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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
Q

What to do if incorrect causative organism identified ?

A

Stop antibiotics and re-culture

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26
Q

What to do for modification of antibiotic treatment ?

A

Seek microbiological advice

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27
Q

Function of further imaging following no resolution of disease treatment

A

MRI
Osteomyelitis might need surgical intervention

28
Q

What is reactive arthritis also known as ?

A

Reiter’s syndrome

28
Q

State the classic trade in Reiter’s syndrome

A

Conjunctivitis
Urethritis
Arthritis

29
Q

When does Reiter’s syndrome occur ?

A

After an infection

e.g. Urogenital or GI tract

Epidemiologically, the disease is more common in men

30
Q

What is associated with reactive arthritis (Reiter’s syndrome) ?

A

HLA-B27

31
Q

Dermatological manifestations of reactive arthritis

A

Keratoderma Blennorrhagicum
Circinate Balanitis
Ulcerative Vulvitis

Nail changes
Oral lesions

32
Q

State some common organisms causing reactive arthritis

A

Chlamydia trachomatis
Shigella flexneri

Escherichia coli

33
Q

How can reactive arthritis be treated ?

A

A full-dose of NSAID with gastric protection and treatment of precipitating factors.

e.g. Chlamydia

34
Q

What is osteomyelitis ?

A

Inflammation of the bone and bone marrow, usually caused by pyogenic bacteria, and rarely by mycobacteria or fungi.

35
Q

How do bones become infected ?

A

Haematogenous spread

Local spread (from septic arthritis )

Compound fracture (open)

Foreign body

36
Q

What causative organism for osteomyelitis is associated with sickle cell disease ?

A

Salmonella

37
Q

What causative organism for osteomyelitis is associated with travel / milk ?

A

Brucella

38
Q

What causative organism for osteomyelitis is associated with prosthesis ?

A

S. epidermidis

39
Q

What causative organism for osteomyelitis is associated in children under 5 ?

A

H influenzae

40
Q

What causative organism for osteomyelitis is associated with UTI ?

A

E. coli and others

41
Q

State the areas most commonly affected by osteomyelitis

A

Femur
Tibia
Calcaneum
Humerus
Fibula

42
Q

Rarities affected by osteomyelitis

A

Radius
Clavicle
Ulna
Iliac crest

43
Q

Describe features of haematogenous spread to bones

A

Usually asymptomatic

Skin sepsis may be present (but is usually absent)

Organisms settle in growing metaphysics near growth plate.

44
Q

Describe features of foreign body causing osteomyelitis

A

Trauma
Shrapnel/ Gun shot wound
Orthopaedic implant (K nail)
Nail through trainer (pseudomonas)

45
Q

State the organisms responsible for osteomyelitis

A

S. aureus (>80%)
S. pyogenes (~5%)

Gram -ve bacteria
M. tuberculosis

46
Q

Signs and Symptoms of osteomyelitis

A

Painful, swollen site
Fever
Reduced movement (may be only sign in very young)

Paraplegia

46
Q

State some preliminary investigations for osteomyelitis

A

Fever
WBC: white blood cell count
ESR: erythrocyte sedimentation rate
CRP: C-reative protein

47
Q

ESR

A

Erythrocyte sedimentation rate

Fast ESR -> higher levels of inflammation

48
Q

Investigations of osteomyelitis

A

Blood culture (take 3 cultures, surgeons may take up to 6)

X-ray
MRI/ Bone scan / CT

Pus (operative sample)

49
Q

State some radiology signs of osteomyelitis on plain film and CT

A

Periosteal elevation
Focal osteopenia
Cortical thinning
Scalloping

50
Q

X-ray for osteomyelitis

A

Signs may be delayed in early infection

51
Q

MRI for osteomyelitis

A

There may be marrow edema

52
Q

Advantage of MRI and bone scans for osteomyelitis

A

More sensitive in early or ambiguous cases

53
Q

Why is MRI preferred for vertebral osteomyelitis ?

A

As it can exclude paravertebral abscess and cord impringement.

54
Q

Involucrum

A

Surrounding live bone

54
Q

Sequestrum

A

Old dead bone

55
Q

Therapeutic regimens for osteomyelitis

A

Ciprofloxacin - for salmonella infection

Isoniazid, Rifampicin, Pyrazinamide, Ethambutol (TB)

Drainage/Removal of Involucrum

56
Q

Prosthetic joint infection information

A

Increasing numbers of patients have prosthetic joint replacement.

Usually older age groups
Complex medical problems

57
Q

Common prosthetic joint replacements

A

Hips and Knees

58
Q

Presenting symptoms of PJ infection

A

Joint pain (95%)
Fever (43%)
Periarticular swelling (38%)
Wound or Cutaneous sinus drainage (32%)

59
Q

Risk factors for PJI

A

Rheumatoid arthritis
Diabetes
Obesity
Concurrent UTIs

Postoperative surgical site infection

60
Q

Microbial etiology of PJIs

A

Staphylococcus aureus

61
Q

How can a prosthetic joint infection (PJI) be diagnosed ?

A

A plain radiograph should be performed

A diagnostic arthrocentesis should be performed unless the diagnosis is evident clinically and surgery is planned.

62
Q

What studies should not be routinely used to diagnose PJI ?

A

Imaging studies such as bone scans, leukocyte scans, MRI, CT and positron emission tomography scans.

63
Q

How can a prosthetic joint infection be managed ?

A

Debridement and Retention

OR

Removal of prosthesis

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

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