Osteomyelitis

Question 1

What are the common syndromes seen with osteomyelitis?

Answer 1

Hematogenous osteomyelitis, vertebral osteomyelitis (discussed elsewhere in this issue), osteomyelitis after trauma, and diabetic foot infection.

Question 2

Which bones are mostly effected in children?

Answer 2

Long bones

Question 3

What is the most likely cause of osteomyelitis in younger adults?

Answer 3

Trauma or surgery

Question 4

What are the most likely causes of osteomyelitis in older adults?

Answer 4

Joint Arthroplasty, diabetes in lower extremities, and vascular disease, and osteomyelitis related to decubitus ulceration.

Question 5

Where in long bones does hematogenous osteomyelitis affect?

Answer 5

The Metaphysis (The ends). Explanation: Slowing of blood flow in vascular loops at the metaphysis near the epiphyseal plates leads to
deposition of microbes and establishment of infection.An inflammatory response ensues, leading to increased pressure in the medullary bone. This pressure causes the
infection to break through to the cortex and, if unchecked, ultimately through the periosteum. . This can lead to decreased blood supply to the periosteum with bone necrosis. Pieces of necrotic bone can separate and are called a sequestrum, which can contain
pus. New bone can begin to form over the injured periosteum; this is known as an involucrum and may partially surround a sequestrum with ongoing drainage

Question 6

Where is vertebral ostemyelitis found?

Answer 6

Vertebral osteomyelitis most commonly arises from the hematogenous deposition of microbes in the metaphysis of the vertebral bodies.

Other notes: The infection then spreads to
the intravertebral disc, which is an avascular structure. Common patterns of infection are often explained by vascular structures, with spread between intramedullary communicating arteries to the metaphyses of a single vertebra and involvement of adjacent vertebral bodies supplied by splitting arteries from a single vertebral artery.
Venous drainage via Batson’s plexus is felt by some experts to contribute to spondylodiscitis metastasizing from a urinary tract focus

Question 7

How can Diabetes Cause osteomyelitis?

Answer 7

Diabetes mellitus may lead to compromised microvascular and macrovascular blood supply to the lower extremities. In the setting of the sensory neuropathy that is also common in diabetes mellitus, patients are predisposed to the development of skin ulceration at points of pressure or trauma, with subsequent colonization with skin flora. Poor vasculature contributes to compromised local immunity and skin healing, promoting the spread of infection to the underlying bone.

Question 8

How do pressure ulcers cause osteomyelitis?

Answer 8

Patients confined to bed or a wheelchair by paralysis or debility are subject to
pressure-related skin ulceration and necrosis, most commonly in the sacral and buttock areas. These ulcerations are colonized frequently by polymicrobial flora emanating from the skin and gastrointestinal tracts, with soft tissue infection spreading to the bones of the pelvis and lower extremities

Question 9

What are the most common bacteria found in hematogenous osteomyelitis?

Answer 9

S. Aureus, and coagulase-negative staphylococci are isolated most commonly.
Beta-hemolytic streptococci
Viridans streptococci
Enterococci
Aerobic Gram-negative bacilli (pseudomonas, enterbacter, escherichia coli)

They may originate from a distance foci, such as a skin abscess or endocarditis, indwelling catheters or injection drug use.

Question 10

Which pathogen is of particular virulence owing to it’s production and tissue release of cytotoxins?

Answer 10

Community acquired MRSA

Question 11

When might we see the following UNCOMMON pathogens in osteomyelitis?
Mycobacterium tuberculosis
Nontuberculosis mycobacteria
Salmonella
Bucella
Eikenella
candida
Endemic mycoses (Blastomyces, coccidioides, sporothrix)
Cryptociccus
Aspergillus

Answer 11

Mycobacterium tuberculosis - from lung infection
Nontuberculosis mycobacteria - Traumatic injury
Salmonella - spinal infection
Bucella - spinal infection
Eikenella
candida - After surgery or trauma in immune compromise, or from indwelling vascular catheters or injection drug use.
Endemic mycoses (Blastomyces, coccidioides, sporothrix) - Southwestern united states)
Cryptociccus - Immunocompromised hosts
Aspergillus

Question 12

How does Hematogenous ostemyelitis present?

