Dr. Loo -- Bone and Joint Infections Flashcards Preview

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Flashcards in Dr. Loo -- Bone and Joint Infections Deck (84)
1

Describe the Lew and Waldwogel classification for osteomyelitis

  • Acute vs. chronic
    • Acute <2 weeks
    • Subacute 2 weeks - 3 months
    • Chronic > 3 months
  • Mechanism of infection
    • Hematogenous
    • Contiguous
  • Presence of vascular insufficiency

2

3 pathophysiologies of osteomyelitis

  • Hematogenous
  • Contiguous spread
  • Direct inoculation of infection to bone from trauma or surgery

3

3 risk factors for hematogenous osteomyelitis in children

  • Immunodeficiency -- chronic granulomatous disorders
  • Bacteremia
  • Sickle cell disease

4

Most common site of hematogenous osteomyelitis in children

Long bones = metaphysis

5

Most common locations of hematogenous osteomyelitis in adults

Vertebrae -- neighboring endplates involved

  1. Lumbar
  2. Thoracic
  3. Cervical

6

Why are neighboring endplates of vertebrae in adults commonly affected by hematogenous osteomyelitis?

They have an artery bifurcating to supply the endplates

7

Most common pathogen in children and adults for hematogenous osteomyelitis

S. aureus (50 - 60%)

8

Virulence factors of S. aureus explaining why it is a common pathogen in hematogenous osteomyelitis

Adhere to bone via adhesins

Can survive within osteoblasts

9

3 pathogens causing hematogenous osteomyelitis in children (besides S. aureus)

  • Streptococcus pneumoniae
  • Streptococcus pyogenes (GAS)
  • Kingella kingae (<4 years old)

10

2 pathogens for hematogenous osteomyelitis in neonates

  • Streptococcus agalactiae (GBS)
  • E. coli

11

Pathogen for hematogenous osteomyelitis in the setting of sickle cell anemia

Salmonella

12

Define the pathophysiology of contiguous osteomyelitis

Infection of bone usually from a skin and soft tissue infection that extends into the adjacent bone (i.e. diabetic patients with longstanding cutaneous ulcers)

Can also occur with prosthetic hardware

13

5 pathogens involved in contiguous osteomyelitis

Polymicrobial

  • Staphylococcus aureus
  • Streptococcus (B-hemolytic)
  • Enterococcus
  • Aerobic gram negative bacilli -- Enterobacteriaceae
  • Anaerobes

14

4 contributing factors to diabetic foot ulcers causing contiguous osteomyelitis

  • Neuropathy
  • Vascular insufficiency
  • Hyperglycemia
  • Poor vision

NOTE: Ulcers larger than 2 x 2 cm usually associated with underlying osteomyelitis

15

8 clinical manifestations of osteomyelitis

  • Pain at involved site, with or without movement
  • Warmth
  • Erythema
  • Swelling
  • Fever (20 - 50%)
  • Long bone = may spread to involve joint
  • Vertebral = may have associated epidural abscess
  • Presence of sinus tract = suggestive of chronic osteomyelitis

16

5 things to check on examination of patient with suspected osteomyelitis

  • Vital signs (temp, fever)
  • Anatomic area of pain
  • Signs of inflammation
  • Wounds as portal of entry
  • Signs of endocarditis (i.e. heart murmur, emboli)

17

Initial assessment of diabetic patients with foot ulcers

Probe to bone

18

4 diagnostic tests for osteomyelitis and their usual results

  • CBC (increased)
  • CRP (increased in 80%)
  • Blood cultures (50% + in hematogenous)
  • Bone biopsy (+ in up to 87% and also send for pathology)

NOTE: Swabs of skin ulcers should not be used (correlatoin with bone biopsy results is poor)

19

How long does it take to see changes due to osteomyelitis on plain X-ray

2 - 4 weeks

20

For what kind of osteomyelitis is plain X-ray useful?

Chronic

21

5 findings on X-ray for chronic osteomyelitis

  • Cortical erosion
  • Periosteal reaction
  • Mixed lucency
  • Sclerosis
  • Sequestra

NOTE: May be difficult to distinguish from Charcot arthropathy

22

Pros and cons of using nuclear scans to diagnose osteomyelitis

  • Pro = sensitive
  • Cons = can be nonspecific; degenerative disease can give false +

23

Imaging of choice for osteomyelitis diagnosis and why

MRI because of excellent resolution and early signs present:

  • Diabetic patients with possible osteomyelitis of foot
  • Vertebral osteomyelitis
  • High NPV

