Infections of Bones, Joints and Limbs Flashcards
Describe septic arthritis.
Who can be affected?
- 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 ~11-50%.
- Fatality is mostly in patients who have multiple sites of septic arthritis.
- Resistance to conventional ABx is increasing.
What are the criteria for diagnosis of septic arthritis?
- Newman definition - 1 of 4 points must be met:
- Isolation of a 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 turbid joint fluid in the presence of previous ABx treatment.
- Postmortem or pathological features suspicious of septic arthritis.
How does septic arthritis typically present?
- 1-2 week hx 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 lower limb) are affected. Any joint can be affected. Common:
- Knee
- Hip
- Lumbosacral spine
- Up to 20% of patients have more than one joint affeted.
- 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 the conditions which make a patient predisposed to septic arthritis?
- Rheumatoid arthritis or OA
- Joint prosthesis
- IV drug use
- Alcoholism
- DM
- Previous intra-articular corticosteroid injection
- Cutaneous ulcers
What are the causative organisms of septic arthritis?
- S. aureus
- S. pyogenes
- S. epidermis
- M. tuberculosis
- Salmonella
- Brucella
- Don’t forget Neisseria gonorrhoeae in those who are sexually active
- Kingella - rare but can cause septic arthritis in children
- Pasteurella - take note of the patient’s hx; if they have been bitten by animals this can cause septic arthritis.
What are the differentials if a patient presents with ?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
- Note! Mimics:
- Cellulitis
- Bursitis
- Phlebitis
Describe the pathogenesis of septic arthritis.
- Infection can be introduced into a joint by:
- Haematogenous spread
- Direct inoculation e.g trauma or iatrogenically
Which investigations should you do if querying septic arthritis?
- If there is a concern regarding septic arthritis, prompt joint aspiration is required. Please contact orthopaedics for any joint other than knees, or for any prosthetic joints.
- Aspiration from an area of clear skin: send for joint aspirate C&S (includes microscopy and crystals - call lab to inform of the sample).
- Peripheral blood cultures.
- Obtain relevant cultures, If suspected gonococcus, request PCR.
- FBC, U&E, CRP, urate (NB - may be normal in acute gout).
- X-ray joint (?evidence of chondrocalcinosis).
- Coagulation screen if appropriate.
- MRI if concerns re osteomyelitis.
Describe the pharmacological management of acute septic arthritis.
-
If the causative organism is thought to be S. aureus:
- IV flucloxacillin 2g qds for 2 weeks then oral therapy.
- Total course 4-6 weeks.
- If penicillin allergy give Clindamycin IV 600mg qds.
- Discuss with orthopaedics for washout.
- If complicated (e.g. recent surgery or GI procedure) it is likely to be a gram negative organism, therefore discuss with infectious diseases or microbiology for ABx advice.
Describe the management of a patient who presents with acute increase in pain with or without swelling in one or more joints.
Describe the management of septic arthritis in secondary care.
Describe reactive arthritis.
- Reiter’s syndrome
- Classic triad of conjunctivitis, urethritis and arthritis.
- Occurring after an infection e.g. urogenital or GI tract.
- Epidemiologically, the disease is more common in men.
- Dermatologic manifestations:
- Keratoderma blennorrhagicum
- Circinate balanitis
- Ulcerative vulvitis
- Nail changes
- Oral lesions
State the organisms which cause septic arthritis.
- Chlamydia trachomatis
- Shigella flexneri
- Salmonella enteritidis / typhimurium / muenchen
- Yersinia enterocolitica
- Pseudotuberculosis
- Campylobacter jejuni / fetus
- Ureaplasma urealyticum
- Clostridium difficile
- Neisseria gonorrhoea
- Borrelia burgdorferi
- Chlamydia pneumoniae
- Escherichia coli
How is reactive arthritis treated?
- Reactive arthritis may be treated with full dose NSAID with gastric protection.
- AND treatment of precipitating factors e.g. chlamydia.
What is osteomyelitis?
Inflammation of the bone and bone marrow usually caused by pyogenic bacteria, and rarely by mycobacteria or fungi.
How do bones become infected in osteomyelitis?
- Haematogenous spread
- Local spread (from septic arthritis or cellulitis)
- Compound fracture
- Foreign body
Which bones are most commonly affected by osteomyelitis?
Which organisms are commonly responsible for infections of the hip following arthroplasty?
Which organisms are commonly responsible for infections of the knee following arthroplasty?
Describe the investigation and diagnosis of a patient who presents with any of the following:
- Sinus tract or persistent wound drainage
- Acute onset of painful prosthesis
- Chronic painful prosthesis
Describe the management of a prosthetic joint infection.
Describe the management of prosthetic joint infection when patients are not a candidate for new prosthesis.