Answer 12

Subacute, or chronic onset of pain at the area of bony involvement. Fever and chills are less common, but can occur with virulent pathogens such as S. Aureus.
May also show soft tissue redness and swelling and evetually a draining sinus tract may occur (sinus tracts more common in trauma or fracture).

Question 13

What do infections associated with vascular insufficiency most commonly show?

Answer 13

Ulcerations, erythema, swelling and drainage that may progress to visible bone in a subacute to chronic fashion. (Fever and chills are less common in this setting)

Question 14

What does vertebral osteomyelitis look like?

Answer 14

Presents with subacute to chronic pain at the involved site, sometimes with fever. Sings of cord compression and compromise emerge in approx 25% of patients, which radiating pain from compressed nerve roots corresponding with involved level, followed by extremity weakness and impaired bowel or bladder function.

Question 15

How is osteomylitis diagnosed?

Answer 15

1. Lower extremity OM - Probing to bone
2. Blood testing,
3. Radiological imaging
4. Microbiology.
5. Kids - blood cultures
6. Adults - biopsy more likely needed

Question 16

In general, what does the treatment of steomylitis required?

Answer 16

The treatment of osteomyelitis often requires a combination of medical and surgical management to accomplish a goal of uninfected, pain-free function.

Because antibiotics penetrate dead or injured bone and infected fluid collections poorly, surgical debridement is a cornerstone of therapy when these are present.
In addition to facilitating the penetration of
antibiotics into affected bone and soft tissue, debridement also offers other advantages. First, it provides an opportunity to obtain deep tissue culture data to direct antibiotic therapy.
Second, because orthopedic hardware creates an avascular surface
for microbial colonization, its removal enhances the possibility of microbiological cure. After the removal of infected dead tissue and hardware, nonunion of bone can be addressed where present. Local antibiotic delivery can be initiated by the placement of antibiotic-containing beads or polymethylmethacrylate cement spacers.
Finally, dead space can be exposed for flap coverage

Question 17

What is the primary regiment for Staphlococci Osteomyelitis in oxacillin (methacillin) sensitive and oxacillin resistant situations?

Answer 17

1. Oxacillin Sensitive - Oxacillin or nafcillin 2g IV ever 4 hours
   Alternatively - vanco, or clinda
2. Oxacillin Resistant - Vancomycin 15mg/kg every 12 hours
   Alternatively - Clindamycin, Daptomycin, Linezolid, levofloxacin

Question 18

What is the primary regiments for Streptococci in osteomyelitis?

Answer 18

1. Pen G 24 million units IV continuously or divided in 6 doses.
2. Ceftriaxone 2g IV daily
3. Cefazolin 2g IV q8h

Question 19

What is the primary regimen for Enterococci in osteomyelitis?

Answer 19

1. Pen G 24 million units IV continuously or divided in 6 doses.

Question 20

Pseudomonas aeruginosa and Enteropacteriaiae primary regiment for osteomyelitis?

Answer 20

1. Cefepim 2g IV every 12 hours
2. Ceftazidime 2g IV ever 8 hours
3. Ceftriaxone (only for Enterobacteriaciae)
4. meropenem

Question 21

What is the most common emperic regimen for osteomyelitis when pending culture for osteomyelitis?

Answer 21

Vancomycin and a third gen cephalosporin or beta lactam/Beta-lactamase inhibitor combination provides broad gram-positive and gram negative coverage

Question 22

How long is treatment for osteomyleitis?

Answer 22

4 to 6 weeks of parenteral abtiobiotic therapy

When infected bone is debrided completely, with mocribiological and pathologic suggestion of a clean margin, antibiotic therapy duration can often be reduced.