24

When is CT scan performed in diagnosis of osteomyelitis

If MRI cannot be obtained

25

One area of body where CT scan is especially good for diagnosis of osteomyelitis

Pelvic area

26

6 things that CT scan can detect in the diagnosis of osteomyelitis

  • Cortical integrity
  • Periosteal reaction
  • Intraosseous gas
  • Sinus tracts
  • Associated abscesses
  • Sequestra

27

3 points of management in terms of surgery to treat osteomyelitis

  • Debridement should be considered for chronic to remove devitalized bone
  • Revascularization may be necessary
  • Surgery usually not required for children unless abscess or devitalized bone

28

First choice antibiotics to treat against MSSA in osteomyelitis

  • Cloxacillin
  • Cefazolin

29

Second choice antibiotic to treat against MSSA in osteomyelitis

Vancomycin

30

First choice antibiotics to treat against MRSA in osteomyelitis

  • Vancomycin
  • Daptomycin

31

Second choice antibiotic to treat against MSSA in osteomyelitis

Linezolid with rifampin

32

First choice antibiotics to treat against penicillin susceptible Streptoccocus in osteomyelitis

  • Penicillin
  • Ceftriaxone
  • Cefazolin

33

Second choice antibiotic to treat against penicillin susceptible streptococcus in osteomyelitis

Vancomycin

34

First choice antibiotic to treat against Enterococcus in osteomyelitis

Ampicillin +/- aminoglycoside

35

Second choice antibiotic to treat against enterococcus in osteomyelitis

Vancomycin +/- aminoglycoside

36

First choice antibiotic to treat against enterobacteriaceae in osteomyelitis

Ceftriaxone

37

Second choice antibiotic to treat against enterobacteriaceae in osteomyelitis

Ciprofloxacin (not if <15 years old)

38

First choice antibiotic to treat against polymicrobial osteomyelitis

  • Ertapenem
  • Pip/tazo

39

Antibiotic duration against osteomyelitis in children

7 - 10 days of IV and then step down to oral if:

  • Afebrile
  • Clinically improving
  • CRP decreased by at least 50%
  • Duration usually 4 weeks but longer may be required in some patients

40

Antibiotic duration against osteomyelitis in adults

6 weeks IV

41

Antibiotic duration for chronic osteomyelitis

Usually requires months of therapy guided by clinical response and imaging

42

3 laboratory parameters to asses during and post treatment of osteomyelitis

  • WBC (usually normalizes within 7 days of therapy)
  • CRP (better than ESR) = more indivative of response to therapy
  • Note side effects of medications

NOTE: Repeat imaging generally not required

43

2 methods of acquisition of joint infection

Hematogenous

Contiguous

44

4 ways contiguous joint infection can be acquired

  • Surgery
  • Trauma
  • Percutaneous puncture
  • Infected skin or bone

45

4 risk factors for native joint infection

  • Pre-existing joint architecture
  • Age > 80 years
  • Diabetes
  • Rheumatoid arthritis

46

Most common pathogen of native joint infection

S. aureus

47

VIrulence factor of S. aureus explaining why it is a pathogen in native joint infection

Bacterial adherence

48

VIrulence factors of N. gonorrhoeae explaining why it is a pathogen in native joint infection

  • Pili adherence
  • Inhibition of host phagocytosis

49

Describe the pathophysiology of native joint infection

  1. Trauma or injury
  2. Increased amount or exposure of host proteins that promote bacterial attachment
  3. Host inflammatory response to bacteria results in joint damage

50

9 clinical features of non-gonococcal native joint infection

  • Monoarticular in 80 - 90%
  • Knee involved in 50%
  • Small joints usually not involved unless contiguous spread
  • Pain
  • Redness
  • Swelling
  • Increased warmth
  • Decreased function
  • Fever in 50%

51

3 clinical features of gonococcal native joint infection

  • Occult bacteremia
  • Complicates 0.5 - 5% of mucosal gonococcal infections
  • Monoarthritis in 40 - 85% in disseminated gonogoccal infection (DGI)

52

3 clinical features of DGI

  • Dermatitis (60%)
  • Tenosynovitis
  • Migratory polyarthralgia or polyarthritis

53

8 lab parameters of native joint infection

  • ↑ Blood WBC
  • ↑ C-reactive protein
  • Fluid analysis
    • WBC > 25,000/mm3
    • Low glucose
    • Nongonococcal
      • Gram stain positive 50%
      • Culture positive in 80-90%
    • Gonococcal
      • Gram stain positive in 25%
      • Culture positive in 20-30% DGI and 50% septic monoarthritis

54

2 body locations where recovery of gonococcal culture for native joint infection is highest

