Septic, Crystal and Reactive Arthritis Flashcards
What are the clinical features of acute mono arthritis?
Inflammation (redness, swelling, heat, pain, loss of function)
+/- fever
+/- leukocytosis and raised CRP
Acute mono-arthritis is septic until proven otherwise. T/F?
True
What are the risk factors of septic arthritis?
Previous arthritis Trauma Diabetes Mellitus Immunosuppression Bacteraemia Sickle cell anaemia Prosthetic joint
Describe the pathogenesis of septic arthritis?
Bacteria enter the joint and deposit in the synovial lining. This can be via haematogenous spread or local invasion and inoculation. There is rapid entry of bacteria into the synovial fluid as there is no basement membrane and the synovial fluid has a close relationship to blood vessels
Which joints are most commonly affected by septic arthritis?
Knee is most common
Hip, ankle, shoulder, wrist and elbow are other common sites
In what age group does polyarticular septic arthritis usually occur?
> 60 years
Polyarticular septic arthritis can commonly occur in patients with what underlying disease?
RA
What are the most common causative organisms of polyarticular septic arthritis?
Streptococcal and staphylococcal infections
Polyarticular septic arthritis has a worse prognosis than monoarticular septic arthritis. T/F?
True
Why should a wide bore needle be used to sample the synovial fluid when infection is suspected?
Pus may be very viscous and difficult to aspirate
What are the expected results from a synovial fluid sample in septic arthritis?
Cell count >50,000 WBCs/mm^3 Differential >75% PMNs Glucose low Gram stain relatively insensitive Culture positive
What causative organisms should be suspected in infectious arthritis in immune compromised individuals?
Aerobic gram negative bacteria
Anaerobic gram negative bacteria
Mycobacterial species
Fungal species (sporotrichosis, cryptococcosis, blastomycosis)
How is septic arthritis managed?
Joint aspiration
Antibiotic therapy
Surgical intervention
How often should a joint be aspirated in septic arthritis?
Daily or more frequently if required
When should surgical intervention. be used in septic arthritis?
If the patient is not responding after 48 hours of appropriate therapy
How should septic. arthritis be monitored to ensure. clearance of infection?
Serial synovial fluid analysis
What diseases can cause crystal arthritis?
Gout
Calcium pyrophosphate deposition disease
What are the risk factors for gout?
Age Male Race Genetic factors Impaired renal function Obesity Alcohol consumption High purine diet HFCS Certain medications
Which medications increase the risk of gout?
Aspirin. (75mg has effect) Diuretics Cyclosporins Pyrazinimide Ethambutol Nicotinic acid
When can a presumptive diagnosis of gout be made. in the absence of synovial. fluid aspiration?
Typical presentation of podagra and a history of gout flare. or hyperuricaemia
What are the differential diagnoses of gout?
Septic arthritis
Psuedogout (CPPD)
What are the goals of treatment for gout?
Relieve pain and reduce inflammation via non-pharmacological methods (e.g. cold packs) and NSAIDs. Long-term goals of treatment are to prevent further. acute attacks, prevent joint damage and eliminate tophi
What lifestyle modifications should be used in gout?
Reduce alcohol
Weight loss
Moderate exercise
Diet modification - reduce purine intake, reduce fructose containing drinks, include skimmed milk, low fat yoghurt, vegetable. protein and cherries every day in diet
Which patients should be treated. for gout?
Recurrent attacks >2 in a year Tophi Chronic gouty arthritis Renal impairment History of urolithiasis Diuretic therapy use Primary gout starting at a young age (<40 years) Very high serum. urate >500 micro mol/L
What two agents can be used as urate lowering therapies in gout?
Allopurinol
Febuxostat
At what dose should allopurinol be started at. and to what dose can it be increased to in the treatment of gout?
Start at 100mg, then increase every 4 weeks by 100mg until 900mg. or reached target urate level
At what dose should febuxostat be started at and to what dose can it be increased to in the treatment of gout?
80mg
Can be increased to 120mg after 4. weeks if not at target urate
What gene is reactive arthritis associated with?
HLA-B27
Why is reactive arthritis not a true septic arthritis?
Because a viable organism cannot be recovered from the joint
Give examples of enteric infections which can cause reactive arthritis?
Salmonella Shigella Yersinia Campylobacter Clostridium
Give examples of GU infections which can cause reactive arthritis?
Chlamydia trachomas
Neisseria gonorrhoea
Mycoplasma genitalium
Ureaplasma urealyticum
In what groups is reactive arthritis common in?
20-40 years ofage
Men
How many weeks post-infection does reactive arthritis occur?
2-6 weeks
Describe the extra-articular presentations of reactive arthritis?
Conjunctivitis, iritis, keratitis, episcleritis
Keratoderma blennorhagica and nail dystrophy
Circinate balanitis
Stomatitis, diarrhoea
Rarely cardiac involvement with. aortitis.
Describe the pathogenesis of reactive arthritis?
Cross reactivity between bacterial antigen and joint tissues leading to a perpetuating Th2 cell mediated response. Persistence of the antigenic material due to failed clearance possible due to polymorphisms of toll-like receptors.
What investigations should be conducted in reactive arthritis?
Joint aspiration Swabs (urethral/cervical) Screen for other related infections Inflammatory markers ESR and CRP Chalmydia serology HLA-B27
How is mild reactive arthritis managed?
NSAIDs and simple analgesia
How is moderate reactive arthritis managed?
NSAIDs
Joint aspiration
Corticosteroid injection
How is severe or prolonged reactive arthritis managed?
DMARDs
What drug can be used in chronic chlamydia related acquired reactive arthritis?
Lymecycline
Most cases of reactive arthritis are self limiting. T/F?
True
