Bone and joint infections Flashcards
(37 cards)
Septic arthritis is commonly [mono-articular / poly-articular]
The most common joint affected by septic arthritis is which joint? [1]
Septic arthritis is commonly mono-articular
Knee most common
When does non-pyogenic (cold) septic arthritis occur? [1]
Which pathogen causes this? [1]
Chronic infection; TB infection
Name an organism that cause septic arthritis for each organism type of bacteria
Gram positive cocci [1]
Gram positive bacilli [1]
Gram negative cocci: [1]
Gram negative bacilli [1]
Gram positive cocci: staphylococcus aureus
Gram positive bacilli: clostridium sp
Gram negative cocci: Neisseria gonorrhoea
Gram negative bacilli: Escherichia coli, pseudomonas aeruginosa, haemophilus influenza
Which populations suffer from septic arthritis the most? [2]
Explain why [1]
Young
Majority older population; undergoing more therapy for alternative diseases (RA; OA)
Describe pathogenesis of septic arthritis in children [1]
Describe pathogenesis of septic arthritis in adults [4]]
Children:
* hematogenous spread: infection elsewhere in the body goes into joint
Adult:
* hematogenous spread most common
* local soft tissue infection
* penetrating trauma
* diagnoistic or therapeutic procedures
What is the most common cause of septic athritis? [1]
Staphylococcus aureus : 90% of all cases
Biggest cause of mortality in septic arthritis is
Staphylococcus aureus
Streptococci spp.
Clostridium sp
Neisseria gonorrhoea
Escherichia coli
Biggest cause of mortality in septic arthritis is
Staphylococcus aureus
Biggest cause of mortality in septic arthritis is
Staphylococcus aureus
Streptococci spp.
Clostridium sp
Neisseria gonorrhoea
Escherichia coli
Biggest cause of mortality in septic arthritis is
Staphylococcus aureus
Septic arthritis
Which pathogen has reduced impact due to vaccination schemes [2]
Haemophilus influenza (paediatric before immunization)
Streptococcus
What are the age related differences in causative organism of septic arthritis?
What is the difference between children and adults regarding which joints are affected by septic arthritis?
Children: more spread out
* Knee most common
* Hip common
* Ankle
* Elbow
Adults:
* Mostly knee joint
* Other joints also affected though
Septic arthritis
What investigations would you conduct to diagnose? [5]
- Elevated ESR
- Children: neutrophilia
- Synovial fluid analysis: yellow & cloudy; lumpy & purelent
- Gram stain positive: due to Staphylococcus aureus being the most common
- Blood culture positive
How would a S. aureus infection appear in culture? [1]
Appears as grape like clusters, on trypticase soy agar plate produces yellow pigment: staphlyoxanthin
Describe how septic arthritis joint (synovial) fluid examination would present [4]
Turbid or purulent
Leukocytes >50,000/mm3, pred. neutrophils
Gram stain positive in one-third
< 25mg/dL glucose (much lower than serum)
How does mycobacterial infection cause radiological changes? [4]
Joint space narrowing
Effusion
Erosions
Cyst formation
Describe pathophysiology of reactive athritis [1]
What are the triad of symptoms? [3]
Post infection (e.g. STDs / salmonella) arthritis can occur couple of weeks later in one joint
Triad of symptoms: urethritis/cervicitis, conjunctivitis and arthritis
In which joints is reactive arthritis most common in? [2]
How does it differ from septic arhritis? [1]
knees, ankles and feet
completely sterile: no bacteria or virus, and normally clears up in a couple days.
Which type of MRI imaging would be best for septic arthritis? [1]
Why? [1]
MRI T2: fluid appears white - easier to see inflammation
Describe radiological changes seen in septic athritis patients? [4]
May see soft tissue swelling
Joint capsule distension
Destructive changes seen after at least 2 weeks
* Erosion of articular surface
* Associated soft tissue swelling
Where does TB primarily spread to? [1]
Most commonly goes to thoracic top lumbar regions
Describe how TB can spread from spine to elsewhere in the body [4]
Can spread into surrounding tissues like psoas major –> iliacus -> sacrioilac joint / & or hip joint –> femoral side of knee
Why does acute blood born osteomyelitis affect children? [2]
Have a very rich blood supply to the bones, especially the metaphyseal ends of the long bones as this is where the growth plate is
The capillary loops near the metaphysis have slow flow/sluggish flow due to a rich blood supply here, meaning they are more at risk for bacterial invasion of the bone from the blood here
Describe how osteomyelitis causes abscesses to grow
- Bacteria enters the bone, it commonly lodges just below the epiphyseal growth plate
- Bone produces new bone around the bacterial infection to try and wall off and contain the bacteria in one location, however it walls it off yet this cannot be accessed by antibiotics as it is walled off.
- Can cause bone to die
