Lecture 17: Septic arthritis and rheumatic fever Flashcards
What are the differential diagnosis for kids with hot swollen joints and fevers?
- > Septic arthritis
- > Rheumatic fever
or
Other reactive arthritis
Trauma
What microbio lab tests would we expect GAS to have?
- Gram positive
- Cocci in chains
- Beta heamolytic
Whats the role of M proteins in group A streptococci?
Virulence factor
Differing M types associated with different clinical syndromes i.e impetigo vs pharygnitis
What acute pyogenic / suppurative infections can GAS cause?
Tonsilitis / pharyngitis Skin - impetigo / cellulitis Scarlet fever Septic arthritis Necrotising fasciitis Toxic shock syndrome Puerperal sepsis
What non-supportive “inflammatory’ delayed sequelae following uncomplicated infections can GAS cause?
Acute rheumatic fever (rheumatic heart disease)
Post streptococcal glomerulonephritis
Write some notes on septic arthritis:
- Suppurative complication of GAS
- Presence of infection from bacteria in the bone marrow and or joint space
- Mostly in chidlhood
- General systemic symptoms include fever and malaise (unwellness), psuedopaeresis (stop moving limb)
- Swelling, erythema and tenderness around the infected joint.
- Clinically joint held in position that maximises intracapsular volume (i.e flexed knee)
- Possible effusion seen on xray
Why are children susceptible to septic arthritis?
- They have growth plates which are highly vascular.
What is the most common cause of septic arthritis?
Stapylococcus aureus
GAS is second most common cause
What are the key points about septic athritis?
- Needs to be diagnosed quickly as early treatment prevents complications such as irreversible damage from growth plate disruption
- Early diagnosis can be difficult i.e clinical presentation in young child (Refusal to walk without localising pain)
- Lower extremities knee, hip and ankle: most common joints affected
- Common causes are Staph aureus and strep pyogenes
What are the treatments for septic arthritis?
- Drainage and washout of the septic joint is often needed for both diagnosis and treatment
- IV antibiotics are needed initially and total course of antibiotics likely to be long
What is rheumatic fever?
- Auto-immune response following throat infection with streptococcus pyogenes
- Generalised inflammation- heart, joints, skin and or brain
- Can cause lasting damage to mitral and or aortic valve (RHD)
- RHD is most common form of childhood heart disease in the world
What is the major criteria for acute rheumatic fever?
- Carditis
- Polyarthritis
- Sydenhams chorea
- Erythema marginatum (Rare rash)
- Subcutaneous nodules (Rare)
What are the minor criteria for acute rheumatic fever?
- Fever
- Polyarthralgia
- History of rheumatic fever
- Raised acute phase reactants (CRP or ESR)
- Prolonged PR interval on ECG
What is the diagnosis of acute rheumatic fever based on?
Cluster of evidence (2 major, one minor symptom) plus evidence of preceeding streptococcal infection.
- Rising or elevated streptococcal AB titres OR
- Positive GAS throat culture
How does arthritis relate to ARF?
- Arthritis is most common presenting symptom
- Extremely painful, unable to weight bear
- Large joints are usually affect, esp knees and ankles
- Polyarthritis is usually asymmetrical and migratory
