Pathology II Flashcards

1
Q

What is osteomyelitis?

A

Inflammation of bone

  • Generally due to infection, mostly by bacteria
  • Progressive infection
  • Inflammatory destruction of bone, followed by new bone formation
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2
Q

What are risk factors for osteomyelitis?

A

Not very common in healthy individuals b/c bone is resistant to infection

Risk factors:

Trauma

Diabetes

Decubitus Ulcers

Intravenous Drug Use

Surgery

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3
Q

How does infection get into the bone?

A
  1. Spread from a contiguous focus of infection
  2. Direct innoculation (trauma, surgery)
  3. Hematogenously
    (long bones and vertebral bodies)
    (long bones common in children)
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4
Q

How does Hematogenous infection occur?

A
  1. Infection enters through nutrient artery and into metaphysis
  2. Bone destruction and absess formation at metaphysis
  3. If young child, can progress to epiphysis and then to joint
  4. In all patients, over time extends through bone, eventually involving compact bone and raises periosteum from cortex, leading to new bone formation
  5. Inflammatory response results in sequestrum
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5
Q

What is sequestrum?

A

Inflammatory response to osteomyelitis results in:

  • Increasee pressure within bone
  • Leading to thrombosis of branches of nutrient artery and compression of capillaries within Haversian canals
  • Resulting in necrosed bone within bone (sequestrum)
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6
Q

What is the clinical presentation of osteomyelitis?

A

Chills, fever, sweats

lethargy, malaise

point tenderness

swelling of tissues over bone

redness of tissues over bone

draining sinus

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7
Q

What are microbiological causes of osteomyelitis?

A

STAPHYLOCOCCUS!

Coagulase-negative Staphylococci

Cat/Dog bite: Pasteurella

Human bite: Eikenella

** IV Drug use:** Pseudomonas

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8
Q

Why is staphylococcus so prevelant in osteomyelitis?

A

S. aureus has Collagen Adhesin (biofilm)

  • Inhibits clearance by immune system
  • Inhibits penetration of antibiotics
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9
Q

How is biofilm produced?

A

Quorum sensing

  1. Bacterial presence signal is synthesized
  2. Signal diffuses through environment
  3. Signal binds to neighboring bacterial receptor
  4. Recetpor binds to promotor
  5. Gene Expression ==> Bacterial attachment, motility, biofilm formation, oxidative stress response, vitamin synthesis
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10
Q

What test are generally used to diagnose osteomyelitis?

A

Radiological Tests:
X-ray (usually need follow up xrays)
MRI (most sensitive and specific)
Nuclear studies
CT scan (better than x-ray)

Probe to bone:
contact with bone through cubitous ulcer, generally +

Blood culture:
Sometimes…

Most Definitive: Bone biopsy

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11
Q

What are general principles for treating osteomyelitis?

A

Acute disease = No bone necrosis, no abscess
Abx alone usually sufficient

Vertebral osteo and terminal digits ==> Abx alone

All others ==> surgical debridement + abx

Antibodies are generally IV for 4-6 weeks

Surgery includes debridement and removal of any hardware in affected area, management of dead space, improvement of blood flow if necessary

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12
Q

How do joints get infected?

A

Primarily by hematogenous seeding

Less common:
 penetrating trauma (bite, injury)
 complication of joint injection w/corticosteroids
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13
Q

What are risk factors for synovial joint infection?

A
  • Other joint diseases:
    RA
    Osteoarthritis
    lupus
    gout
    pseudogout
    prior trauma or injection
  • Prosthetic joint
  • IV drug use
  • Alcoholism
  • Diabetes
  • Cutaneous ulcers and other skin conditions
  • Immune suppression
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14
Q

What is the clinical presentation of Synovial joint infection?

A

Chills and fever

Swollen, red, warm, painful joint

decreased joint mobility

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15
Q

What are common microbiological causes of joint infections?

A

Staphylococcus aureus!

Lyme disease

Gonococcal infection

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16
Q

How is synovial joint infection diagnosed?

A

Synovial Fluid analysis - Drain it!

Gram stain

Culture

WBC count (>50,000 cells/ml c/w septic joint, but also gout/pseudogout)

Gonococcus can be cultured on chocolate agar, isolation from other body parts (cervix, urethra, rectum, etc) produce best results

17
Q

How is synovial joint infection treated?

A

DRAINAGE is key!!!
needle aspiration
arthroscopic drainage
surgical drainage

Antibiotics and joint drainage is necessary

18
Q

What antibiotics are used to treat synovial joint infections?

A

Vancomycin

or

CTX
(Cefotaxamine - a Cephalosporin)

19
Q
A
20
Q

How do you determine between Monoarthritis, Polyarticular, and Pauciarticular arthritis? Why is it important?

A

Mono = 1 joint

Poly = >5 joints

Pauc = 2-4 joints

–> each ahas distinct approaches to treatment!

21
Q

What is arthritis?

A

inflammation within a joint

22
Q

What is arthralgia?

A

joint pain without inflammation

23
Q

What factors do you need to get information on during the HPI for arthritis?

A
  1. Joints involved
  2. chronicity
  3. Exercise
    Aggravates (think osteo) or alleviates (think inflammatory)
  4. AM stiffness
  5. Swollen joints
    Signs of inflammation
    Rubor, calor, dolor, tumor
  6. Fatigue
    (systemic arthritis leads to fatigue)
24
Q

What are characteristics of inflammatory arthritis?

A

Stiffnes >1hr in morning

R/C/D/T (inflammation)

Pain at rest

Improves with exercise

Constitutional complaints

25
Q

What are characteristics of non-inflammatory arthritis?

A

Stiffness < 30min in AM

no signs of inflammation

better with rest

worse with exercise

no constitutional complains

26
Q

How can you differentiate between articular and periarticular pain?

A

Articular
Painful, limited active ROM
Painful, limited passive ROM

Periarticular (not the joint)
Painful, limited active ROM
Full, unlimited passive ROM

27
Q

How do you determine if arthritis is chronic or acute?

A

Acute < 6 weeks

Chronic > 6 weeks

28
Q

What is a differential diagnosis for Acute mono-arthritis?

A

Bacterial (septic)

Crystalline (gout)

Trauma (fracture)

bleeding

internal derangement

29
Q

What is a differential diagnosis for Chronic mono-arthritis?

A

Mycobacterial

Lyme

Fungal

Foreign body

Osteoarthritis

Benign Tumor