Bone
Osteomyelitis
Bacterial osteomyelitis (acute)



Topic Completed: 1 June 2012

Revised: 27 December 2018

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Acute bacterial osteomyelitis
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Cite this page: Borys D Bacterial osteomyelitis (acute). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonebacterialosteomyelitis.html. Accessed May 23rd, 2019.
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

    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)

    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

    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

Contributed by Dr. Mark R. Wick
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Bacterial osteomyelitis of tibia and vertebra in thoracic spine

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
    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)
Microscopic (histologic) images

Contributed by Dr. Mark R. Wick
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Bacterial acute osteomyelitis



Images hosted on other servers:
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Lactobacillus sepsis and osteomyelitis


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Osteomyelitis secondary to direct extension of soft tissue infection

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