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Medicine Year 1 - Semester 2 - Part 2 > Infections of Bones and Joints > Flashcards

Infections of Bones and Joints Flashcards

1
Q

What is septic arthritis ?

A

A serious type of joint infection.

Characterised by HOT, swollen joints.

It is a common medical emergency

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2
Q

Who is affected by septic arthritis ?

A

All ages, but it is more common in elderly people and very young children.

Case fatality rate ~11-50%

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3
Q

What can delayed treatment of septic arthritis lead to ?

A

Irreversible joint damage

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4
Q

State the criteria for the Newman definition of septic arthritis

EXAM Q

A

One of 4 points must be met:

Isolation of the pathogenic organism from an affected joint

Isolation of a pathogenic organism from another source (e.g. blood) in the context of a hot, red joint suspicious of sepsis.

Typical clinical features and turbo joint fluid in the presence of previous antibiotic treatment.

Post-mortem OR pathological features suspicious of septic arthritis.

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5
Q

State the common symptoms of septic arthritis

A

1-2 week history of a red, painful and restricted joint.

In patients in whom bacteria were cultured from synovial fluid:
- fever in 34%
- sweats in 15%
- rigors in 6%

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6
Q

What areas are commonly affected by septic arthritis ?

A

Large joints
- Knee
- Hip
- Lumbosacral spine

Up to 20% of people have more than one joint affected

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7
Q

What can delay presentation of septic arthritis ?

A

Low virulence causative organisms, fungal and mycobacterial infections can delay presentation.

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8
Q

Predisposing conditions to septic arthritis

A

Rheumatoid arthritis / Osteoarthritis
Joint prosthesis

Intravenous drug use
Alcohol excess

Diabetes
Previous intra-articular corticosteroid injection

Cutaneous ulcers

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9
Q

State the 2 most common causative organisms for septic arthritis

Also 2 less common causative organisms

A

Staphylococcus aureus
Streptococcus pyogenes (Group A strep)

Myobacterium tuberculosis
Salmonella

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10
Q

What causative organism for septic arthritis is associated with prosthetic material ?

A

Staphylococcus epidermidis

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11
Q

What causative organism for septic arthritis is associated with infections in children ?

A

Kingella

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12
Q

What causative organism for septic arthritis is associated with animal bites ?

A

Pasturella

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13
Q

What causative organism for septic arthritis is associated with unpasteurised dairy products ?

A

Brucella

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14
Q

What causative organism for septic arthritis is associated with the sexually active ?

A

Neisseria gonorrhoeae

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15
Q

Pathogenesis of septic arthritis

A

Infection can be introduced into a joint by:

  • haematogenous spread
  • direct inoculation e.g. trauma or iatrogenically
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16
Q

Differential diagnosis of septic arthritis

A

Could present as:

  • Crystal arthritis
  • Reactive arthritis
  • Haemathrosis
  • Inflammatory Osteoarthritis

Intra-articular injury

Could also mimic - cellulitis, bursitis, phlebitis

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17
Q

Key investigation for suspected septic arthritis

A

Prompt joint aspiration is required

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18
Q

State some other investigations for diagnosis of septic arthritis

A
  1. Aspiration from an area of clear skin
  2. Peripheral blood cultures
  3. Obtain relevant cultures
  4. FBC, CRP
  5. X-ray joint
  6. Coagulation screen if appropriate
  7. MRI if concerns regarding osteomyelitis
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19
Q

Management for septic arthritis

A

Washout

If complicated, i.e. recent surgery to GI procedure, likely gram -ve organism

So discuss with infectious disease or microbiology for antibiotic advice.

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20
Q

Management of acute septic arthritis caused by staph. aureus

A

IV flucloxacilin for 2 weeks, then oral therapy

4-6 weeks total course

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21
Q

Describe referral for a patient in community with suspected septic arthritis

A

Family doctor
History and Examination

Refer as an emergency to 2ndary care rheumatology, orthopaedics, or A&E.

Must aspirate and other investigations.

Diagnosis, Empirical antibiotic treatment

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22
Q

Describe management of septic arthritis in secondary care

A

Admit patient to hospital

Ensure synovial fluid, blood or any other relevant culture samples are taken.

Commence antibiotics : do not stop until signs and symptoms resolve, and CRP concentrations are returning to normal

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23
Q

How long should antibiotics be given after diagnosis of septic arthritis ?

A

IV used and continued for at least 2 weeks
Oral antibiotics follow, for at least 4 weeks

Don’t stop antibiotics until signs and symptoms resolve, and erythrocyte sedimentation rates or CRP concentrations are returning to normal.

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24
Q

If there is no resolution of disease treatment what steps are taken next ?

