Michael Saccente, M.D.

Hematogenous osteomyelitis Contiguous focus osteomyelitis Osteomyelitis associated with peripheral

vascular disease

Waldvogel FA, Medoff G, Swartz MN.N Engl J Med 1970;282:198, 260, 316

Any acute bone infection can become chronic (~ 10 days)

Chronic osteomyelitis is refractory to cure with antibiotics alone

Devitalized bone serves as a nidus for persistent infection (sequestrum)

Compromised soft tissue envelope, draining sinuses

BacteremiaExtension from

contiguous focusAdherence to bone

Acute inflammation

Increased intraosseous pressure andtoxic oxygen radicals, proteolytic enzymes

Vascular congestion and thrombosis

Bone necrosis

Sequestra

Bacterial persistenceLimited host response

Foreign body

Apposition of new bone

Stabilization

Intracellular survival of microorganisms Impaired delivery of host defenses and

antibiotics into dead bone Role of foreign body

Biofilm Local PMN defect Slow growth of surface-adherent bacteria

Hevroni A and Koplewitz B. N Engl J Med 2007;356:e7

An afebrile 8-year-old Ethiopian girl presented with a limp

Lew DP, Waldvogel FA. NEJM 1997; 336: 999-1007

Unusual locations for hematogenous spread Sternoclavicular C- spine Pubic symphysis

Bacteriology similar to infective endocarditis in IDU S. aureus Aerobic GNB- Pseudomonas Others

Gold standard- histopathologic and microbiologic examination of bone

Hematogenous- blood culture (40%) + imaging Extension into joint- fluid culture + imaging Cultures from a chronic draining sinus may be

unreliable (Mackowiak 1978)

Early identification of disease Identify remote sites of disease Define extent of local disease and

complications Assist in surgical plan Should NOT be used alone to make the

diagnosis of osteomyelitis

Plain radiography 99mTc diphosphonate bone scan 111Indium-labeled WBC scan 67Gallium citrate scan CT MRI

Sensitivity (%) Specificity (%)

Bone scanUncomplicatedComplicated

9495

9533

Gallium scan 81 69

In WBC scanGeneralFracturenonunion

8895

8588

MRI 95 88

From Haas DW, McAndrew MP. Am J Med 1996;101:550

SURGICAL MEDICAL

Debridement Hardware removal Obliteration of dead

space Wound protection Restoration of blood

flow Limb stabilization

Optimization of host factors

Specific antimicrobial therapy

There is only limited evidence upon which to base antibiotic selection

No IDSA guidelines exist (though guidelines for diabetic foot infections were published in 2004 and those for prosthetic joint infections in 2013)

Virtually all severe and some moderate infections require parenteral therapy, at least initially

Oral drugs with high oral bioavailability can be used initially in some cases of osteomyelitis

“Standard of care”*- 4 - 6 weeks parenteral for hematogenous (including vertebral) and contiguous

2 weeks parenteral + 4 weeks oral 6 weeks parenteral + > 3 months oral Initial oral quinolones for susceptible

aerobic GNB

*Mader JT, Norden C, Nelson JD, Calandra GB.

Clin Infect Dis 1992;15(suppl 1):S155

Hematogenous Typically 2 bodies and disk Lumbar > thoracic > cervical

Contiguous from Surgery Trauma Visceral source

Manifestations Back pain, fever, tenderness over spine

Complications Instability/Cord Compression

Neurologic complications in 38% of cases in one study (Am J Med 2005;118:1287)

Extension of infection with abscess

Imaging plus culture of Blood 58% (30-78%) Bone 77% (47-100%)

CT-guided or open biopsy Adjacent abscess

Figure 2. MRI of lumbar spine discitis/osteomyelitis. A. Sagittal T1-weighted images of the lumbar spine in the same patient as figure 1 demonstrate T1-hypointense signal (solid arrows) centered around the L3-4 interspace. B. Post gadolinium sagittal fat-

suppressed T1-weighted images shows marrow (dashed arrows) and disc enhancement with endplate erosions.

