Osteomyelitis, Acute Pyogenic

Key Features

Essentials of Diagnosis

• Fever associated with pain and tenderness of involved bone

• Diagnosis usually requires culture of bone biopsy

• Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

• Radiographs early in the course are typically negative

General Considerations

• Occurs as a consequence of hematogenous dissemination of bacteria, invasion from a contiguous focus of infection, or skin breakdown in the setting of vascular insufficiency

• In sickle cell anemia, Salmonella is the most common pathogen

• In injection drug users, Staphylococcus aureus is most common, but also gram-negative (eg, Pseudomonas aeruginosa and Serratia) infections

• Contiguous focus infections are usually due to S aureus and Staphylococcus epidermidis

Clinical Findings

Symptoms and Signs

HEMATOGENOUS OSTEOMYELITIS

• Associated with sickle cell disease, injection drug users, diabetes mellitus, or the elderly

• High fever, chills, and pain and tenderness of the involved bone

• Polymicrobial infections rare

OSTEOMYELITIS FROM A CONTIGUOUS FOCUS OF INFECTION

• Prosthetic joint replacement, pressure injury (formerly pressure ulcer), neurosurgery, and trauma are common sources of infection

• Localized signs of inflammation are usually evident, but high fever and other signs of toxicity are usually absent

• Septic arthritis and cellulitis can also spread to contiguous bone

• Polymicrobial infections more common than in hematogenous osteomyelitis

OSTEOMYELITIS ASSOCIATED WITH VASCULAR INSUFFICIENCY

• Infection originates from an ulcer or other break in the skin that may appear disarmingly unimpressive

• Bone pain is often absent or muted by an associated neuropathy

• Fever is also commonly absent

• Two of the best bedside clues that the patient has osteomyelitis are

  • The ability to easily advance a sterile probe through a skin ulcer to bone

  • Presence of an ulcer area > 2 cm²

Differential Diagnosis

• Acute hematogenous osteomyelitis should be distinguished from suppurative arthritis, rheumatic fever, and cellulitis

• Subacute forms must be differentiated from tuberculosis or mycotic infections of bone or from bone tumors

• When osteomyelitis involves the vertebrae, it commonly traverses the disk—a finding not observed in bone tumor

• Cellulitis

• Septic arthritis

• Gout

• Diabetic or arterial insufficiency ulcer

• Tuberculous or mycotic bone infection

• Rheumatic fever

• Metastatic cancer

• Charcot arthropathy

• Plasma cell myeloma

• Ewing sarcoma

• Avascular necrosis

Diagnosis

Laboratory Tests

• Blood cultures

• Cultures from overlying ulcers, wounds, or fistulas are unreliable

• ESR and serum CRP

  • Almost always elevated

  • Can be useful parameters to follow during the course of therapy

Imaging Studies

• Early radiographic findings include soft tissue swelling, loss of tissue planes, and periarticular demineralization of bone

• About 2 weeks after onset of symptoms, erosion and ...