Septic arthritis and reactive arthritis Flashcards
What are the causes of acute mono arthritis?
•Infection •Crystal induced: - gout - calcium pyrophosphate •Reactive: - haemarthrosis - systemic rheumatic condition - trauma
What is the clinical presentation of acute mono arthritis?
- Cardinal features of inflammation: rubber, calories, dollar and tumour
- May have fever
- May have leukocytosis and raised CRP
What is acute mono arthritis until proven otherwise?
Septic
What are the risk factors for septic arthritis?
- Previous arthritis
- Trauma
- Diabetes mellitus
- Immunosuppression
- Bacteremia
- Sickle cell anaemia (increased risk of strep and staph)
- Prosthetic joint
What is the pathogenesis of septic arthritis?
•Bacteria enters the joint and deposit in synovial lining
- haematogenous spread
- local invasion/inoculation
•Rapid entry into the synovial fluid (no basement membrane and close relationship to blood vessels)
What is the most common joint involved in septic arthritis?
Knee
What is polyarticular septic arthritis
- Septic arthritis involving multiple joints
* On average 4 involved: knee, elbow, hip and shoulder predominate
What is there a high prevalence of in polyarticular septic arthritis?
Rheumatoid arthritis
What are the most common causative organisms in polyarticualr septic arthritis?
Staph and strep
Why should you use a large bore needle when you suspect infection in a joint?
Pus may be very viscous so difficult to aspirate
What is the management of septic arthritis?
- Joint aspiration: daily or more frequently as needed
- Antibiotic therapy based on gram culture stain and clinical factors
- Surgical intervention- only if pt not responding after 48hrs of appropriate therapy
What is the most common empirical antibiotic therapy for septic arthritis?
Iv flujloxacillin and gentamicin
What are the non modifiable risk factors of gout?
- Age
- MAle
- Race
- genetic
- impaired renal function
What are the modifiable risk factors of gout?
- Obesity
- Alcohol consumption
- High purine diet
- HFCS (high fructose corn syrup)
- Certain medication
Which medications can predispose to gout?
- Aspirin: bimodal effect, large doses increase UA excretion, small doses reduce UA excretion
- diuretics
- cyclosporin
- Pyrazinamide and ethambutol
- Nicotinic acid
When can a diagnosis of gout be made in the absence of synovial fluid aspiration?
- Typical presentation of podagra
- History of gout flares or hyperuricaemia
- Raised sUA between attacks
What are the differential diagnoses in the context of gout?
- Septic arthritis
* CPPD (pseudo gout)
What are the goals of treatment of gout?
- Acute attacks: reduce pain and reduce inflammation: NSAIDs, Coxibs, corticosteroids
- Long term: prevent further acute attacks, prevent joint damage, eliminate tophi
What is seen in the synovial fluid in someone with gout?
Tophi
What are the lifestyle modifications for people with gout?
•Diet: - reduce purine intake - reduce fructose containing drinks - include skimmed milk, low fat yoghurt, vegetable protein and cherries every day •Weight loss - aim 1kg/month and avoid crash diets - avoid high protein diets •moderate exercise •reduce alcohol
Who with gout should you treat?
- Those with recurring attacks (more than 2 in 12 months)
- Tophi
- Chronic gouty arthritis
- Renal impairment
- history of urolithiasis
- Diuretic therapy use
- Primary gout starting at a young age
- Very high serum rate>500micromol/l
What are the rate lowering therapies?
- Allopurinol
* Febuxostat
What is reactive arthritis?
- Seronegative spondyloarthropathies
- Seronegative for Rheumatoid factor
- It develops soon after an infection occurring elsewhere in the body
- No viable organisms can be recovered from the joint
What does reactive arthritis have a strong association with?
HLA-B27
What is SARA?
A subgroup of reactive arthritis related to sexually acquired infection, often chlamydia trachomatis
What are the enteric infections causing reactive arthritis?
- Salmonella
- Shigella
- Yersinia
- Campylobacter
- Clostridium
What are the GU infections causing reactive arthritis?
- Chlamydia trachomatis
- Neisseria gonorrhoea
- Mycoplasma genitalium
- Ureplasma urealyticum
Describe the typical presentation of reA
- Acute onset, usually 2-6 weeks post infection
- Warm, swollen, Tender joints, usually lower limb
- Systemically unwell- elevated inflammatory markers and malaise
- Triad of arthritis, conjunctivitis and urethritis
What is the prognosis of ReA?
- 70% resolve within 3-12 months
* 50% recur
What is the pathogenesis of reactive arthritis?
- May involve cross reactivity between bacterial antigen and joint tissues leading to Th2 cell mediated response
- Persistence of antigenic material due to failed clearance possibly due to polymorphisms of toll like receptor
What are the investigations for reactive arthritis?
- Joint aspiration to exclude sepsis
- Swabs- urethral/cervical
- Screen for other related infections
- Inflammatory markers ESR and CRP
- Chlamydia serology
- HLA-B27 for prognostic not diagnostic reasons
What is the management of mild reactive arthritis?
- NSAID
* Simple analgesia
What is the management of moderate reactive arthritis?
- NAID
- Joint aspiration
- Corticosteroid injection
What is the management of severe or prolonged reactive arthritis?
- Refer to rheumatology
* Consdieration of DMARD
Why should joint effusions be aspirated in the context of reactive arthritis?
To exclude sepsis
What is the effect on the joints in reactive arthritis
- Lower limb asymmetric oligoarthritis
- Dactylitis
- Enthesopathy
- inflammatory back pain
What extra-articular conditions are seen in ReA?
- Conjunctiivitis, iritis, keratitis, episcleritis
- Keratoderma blemmorhagica, nail dystrophy
- Urethritis, prostatitis, cystitis, cervicitis
- Circinate balanitis
- Stomatitis, diarrhoea
