Dr. Loo -- Bone and Joint Infections Flashcards
(84 cards)
1
Q
Describe the Lew and Waldwogel classification for osteomyelitis
A
- Acute vs. chronic
- Acute <2 weeks
- Subacute 2 weeks - 3 months
- Chronic > 3 months
- Mechanism of infection
- Hematogenous
- Contiguous
- Presence of vascular insufficiency
2
Q
3 pathophysiologies of osteomyelitis
A
- Hematogenous
- Contiguous spread
- Direct inoculation of infection to bone from trauma or surgery
3
Q
3 risk factors for hematogenous osteomyelitis in children
A
- Immunodeficiency – chronic granulomatous disorders
- Bacteremia
- Sickle cell disease
4
Q
Most common site of hematogenous osteomyelitis in children
A
Long bones = metaphysis
5
Q
Most common locations of hematogenous osteomyelitis in adults
A
Vertebrae – neighboring endplates involved
- Lumbar
- Thoracic
- Cervical
6
Q
Why are neighboring endplates of vertebrae in adults commonly affected by hematogenous osteomyelitis?
A
They have an artery bifurcating to supply the endplates
7
Q
Most common pathogen in children and adults for hematogenous osteomyelitis
A
*S. aureus *(50 - 60%)
8
Q
Virulence factors of *S. aureus *explaining why it is a common pathogen in hematogenous osteomyelitis
A
Adhere to bone via adhesins
Can survive within osteoblasts
9
Q
3 pathogens causing hematogenous osteomyelitis in children (besides S. aureus)
A
- Streptococcus pneumoniae
- *Streptococcus pyogenes *(GAS)
- *Kingella kingae *(<4 years old)
10
Q
2 pathogens for hematogenous osteomyelitis in neonates
A
- *Streptococcus agalactiae *(GBS)
- E. coli
11
Q
Pathogen for hematogenous osteomyelitis in the setting of sickle cell anemia
A
Salmonella
12
Q
Define the pathophysiology of contiguous osteomyelitis
A
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
Q
5 pathogens involved in contiguous osteomyelitis
A
Polymicrobial
- Staphylococcus aureus
- *Streptococcus *(B-hemolytic)
- Enterococcus
- Aerobic gram negative bacilli – Enterobacteriaceae
- Anaerobes
14
Q
4 contributing factors to diabetic foot ulcers causing contiguous osteomyelitis
A
- Neuropathy
- Vascular insufficiency
- Hyperglycemia
- Poor vision
NOTE: Ulcers larger than 2 x 2 cm usually associated with underlying osteomyelitis
15
Q
8 clinical manifestations of osteomyelitis
A
- 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
Q
5 things to check on examination of patient with suspected osteomyelitis
A
- 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
Q
Initial assessment of diabetic patients with foot ulcers
A
Probe to bone
18
Q
4 diagnostic tests for osteomyelitis and their usual results
A
- 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
Q
How long does it take to see changes due to osteomyelitis on plain X-ray
A
2 - 4 weeks
20
Q
For what kind of osteomyelitis is plain X-ray useful?
A
Chronic
21
Q
5 findings on X-ray for chronic osteomyelitis
A
- Cortical erosion
- Periosteal reaction
- Mixed lucency
- Sclerosis
- Sequestra
NOTE: May be difficult to distinguish from Charcot arthropathy
22
Q
Pros and cons of using nuclear scans to diagnose osteomyelitis
A
- Pro = sensitive
- Cons = can be nonspecific; degenerative disease can give false +
23
Q
Imaging of choice for osteomyelitis diagnosis and why
A
MRI because of excellent resolution and early signs present:
- Diabetic patients with possible osteomyelitis of foot
- Vertebral osteomyelitis
- High NPV
24
Q
When is CT scan performed in diagnosis of osteomyelitis
A
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
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