Osteomyelitis is an infection of the bone acquired hematogenously or by contiguous site infection. In children, hematogenous spread is more common, and the long bones are more often infected. In adults, hematogenously seeded osteomyelitis is seen; however, extension from contiguous sites is more likely. Diabetic foot ulcers and pressure sores are common predisposing conditions.
Tabs Content Clinical Overview Diagnosis
Indications for Testing
Chronic, nonhealing ulcer that can be probed to the bone (eg, diabetic foot ulcer, decubitus ulcer in immobilized patient)
Localized bone pain with signs and/or symptoms of infection
Back pain or neck pain with
Fever
Elevated C-reactive protein (CRP) and/or erythrocyte sedimentation rate (ESR)
Blood-stream infection or infective endocarditis
Recent Staphylococcus aureus bacteremia
New neurological symptoms with or without back pain or neck pain
Laboratory Testing
CBC
May be normal or show leukocytosis or left shift
Leukocyte count may be normal in chronic or indolent osteomyelitis
Normocytic normochromic anemia may be present if infection is chronic (anemia of chronic inflammation)
CRP
Preferred test to detect acute inflammation (Choosing Wisely , American Society for Clinical Pathology, 2016)
Emerging as preferred marker for diagnosis and monitoring of osteomyelitis
Frequently elevated but not specific
Normal ESR and CRP essentially rule out osteomyelitis
Specific types
Vertebral osteomyelitis – use CRP in conjunction with ESR in all patients with clinical signs (Infectious Diseases Society of America [IDSA], 2015)
Diabetic foot osteomyelitis – use CRP with ESR in conjunction with white blood cell (WBC) count to assess severity of infection of ulcer (IDSA, 2012)
ESR (sed rate, Westergren sedimentation rate) – order if CRP not available
Marker of inflammation – increases and decreases more slowly than CRP
Diabetic foot osteomyelitis – ulcer depth >3 mm and ESR >60 mm/hr assist in differentiation of cellulitis from osteomyelitis (IDSA, 2012)
Routine blood culture
Collect prior to antibiotic administration in all suspected cases
≥2 sets of cultures (aerobic and anaerobic) should be obtained from different draws (IDSA, 2015)
Positive cultures may preclude need for bone biopsy
Positive in up to half of cases
Tissue culture
Superficial culture not useful
Bone sample necessary unless organism identified in blood
Bone or deep tissue obtained at debridement, or imaging-guided or surgical biopsy/aspirate
Procalcitonin
Use in conjunction with other inflammatory markers (acute phase reactant)
Elevated in severe bacterial disease (eg, sepsis)
Being evaluated as assessment of osteomyelitis disease severity
Other organism testing for vertebral osteomyelitis (rare organisms)
Test if risk factors or epidemiology appropriate or after no growth of bacterial cultures
Blood cultures and serologic tests for Brucella recommended for patients with vertebral osteomyelitis in endemic areas
Obtain fungal cultures if patient is at risk for fungal vertebral osteomyelitis due to risk factors or epidemiologic factors
Purified protein derivative (PPD) or interferon – gamma release assay for mycobacterium tuberculosis (TB) for at-risk patients
Polymerase chain reaction (PCR)
Not widely available; may be useful if all cultures are negative
Most useful for Bartonella henselae Kingella kingae
Imaging Studies
Criteria for diagnosis
Imaging modalities for osteomyelitis
Plain x-ray films – may not demonstrate presence of osteomyelitis until 10-14 days after infection is established
Negative film does not rule out diagnosis
Evidence for osteomyelitis on film – periosteal lifting or lytic lesions
Magnetic resonance imaging (MRI) – indicated after x-ray or in combination to identify extent of disease
Labeled leukocyte bone scan – indicated in absence of MRI
Computerized tomography (CT) scan – not as sensitive as MRI; not useful if metal is near the infection
Differential Diagnosis
Monitoring
C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
