Bone & joints

Osteomyelitis

Bacterial osteomyelitis (acute)

Author: Dariusz Borys, M.D.

Topic Completed: 1 June 2012

Minor changes: 7 July 2021

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Acute bacterial osteomyelitis

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Table of Contents

Cite this page: Borys D. Bacterial osteomyelitis (acute). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonebacterialosteomyelitis.html. Accessed September 22nd, 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

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

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