contain infectious organisms or be sterile
- May have late recrudescence
- Therapy: total surgical excision (Tunis Med 2007;85:857)
Pathophysiology
- Bacteria proliferate in bone, cause inflammation and necrosis
- Spread along haversian system or medullary cavity within shaft and to periosteum
- Subperiosteal abscesses impair blood supply, which causes more necrosis and often draining sinuses
Sequestrum
- Dead piece of bone
- Gradually separated from living bone by granulation tissue
- May pass through sinus tract
- Avascular and dense on Xray
- Involucrum: sleeve of living tissue created by periosteum which is deposited around sequestrum
Hematogenous spread
- Most common cause
- Usually metaphyseal in children and adults
- Usually long tubular bones of children; involvement of flat bones is more common in adults
Direct extension
- Less common
- May be associated with trauma or rarely iatrogenic implantation of infectious material
- In elderly, may affect vertebral column
- May be associated with systemic urinary tract infection, diabetes (affects small bones in feet)
- In younger adults, associated with immunodeficiency or intravenous drug abuse
Type of bacteria
- 50% of cases are due to unknown bacteria
- 80% of cases with known organisms are due to Staphylococcus aureus, which produces receptors to bone matrix components
- Sickle cell patients may have infections by Salmonella choleraesuis, S. paratyphi B and S. typhimurium
- Neonates are prone to Treponema (periostitis), gram negative rods, Group B Streptococci, Hemophilus influenzae and Listeria species
- Intravenous drug addicts (affecting clavicle, sternoclavicular joint, spine or pelvis): Staphylococcus aureus and coagulase-negative Staphylococcus (Clin Orthop Relat Res 2010;468:2107)
- Post-traumatic cases: Pseudomonas and mixed bacteria
- Other known organisms are E. coli, Pseudomonas and Klebsiella
- Rarely associated with malakoplakia
Sites
- In children, at areas of rapid growth or increased risk of trauma (distal and proximal femur, proximal tibia and humerus, distal radius)
Radiology description
- May be negative early
- Three phase bone scans (with Gallium or Indium scanning), MRI or other studies may be necessary
- Late images show prominent periosteal reaction resembling neoplasm
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Sclerosing osteomyelitis of Garré:
- Lytic bone destruction surrounded by sclerosis
- Chronic disease may resemble malignant bone tumor due to destructive and regenerative bone changes
Radiology images
Treatment
- Surgery to remove dead bone (sequestrum)
- Antibiotics; levels in bone may be lower than serum; often Cloxacillin, Nafcillin, third generation cephalosporins; guided by culture and sensitivity reports and drug minimum inhibitory concentration
Case reports
- 17 month old immunocompetent black girl with disseminated Mycobacterium avium disease (Hum Pathol 1980;11:476)
Gross description
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Varies with patient age:
- Infants under age 1 year often have permanent joint and epiphyseal damage sparing metaphysis and diaphysis
- Children 1 year and older have opposite changes (sparing of joint, damage to metaphysis)
- Adults have joint infection and extensive bone involvement
- Acute disease has pus tracking through bone, periosteal elevation and shell of reactive periosteal bone around necrotic center
- Neonates may have considerable subperiosteal spread
- Chronic disease is accompanied by prominent periosteal bone formation
Microscopic (histologic) description
- Neutrophils (may persist for weeks), lymphocytes and plasma cells with bone necrosis and reactive new bone formation
- Capillary proliferation and fibrosis
- Subtypes include plasma cell osteomyelitis and xanthogranulomatous osteomyelitis (abundant foamy macrophages)
- Bone marrow space replaced by inflammatory tissue
- Salmonella infection may produce tuberculoid granules with variable central necrosis (Am J Surg Pathol 1985;9:531)