Infection and the Orthopedic Patient Flashcards
Pathophysiology of Musculoskeletal Infections: What kinds of bacteria? 4
Bacteria- Large and diversified group
- Gram +
- Gram –
- Anaerobic (no O2)
- Aerobic
Pathophysiology of Musculoskeletal Infections
- Resistance is a problem. Which bug specifically?
- Increased resistance to abx via what?
- What is a major cause of nosocomial infections?
- Staphylococcus aureus
- Increased resistance to antibiotics via Plasmids
- 50% of strains have plasmid mediated resistance - Biofilm:
Major cause of nosocomial infections
Biofilm production and resistance is becoming common in what species and very common in what other species?
- increasingly common in staph species,
2. very common in Pseudomonas
Pathophysiology of Musculoskeletal Infections
Homeostasis: once altered bacteria can enter the body such as in surgery. Why?
3
Environment is compromised by
- diminished blood flow,
- oxygen tension and
- foreign bodies
Pathophysiology of Musculoskeletal Infections
-Blood supply
One of the most important factors in homeostasis
- Multiple studies show as blood flow is ________, the risk of infection increases
- Warming an extremity increases microcirculation and vasodilatation = what?
- reduced
2. increase concentrations of abx’s
Pathophysiology of Musculoskeletal Infections:
Traumatic injury and presence of implants increase the risk of infection
- Osseous trauma is what? 2
- Osseous trauma is what?
- Glycocalyx capsule is what?
- Impairs what? 2
- Biofilm does not just effect foreign material; it can act similarly with what?
- periosteal injury,
- microvascular and macrovascular compromise
- bacteria have an affinity for the exposed binding sites
- composed of fibrous exopolysaccharides within biofilm
- NL immune function and
- abx penetration
- devitalized bone
Pathophysiology of Musculoskeletal Infections
Host susceptibility of infections
1. Factors that decreases local immune response? 4
- Factors that decrease systemic immune response?
6
- Decreased blood flow
- neuropathy,
- trauma,
- medication (NSAID’s, Rh, steroids)
- Renal and liver Dz,
- DM,
- EtOH,
- Rh Dz’s,
- Immunocompromised state
- Malnutrition
Examples of decreased blood flow that will make hosts more susceptible to infection?
4
- PAD,
- venous stasis,
- smoking,
- radiation
Diagnostic Modalities in Musculoskeletal Infections
1. Gold Standard?
- Pts present how? 5
- Other possible symptoms? 5
- Gold standard is culture of suspected fluid or tissues
- Pts often present with
- pain,
- warmth,
- swelling,
- redness and
- refusal to bear weight (children especially) - Other symptoms:
- fever ,chills,
- night sweats,
- nausea,
- vomiting
- loss of joint motion
Diagnostic Modalities in Musculoskeletal Infections
Serology?
7
- CBC with Differential
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Blood cultures
- Gram stain
- Frozen section
- PCR
Diagnostic Modalities in Musculoskeletal Infections
1. Normal WBC, ESR and CRP= what percent of infection?
- ESR: Elevates when and will continue to rise for how long?
- CRP elevates when? Peaks when? Returns to normal?
- Advantage? 2
- Normal WBC, ESR and CRP = 95% chance of no infections process
- ESR: Elevates within 2 days of infection and will continue to rise fore next 3-5 after appropriate tx
- CRP: Elevates within 6hrs, peaks at 48hrs, returns to NL 1 wk after appropriate tx
- More sensitive
- Best indicator for diagnosis and for monitoring tx
Diagnostic Modalities in Musculoskeletal Infections
- What is gram stain good for?
- IL-6: New literature show this can be helpful, especially in what?
- Gram stain
Good for tailoring of specific abx - IL-6- periprosthetic infections
Diagnostic Modalities in Musculoskeletal Infections
Radiology Plain films: 1. What are the earliest findings? 2. When would you see bony changes? 3. What is a brodies abcess?
INFECTION SHOULD ALWAYS BE ON YOUR DX
Always start here: cheap and easy
- Soft tissue swelling, loss of tissue planes are earliest findings
- Bony changes (must have at least 40% bone loss to see on film) usually seen late in the course of infection or in the setting of chronic infections
- Brodies Abscess
- Brodie abscess is an intraosseous abscess related to focus of subacute pyogenic osteomyelitis. Unfortunately, there is no reliable way radiographically to exclude a focus of osteomyelitis. It has a protean radiographic appearance and can occur at any location and in a patient of any age.
