Bone & joints

Osteomyelitis

Bacterial osteomyelitis (acute)


Editorial Board Member: Nasir Ud Din, M.B.B.S.
Deputy Editor-in-Chief: Borislav A. Alexiev, M.D.
Hans Magne Hamnvåg, M.D.
Dariusz Borys, M.D.

Last author update: 18 July 2022
Last staff update: 18 July 2022

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PubMed Search: Bacterial osteomyelitis [TIAB] acute

Hans Magne Hamnvåg, M.D.
Dariusz Borys, M.D.
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Cite this page: Hamnvåg HM, Borys D. Bacterial osteomyelitis (acute). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonebacterialosteomyelitis.html. Accessed January 28th, 2023.
Definition / general
Essential features
Terminology
ICD coding
  • ICD-10: M86.9 - osteomyelitis, unspecified
Epidemiology
  • Hematogenous osteomyelitis
    • Occurs most commonly in children
      • More than half occurs in children younger than 5 years and one quarter in children younger than 2 years
      • M > F
    • Among adults:
  • Nonhematogenous osteomyelitis
    • Among younger adults: occurs most frequently in the setting of trauma and related surgery
    • Among older adults: occurs most frequently as a result of contiguous spread of infection to bone from adjacent soft tissues and joints (diabetic foot wounds or decubitus ulcers) (N Engl J Med 1970;282:198)
Sites
Pathophysiology
Etiology
Diagrams / tables

Images hosted on other servers:

Pathogenesis of osteomyelitis associated septic arthritis

Clinical features
  • Signs and symptoms:
    • Gradual onset of symptoms over several days
    • Dull pain at the involved site
    • Tenderness, warmth, erythema and swelling
    • Fever and rigors may also be present (N Engl J Med 1970;282:198)
Diagnosis
  • Diagnosis of osteomyelitis is established via culture obtained from biopsy of the involved bone
  • Histopathology consistent with osteomyelitis in the absence of positive culture data
  • Typical clinical and radiographic findings together with persistently elevated inflammatory markers in the absence of positive culture and no biopsy interpretation (Clin Infect Dis 2004;39:885)
Laboratory
Radiology description
Radiology images

Contributed by Mark R. Wick, M.D.
Bacterial osteomyelitis of tibia and vertebra in thoracic spine Bacterial osteomyelitis of tibia and vertebra in thoracic spine Bacterial osteomyelitis of tibia and vertebra in thoracic spine

Bacterial osteomyelitis of tibia and vertebra in thoracic spine



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Osteomyelitis of the distal fourth metatarsal

Abnormal T1 weighted signal

Localized increased radioactive tracer uptake

Prognostic factors
  • Chronic osteomyelitis develops in a subset of acute osteomyelitis due to:
    • Delayed treatment
    • Inadequate antibiotics
    • Incomplete surgical debridement of necrotic bone
    • Weakened host defenses (EFORT Open Rev 2017;1:128)
Case reports
Treatment
Gross description
  • Varies with patient age:
  • 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

    Patterns of acute osteomyelitis
  • Osseous changes:
    • Osteonecrosis: bone trabeculae with visually empty osteocyte cavities are detectable as a criterion for necrotic bone tissue especially with EDTA decalcification
    • The bone trabeculae have irregular contours and are fragmented
    • They may be fractured and completely necrotic (so called bone sequester)
    • There are intramedullary granulocyte infiltrates and fibrin exudates
    • In bone tissue with a haemopoietic function (e.g. axial skeleton) there is a reduced or complete lack of haemopoiesis
  • Soft tissue changes:
    • Soft tissue necrosis: criteria for soft tissue necrosis are apoptoses, a tissue eosinophilia, fibrin exudations and a confining texture of the tissue
  • Inflammatory infiltrate pattern:
    • Neutrophilic granulocyte infiltrate: diffuse and grouped deposits (so called microabscesses, ≥ 5 granulocytes) of segmented neutrophilic granulocytes in the usually highly oedematous medullary spaces
    • The neutrophilic granulocytes are PAS cytoplasmic, coarsely granular positive and display a plumped, pyknotic chromatin texture (granulocyte apoptosis with pathogen phagocytosis and NETosis)
    • Immunohistochemically there is a specific intensive, coarsely granular, predominantly cytoplasmic CD15 positivity
    • Osteoclasts are also detectable alongside neutrophilic granulocytes on the irregular trabecular surface

    Patterns of chronic osteomyelitis
  • Osseous changes:
    • Bone neogenesis: spongy osseous tissue with reactive network bone neogenesis (POL detection of irregularly running fibrils), the bone surface is bordered by osteoblasts
    • Medullary space fibrosis with ectatic sinus
    • The medullary space tissue shows fibrosing with granulation tissue formation
    • The infiltrate consists of macrophages, lymphocytes, plasma cells and a few neutrophilic granulocytes
  • Soft tissue changes: there is fibrosing with granulation tissue formation, the infiltrate consists of macrophages, lymphocytes, plasma cells and a few neutrophilic granulocytes
  • Inflammatory infiltrate pattern:
    • Lymphocyte / macrophage / plasma cell infiltrate: in the highly fibrosed medullary spaces there is a lymphocyte and macrophage rich, sometimes also plasma cell rich, sometimes focal, sometimes inflammatory infiltration with a few neutrophilic granulocytes

  • 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 replaced by inflammatory tissue
  • Salmonella infection may produce tuberculoid granules with variable central necrosis (Am J Surg Pathol 1985;9:531)
  • Osteoblastic bone resorption
  • Bitten bone (chewed, scalloped bone)
  • Bone necrosis
  • Vessel damage
  • Vascular thrombosis
  • Marrow infarction
  • Dirty marrow (J Foot Ankle Surg 2020;59:75, GMS Interdiscip Plast Reconstr Surg DGPW 2014;3:Doc08)
Microscopic (histologic) images

Contributed by Dariusz Borys, M.D. and Mark R. Wick, M.D.
Acute osteomyelitis

Acute osteomyelitis

 Bacterial acute osteomyelitis  Bacterial acute osteomyelitis

Bacterial acute osteomyelitis

Positive stains
Sample pathology report
  • Femur, debridement (partial excision):
    • Fragments of scalloped viable and non-viable bone with surrounding acute inflammatory infiltrate, consistent with acute osteomyelitis
Differential diagnosis
Board review style question #1

Hematogenous osteomyelitis is usually

  1. Monomicrobial and most common organism involved is Staphylococcus aureus
  2. Monomicrobial and most common organism involved is Streptococcus pyogenes
  3. Polymicrobial and most common organism involved is Staphylococcus aureus
  4. Polymicrobial and most common organism involved is Streptococcus agalactiae
  5. Polymicrobial and most common organism involved is Streptococcus pyogenes
Board review style answer #1
B. Monomicrobial and most common organism involved is Streptococcus pyogenes

Comment Here

Reference: Bacterial osteomyelitis (acute)
Board review style question #2
Most common microbial etiology of bacterial osteomyelitis in neonatal age group is

  1. Salmonella typhi, Staphylococcus aureus, Streptococcus agalactiae
  2. Staphylococcus aureus, Klebsiella, Streptococcus pneumoniae
  3. Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli
  4. Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli
Board review style answer #2
D. Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli

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Reference: Bacterial osteomyelitis (acute)
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