A 2 week course of pathogen directed parenteral or highly bioavailable oral therapy is adequate to treat residual soft tissue infections, with good clinical follow-up maintained to ensure ongoing treatment.

Note: When gram negative bacilli are isolcated and culture and are fluoroquinolone susceptible, these highly bioavailable agents can be use din ihigh doses as an oral regimen.

Question 23

Why shouldn’t we use swab cultures for osteomyelitis in diabetic patients?

Answer 23

Given the difficulty of healing wounds in poorly vascularized limbs, it is tempting to tailor antimicrobial therapy to the results of swab cultures. This approach has multiple drawbacks.
First, there is frequently discordance between wound and deep soft tissue or bone
cultures. In addition, swab cultures are inadequate for anaerobic culture. For this
reason, the diabetic foot infection guideline of the Infectious Diseases Society of
America recommends against the use of swab cultures, especially of undebrided
wounds.32 More accurate microbiologic data are obtained by submission of transcutaneous biopsy or intraoperative specimens for culture

Question 24

What is the recommended therapy for diabetic foot osteomyelitis infections?
What about if the patient has a beta-lactam allergy?

Answer 24

Most often used are beta-lactam/beta lactamase inhibitor combinations including ampicillin/sulbactam, piperacillin/tazobactam,
and ticarcillin/clavulanate, although a systematic review failed to favor any 1 agent.

When the patient has a true beta lactam allergy, a fluoroquinolone may be combined with metronidazole or clindamycin. MRSA coverage
(usually vancomycin) should be included in areas with high prevalence or when the patient has a history of MRSA infections.

Question 25

What are the most commonly isolated pathogens in osteomylitis after trauma? How is treatment determined?

Answer 25

S. auerus, coagulase negative stafpylocicci, and aerobic gram-negative bacilli

Bone and Tissue cultures guide pathogen direted antimicrobial therapy.

Question 26

How common are bone and joint infections in sickle cell disease?

Answer 26

10% of patients

Question 27

What bacterial species are most common in osteomyelitis in sickle cell disease?

Answer 27

Samonella and S. Aureus

Question 28

What are the two major routes of getting osteomyletis in injection drug use?

Answer 28

Hematogenous and inoculation

The most common route is hematogenous, with a variety of joints and sometimes multiple joints potentially involved, including hips, knees, ankles, the sternoclavicular joints, and the spine. Endocarditis may be an intermediary in this process, with seeded heart valves secondarily infecting bone and joint sites

Question 29

What are the most commonly isolated pathogens in injection drug use in osteomyelitis?

Answer 29

S. Aurea (especially MRSA), P. Aeruginosia, Eikenella corodens and candida species.
Injection drug users also have increase risk of exposure to M. Tuberculosis which can infect bone, especially in the thoracic spine.

Question 30

What is the issue with osteomyelitis and hemodialysis?

Answer 30

Patients undergoing hemodialysis require frequent access of the vascular tree. Although bloodstream infections are less common in patients using indwelling fistulas for access, they are relatively common in patients using vascular catheters for access.
This places hemodialysis patients at risk for seeding of musculoskeletal sites, a risk that may be multiplied by diabetes mellitus, which is a common cause of end-stage renal disease.42 S aureus, often methicillin-resistant, is the most common pathogen in multiple categories of infection of hemodialysis patients, including osteomyelitis. Coagulase-negative staphylococci, enterococci, aerobic gram-negative bacilli, and
Candida species are also identified. Multiple sites may be seeded, including spine and large joints. Medical/surgical treatment of musculoskeletal infection in hemodialysis is as detailed for other patient populations.

Question 31

What is the most common source of infection of the bony pelvis?

Answer 31

from a continguous focus from a stage 4 decubitus ulcer to the sacral area.

Question 32

How long is treatment usually for CHRONIC osteomyelitis of the Bony Pelvis?

Answer 32

6 to 8 weeks with BROAD spectrum antibiotics, but it is often uncurable.