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Bacterial osteomyelitis (acute)

Reviewers: Dariusz Borys, M.D. (see Reviewers page)
Revised: 9 August 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


● 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)


● 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


● 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


● 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

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


● 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

Micro 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)

Micro images

Bacterial acute osteomyelitis - contributed by Dr. Mark R. Wick


Lactobacillus sepsis and osteomyelitis


Osteomyelitis secondary to direct extension of soft tissue infection

Virtual Slides


End of Bone > Osteomyelitis > Bacterial osteomyelitis (acute)

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