Recommended after 4 weeks of antimicrobial therapy for vertebral osteomyelitis to evaluate response (IDSA, 2015)
CRP likely as effective alone
Background
Epidemiology
Incidence (Kremers, 2015)
21.8/100,000 person-years (U.S. adults)
8.8/100,000 (U.S. children)
Sex – M>F
Children – more than 50% occur in children <5 years
Adults – incidence increases with age
Risk Factors
Children
Blunt trauma
Postoperative
Adults
Peripheral vascular disease
Diabetes mellitus Renal or hepatic failureImmunosuppression
Malignancy
Neuropathy
Intravenous drug use
Trauma
Surgery – particularly prosthetic implants
Organisms
Most common organism
Diabetes mellitus, peripheral vascular disease
Streptococcus sppCoagulase-positive and -negative Staphylococcus spp
Enterococcus sppAnaerobic spp, often polymicrobial
Intravenous drug use
Infants and children
Neonates
Hemoglobinopathies
Uncommon pathogens
Fungal and mycobacterial pathogens
Clinical Presentation
Constitutional – fever, nonspecific pain
Soft-tissue inflammation overlying area of osteomyelitis
Open and nonhealing wound over area of bone
Vertebral disease – may present with severe back pain
Children
Limping, reluctance to walk
Fever
Focal tenderness
Swelling
ARUP Lab Tests
Initial test for differentiating bacterial from viral infection
Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)
Nonspecific test used to detect inflammation associated with infections, cancers, and autoimmune diseases
Detect presence of bacteria in blood
If anaerobic infection is suspected, send specimen under anaerobic conditions
Detect Bartonella spp in blood, cerebrospinal fluid (CSF), or tissue
Medical Experts Fisher, Mark A., PhD, D(ABMM), Medical Director, Bacteriology, and Special Microbiology, Antimicrobial Susceptibility Testing, at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah
Genzen, Jonathan R., MD, PhD, Chief Operations Officer, Medical Director of Automated Core Laboratory and Farmington Health Center Clinical Laboratory, at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah
References Choosing Wisely . An initiative of the ABIM Foundation. [Accessed: Aug 2019]Lipsky BA, Berendt AR, Cornia PB, Pile JC, Peters EJ, Armstrong DG, Deery G, Embil JM, Joseph WS, Karchmer AW, Pinzur MS, Senneville E, Infectious Diseases Society of America. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012; 54(12): e132-73. PubMed Berbari EF, Kanj SS, Kowalski TJ, Darouiche RO, Widmer AF, Schmitt SK, Hendershot EF, Holtom PD, Huddleston PM, Petermann GW, Osmon DR. 2015 Infectious Diseases Society of America (IDSA) Clinical Practice Guidelines for the Diagnosis and Treatment of Native Vertebral Osteomyelitis in Adults. Clin Infect Dis. 2015; 61(6): e26-46. PubMed Hingorani A, LaMuraglia GM, Henke P, Meissner MH, Loretz L, Zinszer KM, Driver VR, Frykberg R, Carman TL, Marston W, Mills JL, Murad MH. The management of diabetic foot: A clinical practice guideline by the Society for Vascular Surgery in collaboration with the American Podiatric Medical Association and the Society for Vascular Medicine. J Vasc Surg. 2016; 63(2 Suppl): 3S-21S. PubMed ACR Appropriateness Criteria: Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus . American College of Radiology. Reston, VA [Last review date: 2012; Accessed: May 2017] Calhoun JH, Manring MM. Adult osteomyelitis. Infect Dis Clin North Am. 2005; 19(4): 765-86. PubMed
Hatzenbuehler J, Pulling TJ. Diagnosis and management of osteomyelitis. Am Fam Physician. 2011; 84(9): 1027-33. PubMed
Kremers HM, Nwojo ME, Ransom JE, Wood-Wentz CM, Melton J, Huddleston PM. Trends in the epidemiology of osteomyelitis: a population-based study, 1969 to 2009. J Bone Joint Surg Am. 2015; 97(10): 837-45. PubMed
Palestro CJ, Love C, Miller TT. Infection and musculoskeletal conditions: Imaging of musculoskeletal infections. Best Pract Res Clin Rheumatol. 2006; 20(6): 1197-218. PubMed
Peltola H, Pääkkönen M. Acute osteomyelitis in children. N Engl J Med. 2014; 370(4): 352-60. PubMed
Schmitt SK. Osteomyelitis. Infect Dis Clin North Am. 2017; 31(2): 325-338. PubMed
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