A

Consider:

  • incorrect causative organism
  • modification of antibiotic treatment
  • alternative foci of infection of systemic sepsis
  • further imaging
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25
What to do if incorrect causative organism identified ?
Stop antibiotics and re-culture
26
What to do for modification of antibiotic treatment ?
Seek microbiological advice
27
Function of further imaging following no resolution of disease treatment
MRI Osteomyelitis might need surgical intervention
28
What is reactive arthritis also known as ?
Reiter's syndrome
28
State the classic trade in Reiter's syndrome
Conjunctivitis Urethritis Arthritis
29
When does Reiter's syndrome occur ?
After an infection e.g. Urogenital or GI tract Epidemiologically, the disease is more common in men
30
What is associated with reactive arthritis (Reiter's syndrome) ?
HLA-B27
31
Dermatological manifestations of reactive arthritis
Keratoderma Blennorrhagicum Circinate Balanitis Ulcerative Vulvitis Nail changes Oral lesions
32
State some common organisms causing reactive arthritis
Chlamydia trachomatis Shigella flexneri Escherichia coli
33
How can reactive arthritis be treated ?
A full-dose of NSAID with gastric protection and treatment of precipitating factors. e.g. Chlamydia
34
What is osteomyelitis ?
Inflammation of the bone and bone marrow, usually caused by pyogenic bacteria, and rarely by mycobacteria or fungi.
35
How do bones become infected ?
Haematogenous spread Local spread (from septic arthritis ) Compound fracture (open) Foreign body
36
What causative organism for osteomyelitis is associated with sickle cell disease ?
Salmonella
37
What causative organism for osteomyelitis is associated with travel / milk ?
Brucella
38
What causative organism for osteomyelitis is associated with prosthesis ?
S. epidermidis
39
What causative organism for osteomyelitis is associated in children under 5 ?
H influenzae
40
What causative organism for osteomyelitis is associated with UTI ?
E. coli and others
41
State the areas most commonly affected by osteomyelitis
Femur Tibia Calcaneum Humerus Fibula
42
Rarities affected by osteomyelitis
Radius Clavicle Ulna Iliac crest
43
Describe features of haematogenous spread to bones
Usually asymptomatic Skin sepsis may be present (but is usually absent) Organisms settle in growing metaphysics near growth plate.
44
Describe features of foreign body causing osteomyelitis
Trauma Shrapnel/ Gun shot wound Orthopaedic implant (K nail) Nail through trainer (pseudomonas)
45
State the organisms responsible for osteomyelitis
S. aureus (>80%) S. pyogenes (~5%) Gram -ve bacteria M. tuberculosis
46
Signs and Symptoms of osteomyelitis
Painful, swollen site Fever Reduced movement (may be only sign in very young) Paraplegia
46
State some preliminary investigations for osteomyelitis
Fever WBC: white blood cell count ESR: erythrocyte sedimentation rate CRP: C-reative protein
47
ESR
Erythrocyte sedimentation rate Fast ESR -> higher levels of inflammation
48
Investigations of osteomyelitis
Blood culture (take 3 cultures, surgeons may take up to 6) X-ray MRI/ Bone scan / CT Pus (operative sample)
49
State some radiology signs of osteomyelitis on plain film and CT
Periosteal elevation Focal osteopenia Cortical thinning Scalloping
50
X-ray for osteomyelitis
Signs may be delayed in early infection
51
MRI for osteomyelitis
There may be marrow edema
52
Advantage of MRI and bone scans for osteomyelitis
More sensitive in early or ambiguous cases
53
Why is MRI preferred for vertebral osteomyelitis ?
As it can exclude paravertebral abscess and cord impringement.
54
Involucrum
Surrounding live bone
54
Sequestrum
Old dead bone
55
Therapeutic regimens for osteomyelitis
Ciprofloxacin - for salmonella infection Isoniazid, Rifampicin, Pyrazinamide, Ethambutol (TB) Drainage/Removal of Involucrum
56
Prosthetic joint infection information
Increasing numbers of patients have prosthetic joint replacement. Usually older age groups Complex medical problems
57
Common prosthetic joint replacements
Hips and Knees
58
Presenting symptoms of PJ infection
Joint pain (95%) Fever (43%) Periarticular swelling (38%) Wound or Cutaneous sinus drainage (32%)
59
Risk factors for PJI
Rheumatoid arthritis Diabetes Obesity Concurrent UTIs Postoperative surgical site infection
60
Microbial etiology of PJIs
Staphylococcus aureus
61
How can a prosthetic joint infection (PJI) be diagnosed ?
A plain radiograph should be performed A diagnostic arthrocentesis should be performed unless the diagnosis is evident clinically and surgery is planned.
62
What studies should not be routinely used to diagnose PJI ?
Imaging studies such as bone scans, leukocyte scans, MRI, CT and positron emission tomography scans.
63
How can a prosthetic joint infection be managed ?
Debridement and Retention OR Removal of prosthesis

Medicine Year 1 - Semester 2 - Part 2 (53 decks)

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