Cervix and urethra

55

4 findings on plain X-ray for native joint infection

  • Soft tissue swelling
  • Joint space loss
  • Periosteal rection
  • Subchondral bone destruction

56

2 uses for ultrasound in diagnosis of native joint infection

Effusion confirmation and aspiration

57

3 uses for CT scan in diagnosis of native joint infection

  • Erosive bone changes
  • Joint effusions
  • Good for deep articulations

58

5 imaging techniques for diagnosis of native joint infection

  • Plain X-ray
  • Ultrasound
  • CT scan
  • MRI (Sensitive)
  • Bone and gallium scans

59

Empiric treatment for native joint infection with a gram positive cocci stain

Vancomycin

60

Empiric treatment for native joint infection with a gram negative cocci stain

Ceftriaxone

61

4 Empiric treatments for native joint infection with a gram negative rods stain

  • Ceftriazone
  • Ceftazidime
  • Pip/tazo
  • Carbapenem

62

2 empiric treatments for native joint infection with a gram negative stain

  • Vancomycin + Ceftriaxone
  • Vancomycin + Ciprofloxacin (not in kids)

63

Duration of empiric treatment for native joint infection

4 - 6 weeks

64

Surgical treatment for native joint infection

Drainage via

  • Daily closed needle aspiration
  • Arhtroscopy-irrigation of joint, lysis of adhesions and removal of purulent material

65

3 lab parameters to look out for with monitoring during and post treatment in native joint infection (and their usual results)

  • WBC (usually normalizes within 7 days of therapy)
  • CRP = more indicative of response to therapy
  • Side effects of meds:
    • Exam CBC
    • Renal function
    • LFTs

NOTE: Repeat imaging generally not required

66

7 risk factors for prosthetic joint infection

  • Prior surgery at the same site
  • Rheumatoid arthritis
  • Immunocompromised
  • Diabetes
  • Age
  • Prolonged operation > 2.5 hours
  • Delayed wound healing

67

How is hematogenous prosthetic joint infection acquired?

Secondary infection

68

How is contiguous prosthetic joint infection acqured

Wound infection

Impaired wound healing

69

2 pathogens commonly associated with prosthetic joint infection

  • S. aureus
  • Coagulase negative Staphylococcus

70

Pathophysiology of prosthetic joint infection

  1. Traum or injury
  2. Increased amount or exposure of host derived proteins that promote bacterial attachment
  3. Foreign Body and cement permit bacteria to persist on avascular surfaces

71

4 clinical features of prosthetic joint infection

  • Joint pain
  • Fever
  • Periarticular swelling
  • Cutaneous sinus drainage

72

3 diagnostic tests for prosthetic joint infection

  • ↑ Blood WBC

  • ↑ C-reactive protein

    • Sensitivity 70-90%

    • Specificity 80-85%

  • Fluid analysis

    • WBC > 1500/mm3 with neutrophil predominance

    • Gram stain and culture-sensitivity 50-75%

NOTE: May need 5-6 tissue specimens taken at OR

73

Number of positive specimens to indicate prosthetic joint infection

3

74

5 findings on plain X-ray for prosthetic joint infection

  • Lucencies
  • Migration of prosthesis
  • Cement fractures
  • Periosteal reaction
  • Motion of components on stress view

75

Procedure with highest success rate for treating prosthetic joint infection and describe the procedure

2-step procedure (95% success)

  1. Removal of prosthesis
  2. Administration of antibiotics for 6 weeks
  3. Re-implantation of new prosthesis

76

2 alternative treatments to the 2-step treatment for prosthetic jiont infection

  • Antibiotic impregnated cement
  • Debridement with retention of prosthesis + 3 - 6 months of antibiotics

77

Duration of antibiotic treatment for prosthetic joint infection

6 weeks IV followed by oral

78

When may rifampin be added to the regimen of treatment for prosthetic joint infection

If staphylococcus isolated to help with biofilm penetration

79

Treatment for those with prosthetic joint infection who cannot have surgery

Lifelong suppressive therapy

80

First choice antibiotic against Staphylococcus coagulase negative

  • Depends on sensitivities
  • Check if oxacillin susceptible
  • Vancomycin

81

Second choice antibiotic against Staphylococcus coagulase negative

Daptomycin

82

3 preventive measures against prosthetic joint infection

  • Before surgery, evaluate for dental problems
  • Antibiotic prophylaxis -- standard
  • OR rooms -- laminar airflow HEPA filtered

83

2 situations where antibiotic prophylaxis against prosthetic joint infection in dental and urological procedures may be routine

  • Previous prosthetic infections
  • Immunosuppression

84