Infections of Bones and Joints Flashcards
What is septic arthritis?
• Hot swollen joint(s) = common medical emergency.
• All ages can be affected but septic arthritis is more
common in elderly people and very young children.
• Delayed treatment can lead to irreversible joint damage.
• Case-fatality approx 11%-50%.
• Resistance to conventional antibiotics is increasing.
What is the Newman definition to diagnose septic arthritis?
One of:
(1)isolation of a pathogenic organism from an affected
joint
(2)isolation of a pathogenic organism from another source (e.g., blood) in the context of a hot red joint suspicious of sepsis
(3)typical clinical features and turbid joint fluid in the presence of previous antibiotic treatment
(4)post-mortem or pathological features suspicious of septic arthritis.
What is the typical presentation in a case of septic arthritis?
• 1–2 week history of a red, painful, and restricted joint.
• In patients in whom bacteria were cultured from synovial fluid:
– fever was recorded in 34%
– sweats in 15%
– rigors in 6%
• Generally, large joints (typically leg) are affected. Common areas - Knee Hip, Lumbosacral spine (any joint is possible)
• Up to 20% of patients have more than one joint affected.
• If pre-existing arthritis, the joint(s) will show signs out of proportion to
disease
• Low virulence causative organisms and fungal and mycobacterial infections can delay presentation.
What are some predisposing conditions for septic arthritis?
- Rheumatoid arthritis orosteoarthritis
- Joint prosthesis
- Intravenousdrugabuse
- Alcoholism
- Diabetes
- Previous intra-articular corticosteroid injection
- Cutaneous ulcers
What are some causative organisms for septic arthritis?
- S.aureus
- S.pyogenes
- S.epidermidis
- M.tuberculosis
- Salmonella
- Brucella (from unpasteurised dairy products),
- Don’t forget Neisseria gonorrhoeae in sexually active
- Kingella can cause infections in children
- Pasturella can cause infections in animal bites
What would a differential diagnosis be for the symptoms of septic arthritis?
Septic arthritis
Crystal arthritis (Gout, Calcium Pyrophosphate Disease
Reactive Arthritis
Monoarticular presentation of polyarthritis
Intra-articular injury (fracture, meniscal tear etc)
Haemarthrosis
Inflammatory OA
NB mimics eg cellulitis, bursitis, phlebitis
Describe the pathogenesis of bone + joint infection of septic arthritis
Or
How can infection be introduced into a joint?
– haematogenous spread
– direct inoculation e.g. trauma or iatrogenically.
How should one investigate a potential septic arthritis?
Prompt joint aspiration is required - contact ortho for any joint other than knees, or for prosthetics
- Aspiration from an area of clear skin: send for joint aspirate C&S (includes microscopy and crystals - call lab to inform them of sample)
- Peripheral blood cultures
- Obtain relevant cultures. If suspected gonococcus, request PCR
- FBC, U&Es, CRP, urate (NB - may be normal in acute gout)
- X-ray joint (?evidence of chonedrocalcinosis)
- Coagulation screen if appropriate
- MRI if concerns regarding osteomyelitis
How should acute septic arthritis be managed?
- Discuss with orthopaedics for washout
- If complicated e.g. recent surgery or GI procedure likely Gram negative organism therefore discuss with infectious disease or microbiology for antibiotic advice
IV flucloxacillin 2g qds for 2 weeks then oral therapy
Total course 4-6 weeks
If penicillin allergy Clindamycin IV 600mg qds
What is reactive arthritis?
- Reiter’s syndrome, also known as reactive arthritis -classic triad conjunctivitis, urethritis, and arthritis
- Occurring after an infection e.g. urogenital or GI tract.
- Epidemiologically, the disease is more common in men
- HLA-B27 is associated with reactive arthritis
• Dermatologic manifestations – keratoderma blennorrhagicum – circinate balanitis – ulcerative vulvitis – nailchanges – oral lesions
What organisms induce reactive arthritis?
