Mss 03: Bone Infections

Front 1

What is the term that encompasses bone infections?

Back 1

Osteomyelitis

Front 2

What are the categories of Osteomyelitis?

Back 2

- Hematogenous
- Direct Implantation
- Contiguous
- Infection of Prosthetic Device

Front 3

What is the cause of Hematogenous Osteomyelitis?

Back 3

Seeding of bone related to a previous bacteremia (e.g., vertebral bodies and disc are irregular and loose; bacteria got into disc and then spread into vertebral bodies)

Front 4

What is the cause of Direct Implantation Osteomyelitis?

Back 4

Penetrating injury

Front 5

What is the cause of Contiguous Osteomyelitis?

Back 5

Direct spread of bacteria from an overlying wound or pressure ulcer (common in diabetes)

Front 6

What is the cause of Osteomyelitis from Prosthetic Devices?

Back 6

When there is an infection on the prosthetic material that is implanted in the bone, it spreads to the adjacent bone
(picture: before & 3 months later)

Front 7

What kind of Osteomyelitis is most common in children?

Back 7

Hematogenous (results from seeding of bone related to a previous bacteremia)

Front 8

What kind of Osteomyelitis is most common in adults?

Back 8

- Contiguous (from direct spread of bacteria from overlying wound or pressure ulcer)
- Infection of Prosthetic Device

Front 9

What can happen when someone has an infection caused by their prosthetic joint?

Back 9

Can cause joint loosening and leading to joint needing to be removed

Front 10

What are the most common bacteria that cause Hematogenous Osteomyelitis?

Back 10

- Staphylococcus aureus
- Streptococcus species
- Gram-negatives
* Mycobacterium tuberculosis
* Salmonella species (in sickle cell)
(* = unique to this type)

Front 11

What are the most common bacteria that cause Osteomyelitis by Direct Implantation?

Back 11

* Pseudomonas aeruginosa - water dwelling bacteria (e.g., it gets into wet sneakers and they if they step on nail it gets directly into bone)

Front 12

What are the most common bacteria that cause Contiguous Osteomyelitis?

Back 12

- Staphylococcus aureus
- Gram-negatives
- Streptococcus species
* Anaerobes
* Candida species
(* = unique to this type)

Front 13

What are the most common bacteria that cause Prosthetic Joint Osteomyelitis?

Back 13

* Coagulase negative Staphylococci
- Staphylococcus aureus
- Gram-negatives
- Streptococcus species
(* = unique to this type)

Front 14

What bacteria all can commonly cause Hematogenous, Contiguous and Prosthetic Joint Osteomyelitis?

Back 14

- Staphylococcus aureus
- Streptococcus species
- Gram-negatives

Front 15

What are the general characteristics of Osteomyelitis?

Back 15

- Chronic infections
- Difficult to eradicate
- Damages periosteum - may result in pieces of dead bone (sequestrum) or new external bone formation (involucrum)
- May involve localized abscesses (Brodie's abscesses)

Front 16

How can you diagnose Osteomyelitis?

Back 16

- X-rays not very sensitive
- Bone/WBC scans or MRI more effective
- Bone biopsies or blood cultures (sometimes) to determine bacteria

Front 17

In contiguous osteomyelitis, how do the bacteria in the ulcer compare to the bacteria in the bone?

Back 17

Cultures of open ulcers overlying contiguous osteomyelitis are notoriously unreliable; bacteria in bone underneath may be entirely different

Front 18

What happens if a bone biopsy can't be done or culture results are negative in osteomyelitis?

Back 18

Need to try empiric treatment of antibiotics

Front 19

What can make Osteomyelitis particularly difficult to treat?

Back 19

Biofilms may develop on infected bone (or especially on prostheses)

Front 20

What are biofilms?

Back 20

- Aggregations of microorganisms adherent to a surface, particularly to a hard surface like bone or teeth or prosthetic materials
- Microorganisms frequently are embedded in matrix they produce called slime or extracellular polymeric substance or glycocalyx

Front 21

What is "slime" / "extracellular polymeric substance" / "glycocalyx"?

Back 21

A matrix produced by microorganisms in biofilms that the microorganisms adhere to

Front 22

How do bacteria in biofilms compare to those that are planktonic (suspended)?

Back 22

Biochemistry and physiology are often very different; biofilm bacteria are more resistant to antibiotics

Front 23

How do you treat Osteomyelitis?

Back 23

- Long courses of antibiotics
- 6 weeks of IV antibiotics
- Sometimes months of oral antibiotics may be needed too (especially for prosthetic infections)
- Sometimes surgery to remove sequestra or prostheses (when antibiotics fail)

Front 24

What antibiotic is particularly good for treating biofilm organisms?

Back 24

Rifampin

Front 25

What is necessary for antibiotic treatment to be effective?

Back 25

If bone is covered by tissue (otherwise new organisms can continuously invade bone)