Chapter 20.4 Osteomyelitis Flashcards
What is osteomyelitis?
An inflammatory condition of bone most commonly caused by infectious agents such as bacteria, fungi, or occasionally viruses.
What are the two classifications of osteomyelitis based on origin?
- Hematogenous
- Posttraumatic
What are the two clinical forms of posttraumatic osteomyelitis?
- Acute
- Chronic
What is the most common clinical entity seen in small animal practice regarding osteomyelitis?
Chronic posttraumatic osteomyelitis
What are the main treatment modalities for posttraumatic osteomyelitis?
- Aggressive surgical debridement
- Fracture stabilization
- Long-term antimicrobial therapy
What is the most common causative bacterium in chronic osteomyelitis cases?
Staphylococcus intermedius
List some Gram-negative organisms that can cause osteomyelitis.
- Escherichia coli
- Pseudomonas
- Proteus
- Klebsiella
True or False: Most open fractures are contaminated at the time of presentation.
True
What is required for bacteria to cause osteomyelitis?
Bacteria must contaminate and colonize the bone and surrounding tissues.
What local factors contribute to the formation of osteomyelitis?
- Tissue ischemia
- Bacterial inoculation
- Bone necrosis and sequestration
- Fracture instability
- Foreign material implantation
What role does fracture instability play in osteomyelitis?
It perpetuates the persistence of infection in the bone.
What is the primary mechanism in biomaterial-centered sepsis?
Microbial colonization of biomaterials and adjacent damaged tissues.
What are the three components of any biofilm?
- The offending microbe(s)
- The microbe-produced glycocalyx
- The host biomaterial surface
How do biofilms protect bacteria from antibiotics?
- They impede cellular phagocytosis
- They inhibit antibody ingress
- They alter B- and T-cell responses
What is the growth pattern of bacteria in a biofilm compared to planktonic bacteria?
Biofilm bacteria exhibit a quiescent (near dormant) growth pattern.
What environmental factors in a biofilm can adversely affect antimicrobial activity?
- Lowering of pH
- Increasing pCO2
- Decreasing pO2 and hydration levels
Fill in the blank: The presence and vigor of the biofilm can be argued as the single most important factor in the ability to successfully treat _______.
[implant-associated chronic infections]
What changes in the microenvironment can decrease the activity of aminoglycosides and macrolides?
An increasingly acidic environment with elevated pCO2.