Many, including:
– Chlamydia trachomatis – Shigella flexneri – Salmonella enteritidis/typhimurium/muenchen – Yersinia enterocolitica – Yersinia pseudotuberculosis (Pseudotuberculosis) – Campylobacter jejuni/fetus – Ureaplasma urealyticum – Clostridium difficile – Neisseria gonorrhoeaa – Borrelia burgdorferi – Chlamydia pneumoniae – Escherichia coli
How Amy reactive arthritis be treated>
Reactive arthritis may be treated with full dose NSAID with gastric protection and treatment of precipitating factors e.g. Chlamydia
What is osteomyelitis?
• Osteomyelitis - inflammation of the bone and bone marrow usually caused by pyogenic bacteria, and rarely by mycobacteria or fungi
How do bones become infected with osteomyelitis?
• Haematogenous spread • Local spread (from septic arthritis) • Compound fracture (open) • Foreign body
What predispositions to osteomyelitis may an individual have?
• Sickle cell disease • Travel/milk • Prosthesis • Children under 5 (rare in countries with Hib vaccination programme) • UTI Each predisposition has an associated organism cause
What areas are most commonly affected by osteomyelitis?
The humerus and the bones of the leg: femur, tibia, fibula, calcaneum
Describe the haematogenous spread of osteomyelitis to the bones
• Usually asymptomatic
• Skin sepsis may be present (but is usually
absent)
• Organisms settle in growing metaphysis near growth plate
What foreign bodies may cause osteomyelitis?
- Trauma
- Shrapnel/Gun shot wound
- Orthopaedic implant (K nail)
- Nail through trainer (Pseudomonas)
What are the most common organisms responsible for osteomyelitis?
- S. aureus (>80%)
- S. pyogenes (~5%)
- Gram negative bacteria • M. tuberculosis
What are the symptoms/signs of osteomyelitis?
- Painful swollen site
- Fever
- Reduced movement (may be only sign in very young)
- Paraplegia
What preliminary investigations should one perform with suspected osteomyelitis?
- Fever
- WBC
- ESR
- CRP
What should you look out for in imaging for suspected osteomyelitis?
- Radiology signs of osteomyelitis on plain film and CT include:
- periosteal elevation •Focal osteopenia •Cortical thinning •Scalloping
- xray- these signs can be delayed in early infection
- There may be marrow edema on MRI
- MRI and bone scans are more sensitive in early or ambiguous cases
- MRI is preferred for vertebral osteomyelitis as it can exclude paravertebral abscess and cord impringement.
How should one investigate osteomyelitis?
Investigations • Bloodculture • X-ray • MRI/CT/Bonescan • Pus
Notes:
• Take 3 cultures (surgeons may take up to 6)
• May be negative early on in the course of infection
• Operative sample
What therapeutic regimens may you use for osteomyelitis?
If acute: Flucloxacillin IV 2g qds
2 weeks minimumIV followed by oral therapy
Total course is 4-6 weeks
If penicillin allergy Clindamycin IV 600mg qds
Seek specialist advice
If chronic: Oral Flucloxacillin 1g qds
If MRSA or penicillin allergy oral doxycycline or co-trimoxazole (check sensitivities)
If coliforms suspected seek specialist advice
If MRSA: Vancomycin IV
Dosing as per local guidance
Aim for trough level of 15-20mg/L
Seek specialist advice
• Alternatives empirical
- Ciprofloxacin (for Salmonella infection)
- Isoniazid, Rifampicin, Pyrazinamide, Ethambutol (tuberculosis)
• Drainage/Removal of involucrum
What therapeutic regimen should you use for acute osteomyelitis?
Flucloxacillin IV 2g qds
2 weeks minimumIV followed by oral therapy
Total course is 4-6 weeks
If penicillin allergy Clindamycin IV 600mg qds
Seek specialist advice
What therapeutic regimen should you use for chronic osteomyelitis?
Oral Flucloxacillin 1g qds
If MRSA or penicillin allergy oral doxycycline or co-trimoxazole (check sensitivities)
If coliforms suspected seek specialist advice
What therapeutic regimen should you use for MRSA osteomyelitis?
Vancomycin IV
Dosing as per local guidance
Aim for trough level of 15-20mg/L
Seek specialist advice
Discuss a bit abt prosthetic joints
- Increasing numbers of patients have prosthetic joint replacement
- Usually older age groups
- Complex medical problems
- Hips, knees most common