Diagnostic Modalities in Musculoskeletal Infections
- What is the next step after plain film?
- Other scans available? 3
- Bone Scan: (three phase bone scan, Tc 99m)
- “Vague” test - Other scans-
- Indium 111 leukocyte nuclear scan: (84% sen and 75-94% spec)
- Gallium citrate scan: (70-80% sen)
- PET scan: (99% sen and 88% spec): Expensive and time consuming
Diagnostic Modalities in Musculoskeletal Infections
MRI:
1. Often used for?
2. Can be highly sensitive or specific?
3. Cost?
4. Normal bone marrow will look how on MRI?
5. What could be indicative of infection?
6. Useful for anatomy findings such as? 2
- Often used for infection
- Can be highly sensitive
- Expensive
- Normal bone narrow = high signal on T1
- Low T1 signal could be indicative of infection
- Useful for anatomy findings:
- abscess
- sinus tracts
Musculoskeletal Infections in Adults
1. Most common in pts with what? 3
- Osteomyelitis types? 2
- open fractures,
- DM foot infection
- recent surgery
- Hematogenous (transferred by the blood)
-Contiguous focus (caused by a prior infection)
Osteomyelitis:
- Hematogenous (transferred by the blood) example?
- Contiguous focus is subdivided based on what?
- Example: Vertebral osteomyelitis
2. Subdivided based on presence or absence of vascular insufficiency
Musculoskeletal Infections in Adults
1. Alternative classification
Describes the anatomic involvement: What are stages 1-4?
- Host descriptions? 3
1. Describes the anatomic involvement Stage 1: Medullary Stage 2: Superficial Stage 3: Localized Stage 4: Diffuse
- Describes the host
- Normal
- Compromised
- Treatment worse than the disease
Musculoskeletal Infections in Adults Hematogenous Osteomyelitis 1. What % of all adult pts? 2. Gender? 3. Whats the most common site? Followed by? 3 4. Most common bacteria? 5. Pts present how?
- 20% of all adult pts
- More common in males
- Vertebrae is the most common site,
- followed by long bones, pelvis and clavicle - S. aureus is the most common bacteria
- Pts present with pain and constitutional symptoms (fever, chills, swelling, erythema) either acutely or long standing
Musculoskeletal Infections in Adults Vertebral Osteomyelitis 1. What age group? 2. Mortality? 3. May involve what? 2 4. What area is most common? 5. Bug? 6. What in IV drug users? 7. Pts present how? 8. What can result with motor/sensory deficits occurring in 15% of pts? 2
Vertebral Osteomyelitis
- > 50 yo (1-2% are children mean 7.5 yo)
- Death is rare
- May involve
- 2 adjacent vertebrae and
- the disk (diskitis) - Lumbar is most common 45%, thoracic 35%, cervical 20%
- S. aureus is the most common
- Pseudomonas in IV drug users
- Pts present w/ fever, pain over the area for 3 wks to 3 months
- Meningitis and abscesses can result with motor/sensory deficits occurring in 15% of pts
Contiguous-focus Osteomyelitis
1. Without generalized vasc insufficiency can be cause by what? 3
- Common when? 4
- what is the most common bacteria?
- Infection occurs about when after the primary cause of the infection?
- Pts report what symptoms? 3
- Leads to decreased what? 3
- trauma with direct contact to bone,
- infection spread from soft tissue, or
- by nosocomial infection
- ORIF,
- prosthetics,
- open fx’s and
- chronic soft tissue infections
- S. aureus
- 1 month
- pain and fever with drainage of the area
- bone stability,
- necrosis and
- soft tissue damage
Musculoskeletal Infections in Adults
Contiguous-focus osteomyelitis w/ general vas insufficiency
- Commonly in who?
- Where?
- Mutiple bugs like? 4
- Present with what? 2 Due to what? 2
- Diabetics
- Small bones of the feet
- Multiple bugs:
- staph,
- strep,
- enterococcus,
- G- bacilli - Present with
-ulcers,
-multiple foot problems all
due to
-peripheral neuropathy and
-small vessel disease