Vertebral osteomyelitis without abscess can be cured without surgery

No prospective trials Select agent based on in vitro susceptibility

data Duration is usually 6 weeks Usually entire course is intravenous, but switch

to oral FQ is acceptable for a susceptible gram negative

Diagnosis Open biopsy after CT-guided attempts have failed

Relieve cord compression Drain epidural abscess Drain other abscesses when CT-guided

attempts have failed Debridement when medical management has

failed Remove hardware

Skin ulceration or soft tissue infection of foot

Visualize or probe to bone?

Yes No

Presumptive osteo

Plain x-ray

Neg

c/w osteo

Severe peripheral neuropathy

No Yes

High clinical suspicion?

Yes No

WBC or MRI

Suggestive of osteo

Neg

Rx as soft tissue infx,f/u x-ray

Approx mean (range)

Test Sensitivity (%) Specificity (%) PPV (%)

Plain X-ray 60 (28 – 93) 66 (50 –92) 74 – 87

Tc99m bonescan

86 (68 – 100) 45 (0 –79) 43 – 87

In111 WBC 89 (45 –100) 78 (29 –100) 75 – 85

MRI 99 (29 –100) 83 (71 –100) 50 –100

From Lipsky BA. Clin Infect Dis 1997;25:1318

As of 1996, 5 published prospective comparative trials involving 154 patients

Heterogeneous patient types, microbiology, surgical intervention

Debridement obscures the effect of antibiotics Long follow-up

Osteo documented or suspected

Sepsis, plantar abscess, gas in tissues Yes

No

Immediate surgery,cultures,

antibiotics

Assess blood flow, tissue oxygenation, +/- vascular surgery

Not surgical candidate, does not desire surgery

Suppressive antibiotics

Amputation

Perioperative

All infected bone removed

2 weeks

Not all infectedbone removed

4-6 weeks

Definition

Type 1 + intraoperative cultures during revision for what was thought to be a mechanical problem

Type 2 Early postop infection diagnosed within 1 month of index arthroplasty

Type 3 Acute hematogenous infection of a previously well prosthesis

Type 4 Late chronic infection diagnosed > 1 month after index arthroplasty

Prosthetic Joint Infections: Bane of Orthopedists,Challenge for Infectious Disease Specialists

Joseph R. LentinoClinical Infectious Diseases 2003; 36:1157–61

Prosthetic Joint Infections: Bane of Orthopedists,Challenge for Infectious Disease Specialists

Joseph R. LentinoClinical Infectious Diseases 2003; 36:1157–61

Causes of Infection Associated with Prosthetic Joints

Del Pozo J, Patel R. N Engl J Med 2009;361:787-794

Prosthetic Joint Infections: Bane of Orthopedists,Challenge for Infectious Disease Specialists

Joseph R. LentinoClinical Infectious Diseases 2003; 36:1157–61

A radiolucent line along the prosthesis-bone interface suggests loosening

Scanning Electron Micrograph of a Staphylococcus epidermidis Biofilm on Foreign Material. Bacteria grow in multicellular clusters. The scale bar represents 10 microm. (Photograph courtesy of Robin Patel, Mayo Clinic College of Medicine). From: Zimmerli: N Engl J Med, Volume 351(16).October 14, 2004.1645-1654

Bacteria attach to a solid surface When microbial density is high, cell-to-cell signaling

activates the genes involved in the production of glycocalyx (quorum sensing)

The result is a complex community of bacteria that functions almost as a multicellular organism

Individual bacteria within the biofilm enter into a metabolically inactive state

These stationary phase bacteria are resistant to antimicrobial killing and host defenses

Resection with replacement One stage Two stage

Debridement with retention Resection without replacement No surgery

Short duration of symptoms Definitive microbiology Use of an agent which is active against

stationary phase, adherent bacteria (rifampin) No loose implants No MRSA

Small number of patients (safety advisor stopped study after 33 patients were enrolled)

Only 24 patients completed the study Cure rates

12/12 in rifampin group 7/12 in placebo arm

Algorithm for the Treatment of Infection Associated with a Prosthetic Joint

Del Pozo J, Patel R. N Engl J Med 2009;361:787-794